Open Access

Expression of PGC1α in glioblastoma multiforme patients

  • Authors:
    • Sang Yeon Cho
    • Seon‑Hwan Kim
    • Min‑Hee Yi
    • Enji Zhang
    • Eunjee Kim
    • Jisoo Park
    • Eun‑Kyeong Jo
    • Young Ho Lee
    • Min Soo Park
    • Yonghyun Kim
    • Jongsun Park
    • Dong Woon Kim
  • View Affiliations

  • Published online on: April 3, 2017     https://doi.org/10.3892/ol.2017.5972
  • Pages: 4055-4076
  • Copyright: © Cho et al. This is an open access article distributed under the terms of Creative Commons Attribution License.

Metrics: Total Views: 0 (Spandidos Publications: | PMC Statistics: )
Total PDF Downloads: 0 (Spandidos Publications: | PMC Statistics: )


Abstract

Peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) is a key modulator of mitochondrial biogenesis. It is a coactivator of multiple transcription factors and regulates metabolic processes. However, little is known about the expression and function of PGC1α in glioblastoma multiforme (GBM), the most prevalent and invasive type of brain tumor. The purpose of the present study was to investigate the biological function, localization and expression of PGC1α in GBM. It was observed that PGC1α expression is increased in the tumor cells, and a higher level of expression was observed in the mitochondria. Bioinformatics analyses identified that metabolic and mitochondrial genes were highly expressed in GBM cells, with a high PGC1α mRNA expression. Notably, mitochondrial function-associated genes were highly expressed in cells alongside high PGC1α expression. Collectively, the results of the present study indicate that PGC1α is associated with mitochondrial dysfunction in GBM and may have a role in tumor pathogenesis and progression.

Introduction

Peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) regulates metabolism (1,2), mitochondrial biogenesis and energy homeostasis (3,4). A number of studies have reported PGC1α as a central regulator of thermogenesis, mitochondrial biogenesis and adaptation to fasting in brown adipose tissue, skeletal muscle, cardiac muscle and the liver (1,5). By contrast, PGC1α in the central nervous system is less associated with energy state or thermogenesis (6). PGC1α expression in the central nervous system is high in the embryonic and early postnatal stages, but is decreased during maturation. PGC1α is expressed mostly by γ-aminobutyric acid-ergic neurons; however, a low level of PGC1α is also expressed in glia in the mature brain (7). There is a significant association between PGC1α and the metabolism of reactive oxygen species. PGC1α-null mice are considerably more sensitive to the neurodegenerative effects of the oxidative stressors 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and kainic acid, which suggests that PGC1α has a role in cellular antioxidant defense (8).

Numerous clinical studies have reported a significant association between PGC1α and a number of types of cancer. In breast, colon and ovarian cancer (912), a significant decrease in PGC1α expression accelerated the ‘Warburg effect’, which allows cancer cells to switch from mitochondrial to glycolytic metabolism to meet the metabolic requirements of proliferation (13). By contrast, increased PGC1α expression is present in melanoma, with a corresponding decrease in patient survival (14). The role of PGC1α in a number of cancer types remains unclear and warrants further studies.

Glioblastoma multiforme (GBM) is the most prevalent and invasive type of brain tumor. It aggressively infiltrates and spreads to the surrounding brain tissue via extensive microvascular proliferation. Numerous necrotic areas surrounded by palisading tumor cells are often observed (15). Although novel therapeutic strategies and improved clinical diagnostics have been introduced, GBM remains one of the most fatal diseases (16). An extensive amount of research has been performed to determine the mechanisms of unlimited proliferation in GBM, as well as its robust resistance to existing drugs and therapies (17,18) In the present study, the expression of PGC1α in normal cortical tissues and GBM tissues was compared. The results of the present study indicate that PGC1α may be a novel biomarker for GBM, as well as a novel target for future GBM therapy development.

Materials and methods

Patient samples

All experiments were performed in accordance with approved guidelines of Chungnam National University Hospital (CNUH; Daejeon, Republic of Korea). The Institutional Review Board of the CNUH approved the experimental protocols and all patients provided written informed consent prior to surgery. A total of 49 patients undergoing tumor resection surgeries at the Department of Neurosurgery, CNUH were enrolled, and pathological diagnoses were confirmed by the Department of Pathology, CNUH via immunohistochemistry. First-time GBM diagnosis was used as the selection criterion, resulting in 26 patient samples that were included in the present study (Table I). The mean age of the patients was 58 years (range, 35 to 74 years). Normal brain tissue samples were obtained from cadavers or from autopsies of surrounding normal brain tissues of consenting GBM patients that underwent surgery (approval no. CNUH 2013-11-006).

Table I.

Patient demographics and tumor characteristics.

Table I.

Patient demographics and tumor characteristics.

Case no.Agea (years)GenderPathological diagnosisKi-67 (%)Resection area
  164MGBM20Left, parietal lobe
  256FGBM20Right, frontal lobe
  358MGBM20Left, temporal lobe
  460MGBM20Left, temporal lobe
  540MGBM20Left, frontal lobe
  635MGBM20Left, frontal lobe
  756FGBM20Right, frontal lobe
  863MGBM20Right, parietal lobe
  972MGBM20Right, occipital lobe
1066FGBM40Left, parietal lobe
1149FGBM15Left, temporal lobe
1244MGiant cell GBM40Right, frontal lobe
1377FGBM40Right frontal lobe
1455MGBM cerebri20Right, frontal lobe
1571FGBM90Right, parietal lobe
1651MGBM30Left, temporal lobe
1756MGBM20Right, midbrain
1861MGBM30Left, temporal lobe
1952FGBM30Left, parietal lobe
2045MGBM40Right, temporal lobe
2171FGBM30Right, frontal lobe
2255MGBM20Left, temporal lobe
2352MGBM50Left, parietal lobe
2457MGBM40Right, temporal lobe
2574MGBM40Right, parietal lobe
2674MGBM25Left, insular

a Mean, 58.23 years. GBM, glioblastoma multiforme.

Tissue microarray and immunostaining

Tissue microarrays (TMA) were used to perform the comparative histological analysis of normal brain and GBM tissues. The paraffin-embedded sample tissues were de-paraffinized and rehydrated in a graded alcohol series. Tissues were retrieved using 0.01 M citrate buffer (pH 6.0) and heated in a microwave vacuum histoprocessor (RHS-1; Milestone Medical, Bergamo, Italy) at a controlled temperature of 121°C for 15 min. Following washing with phosphate-buffered saline (pH 7.4), tissue sections were incubated with anti-PGC1α antibody (1:200; Santa Cruz Biotechnology, Inc., Dallas, TX, USA; #SC13067) overnight in a humidity chamber at 4°C. Immunohistochemical staining of the tissue sections was performed using avidin-biotin peroxidase complex as previously described (19,20). Additional TMA samples of normal cortex and GBM tissues were obtained from US Biomax, Inc. (Rockville, MD, USA).

All immunostaining was performed with antibodies that detected the N-terminal epitope of PGC1α (1:200; Santa Cruz Biotechnology, Inc.; #sc-13067). For immunofluorescence analysis, PGC1α and COX4 (1:200; Cell Signaling Technology, Inc., Danvers, MA, USA; #4D11-B3-E8) were used as above but with either a Cy3-conjugated antibody (1:500; anti-rabbit; GE Healthcare Life Sciences Chalfont, UK; #PA43004) or a Cy2-conjugated secondary antibody (1:200; anti-mouse; GE Healthcare Life Sciences; #PA42002). Cell nuclei were visualized with DAPI, and double-stained sections were visualized using an Axiophot microscope (Carl Zeiss AG, Oberkochen, Germany).

