EZH2 Contributes to Anoikis Resistance and Promotes Epithelial Ovarian Cancer Peritoneal Metastasis by Regulating m6A

Abstract

Objective

Histone modification has a significant effect on gene expression. Enhancer of zeste homolog 2 (EZH2) contributes to the epigenetic silencing of target chromatin through its roles as a histone-lysine N-methyltransferase enzyme. The development of anoikis resistance in tumor cells is considered to be a critical step in the metastatic process of primary malignant tumors. The purpose of this study was to investigate the effect and mechanism of anoikis resistance in ovarian adenocarcinoma peritoneal metastasis.

Methods

In addition to examining EZH2 protein expression in ovarian cancer omental metastatic tissues, we established a model of ovarian cancer cell anoikis and a xenograft tumor model in nude mice. Anoikis resistance and ovarian cancer progression were tested after EZH2 and N6-methyladenosine (m6A) levels were modified.

Results

EZH2 expression was significantly higher in ovarian cancer omental metastatic tissues than in normal ovarian tissues. Reducing the level of EZH2 decreased the level of m6A and ovarian cancer cell anoikis resistance in vitro and inhibited ovarian cancer progression in vivo. M6a regulation altered the effect of EZH2 on anoikis resistance.

Conclusion

Our results indicate that EZH2 contributes to anoikis resistance and promotes ovarian adenocarcinoma abdominal metastasis by m6A modification. Our findings imply the potential of the clinical application of m6A and EZH2 for patients with ovarian cancer.

Keywords

anoikis / heterografts / N6-methyladenosine / enhancer of zeste homolog 2 / ovarian neoplasms

References

[1] NaoraH, MontellDJ. Ovarian cancer metastasis: integrating insights from disparate model organisms. Nat Rev Cancer, 2005, 5(5): 355-366

[2] AyantundeAA, ParsonsSL. Pattern and prognostic factors in patients with malignant ascites: a retrospective study. Ann Oncol, 2007, 18(5): 945-949

[3] SonodaY. Management of early ovarian cancer. Oncology (Williston Park), 2004, 18(3): 343-356

[4] SimpsonCD, AnyiweK, SchimmerAD. Anoikis resistance and tumor metastasis. Cancer Lett, 2008, 272(2): 177-185

[5] FrankelA, RosenK, FilmusJ, et al.. Induction of anoikis and suppression of human ovarian tumor growth in vivo by down-regulation of Bcl–X(L). Cancer Res, 2001, 61(12): 4837-4841

[6] SoodAK, Armaiz-PenaGN, HalderJ, et al.. Adrenergic modulation of focal adhesion kinase protects human ovarian cancer cells from anoikis. J Clin Invest, 2010, 120(5): 1515-1523

[7] CaoR, ZhangY. The functions of E(Z)/EZH2-mediated methylation of lysine 27 in histone H3. Curr Opin Genet Dev, 2004, 14(2): 155-164

[8] EggerG, LiangG, AparicioA, et al.. Epigenetics in human disease and prospects for epigenetic therapy. Nature, 2004, 429(6990): 457-463

[9] HuangH, WengH, SunW, et al.. Recognition of RNA N(6)-methyladenosine by IGF2BP proteins enhances mRNA stability and translation. Nat Cell Biol, 2018, 20(3): 285-295

[10] XiangY, LaurentB, HsuCH, et al.. RNA m(6)A methylation regulates the ultraviolet-induced DNA damage response. Nature, 2017, 543(7646): 573-576

[11] WengH, HuangH, WuH, et al.. METTL14 Inhibits Hematopoietic Stem/Progenitor Differentiation and Promotes Leukemogenesis via mRNA m(6)A Modification. Cell Stem Cell, 2018, 22(2): 191-205.e9

[12] SuR, DongL, LiC, et al.. R-2HG Exhibits Anti-tumor Activity by Targeting FTO/m(6)A/MYC/CEBPA Signaling. Cell, 2018, 172(1–2): 90-105.e23

[13] VaramballyS, DhanasekaranSM, ZhouM, et al.. The polycomb group protein EZH2 is involved in progression of prostate cancer. Nature, 2002, 419(6907): 624-629

[14] BachmannIM, HalvorsenOJ, CollettK, et al.. EZH2 expression is associated with high proliferation rate and aggressive tumor subgroups in cutaneous melanoma and cancers of the endometrium, prostate, and breast. J Clin Oncol, 2006, 24(2): 268-273

