Disruption of the FOXM1 Regulatory Region Inhibits Tumor Progression in Ovarian Cancer by CRISPR‐Cas9

Ovarian cancer is the seventh most common lethal tumor among women in the world. FOXM1 is a transcription factor implicated in the initiation and progression of ovarian cancer by regulating key oncogenic genes. The role of regulatory regions in regulating the expression of FOXM1 in ovarian cancer is not completely clarified. Treatment with bromodomain and extraterminal (BET) inhibitors JQ-1 and I-BET were explored in ovarian cancer cell lines (OVCAR3, A2780, or SKOV3) to evaluate FOXM1 expression and biological behavior by qPCR, CCK8 assay, colony formation assay, wound-healing, and transwell assays. The regulatory regions (enhancer sequence spanning promoter or exon 1) of FOXM1 were deleted using CRISPR-Cas9 in the OVCAR3 cell line. FOXM1 expression and tumor biological behavior were further assessed in FOXM1 regulatory regions deleted OVCAR3 cell line. The mouse xenograft model was assessed at the indicated time points following subcutaneous injection of enhancer-deleted cells. Treatment with the JQ-1 and I-BET reduced the expression of FOXM1, decreasing cell proliferation, migration, and invasion in a panel of ovarian cancer cell lines including OVCAR3, A2780, and SKOV3 cells. By mining the published ChIP-sequencing data (H3K27Ac) from 12 ovarian cancer cell lines, we identified a potential enhancer and promoter region. Deletion of the spanning enhancer and promoter region of FOXM1 reduced mRNA and protein expression. Similarly, cell proliferation, migration, invasion, and tumorigenesis in both cells and mouse xenograft models were significantly attenuated. Our study demonstrates that JQ-1 and I-BET can regulate the expression of the FOXM1 gene-relating network. These data also indicate that disruption of the span enhancer and promoter region activity of FOXM1 has a vital role in the anti-ovarian cancer effect, hiding a potential opportunity for the evaluation of this non-coding DNA deletion disrupts the FOXM1 transcriptional network in ovarian cancer development.