Bioinformatics

The mRNA expression of 18,988 probes from 38 GBM cell lines was analyzed using the publicly available Broad-Novartis Cancer Cell Line Encyclopedia (CCLE) database (https://portals.broadinstitute.org/ccle/home) (21). The level of PGC1α mRNA expression among the 38 GBM cell lines was determined using CCLE. The mRNA expression data was normalized using the RankNormalize module in GenePattern (http://www.broadinstitute.org/cancer/software/genepattern). Gene Neighbors and Class Neighbors modules in GenePattern (http://www.broadinstitute.org/cancer/software/genepattern) were used to select genes that were closely associated with PGC1α (22). Hierarchical clustering was performed using complete linkage and Pearson rank-correlation distance with software provided by GenePattern (HierarchicalClustering; version 6). The colors in the heat-maps show the relative gene expression compared to the mean expression, with red being higher and blue lower. From the 18,988 gene set, 100 genes that were most correlated with PGC1α were selected for classification by Gene Ontology Enrichment Analysis (GO terms) using Database for Annotation, Visualization and Integrated Discovery (DAVID; http://david.abcc.ncifcrf.gov) (23). Differentially expressed genes (DEGs) were classified according to GO terms based on their biological process, molecular function or cellular component. DAVID provided an overview of extensive pathways (www.biocarta.com) in which various genes interacted, as well as the number of DEGs per pathway with a P-value representing gene enrichment. Gene enrichment score with P<0.05 represents a strong association rather than random chance (23). For genes with unknown biological processes, GeneMANIA database (http://www.genemania.org) was used to predict their function (24).

Statistical analysis

ImageJ software (version 1.47; National Institutes of Health, Bethesda, MD, USA) was used to quantify the optical density (pixels/mm2) or the intensity of images. The results from immunohistochemical staining were analyzed by a paired t-test between two groups. Data were presented as the mean ± standard error. Statistical analyses were performed using the Prism 5.0 software (GraphPad Prism Software, Inc., La Jolla, CA, USA). P<0.05 was considered to indicate a statistically significant difference. Data transformation (log conversion) selection and statistical analyses were performed with either the Microsoft Excel 11.0 (Microsoft Corporation, Redmond, WA, USA) or Prism 5.0 software.

Results

PGC1α is highly and variably expressed in GBM patients

To determine the association between PGC1α and GBM, levels of PGC1α protein in GBM and control (normal cortex) tissues were compared using publicly available TMAs from US Biomax, Inc. (Fig. 1). PGC1α was weakly detectable in the nuclei of cortical tissues in the control, whereas it was highly and sporadically expressed throughout the GBM tissues. Furthermore, PGC1α was mostly expressed within the cytoplasm with pale nucleic density (Fig. 1A). Bright-field immunohistochemical analysis of TMA images using a densitometer revealed that PGC1α expression varied between tumor samples (Fig. 1B).

For additional validation, PGC1α mRNA levels were determined in GBM cell lines (n=38) using the Broad-Novartis CCLE database (21). Comparative analysis of PGC1α expression in GBM and five other types of cancer, including liver, ovarian, endometrial, breast and prostate carcinoma revealed that although there were variations in PGC1α mRNA expression between the GBM cell lines (Fig. 1D), the level of expression was increased in GBM compared to other cancer cell lines (Fig. 1C). Overall, these data demonstrate that PGC1α expression was increased in a subpopulation of GBM cells.

PGC1α is localized to the mitochondria in GBM

As a transcriptional coactivator, PGC1α is reported to be localized in the nuclei of the normal cortex (25). However, immunofluorescence analysis demonstrated localization of PGC1α in the perinuclear or cytoplasmic areas of GBM tissues (Fig. 2A). To confirm the subcellular localization of PGC1α, double staining with anti-PGC1α and anti-COX4 (a mitochondrial marker) antibodies was employed. There was a certain level of colocalization of PGC1α and COX4, thereby indicating that PGC1α was expressed in the mitochondria in GBM in addition to the perinuclear or cytoplasmic areas (Fig. 2B).

Gene Neighbors of PGC1α

Bioinformatics analysis of PGC1α-associated genes was performed. PGC1α mRNA expression levels detected in the GBM cell lines (n=38; Table II) ranged from 3.71 (log2) to 8.83 (log2), which corresponds to a fold-change of 2.38. A total of 100 genes that were strongly correlated with PGC1α were selected using Gene Neighbors (Fig. 3A) and classified using DAVID (23). Genes with significant differences (P<0.05) were classified into two groups based on GO terms: Biological process and cellular components (Tables III and IV). Genes highly expressed in GBM cell lines were largely associated with the generation of metabolite precursors and energy (e.g., the hexose or monosaccharide metabolic processes), oxidation reduction (e.g., mitochondrial electron transport, nicotinamide adenine dinucleotide to ubiquinone and the oxidoreduction coenzyme metabolic process), energy derivation by the oxidation of organic compounds [e.g., acetyl-CoA metabolic and catabolic processes, oxidative phosphorylation, tricarboxylic acid (TCA) cycle, aerobic respiration and glycolysis, and coenzyme metabolic and catabolic processes (e.g., cofactor catabolic process) (Fig. 3B). Notably, highly expressed genes were associated with the mitochondria (e.g., mitochondrial membrane, mitochondrial matrix and mitochondrial respiratory chain), organelle membranes (e.g., organelle inner membrane) and the cellular envelope (Fig. 3C). This observation is in agreement with the finding that PGC1α is localized in the mitochondria in GBM as previously described.

Table II.

List of GBM cell lines.

Table II.

List of GBM cell lines.

GBM cell linesPGC1α mRNA
LNZ3088.83
LN4648.79
DBTRG05MG8.65
LN2358.40
SNU6267.65
GB17.45
YKG16.64
U3436.59
LN4286.52
SNB196.49
GMS106.27
LN3406.17
KNS816.11
8MGBA5.72
SNU2015.63
T98G5.53
YH135.33
LN3825.19
CAS15.11
U1784.71
SF2954.69
SNU11054.62
SNU4894.60
DKMG4.42
BECKER4.30
42MGBA4.29
KG1C4.22
A1724.17
LN4434.13
LN2154.09
AM384.04
LN184.04
M059K4.02
LN2294.00
KNS604.00
SF1723.84
SNU4663.74
KS13.71

[i] GBM, glioblastoma multiforme; PGC1α, proliferator-activated receptor γ coactivator 1α.

Table III.

List of Gene Neighbors of peroxisome proliferator-activated receptor γ coactivator 1α differentially expressed in glioblastoma multiforme cells.

Table III.

List of Gene Neighbors of peroxisome proliferator-activated receptor γ coactivator 1α differentially expressed in glioblastoma multiforme cells.

