MicroRNA-let-7a regulates cell autophagy by targeting Rictor in gastric cancer cell lines MGC-803 and SGC-7901

Fan,Hao; Jiang,Mingkun; Li,Bowen; He,Yu; Huang,Chi; Luo,Dakui; Xu,Hao; Yang,Li; Zhou,Jundong

doi:10.3892/or.2018.6194

MicroRNA-let-7a regulates cell autophagy by targeting Rictor in gastric cancer cell lines MGC-803 and SGC-7901

Authors:
- Hao Fan
- Mingkun Jiang
- Bowen Li
- Yu He
- Chi Huang
- Dakui Luo
- Hao Xu
- Li Yang
- Jundong Zhou
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Affiliations: Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China, The Core Laboratory of The Suzhou Cancer Center and Department of Radiotherapy, Nanjing Medical University Affiliated Suzhou Hospital, Suzhou, Jiangsu 215001, P.R. China
Published online on: January 5, 2018 https://doi.org/10.3892/or.2018.6194
Pages: 1207-1214

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Abstract

miR-let-7a is the most widely studied miRNA, whose functions have been well-established by scientists in both carcinogenesis and progression of human cancer, including gastric cancer (GC). However, to date there is a lack of information concerning the relationship between miR-let-7a and cellular autophagy. Using western blotting and immunofluorescence, we determined that upregulation of miR-let-7a led to increased cellular autophagic level, whereas miR-let-7a suppression decreased autophagy activity in GC cells. To further elucidate the mechanisms underlying this, we screened potential targets of miR-let-7a using bioinformatics analyses, validated by a series of assays. Our results indicated that Rptor independent companion of mTOR complex 2 (Rictor) was a direct target of miR-let-7a. In addition, rescue experiments in vitro showed that miR-let-7a promoted cellular autophagic level by inhibiting Rictor expression in GC cells. Furthermore, as an upstream executor of Akt-mTOR signaling pathway, we found that Rictor elaborated its effect on autophagy by phosphorylating Akt and mTOR, and this regulatory process could also be mediated by miR-let-7a. Taken together, our results present a novel role for miR-let-7a in GC which modulates autophagy by targeting Rictor, following the regulation of Akt-mTOR signal pathway.

