RBM17 Promotes the Chemoresistance of Oral Squamous Cancer Cells Through Checkpoint Kinase 1.

Oral squamous cell carcinoma (OSCC) is one of the most common types of cancer in the head and neck region. In advanced stages of OSCC, chemotherapy is commonly used for treatment, despite some cancer cells having low sensitivity to anticancer drugs. We focused on RBM17/SPF45 as an essential drug-sensitizing factor in the context of malignant cells acquiring chemoresistance. Here, we demonstrate how RBM17 affects anticancer drug resistance in OSCC and we suggest the possible mechanism underlying its effects. After exposing oral cancer cell lines to fluorouracil (5-FU) and cisplatin, but not paclitaxel, the gene and protein expression of RBM17 increased. We found that siRNA-mediated RBM17-knockdown of the cell lines gained a significantly higher sensitivity to 5-FU, which was remarkably followed by a decrease in the expression of checkpoint kinase 1 (CHEK1) protein, whereas treatment with a CHEK1 inhibitor did not affect RBM17 protein expression in the oral cancer cell lines. These results indicate that RBM17 is a factor involved in the development of resistance to cytotoxic chemotherapy. We propose the underlying mechanism that RBM17 promotes CHEK1 protein expression in the ATM/ATR pathway, triggering the development of chemoresistance in cancer cells.