Gene symbolDescription
Generation of precursor metabolites and energy
  ATP5JATP synthase, H+ transporting, mitochondrial Fo complex, subunit F6
  ATP5BATP synthase, H+ transporting, mitochondrial F1 complex, β polypeptide
  NDUFA1NADH dehydrogenase (ubiquinone) 1α subcomplex, 1, 7.5 kDa
  NDUFA4NADH dehydrogenase (ubiquinone) 1α subcomplex, 4, 9 kDa
  NDUFA7NADH dehydrogenase (ubiquinone) 1α subcomplex, 7, 14.5 kDa
  ACO2Aconitase 2, mitochondrial
  GYG2Glycogenin 2
  IDH3AIsocitrate dehydrogenase 3 (NAD+) α
  MDH1Malate dehydrogenase 1, NAD (soluble)
  MCHR1 Melanin-concentrating hormone receptor 1
  OGDHLOxoglutarate dehydrogenase-like
  PDHA1Pyruvate dehydrogenase (lipoamide) α 1
Oxidation reduction
  NDUFA1NADH dehydrogenase (ubiquinone) 1α subcomplex, 1, 7.5 kDa
  NDUFA4NADH dehydrogenase (ubiquinone) 1α subcomplex, 4, 9 kDa
  NDUFA7NADH dehydrogenase (ubiquinone) 1α subcomplex, 7, 14.5 kDa
  AIFM1Apoptosis-inducing factor, mitochondrion-associated, 1
  CYP27A1Cytochrome p450, family 27, subfamily A, polypeptide 1
  COX5ACytochrome c oxidase subunit Va
  HCCSHolocytochrome c synthase
  IDH3AIsocitrate dehydrogenase 3 (NAD+) α
  MDH1Malate dehydrogenase 1, NAD (soluble)
  OGDHLOxoglutarate dehydrogenase-like
  PIPOXPipecolic acid oxidase
  PRODHProline dehydrogenase (oxidase) 1
  PDHA1Pyruvate dehydrogenase (lipoamide) α 1
Energy derivation by oxidation of organic compounds
  NDUFA1NADH dehydrogenase (ubiquinone) 1α subcomplex, 1, 7.5 kDa
  NDUFA4NADH dehydrogenase (ubiquinone) 1α subcomplex, 4, 9 kDa
  NDUFA7NADH dehydrogenase (ubiquinone) 1α subcomplex, 7, 14.5 kDa
  ACO2Aconitase 2, mitochondrial
  GYG2Glycogenin 2
  IDH3AIsocitrate dehydrogenase 3 (NAD+) α
  MDH1Malate dehydrogenase 1, NAD (soluble)
Cellular respiration
  NDUFA1NADH dehydrogenase (ubiquinone) 1α subcomplex, 1, 7.5 kDa
  NDUFA4NADH dehydrogenase (ubiquinone) 1α subcomplex, 4, 9 kDa
  NDUFA7NADH dehydrogenase (ubiquinone) 1α subcomplex, 7, 14.5 kDa
  ACO2Aconitase 2, mitochondrial
  IDH3AIsocitrate dehydrogenase 3 (NAD+) α
  MDH1Malate dehydrogenase 1, NAD (soluble)
Acetyl-CoA metabolic process
  ACO2Aconitase 2, mitochondrial
  ACSS1Acyl-CoA synthetase short-chain family member 1
  IDH3AIsocitrate dehydrogenase 3 (NAD+) α
  MDH1Malate dehydrogenase 1, NAD (soluble)
Coenzyme metabolic process
  ACO2Aconitase 2, mitochondrial
  ACSS1Acyl-CoA synthetase short-chain family member 1
  IDH3AIsocitrate dehydrogenase 3 (NAD+) α
  MDH1Malate dehydrogenase 1, NAD (soluble)
Oxidation phosphorylation
  ATP5JATP synthase, H+ transporting, mitochondrial Fo complex, subunit F6
  ATP5BATP synthase, H+ transporting, mitochondrial F1 complex, β polypeptide
  NDUFA1NADH dehydrogenase (ubiquinone) 1 α subcomplex, 1, 7.5 kDa
  NDUFA4NADH dehydrogenase (ubiquinone) 1 α subcomplex, 4, 9 kDa
  NDUFA7NADH dehydrogenase (ubiquinone) 1 α subcomplex, 7, 14.5 kDa
Cofactor metabolic process
  ACO2Aconitase 2, mitochondrial
  ACSS1Acyl-CoA synthetase short-chain family member 1
  COQ9Coenzyme Q9 homolog (S. cerevisiae)
  IDH3AIsocitrate dehydrogenase 3 (NAD+) α
  MDH1Malate dehydrogenase 1, NAD (soluble)
  PIPOXPipecolic acid oxidase
Acetyl-CoA catabolic process
  ACO2Aconitase 2, mitochondrial
  IDH3AIsocitrate dehydrogenase 3 (NAD+) α
  MDH1Malate dehydrogenase 1, NAD (soluble)
Tricarboxylic acid cycle
  ACO2Aconitase 2, mitochondrial
  IDH3AIsocitrate dehydrogenase 3 (NAD+) α
  MDH1Malate dehydrogenase 1, NAD (soluble)
Coenzyme catabolic process
  ACO2Aconitase 2, mitochondrial
  IDH3AIsocitrate dehydrogenase 3 (NAD+) α
  MDH1Malate dehydrogenase 1, NAD (soluble)
Cofactor catabolic process
  ACO2Aconitase 2, mitochondrial
  IDH3AIsocitrate dehydrogenase 3 (NAD+) α
  MDH1Malate dehydrogenase 1, NAD (soluble)
Aerobic respiration
  ACO2Aconitase 2, mitochondrial
  IDH3AIsocitrate dehydrogenase 3 (NAD+) α
  MDH1Malate dehydrogenase 1, NAD (soluble)
Hexose metabolic process
  PFKFB3 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3
  GYG2Glycogenin 2
  MDH1Malate dehydrogenase 1, NAD (soluble)
  OGDHLOxoglutarate dehydrogenase-like
  PDHA1Pyruvate dehydrogenase (lipoamide) α 1
Mitochondrial electron transport,
NADH to ubiquinone
  NDUFA1NADH dehydrogenase (ubiquinone) 1 α subcomplex, 1, 7.5 kDa
  NDUFA4NADH dehydrogenase (ubiquinone) 1 α subcomplex, 4, 9 kDa
  NDUFA7NADH dehydrogenase (ubiquinone) 1 α subcomplex, 7, 14.5 kDa
Glycolysis
  MDH1Malate dehydrogenase 1, NAD (soluble)
  OGDHLOxoglutarate dehydrogenase-like
  PDHA1Pyruvate dehydrogenase (lipoamide) α 1
Monosaccharide metabolic process
  PFKFB3 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3
  GYG2Glycogenin 2
  MDH1Malate dehydrogenase 1, NAD (soluble)
  OGDHLOxoglutarate dehydrogenase-like
  PDHA1Pyruvate dehydrogenase (lipoamide) α 1
Oxidoreduction coenzyme metabolic process
  COQ9Coenzyme Q9 homolog (S. cerevisiae)
  IDH3AIsocitrate dehydrogenase 3 (NAD+) α
  MDH1Malate dehydrogenase 1, NAD (soluble)
Unknown biological process
  CEND1Cell cycle exit and neuronal differentiation 1
  COX7BCytochrome c oxidase subunit VIIb
  TMCC2Transmembrane and coiled-coil domain family 2
  SOX13SRY (sex determining region Y)-box 13
  BTBD3BTB (POZ) domain containing 3
  ZNF222Zinc finger protein 222
  DCUN1D2DCN1, defective in cullin neddylation 1, domain containing 2
  MFSD2AMajor facilitator superfamily domain containing 2A
  CX3CL1Chemokine (C-X3-C motif) ligand 1
  GSTM4Glutathione S-transferase mu 4
  PIGA Phosphatidylinositol glycan anchor biosynthesis, class A
  ITPKB Inositol-trisphosphate 3-kinase B
  TSPAN16Tetraspanin 16
  CHCHD3 Coiled-coil-helix-coiled-coil-helix domain containing 3
  APOOApolipoprotein O
  AKAP11A kinase (PRKA) anchor protein 11
  NEBLNebulette
  SCUBE3Signal peptide, CUB domain, EGF-like 3
  RRAGDRas-related GTP binding D
  IGHV1-2Immunoglobulin heavy variable 1–2
  RRAGDRas-related GTP binding D
  TRIM2Tripartite motif containing 2
  TLE6Transducin-like enhancer of split 6 (E(sp1) homolog, Drosophila)
  LINC00461Long intergenic non-protein coding RNA 461
  SLC25A25Solute carrier family 25 (mitochondrial carrier; phosphate carrier), member 25
  SLC25A11Solute carrier family 25 (mitochondrial carrier; oxoglutarate carrier), member 11
  IVNS1ABPInfluenza virus NS1A binding protein
  HEY1 Hairy/enhancer-of-split related with YRPW motif 1
  NDRG2NDRG family member 2
  COX5BCytochrome c oxidase subunit Vb
  MRPL34Mitochondrial ribosomal protein L34
  STK32ASerine/threonine kinase 32A
  MEGF8Multiple EGF-like-domains 8
  ATP1A1ATPase, Na+/K+ transporting, α 1 polypeptide
  RBPMS2RNA binding protein with multiple splicing 2
  LPLLipoprotein lipase
  FURINFurin (paired basic amino acid cleaving enzyme)
  ASAH1N-acylsphingosine amidohydrolase (acid ceramidase) 1
  KLHL15Kelch-like family member 15
  BTBD1BTB (POZ) domain containing 1
  PTCD3Pentatricopeptide repeat domain 3
  RBM38RNA binding motif protein 38
  LYNX1Ly6/neurotoxin 1
  EFHA1Mitochondrial calcium uptake 2
  NCOA1Nuclear receptor coactivator 1
  KIF13BKinesin family member 13B
  FAM199XFamily with sequence similarity 199, X-linked
  RPRMReprimo, TP53 dependent G2 arrest mediator candidate
  ZNF462Zinc finger protein 462
  ANXA13Annexin A13
  SPG20OSSPG20 opposite strand
  GPR98G protein-coupled receptor 98
  GKGlycerol kinase
  UCK1Uridine-cytidine kinase 1
  LNX2Ligand of numb-protein X 2
  SPG20Spastic paraplegia 20 (Troyer syndrome)
  WNK3WNK lysine deficient protein kinase 3
  LOC100506108LOC100506108
  GCNT2Glucosaminyl (N-acetyl) transferase 2, I-branching enzyme (I blood group)
  SLC31A1Solute carrier family 31 (copper transporter), member 1
  OSTM1Osteopetrosis associated transmembrane protein 1
  TMF1TATA element modulatory factor 1
  TSPAN3Tetraspanin 3
  COL4A3Collagen, type IV, α3 (Goodpasture antigen)
  GPM6BGlycoprotein M6B
  PELI2Pellino E3 ubiquitin protein ligase family member 2
  LOC401431LOC401431
  UBAC1UBA domain containing 1
  ATG4DAutophagy related 4D, cysteine peptidase
  COMMD6COMM domain containing 6
  FAM65BFamily with sequence similarity 65, member B
  TMEM2Transmembrane protein 2
  ASB9Ankyrin repeat and SOCS box containing 9
  BCAMBasal cell adhesion molecule (Lutheran blood group)
  KIF16BKinesin family member 16B
  CHKACholine kinase α
  PPM1EProtein phosphatase, Mg2+/Mn2+ dependent, 1E
  CA2Carbonic anhydrase II

