Knockdown of dickkopf2 inhibits vascular endothelia growth factor expression through the Wnt/β-catenin signaling pathway in human retinal pigment epithelial cells under hypoxic conditions

Zhao,Yu; Wu,Bin; Liu,Ye; Xu,Jun; Yan,Qichang; Zhang,Jinsong

doi:10.3892/etm.2018.5915

Knockdown of dickkopf2 inhibits vascular endothelia growth factor expression through the Wnt/β-catenin signaling pathway in human retinal pigment epithelial cells under hypoxic conditions

Authors:
- Yu Zhao
- Bin Wu
- Ye Liu
- Jun Xu
- Qichang Yan
- Jinsong Zhang
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Affiliations: Department of Ophthalmology, The Fourth Affiliated Hospital of China Medical University, Shenyang, Liaoning 110005, P.R. China
Published online on: February 28, 2018 https://doi.org/10.3892/etm.2018.5915
Pages: 4056-4060

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Abstract

Hypoxia has been demonstrated to be a proangiogenic factor that induces vascular endothelial growth factor (VEGF) in retinal pigment epithelial (RPE) cells. Dickkopf2 (DKK2), originally known as Wnt antagonist, has recently been demonstrated to have an important regulatory role in angiogenesis; however, the specific role of DKK2 in RPE cells is not known. In the present study, the effects of DKK2 on VEGF expression under hypoxic conditions were investigated, as well as the molecular mechanisms involved. The results demonstrated that the expression of DKK2 was markedly increased under hypoxic conditions compared with normoxic conditions. Knockdown of DKK2 markedly attenuated the CoCl2‑induced expression of hypoxia‑inducible factor (HIF)‑1α and VEGF in RPE cells. Furthermore, knockdown of DKK2 markedly inhibited the expression of β‑catenin induced by hypoxia. In conclusion, the findings of the present study demonstrate that knockdown of DKK2 inhibits the hypoxia‑induced production of VEGF by suppressing the activation of the Wnt/β-catenin signaling pathway.

