Alternative splicing of VEGFA is regulated by RBM10 in endometrial cancer

Abstract Vascular endothelial growth factor A (VEGFA) gene has three alternative exons which results in multiple isoforms. VEGFA has been found overexpressed in patients with endometrial cancer, but the VEGFA expression pattern and how it is regulated are still unknown. The level of VEGFA transcripts and protein isoforms were detected by semi‐quantitative Polymerase chain reaction (PCR) and immunoblotting in 29 paired endometrial tumor and adjacent nontumor control tissues. The level of three alternative splicing related proteins: RBM5, RBM6, and RBM10 was determined by immunoblotting. The H3K27Ac level in RBM10 promoter region was detected by ChIP‐PCR. The RBM10 promoter region methylation level were quantified by methylation‐sensitive high resolution melting. VEGFA165a was overexpressed and VEGFA165b level was reduced in tumors. RBM10 level was reduced in tumors. RBM10 level was negatively correlated with VEGFA165a level and positively correlated with VEGFA165b level in tumors. Using HEC‐1‐A and RL95‐2 cells, we confirmed that VEGFA165a/b expressed pattern was controlled by RBM10. MALAT1 level was increased in tumors but not involved in VEGFA alternative splicing. Reduced H3K27Ac level and increased DNA methylation in the promoter region controlled RBM10 expression in tumors. VEGFA alternative splicing in endometrial cancer was regulated by RBM10, the expression of which was controlled by histone acetylation and DNA methylation.