Table IV.

Annotated summary of Gene Neighbors of peroxisome proliferator-activated receptor γ coactivator 1α.

Table IV.

Annotated summary of Gene Neighbors of peroxisome proliferator-activated receptor γ coactivator 1α.

Functional roleGenesP-value-Log (P-value)
Biological process
  Generation of precursor metabolites and energy12 5.50×107   6.26
  Oxidation reduction13 9.60×105   4.02
  Energy derivation by oxidation of organic compounds  7 9.80×105   4.01
  Cellular respiration  6 1.40×104   3.85
  Acetyl-CoA metabolic process  4 5.40×104   3.27
  Coenzyme metabolic process  6 1.20×103   2.92
  Oxidative phosphorylation  5 1.60×103   2.80
  Cofactor metabolic process  6 3.40×103   2.47
  Tricarboxylic acid cycle  3 6.20×103   2.21
  Acetyl-CoA catabolic process  3 6.20×103   2.21
  Coenzyme catabolic process  3 7.90×103   2.10
  Cofactor catabolic process  3 1.10×102   1.96
  Aerobic respiration  3 1.40×102   1.85
  Hexose metabolic process  5 1.70×102   1.77
  Mitochondrial electron transport, NADH to ubiquinone  3 2.00×102   1.70
  Glycolysis  3 2.50×102   1.60
  Monosaccharide metabolic process  5 2.80×102   1.55
  Oxidoreduction coenzyme metabolic process  3 3.00×102   1.52
Cellular component
  Mitochondrial part22 3.40×101211.47
  Mitochondrion25 1.20×109   8.92
  Mitochondrial envelope16 5.90×109   8.23
  Mitochondrial inner membrane14 9.20×109   8.04
  Mitochondrial membrane15 2.20×108   7.66
  Organelle inner membrane14 2.20×108   7.66
  Organelle envelope16 9.80×107   6.01
  Envelope16 1.00×106   6.00
  Mitochondrial lumen  9 3.20×105   4.49
  Mitochondrial matrix  9 3.20×105   4.49
  Organelle membrane18 6.40×105   4.19
  Mitochondrial membrane part  6 6.00×104   3.22
  Mitochondrial respiratory chain  4 5.20×103   2.28
  Respiratory chain  4 8.00×103   2.10
  Respiratory chain complex I  3 2.20×102   1.66
  Mitochondrial respiratory chain complex I  3 2.20×102   1.66
  NADH dehydrogenase complex  3 2.20×102   1.66
  Cell surface  6 4.20×102   1.38
  Mitochondrial proton-transporting ATP synthase complex  2 9.90×102   1.00

[i] The dataset of significantly changed genes were identified using the Database for Annotation, Visualization and Integrated Discovery (DAVID; http://david.abcc.ncifcrf.gov) (P<0.05). ATP, adenosine triphosphate; NADH, reduced Nicotinamide adenine dinucleotide.

PGC1α expression is highly correlated with mitochondrial function in GBM

Two-way hierarchical clustering of targeted gene sets was performed between five GBM cell lines with the highest (LNZ308, LN464, DBTRG05MG, LN235 and SNU626) and lowest levels (LN229, KNS60, SF172, SNU466 and KS1) of PGC1α expression. The expression of TCA cycle-(P<0.0001), oxidative phosphorylation (OXPHOS)-(P<0.0001) and lipogenesis-associated genes (P<0.01) was significantly increased in the PGC1α-upregulated cells compared with the PGC1α-downregulated cells (Fig. 4A-C). Furthermore, the expression of antioxidant-associated genes was significantly increased in the PGC1α-upregulated cell lines compared with the PGC1α-downregulated cell lines (Fig. 4D; P<0.0001). Taken together, the data in Figs. 3 and 4 suggest that metabolic and mitochondrial genes were highly expressed in parallel with PGC1α. Notably, genes associated with mitochondrial functions, including TCA cycle, OXPHOS, lipogenesis and antioxidant genes, were highly expressed in cells with high PGC1α levels (Fig. 4), which corroborates the results from a recent study (26) and the colocalization data as previously described in the present study.

Class Neighbors of PGC1α up- and downregulated GBM cell lines

Bioinformatics analysis using Class Neighbors yielded two classes of GBM cell lines. Class A contained the ten most PGC1α-upregulated GBM cell lines, and class B contained the ten most PGC1α-downregulated GBM cell lines (Fig. 5A). Out of a total of 18,988 probe sets, 100 genes that were most strongly correlated with classes A and B and most highly expressed were selected. DAVID analysis classified these genes into three groups based on GO terms: i) Biological process, ii) molecular function and iii) cellular components (Fig. 5B and C; Tables VVIII). GeneMANIA database analysis resulted in the identification of 52 genes with previously unknown biological interactions with PGC1α, including necdin (NDN).

Table V.

List of class A genes highly expressed in peroxisome proliferator-activated receptor γ coactivator 1α-upregulated glioblastoma multiforme cells.

Table V.

List of class A genes highly expressed in peroxisome proliferator-activated receptor γ coactivator 1α-upregulated glioblastoma multiforme cells.