[15] RamanJD, MonganNP, TickooSK, et al.. Increased expression of the polycomb group gene, EZH2, in transitional cell carcinoma of the bladder. Clin Cancer Res, 2005, 11(24Pt1): 8570-8576

[16] ChenWW, QiJW, HangY, et al.. Simvastatin is beneficial to lung cancer progression by inducing METTL3-induced m6A modification on EZH2 mRNA. Eur Rev Med Pharmacol Sci, 2020, 24(8): 4263-4270

[17] HuS, YuL, LiZ, et al.. Overexpression of EZH2 contributes to acquired cisplatin resistance in ovarian cancer cells in vitro and in vivo. Cancer Biol Ther, 2010, 10(8): 788-795

[18] GuoJ, CaiJ, YuL, et al.. EZH2 regulates expression of p57 and contributes to progression of ovarian cancer in vitro and in vivo. Cancer Sci, 2011, 102(3): 530-539

[19] SauvageauM, SauvageauG. Polycomb group proteins: multi-faceted regulators of somatic stem cells and cancer. Cell Stem Cell, 2010, 7(3): 299-313

[20] LiX, GonzalezME, ToyK, et al.. Targeted overexpression of EZH2 in the mammary gland disrupts ductal morphogenesis and causes epithelial hyperplasia. Am J Pathol, 2009, 175(3): 1246-1254

[21] PiuntiA, PasiniD. Epigenetic factors in cancer development: polycomb group proteins. Future Oncol, 2011, 7(1): 57-75

[22] SuvaML, RiggiN, JaniszewskaM, et al.. EZH2 is essential for glioblastoma cancer stem cell maintenance. Cancer Res, 2009, 69(24): 9211-9218

[23] RizzoS, HerseyJM, MellorP, et al.. Ovarian cancer stem cell-like side populations are enriched following chemotherapy and overexpress EZH2. Mol Cancer Ther, 2011, 10(2): 325-335

[24] GonzalezME, LiX, ToyK, et al.. Downregulation of EZH2 decreases growth of estrogen receptor-negative invasive breast carcinoma and requires BRCA1. Oncogene, 2009, 28(6): 843-853

[25] CreaF, HurtEM, MathewsLA, et al.. Pharmacologic disruption of Polycomb Repressive Complex 2 inhibits tumorigenicity and tumor progression in prostate cancer. Mol Cancer, 2011, 10: 40

[26] PanY, MaP, LiuY, et al.. Multiple functions of m(6) A RNA methylation in cancer. J Hematol Oncol, 2018, 11(1): 48

[27] CuiQ, ShiH, YeP, et al.. m(6)A RNA methylation regulates the self-renewal and tumorigenesis of glioblastoma stem cells. Cell Rep, 2017, 18(11): 2622-2634

[28] LiZ, WengH, SuR, et al.. FTO Plays an Oncogenic Role in Acute Myeloid Leukemia as a N6-Methyladenosine RNA Demethylase. Cancer Cell, 2017, 31(1): 127-141

[29] HuangW, QiCB, LvSW, et al.. Determination of DNA and RNA methylation in circulating tumor cells by mass spectrometry. Anal Chem, 2016, 88(2): 1378-1384

[30] ChenM, WeiL, LawCT, et al.. RNA N6-methyladenosine methyltransferase-like 3 promotes liver cancer progression through YTHDF2-dependent posttranscriptional silencing of SOCS2. Hepatology, 2018, 67(6): 2254-2270

[31] HeX, OtaT, LiuP, et al.. Downregulation of HtrA1 promotes resistance to anoikis and peritoneal dissemination of ovarian cancer cells. Cancer Res, 2010, 70(8): 3109-3118

[32] BrackenAP, PasiniD, CapraM, et al.. EZH2 is downstream of the pRB-E2F pathway, essential for proliferation and amplified in cancer. EMBO J, 2003, 22(20): 5323-5335

[33] LeeJ, SonMJ, WoolardK, et al.. Epigenetic mediated dysfunction of the bone morphogenetic protein pathway inhibits differentiation of glioblastoma-initiating cells. Cancer Cell, 2008, 13(1): 69-80

[34] ZhouS, BaiZL, XiaD, et al.. FTO regulates the chemo-radiotherapy resistance of cervical squamous cell carcinoma (CSCC) by targeting beta-catenin through mRNA demethylation. Mol Carcinog, 2018, 57(5): 590-597

[35] KwokCT, MarshallAD, RaskoJE, et al.. Genetic alterations of m(6)A regulators predict poorer survival in acute myeloid leukemia. J Hematol Oncol, 2017, 10(1): 39