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1	Ferlay J, Soerjomataram I, Dikshit R, Eser S, Mathers C, Rebelo M, Parkin DM, Forman D and Bray F: Cancer incidence and mortality worldwide: Sources, methods and major patterns in GLOBOCAN 2012. Int J Cancer. 136:E359–E386. 2015. View Article : Google Scholar : PubMed/NCBI
2	Yang L, Parkin DM, Ferlay J, Li L and Chen Y: Estimates of cancer incidence in China for 2000 and projections for 2005. Cancer Epidemiol Biomarkers Prev. 14:243–250. 2005.PubMed/NCBI
3	de Martel C, Forman D and Plummer M: Gastric cancer: Epidemiology and risk factors. Gastroenterol Clin North Am. 42:219–240. 2013. View Article : Google Scholar : PubMed/NCBI
4	Song IS, Oh NS, Kim HT, Ha GH, Jeong SY, Kim JM, Kim DI, Yoo HS, Kim CH and Kim NS: Human ZNF312b promotes the progression of gastric cancer by transcriptional activation of the K-ras gene. Cancer Res. 69:3131–3139. 2009. View Article : Google Scholar : PubMed/NCBI
5	Pietrocola F, Izzo V, Niso-Santano M, Vacchelli E, Galluzzi L, Maiuri MC and Kroemer G: Regulation of autophagy by stress-responsive transcription factors. Semin Cancer Biol. 23:310–322. 2013. View Article : Google Scholar : PubMed/NCBI
6	Levine B and Klionsky DJ: Development by self-digestion: Molecular mechanisms and biological functions of autophagy. Dev Cell. 6:463–477. 2004. View Article : Google Scholar : PubMed/NCBI
7	He C and Klionsky DJ: Regulation mechanisms and signaling pathways of autophagy. Annu Rev Genet. 43:67–93. 2009. View Article : Google Scholar : PubMed/NCBI
8	Liang C and Jung JU: Autophagy genes as tumor suppressors. Curr Opin Cell Biol. 22:226–233. 2010. View Article : Google Scholar : PubMed/NCBI
9	Moreau K, Luo S and Rubinsztein DC: Cytoprotective roles for autophagy. Curr Opin Cell Biol. 22:206–211. 2010. View Article : Google Scholar : PubMed/NCBI
10	Wang MC, Wu AG, Huang YZ, Shao GL, Ji SF, Wang RW, Yuan HJ, Fan XL, Zheng LH and Jiao QL: Autophagic regulation of cell growth by altered expression of Beclin 1 in triple-negative breast cancer. Int J Clin Exp Med. 8:7049–7058. 2015.PubMed/NCBI
11	Sui H, Shi C, Yan Z and Li H: Combination of erlotinib and a PARP inhibitor inhibits growth of A2780 tumor xenografts due to increased autophagy. Drug Des Devel Ther. 9:3183–3190. 2015. View Article : Google Scholar : PubMed/NCBI
12	Tanzer A and Stadler PF: Molecular evolution of a microRNA cluster. J Mol Biol. 339:327–335. 2004. View Article : Google Scholar : PubMed/NCBI
13	Selbach M, Schwanhäusser B, Thierfelder N, Fang Z, Khanin R and Rajewsky N: Widespread changes in protein synthesis induced by microRNAs. Nature. 455:58–63. 2008. View Article : Google Scholar : PubMed/NCBI
14	Frankel LB, Wen J, Lees M, Høyer-Hansen M, Farkas T, Krogh A, Jäättelä M and Lund AH: microRNA-101 is a potent inhibitor of autophagy. EMBO J. 30:4628–4641. 2011. View Article : Google Scholar : PubMed/NCBI
15	Brest P, Lapaquette P, Souidi M, Lebrigand K, Cesaro A, Vouret-Craviari V, Mari B, Barbry P, Mosnier JF, Hébuterne X, et al: A synonymous variant in IRGM alters a binding site for miR-196 and causes deregulation of IRGM-dependent xenophagy in Crohn's disease. Nat Genet. 43:242–245. 2011. View Article : Google Scholar : PubMed/NCBI
16	Kovaleva V, Mora R, Park YJ, Plass C, Chiramel AI, Bartenschlager R, Döhner H, Stilgenbauer S, Pscherer A, Lichter P, et al: miRNA-130a targets ATG2B and DICER1 to inhibit autophagy and trigger killing of chronic lymphocytic leukemia cells. Cancer Res. 72:1763–1772. 2012. View Article : Google Scholar : PubMed/NCBI
17	Tang R, Yang C, Ma X, Wang Y, Luo D, Huang C, Xu Z, Liu P and Yang L: MiR-let-7a inhibits cell proliferation, migration, and invasion by down-regulating PKM2 in gastric cancer. Oncotarget. 7:5972–5984. 2016.PubMed/NCBI