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1	Jager RD, Mieler WF and Miller JW: Age-related macular degeneration. N Engl J Med. 358:2606–2617. 2008. View Article : Google Scholar : PubMed/NCBI
2	Schwesinger C, Yee C, Rohan RM, Joussen AM, Fernandez A, Meyer TN, Poulaki V, Ma JJ, Redmond TM, Liu S, et al: Intrachoroidal neovascularization in transgenic mice overexpressing vascular endothelial growth factor in the retinal pigment epithelium. Am J Pathol. 158:1161–1172. 2001. View Article : Google Scholar : PubMed/NCBI
3	Sheridan CM, Pate S, Hiscott P, Wong D, Pattwell DM and Kent D: Expression of hypoxia-inducible factor-1alpha and-2alpha in human choroidal neovascular membranes. Graefes Arch Clin Exp Ophthalmol. 247:1361–1367. 2009. View Article : Google Scholar : PubMed/NCBI
4	Dong X, Wang YS, Dou GR, Hou HY, Shi YY, Zhang R, Ma K, Wu L, Yao LB, Cai Y and Zhang J: Influence of Dll4 via HIF-1a-VEGF signaling on the angiogenesis of choroidal neovascularization under hypoxic conditions. PLoS One. 6:e184812011. View Article : Google Scholar : PubMed/NCBI
5	Mousa SA, Lorelli W and Campochiaro PA: Role of hypoxia and extracellular matrix-integrin binding in the modulation of angiogenic growth factors secretion by retinal pigmented epithelial cells. J Cell Biochem. 74:135–143. 1999. View Article : Google Scholar : PubMed/NCBI
6	Krupnik VE, Sharp JD, Jiang C, Robison K, Chickering TW, Amaravadi L, Brown DE, Guyot D, Mays G, Leiby K, et al: Functional and structural diversity of the human Dickkopf gene family. Gene. 238:301–313. 1999. View Article : Google Scholar : PubMed/NCBI
7	Kawakita A, Yanamoto S, Yamada S-i, Naruse T, Takahashi H, Kawasaki G and Umeda M: MicroRNA-21 promotes oral cancer invasion via the Wnt/β-catenin pathway by targeting DKK2. Pathol Oncol Res. 20:253–261. 2014. View Article : Google Scholar : PubMed/NCBI
8	Hirata H, Hinoda Y, Nakajima K, Kawamoto K, Kikuno N, Kawakami K, Yamamura S, Ueno K, Majid S, Saini S, et al: Wnt antagonist gene DKK2 is epigenetically silenced and inhibits renal cancer progression through apoptotic and cell cycle pathways. Clin Cancer Res. 15:5678–5687. 2009. View Article : Google Scholar : PubMed/NCBI
9	Zhu J, Zhang S, Gu L and Di W: Epigenetic silencing of DKK2 and Wnt signal pathway components in human ovarian carcinoma. Carcinogenesis. 33:2334–2343. 2012. View Article : Google Scholar : PubMed/NCBI
10	Min JK, Park H, Choi HJ, Kim Y, Pyun BJ, Agrawal V, Song BW, Jeon J, Maeng YS, Rho SS, et al: The WNT antagonist Dickkopf2 promotes angiogenesis in rodent and human endothelial cells. J Clin Invest. 121:1882–1893. 2011. View Article : Google Scholar : PubMed/NCBI
11	Park H, Jung HY, Choi HJ, Kim DY, Yoo JY, Yun CO, Min JK, Kim YM and Kwon YG: Distinct roles of DKK1 and DKK2 in tumor angiogenesis. Angiogenesis. 17:221–234. 2014. View Article : Google Scholar : PubMed/NCBI
12	Livak KJ and Schmittgen TD: Analysis of relative gene expression data using real-tie quantitative PCR and the 2(-Delta Delta C(T)) Method. Methods. 25:402–408. 2001. View Article : Google Scholar : PubMed/NCBI
13	Pugh CW and Ratcliffe PJ: Regulation of angiogenesis by hypoxia: Role of the HIF system. Nat Med. 9:677–684. 2003. View Article : Google Scholar : PubMed/NCBI
14	Semenza GL: Hydroxylation of HIF-1: Oxygen sensing at the molecular level. Physiology (Bethesda). 19:176–182. 2004.PubMed/NCBI
15	Semenza GL: HIF-1: Mediator of physiological and pathophysiological responses to hypoxia. J Appl Physiol (1985). 88:1474–1480. 2000. View Article : Google Scholar : PubMed/NCBI
16	Bouvard B, Abed E, Yéléhé-Okouma M, Bianchi A, Mainard D, Netter P, Jouzeau JY, Lajeunesse D and Reboul P: Hypoxia and vitamin D differently contribute to leptin and dickkopf-related protein 2 production in human osteoarthritic subchondral bone osteoblasts. Arthritis Res Ther. 16:4592014. View Article : Google Scholar : PubMed/NCBI
17	Yang XM, Wang YS, Zhang J, Li Y, Xu JF, Zhu J, Zhao W, Chu DK and Wiedemann P: Role of PI3K/Akt and MEK/ERK in mediating hypoxia-induced expression of HIF-1alpha and VEGF in laser-induced rat choroidal neovascularization. Invest Ophthalmol Vis Sci. 50:1873–1879. 2009. View Article : Google Scholar : PubMed/NCBI
18	Hata Y, Nakagawa K and Sueishi K, Ishibashi T, Inomata H, Ueno H and Sueishi K: Hypoxia-induced expression of vascular endothelial growth factor by retinal glial cells promotes in vitro angiogenesis. Virchows Arch. 426:479–486. 1995. View Article : Google Scholar : PubMed/NCBI
19	Liu Y, Cox SR, Morita T and Kourembanas S: Hypoxia regulates vascular endothelial growth factor gene expression in endothelial cells identification of a 5′ enhancer. Circ Res. 77:638–643. 1995. View Article : Google Scholar : PubMed/NCBI
20	Akeno N, Czyzyk-Krzeska MF, Gross TS and Clemens TL: Hypoxia induces vascular endothelial growth factor gene transcription in human osteoblast-like cells through the hypoxia-inducible factor-2α. Endocrinology. 142:959–962. 2001. View Article : Google Scholar : PubMed/NCBI
21	Park JJ, Hwang SJ, Park JH and Lee HJ: Chlorogenic acid inhibits hypoxia-induced angiogenesis via down-regulation of the HIF-1α/AKT pathway. Cell Oncol (Dordr). 38:111–118. 2015. View Article : Google Scholar : PubMed/NCBI
22	Horiuchi A, Imai T, Shimizu M, Oka K, Wang C, Nikaido T and Konishi I: Hypoxia-induced changes in the expression of VEGF, HIF-1 alpha and cell cycle-related molecules in ovarian cancer cells. Anticancer Res. 22:2697–2702. 2001.
23	Zhou T, Hu Y, Chen Y, Zhou KK, Zhang B, Gao G and Ma JX: The pathogenic role of the canonical Wnt pathway in age-related macular degeneration. Invest Ophthalmol Vis Sci. 51:4371–4379. 2010. View Article : Google Scholar : PubMed/NCBI
24	Easwaran V, Lee SH, Inge L, Guo L, Goldbeck C, Garrett E, Wiesmann M, Garcia PD, Fuller JH, Chan V, et al: beta-Catenin regulates vascular endothelial growth factor expression in colon cancer. Cancer Res. 63:3145–3153. 2003.PubMed/NCBI
25	Daneman R, Agalliu D, Zhou L, Kuhnert F, Kuo CJ and Barres BA: Wnt/beta-catenin signaling is required for CNS, but not non-CNS, angiogenesis. Proc Natl Acad Sci USA. 106:641–646. 2009. View Article : Google Scholar : PubMed/NCBI
26	Clevers H and Nusse R: Wnt/β-catenin signaling and disease. Cell. 149:1192–1205. 2012. View Article : Google Scholar : PubMed/NCBI
27	Hu Y, Chen Y, Lin M, Lee K, Mott RA and Ma JX: Pathogenic role of the Wnt signaling pathway activation in laser-induced choroidal neovascularization. Invest Ophthalmol Vis Sci. 54:141–154. 2013. View Article : Google Scholar : PubMed/NCBI
28	Mitani T, Harada N, Nakano Y, Inui H and Yamaji R: Coordinated action of hypoxia-inducible factor-1α and β-catenin in androgen receptor signaling. J Biol Chem. 287:33594–33606. 2012. View Article : Google Scholar : PubMed/NCBI