CTCF promotes epithelial ovarian cancer metastasis by broadly controlling the expression of metastasis-associated genes

CCCTC-binding factor (CTCF) is an 11 zinc fingers transcription factor that functions as both an oncogenic and tumor suppressor, depending on the cancer types, through epigenetic regulation. Epigenetic regulation including DNA methylation and histone modifications are critically involved in cancer metastasis. We then hypothesized that CTCF might play a vital role in epithelial ovarian cancer metastasis. Firstly, we found that CTCF expression was elevated in ovarian cancer tissues compared to non-tumor tissues. The elevated expression of CTCF predicts poor prognosis of ovarian cancer patients. Then, we revealed that CTCF knockdown significantly inhibited the migration, invasion and metastasis of ovarian cancer cells, although it had no effect on cell proliferation and tumor growth, which have been demonstrated with both in vitro and in vivo experiments. More importantly, we observed a higher CTCF expression in metastatic lesions than that in primary lesions from ovarian cancer patients. Mechanically, PCR array demonstrated that CTCF might regulate a series of metastasis associated genes, including CTBP1, SERPINE1 and SRC. Finally, we observed positive correlations between CTCF expression and those three genes in epithelial ovarian cancer specimens. In conclusion, this study demonstrates that CTCF is an oncogene in ovarian cancer to promote tumor metastasis through broadly controlling the expression of metastasis-associated genes. Our findings suggest CTCF could be a novel drug target to treat ovarian cancer by interfering with cancer cell metastasis. Overall design: Examination of CTCF binding site using SKOV3 cell lines