GeneDescriptionScoreP-valueFold-changeUpa meanDownamean
Developmental processes
  CLEC2BC-type lectin domain family 2, member B2.63 3.2×1031.445.884.09
  EFHD1EF-hand domain family, member D12.22 4.4×1021.316.034.61
  EPHA3EPH receptor A32.45 1.9×1021.395.333.83
  HHIPL2HHIP-like 23.52 2.6×1031.215.494.53
  MAMDC2MAM domain containing 22.49 2.2×1021.426.764.77
  POU3F2POU class 3 homeobox 22.54 2.6×1021.407.205.15
  BHLHE41Basic helix-loop-helix family, member e412.92 6.2×1031.266.144.89
  CDH6Cadherin 6, type 2, K-cadherin (fetal kidney)2.80 1.1×1021.355.834.31
  CELSR2Cadherin, EGF LAG seven-pass G-type receptor 22.80 1.2×1021.217.786.42
  CXCR4Chemokine (C-X-C motif) receptor 42.55 1.5×1021.446.044.20
  CNIH3Cornichon family AMPA receptor auxiliary protein 32.41 3.3×1021.417.225.11
  CCNA1Cyclin A12.56 1.1×1021.325.714.32
  FABP7Fatty acid binding protein 7, brain2.26 3.1×1021.576.874.38
  FBLN1Fibulin 12.62 1.9×1021.277.355.78
  FOXA2Forkhead box A22.18 6.2×1021.365.564.09
  GPM6BGlycoprotein M6B2.14 4.8×1021.467.605.19
  HES1Hairy and enhancer of split 1, (Drosophila)3.29 4.2×1031.218.426.98
  HEY1 Hairy/enhancer-of-split related with YRPW motif 12.49 2.3×1021.288.166.39
  IRX1Iroquois homeobox 12.81 8.4×1031.486.614.47
  JAG1Jagged 13.16 6.0×1031.227.896.48
  MYL5Myosin, light chain 5, regulatory3.19 5.6×1031.256.735.40
  NRG2Neuregulin 22.73 1.4×1021.224.994.09
  NRP2Neuropilin 22.75 1.2×1021.256.745.40
  PTHLHParathyroid hormone-like hormone2.46 1.9×1021.426.774.75
  PRICKLE2Prickle homolog 2 (Drosophila)2.46 2.3×1021.228.156.70
  SALL1Sal-like 1 (Drosophila)2.41 2.5×1021.366.835.04
  SCUBE3Signal peptide, CUB domain, EGF-like 32.63 3.6×1031.347.765.78
  TLR4Toll-like receptor 42.82 9.8×1031.366.294.61
Signal transduction
  EPHA3EPH receptor A32.45 1.9×1021.395.333.83
  GPR56G protein-coupled receptor 563.00 9.4×1031.267.686.07
  PDZRN3PDZ domain containing ring finger 32.61 1.5×1021.398.005.75
  RASSF2Ras association (RalGDS/AF-6) domain 2 family member3.25 1.0×1031.506.644.44
  WNK3WNK lysine deficient protein kinase 33.06 5.4×1031.215.254.36
  CDH6Cadherin 6, type 2, K-cadherin (fetal kidney)2.80 1.1×1021.355.834.31
  CELSR2Cadherin, EGF LAG seven-pass G-type receptor 22.80 1.2×1021.217.786.42
  CXCR4Chemokine (C-X-C motif) receptor 42.55 1.5×1021.446.044.20
  CX3CL1Chemokine (C-X3-C motif) ligand 14.01 8.0×1041.265.894.67
  CNIH3Cornichon family AMPA receptor auxiliary protein 32.41 3.3×1021.417.225.11
  FABP7Fatty acid binding protein 7, brain2.26 3.1×1021.576.874.38
  FBLN1Fibulin 12.62 1.9×1021.277.355.78
  FOXA2Forkhead box A22.18 6.2×1021.365.564.09
  ITPR1Inositol 1,4,5-trisphosphate receptor, type 12.68 1.4×1021.256.995.60
  ITPKB Inositol-trisphosphate 3-kinase B2.60 1.9×1021.206.695.58
  NRG2Neuregulin 22.73 1.4×1021.224.994.09
  NPY1RNeuropeptide Y receptor Y12.00 5.5×1021.415.734.08
  NRP2Neuropilin 22.75 1.2×1021.256.745.40
  PDE4BPhosphodiesterase 4B, cAMP-specific2.59 2.1×1021.266.835.42
  PDGFRLPlatelet-derived growth factor receptor-like2.55 2.5×1021.296.765.22
  SFRP1Secreted frizzled-related protein 12.33 3.5×1021.427.775.46
  SCG2Secretogranin II2.50 2.0×1021.438.085.64
  SCUBE3Signal peptide, CUB domain, EGF-like 32.63 3.6×1031.347.765.78
  TLR4Toll-like receptor 42.82 9.8×1031.366.294.61
  TMTC1Transmembrane and tetratricopeptide repeat containing 12.43 2.5×1021.296.104.72
Ectoderm development
  EPHA3EPH receptor A32.45 1.9×1021.395.333.83
  CDH6Cadherin 6, type 2, K-cadherin (fetal kidney)2.80 1.1×1021.355.834.31
  CELSR2Cadherin, EGF LAG seven-pass G-type receptor 22.80 1.2×1021.217.786.42
  CXCR4Chemokine (C-X-C motif) receptor 42.55 1.5×1021.446.044.20
  FABP7Fatty acid binding protein 7, brain2.26 3.1×1021.576.874.38
  FOXA2Forkhead box A22.18 6.2×1021.365.564.09
  GPM6BGlycoprotein M6B2.14 4.8×1021.467.605.19
  HES1Hairy and enhancer of split 1, (Drosophila)3.29 4.2×1031.218.426.98
  HEY1 Hairy/enhancer-of-split related with YRPW motif 12.49 2.3×1021.288.166.39
  IRX1Iroquois homeobox 12.81 8.4×1031.486.614.47
  JAG1Jagged 13.16 6.0×1031.227.896.48
  NRG2Neuregulin 22.73 1.4×1021.224.994.09
  NRP2Neuropilin 22.75 1.2×1021.256.745.40
Cell structure and motility
  CELSR2Cadherin, EGF LAG seven-pass G-type receptor 22.80 1.2×1021.217.786.42
  CXCR4Chemokine (C-X-C motif) receptor 42.55 1.5×1021.446.044.20
  COL7A1Collagen, type VII, α 12.53 2.0×1021.268.296.58
  DCLK1Doublecortin-like kinase 12.69 1.6×1021.214.914.06
  DNM3Dynamin 32.22 3.7×1021.216.135.06
  DYNC1I1Dynein, cytoplasmic 1, intermediate chain 12.85 1.1×1021.427.895.55
  FOXA2Forkhead box A22.18 6.2×1021.365.564.09
  GPM6BGlycoprotein M6B2.14 4.8×1021.467.605.19
  ITPR1Inositol 1,4,5-trisphosphate receptor, type 12.68 1.4×1021.256.995.60
  JAG1Jagged 13.16 6.0×1031.227.896.48
  MYL5Myosin, light chain 5, regulatory3.19 5.6×1031.256.735.40
  PRICKLE2Prickle homolog 2 (Drosophila)2.46 2.3×1021.228.156.70
  SPP1Secreted phosphoprotein 10.82 4.2×1011.037.037.22
Neurogenesis
  EPHA3EPH receptor A32.45 1.9×1021.395.333.83
  CDH6Cadherin 6, type 2, K-cadherin (fetal kidney)2.80 1.1×1021.355.834.31
  CELSR2Cadherin, EGF LAG seven-pass G-type receptor 22.80 1.2×1021.217.786.42
  CXCR4Chemokine (C-X-C motif) receptor 42.55 1.5×1021.446.044.20
  FOXA2Forkhead box A22.18 6.2×1021.365.564.09
  GPM6BGlycoprotein M6B2.14 4.8×1021.467.605.19
  HES1Hairy and enhancer of split 1, (Drosophila)3.29 4.2×1031.218.426.98
  HEY1 Hairy/enhancer-of-split related with YRPW motif 12.49 2.3×1021.288.166.39