18	Sarbassov DD, Ali SM, Kim DH, Guertin DA, Latek RR, Erdjument-Bromage H, Tempst P and Sabatini DM: Rictor, a novel binding partner of mTOR, defines a rapamycin-insensitive and raptor-independent pathway that regulates the cytoskeleton. Curr Biol. 14:1296–1302. 2004. View Article : Google Scholar : PubMed/NCBI
19	Laplante M and Sabatini DM: mTOR signaling in growth control and disease. Cell. 149:274–293. 2012. View Article : Google Scholar : PubMed/NCBI
20	Huang N, Wu J, Qiu W, Lyu Q, He J, Xie W, Xu N and Zhang Y: MiR-15a and miR-16 induce autophagy and enhance chemosensitivity of Camptothecin. Cancer Biol Ther. 16:941–948. 2015. View Article : Google Scholar : PubMed/NCBI
21	Wan G, Xie W, Liu Z, Xu W, Lao Y, Huang N, Cui K, Liao M, He J, Jiang Y, et al: Hypoxia-induced MIR155 is a potent autophagy inducer by targeting multiple players in the MTOR pathway. Autophagy. 10:70–79. 2014. View Article : Google Scholar : PubMed/NCBI
22	Liu K, Huang J, Xie M, Yu Y, Zhu S, Kang R, Cao L, Tang D and Duan X: MIR34A regulates autophagy and apoptosis by targeting HMGB1 in the retinoblastoma cell. Autophagy. 10:442–452. 2014. View Article : Google Scholar : PubMed/NCBI
23	Korkmaz G, Le Sage C, Tekirdag KA, Agami R and Gozuacik D: miR-376b controls starvation and mTOR inhibition-related autophagy by targeting ATG4C and BECN1. Autophagy. 8:165–176. 2012. View Article : Google Scholar : PubMed/NCBI
24	Faller WJ, Jackson TJ, Knight JR, Ridgway RA, Jamieson T, Karim SA, Jones C, Radulescu S, Huels DJ, Myant KB, et al: mTORC1-mediated translational elongation limits intestinal tumour initiation and growth. Nature. 517:497–500. 2015. View Article : Google Scholar : PubMed/NCBI
25	Xu J, Wang Y, Tan X and Jing H: MicroRNAs in autophagy and their emerging roles in crosstalk with apoptosis. Autophagy. 8:873–882. 2012. View Article : Google Scholar : PubMed/NCBI
26	Mazumder A, Bose M, Chakraborty A, Chakrabarti S and Bhattacharyya SN: A transient reversal of miRNA-mediated repression controls macrophage activation. EMBO Rep. 14:1008–1016. 2013. View Article : Google Scholar : PubMed/NCBI
27	Su Z, Yang Z, Xu Y, Chen Y and Yu Q: MicroRNAs in apoptosis, autophagy and necroptosis. Oncotarget. 6:8474–8490. 2015. View Article : Google Scholar : PubMed/NCBI
28	Kimura S, Fujita N, Noda T and Yoshimori T: Monitoring autophagy in mammalian cultured cells through the dynamics of LC3. Methods Enzymol. 452:1–12. 2009. View Article : Google Scholar : PubMed/NCBI
29	Klionsky DJ, Abeliovich H, Agostinis P, Agrawal DK, Aliev G, Askew DS, Baba M, Baehrecke EH, Bahr BA, Ballabio A, et al: Guidelines for the use and interpretation of assays for monitoring autophagy in higher eukaryotes. Autophagy. 4:151–175. 2008. View Article : Google Scholar : PubMed/NCBI
30	Mathew R, Karp CM, Beaudoin B, Vuong N, Chen G, Chen HY, Bray K, Reddy A, Bhanot G, Gelinas C, et al: Autophagy suppresses tumorigenesis through elimination of p62. Cell. 137:1062–1075. 2009. View Article : Google Scholar : PubMed/NCBI
31	Jung CH, Ro SH, Cao J, Otto NM and Kim DH: mTOR regulation of autophagy. FEBS Lett. 584:1287–1295. 2010. View Article : Google Scholar : PubMed/NCBI
32	Sarbassov DD, Guertin DA, Ali SM and Sabatini DM: Phosphorylation and regulation of Akt/PKB by the rictor-mTOR complex. Science. 307:1098–1101. 2005. View Article : Google Scholar : PubMed/NCBI
33	Liu Y, Sun Y and Zhao A: MicroRNA-134 suppresses cell proliferation in gastric cancer cells via targeting of GOLPH3. Oncol Rep. 37:2441–2448. 2017. View Article : Google Scholar : PubMed/NCBI
34	Ying J, Xu Q, Liu B, Zhang G, Chen L and Pan H: The expression of the PI3K/AKT/mTOR pathway in gastric cancer and its role in gastric cancer prognosis. Onco Targets Ther. 8:2427–2433. 2015. View Article : Google Scholar : PubMed/NCBI
35	Shintani T and Klionsky DJ: Autophagy in health and disease: A double-edged sword. Science. 306:990–995. 2004. View Article : Google Scholar : PubMed/NCBI