Overexpression of MSK1 is associated with tumor aggressiveness and poor prognosis in colorectal cancer

Background/Aims Mitogen- and stress-activated protein kinase 1 (MSK1) has recently been implicated in cell proliferation and neoplastic transformation. However, the involvement of MSK1 in colorectal cancer (CRC) has not been addressed. This study aimed to evaluate the expression and potential functions of MSK1 in CRC. Methods The MSK1 expression was investigated by immunohistochemistry, western blot and reverse transcription-polymerase chain reaction. The associations between clinicopathological characteristics and MSK1 expression were assessed. Kaplan–Meier analysis and Cox regression models were carried out. CRC cells with MSK1 knockdown or overexpression were generated. A range of experiments were performed to demonstrate MSK1’s role in CRC. Results MSK1 was overexpressed in 148 out of 329 CRC patients. CRC patients with high MSK1 expression had shorter overall survival than those with low MSK1 (P = 0.033), especially among patients with stage III tumors (P = 0.005). Knockdown of MSK1 in CRC cells suppressed cell proliferation, anchorage-independent growth, migration and invasion, and promoted 5-fluorouracil chemosensitivity and intracellular NADP⁺/NADPH ratio. However, overexpression of MSK1 had the opposite effects. Conclusions Overexpression of MSK1 is associated with poor prognosis in CRC and is connected to tumor aggressiveness. MSK1 is a potential target for new therapies and a candidate of biomarker for prognosis.