  IRX1Iroquois homeobox 12.81 8.4×1031.486.614.47
  JAG1Jagged 13.16 6.0×1031.227.896.48
  NRG2Neuregulin 22.73 1.4×1021.224.994.09
  NRP2Neuropilin 22.75 1.2×1021.256.745.40
Cell communication
  CDH6Cadherin 6, type 2, K-cadherin (fetal kidney)2.80 1.1×1021.355.834.31
  CELSR2Cadherin, EGF LAG seven-pass G-type receptor 22.80 1.2×1021.217.786.42
  FABP7Fatty acid binding protein 7, brain2.26 3.1×1021.576.874.38
  FBLN1Fibulin 12.62 1.9×1021.277.355.78
  FOXA2Forkhead box A22.18 6.2×1021.365.564.09
  ITPR1Inositol 1,4,5-trisphosphate receptor, type 12.68 1.4×1021.256.995.60
  NRG2Neuregulin 22.73 1.4×1021.224.994.09
  SFRP1Secreted frizzled-related protein 12.33 3.5×1021.427.775.46
  SCG2Secretogranin II2.50 2.0×1021.438.085.64
  SCUBE3Signal peptide, CUB domain, EGF-like 32.63 3.6×1031.347.765.78
  TMTC1Transmembrane and tetratricopeptide repeat containing 12.43 2.5×1021.296.104.72
Mesoderm development
  EFHD1EF-hand domain family, member D12.22 4.4×1021.316.034.61
  EPHA3EPH receptor A32.45 1.9×1021.395.333.83
  FBLN1Fibulin 12.62 1.9×1021.277.355.78
  FOXA2Forkhead box A22.18 6.2×1021.365.564.09
  MYL5Myosin, light chain 5, regulatory3.19 5.6×1031.256.735.40
  NRP2Neuropilin 22.75 1.2×1021.256.745.40
  PTHLHParathyroid hormone-like hormone2.46 1.9×1021.426.774.75
  SCUBE3Signal peptide, CUB domain, EGF-like 32.63 3.6×1031.347.765.78
Cell structure
  CELSR2Cadherin, EGF LAG seven-pass G-type receptor 22.80 1.2×1021.217.786.42
  COL7A1Collagen, type VII, α12.53 2.0×1021.268.296.58
  DCLK1Doublecortin-like kinase 12.69 1.6×1021.214.914.06
  DNM3Dynamin 32.22 3.7×1021.216.135.06
  DYNC1I1Dynein, cytoplasmic 1, intermediate chain 12.85 1.1×1021.427.895.55
  FOXA2Forkhead box A22.18 6.2×1021.365.564.09
  GPM6BGlycoprotein M6B2.14 4.8×1021.467.605.19
  SPP1Secreted phosphoprotein 10.82 4.2×1011.037.037.22
Unknown biological process
  RNF182Ring finger protein 1822.22 3.9×1021.278.416.64
  ACSS3Acyl-CoA synthetase short-chain family member 32.48 3.3×1021.286.525.08
  GSTM4Glutathione S-transferase mu 44.79 4.0×1041.417.935.62
  LINC00461Long intergenic non-protein coding RNA 4614.67 6.0×1041.559.315.99
  FAM70ATransmembrane protein 255A3.80 6.0×1041.727.464.33
  COL21A1Collagen, type XXI, α14.49 4.0×1041.747.614.38
  METTL7AMethyltransferase like 7A3.32 5.0×1031.498.065.40
  GMPRGuanosine monophosphate reductase0.33 7.5×1011.018.818.94
  NID1Nidogen 12.36 2.8×1021.269.127.23
  KIAA0895KIAA08952.04 5.5×1021.216.575.44
  C8orf4Chromosome 8 open reading frame 40.91 3.7×1011.0410.029.67
  SEL1L3Sel-1 suppressor of lin-12-like 3 (Caenorhabditis elegans)2.19 4.3×1021.338.996.76
  GPC4Glypican 42.55 2.2×1021.418.556.07
  PLEKHG1Pleckstrin homology domain containing, family G (with RhoGef domain) member 12.47 2.8×1021.386.364.62
  PIPOXPipecolic acid oxidase3.29 4.0×1041.686.463.84
  FAM65BFamily with sequence similarity 65, member B2.56 1.1×1021.395.573.99
  C7orf57Chromosome 7 open reading frame 572.17 4.2×1021.465.563.80
  PPP2R2BProtein phosphatase 2, regulatory subunit B, β3.58 2.8×1031.617.444.62
  SERP2Stress-associated endoplasmic reticulum protein family member 22.11 5.2×1021.226.195.09
  SOX2SRY (sex determining region Y)-box 21.23 2.5×1011.044.073.92
  RPRMReprimo, TP53 dependent G2 arrest mediator candidate0.43 6.9×1011.013.994.04
  MFSD2AMajor facilitator superfamily domain containing 2A3.69 2.0×1031.307.335.63
  PELI2Pellino E3 ubiquitin protein ligase family member 22.91 1.1×1021.297.335.68
  GCNT2Glucosaminyl (N-acetyl) transferase 2, I-branching enzyme (I blood group)2.40 3.3×1021.227.596.22
  SLC16A4Solute carrier family 16, member 42.88 1.1×1021.398.005.77
  SH3BGRSH3 domain binding glutamic acid-rich protein1.58 1.3×1011.0510.6410.12
  WDR31WD repeat domain 313.54 2.8×1031.205.834.86
  SLC16A9Solute carrier family 16, member 92.07 4.4×1021.236.405.19
  GSTT1Glutathione S-transferase theta 12.91 1.3×1021.407.415.31
  NDPNorrie disease (pseudoglioma)2.53 2.4×1021.507.625.09
  NDNNecdin, melanoma antigen (MAGE) family member2.42 2.9×1021.447.595.27
  ASB9Ankyrin repeat and SOCS box containing 92.20 4.3×1021.267.035.58
  LONRF2LON peptidase N-terminal domain and ring finger 22.08 6.0×1021.376.104.44
  SPHARS-phase response (cyclin related)2.62 1.8×1021.227.496.12
  RNF144ARing finger protein 144A2.62 1.6×1021.247.075.71
  SERINC5Serine incorporator 54.07 1.4×1031.2010.738.95
  RRAGDRas-related GTP binding D2.42 3.0×1021.288.296.48
  OGDHLOxoglutarate dehydrogenase-like2.65 1.5×1021.256.365.11
  CEND1Cell cycle exit and neuronal differentiation 13.91 1.0×1031.246.385.14
  RBPMS2RNA binding protein with multiple splicing 22.11 4.6×1021.266.345.03
  SULF2Sulfatase 22.69 1.9×1021.508.015.33
  MMP7Matrix metallopeptidase 7 (matrilysin, uterine)2.97 2.0×1031.245.144.15
  SLC2A12Solute carrier family 2 (facilitated glucose transporter), member 122.95 8.4×1031.356.314.67
  GFPT2 Glutamine-fructose-6-phosphate transaminase 22.24 3.7×1021.298.356.46
  SOX9SRY (sex determining region Y)-box 92.18 4.3×1021.319.427.17
  C5orf46Chromosome 5 open reading frame 462.29 3.2×1021.348.926.67
  CPCeruloplasmin (ferroxidase)2.35 3.3×1021.054.244.03
  GPNMBGlycoprotein (transmembrane) nmb2.85 1.1×1021.3510.047.46
  SERPINI1Serpin peptidase inhibitor, clade I (neuroserpin), member 12.35 3.5×1021.327.425.63
  TPRG1Tumor protein p63 regulated 12.36 3.5×1021.305.123.94
  PITX2Paired-like homeodomain 22.09 5.6×1021.325.444.13

a Up, and down mean refers to the mean of the specific gene expression levels in the ten most PGC1a up- or downregulated cell lines.

Table VIII.

Annotated summary of class B of peroxisome proliferator-activated receptor γ, coactivator 1α.

Table VIII.

Annotated summary of class B of peroxisome proliferator-activated receptor γ, coactivator 1α.

Functional roleGenesP-value-Log (P-value)
Biological process
  MHCII-mediated immunity  3 8.20×1032.09
  Signal transduction27 9.70×1032.01
  Intracellular signaling cascade11 1.10×1021.96
  Cell surface receptor mediated signal transduction16 1.40×1021.85
  T-cell mediated immunity  5 1.40×1021.85
  Ligand-mediated signaling   7 1.60×1021.80
  Calcium mediated signaling   4 2.00×1021.70
  Other oncogenesis   3 4.30×1021.37
  Cell communication11 6.90×1021.16
Cellular component
  MHC protein complex   4 2.90×1032.54
  Extracellular matrix   7 7.80×1032.11
  Extracellular region part12 8.40×1032.08
  MHC class II protein complex   3 9.30×1032.03
  Extracellular region18 2.10×1021.68
  Proteinaceous extracellular matrix   6 2.30×1021.64
  Apical plasma membrane   4 2.90×1021.54
  Chromatin assembly complex   2 3.00×1021.52
  Microsome   5 3.20×1021.49
  Vesicular fraction   5 3.50×1021.46
  Apical part of cell   4 6.10×1021.21

[i] The dataset of significantly changed genes were identified using the Database for Annotation, Visualization and Integrated Discovery (DAVID; http://david.abcc.ncifcrf.gov) (P<0.05). MHC, Major Histocompatibility Complex.

In addition, when genes were analyzed according to cell signaling pathway (BioCarta database), 3 signaling pathways in class A and 5 in class B were identified as statistically significant (P<0.05; Table IX). The results of the present study demonstrate that class A genes play roles in signaling pathways associated with metabolic and mitochondrial electron transport and that class B genes are involved in signaling pathways associated with differentiation and immune function.

Table IX.

Differentially regulated signaling pathways in classes A and B.

Table IX.

Differentially regulated signaling pathways in classes A and B.

Signaling pathways NumberaP-value
Class A
  Electron transport reaction in mitochondria3 2.1×10−2
  Shuttle for transfer of acetyl groups from mitochondria to the cytosol3 2.8×10−2
  Role of PPAR-γ coactivators in obesity and thermogenesis3 3.5×10−2
Class B
  Th1/Th2 differentiation5 6.3×10−3
  Cytokines and inflammatory response5 1.6×10−2
  Bystander B-cell activation3 3.6×10−2
  IL12- and Stat4-dependent signaling pathway in Th1 development4 4.0×10−2
  Dendritic cells in regulating Th1 and Th2 development4 4.5×10−2

{ label (or @symbol) needed for fn[@id='tfn8-ol-0-0-5972'] } Using the Database for Annotation, Visualization and Integrated Discovery (DAVID; http://david.abcc.ncifcrf.gov) differentially regulated signaling pathways in class A and B were identified using the dataset of significantly changed genes (P<0.05).

a Number of significantly changed genes per pathway. PPAR, peroxisome proliferator activated receptor; IL, interleukin 12; NF-κB, nuclear factor-κB; NK, natural killer; Th, T helper.

Discussion

The objective of the present study was to investigate the association between aberrant expression of PGC1α and GBM, and the role PGC1α may have in patient survival. Protein level data demonstrated that PGC1α expression was increased in a subpopulation of tumor cells, although there were variations between different GBM cell lines and patients. PGC1α localization was identified to differ between GBM tissues and the normal cortex (Fig. 2). These results corroborated with a previous study that detected a brain-specific isoform of PGC1α in the cytoplasm rather than the nucleus (27). It was also reported that the PGC1α isoform becomes localized in the mitochondria via phosphatase and tensin homolog-induced putative kinase 1 and voltage-dependent anion channel (28).

This present study also demonstrated that PGC1α was expressed in the mitochondria of GBM cells. Based on these corroborating results, it is predicted that PGC1α-mediated mitochondrial biogenesis and respiration is increased in GBM cells.

To investigate the role PGC1α has in GBM cells, several bioinformatics analyses were performed. The analyses demonstrated that metabolic and mitochondrial genes were highly correlated with PGC1α in a number of GBM cell lines. Class Neighbors analysis classified PGC1α-expressing GBM cell lines into two groups: Class A and B. Class A contained genes associated with development, neurogenesis, cell structure and motility. Class B contained genes associated with immunity, oncogenesis and signaling, including intracellular, T cell-mediated, ligand-mediated and-calcium mediated pathways. Class A genes are involved in mitochondrial and metabolic pathways, whilst class B genes are involved in differentiation and immune pathways. These data reinforce the hypothesis that PGC1α may have an important role in regulating mitochondrial and metabolic signaling pathways in the GBM microenvironment.

A notable result was the association of NDN with PGC1α. NDN is reported to function as a tumor suppressor in GBM (29) and controls the proliferation of white adipose progenitor cells (30). NDN interacts with PGC1α via nicotinamide adenine dinucleotide dependent protein deacetylase (Sirt-1) and two transcription factors, E2F1 and P53, suggesting that interactions with these cell cycle regulating factors are key to its function (31). Therefore, it is hypothesized that PGC1α enhances antioxidant capacity in GBM by interacting with NDN and Sirt1, leading to delayed progression of necrosis and ultimately increasing overall patient survival. Future studies that elucidate the molecular interactions of PGC1α are required to derive improved insights into the diagnosis, prognosis and treatment of GBM.

Acknowledgements

This work was financially supported by the Chungnam National University Hospital Research Fund in 2012 (SH Kim) and the Basic Science Research Program through the National Research Foundation of Korea, which was funded by the Ministry of Science, ICT and Future Planning (grant no. 2013R1A1A1A05006966) and the Ministry of Education, Science & Technology of South Korea (grant nos. 2012R1A1A2004714 and 2012M3A9B6055302).

References

1 

Finck BN and Kelly DP: PGC-1 coactivators: Inducible regulators of energy metabolism in health and disease. J Clin Invest. 116:615–622. 2006. View Article : Google Scholar : PubMed/NCBI

2 

Knutti D and Kralli A: PGC-1, a versatile coactivator. Trends Endocrinol Metab. 12:360–365. 2001. View Article : Google Scholar : PubMed/NCBI

3 

Scarpulla RC: Metabolic control of mitochondrial biogenesis through the PGC-1 family regulatory network. Biochim Biophys Acta. 1813:1269–1278. 2011. View Article : Google Scholar : PubMed/NCBI

4 

Puigserver P and Spiegelman BM: Peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1 alpha): Transcriptional coactivator and metabolic regulator. Endocr Rev. 24:78–90. 2003. View Article : Google Scholar : PubMed/NCBI

5 

Lin J, Handschin C and Spiegelman BM: Metabolic control through the PGC-1 family of transcription coactivators. Cell Metab. 1:361–370. 2005. View Article : Google Scholar : PubMed/NCBI

6 

Tritos NA, Mastaitis JW, Kokkotou EG, Puigserver P, Spiegelman BM and Maratos-Flier E: Characterization of the peroxisome proliferator activated receptor coactivator 1 alpha (PGC 1alpha) expression in the murine brain. Brain Res. 961:255–260. 2003. View Article : Google Scholar : PubMed/NCBI

7 

Cowell RM, Blake KR and Russell JW: Localization of the transcriptional coactivator PGC-1alpha to GABAergic neurons during maturation of the rat brain. J Comp Neurol. 502:1–18. 2007. View Article : Google Scholar : PubMed/NCBI

8 

St-Pierre J, Drori S, Uldry M, Silvaggi JM, Rhee J, Jäger S, Handschin C, Zheng K, Lin J, Yang W, et al: Suppression of reactive oxygen species and neurodegeneration by the PGC-1 transcriptional coactivators. Cell. 127:397–408. 2006. View Article : Google Scholar : PubMed/NCBI

9 

Watkins G, Douglas-Jones A, Mansel RE and Jiang WG: The localisation and reduction of nuclear staining of PPARgamma and PGC-1 in human breast cancer. Oncol Rep. 12:483–488. 2004.PubMed/NCBI

10 

Feilchenfeldt J, Brüundler MA, Soravia C, Tötsch M and Meier CA: Peroxisome proliferator-activated receptors (PPARs) and associated transcription factors in colon cancer: Reduced expression of PPARgamma-coactivator 1 (PGC-1). Cancer lett. 203:25–33. 2004. View Article : Google Scholar : PubMed/NCBI

11 

Jiang WG, Douglas-Jones A and Mansel RE: Expression of peroxisome-proliferator activated receptor-gamma (PPARgamma) and the PPARgamma co-activator, PGC-1, in human breast cancer correlates with clinical outcomes. Int J Cancer. 106:752–757. 2003. View Article : Google Scholar : PubMed/NCBI

12 

Zhang Y, Ba Y, Liu C, Sun G, Ding L, Gao S, Hao J, Yu Z, Zhang J, Zen K, et al: PGC-1alpha induces apoptosis in human epithelial ovarian cancer cells through a PPARgamma-dependent pathway. Cell Res. 17:363–373. 2007. View Article : Google Scholar : PubMed/NCBI

13 

Heiden MG Vander, Cantley LC and Thompson CB: Understanding the Warburg effect: The metabolic requirements of cell proliferation. Science. 324:1029–1033. 2009. View Article : Google Scholar : PubMed/NCBI

14 

Vazquez F, Lim JH, Chim H, Bhalla K, Girnun G, Pierce K, Clish CB, Granter SR, Widlund HR, Spiegelman BM and Puigserver P: PGC1α expression defines a subset of human melanoma tumors with increased mitochondrial capacity and resistance to oxidative stress. Cancer cell. 23:287–301. 2013. View Article : Google Scholar : PubMed/NCBI

15 

Plate KH and Risau W: Angiogenesis in malignant gliomas. Glia. 15:339–347. 1995. View Article : Google Scholar : PubMed/NCBI

16 

Stupp R, Mason WP, van den Bent MJ, Weller M, Fisher B, Taphoorn MJ, Belanger K, Brandes AA, Marosi C, Bogdahn U, et al: Radiotherapy plus concomitant and adjuvant temozolomide for glioblastoma. N Engl J Med. 352:987–996. 2005. View Article : Google Scholar : PubMed/NCBI

17 

Cancer Genome Atlas Research Network, . Comprehensive genomic characterization defines human glioblastoma genes and core pathways. Nature. 455:1061–1068. 2008. View Article : Google Scholar : PubMed/NCBI

18 

Verhaak RG, Hoadley KA, Purdom E, Wang V, Qi Y, Wilkerson MD, Miller CR, Ding L, Golub T, Mesirov JP, et al: Integrated genomic analysis identifies clinically relevant subtypes of glioblastoma characterized by abnormalities in PDGFRA, IDH1, EGFR, and NF1. Cancer Cell. 17:98–110. 2010. View Article : Google Scholar : PubMed/NCBI

19 

Lee YS, Kang JW, Lee YH and Kim DW: ID4 mediates proliferation of astrocytes after excitotoxic damage in the mouse hippocampus. Anat Cell Biol. 44:128–134. 2011. View Article : Google Scholar : PubMed/NCBI

20 

Yi MH, Kim S, Zhang E, Kang JW, Park JB, Lee YH, Chung CK, Kim YM and Kim DW: IQGAP1 expression in spared CA1 neurons after an excitotoxic lesion in the mouse hippocampus. Cell Mol Neurobiol. 33:1003–1012. 2013. View Article : Google Scholar : PubMed/NCBI

21 

Barretina J, Caponigro G, Stransky N, Venkatesan K, Margolin AA, Kim S, Wilson CJ, Lehár J, Kryukov GV, Sonkin D, et al: The cancer cell line encyclopedia enables predictive modelling of anticancer drug sensitivity. Nature. 483:603–607. 2012. View Article : Google Scholar : PubMed/NCBI

22 

Golub TR, Slonim DK, Tamayo P, Huard C, Gaasenbeek M, Mesirov JP, Coller H, Loh ML, Downing JR, Caligiuri MA, et al: Molecular classification of cancer: Class discovery and class prediction by gene expression monitoring. Science. 286:531–537. 1999. View Article : Google Scholar : PubMed/NCBI

23 

Huang DW, Sherman BT, Tan Q, Collins JR, Alvord WG, Roayaei J, Stephens R, Baseler MW, Lane HC and Lempicki RA: The DAVID gene functional classification tool: A novel biological module-centric algorithm to functionally analyze large gene lists. Genome Biol. 8:R1832007. View Article : Google Scholar : PubMed/NCBI

24 

Vlasblom J, Zuberi K, Rodriguez H, Arnold R, Gagarinova A, Deineko V, Kumar A, Leung E, Rizzolo K, Samanfar B, et al: Novel function discovery with GeneMANIA: A new integrated resource for gene function prediction in Escherichia coli. Bioinformatics. 31:306–310. 2015. View Article : Google Scholar : PubMed/NCBI

25 

Meng H, Liang HL and Wong-Riley M: Quantitative immuno-electron microscopic analysis of depolarization-induced expression of PGC-1alpha in cultured rat visual cortical neurons. Brain Res. 1175:10–16. 2007. View Article : Google Scholar : PubMed/NCBI

26 

Deighton RF, Le Bihan T, Martin SF, Gerth AM, McCulloch M, Edgar JM, Kerr LE, Whittle IR and McCulloch J: Interactions among mitochondrial proteins altered in glioblastoma. J Neurooncol. 118:247–256. 2014. View Article : Google Scholar : PubMed/NCBI

27 

Soyal SM, Felder TK, Auer S, Hahne P, Oberkofler H, Witting A, Paulmichl M, Landwehrmeyer GB, Weydt P and Patsch W; European Huntington Disease Network, : A greatly extended PPARGC1A genomic locus encodes several new brain-specific isoforms and influences Huntington disease age of onset. Hum Mol Genet. 21:3461–3473. 2012. View Article : Google Scholar : PubMed/NCBI

28 

Choi J, Batchu VV, Schubert M, Castellani RJ and Russell JW: A novel PGC-1α isoform in brain localizes to mitochondria and associates with PINK1 and VDAC. Biochem Biophys Res Commun. 435:671–677. 2013. View Article : Google Scholar : PubMed/NCBI

29 

Chapman EJ and Knowles MA: Necdin: A multi functional protein with potential tumor suppressor role? Mol Carcinog. 48:975–981. 2009. View Article : Google Scholar : PubMed/NCBI

30 

Fujiwara K, Hasegawa K, Ohkumo T, Miyoshi H, Tseng YH and Yoshikawa K: Necdin controls proliferation of white adipocyte progenitor cells. PloS One. 7:e309482012. View Article : Google Scholar : PubMed/NCBI

31 

Niinobe M, Koyama K and Yoshikawa K: Cellular and subcellular localization of necdin in fetal and adult mouse brain. Dev Neurosci. 22:310–319. 2000. View Article : Google Scholar : PubMed/NCBI

Related Articles

Journal Cover

June-2017
Volume 13 Issue 6

Print ISSN: 1792-1074
Online ISSN:1792-1082

Sign up for eToc alerts

Recommend to Library

Copy and paste a formatted citation
x
Spandidos Publications style
Cho SY, Kim SH, Yi MH, Zhang E, Kim E, Park J, Jo EK, Lee YH, Park MS, Kim Y, Kim Y, et al: Expression of PGC1α in glioblastoma multiforme patients. Oncol Lett 13: 4055-4076, 2017
APA
Cho, S.Y., Kim, S., Yi, M., Zhang, E., Kim, E., Park, J. ... Kim, D.W. (2017). Expression of PGC1α in glioblastoma multiforme patients. Oncology Letters, 13, 4055-4076. https://doi.org/10.3892/ol.2017.5972
MLA
Cho, S. Y., Kim, S., Yi, M., Zhang, E., Kim, E., Park, J., Jo, E., Lee, Y. H., Park, M. S., Kim, Y., Park, J., Kim, D. W."Expression of PGC1α in glioblastoma multiforme patients". Oncology Letters 13.6 (2017): 4055-4076.
Chicago
Cho, S. Y., Kim, S., Yi, M., Zhang, E., Kim, E., Park, J., Jo, E., Lee, Y. H., Park, M. S., Kim, Y., Park, J., Kim, D. W."Expression of PGC1α in glioblastoma multiforme patients". Oncology Letters 13, no. 6 (2017): 4055-4076. https://doi.org/10.3892/ol.2017.5972