USP39 promotes colorectal cancer growth and metastasis through the Wnt/β-catenin pathway.

In the present study, we first examined the expression of USP39 protein using tissue array containing 90 colorectal cancer (CRC) tissues and 9 clinical samples, and observed that it has significantly higher expression in cancer tissues as compared to the corresponding adjacent normal tissues. Also, we tested USP39 expression level in four CRC cancer cell lines and identified that it indeed had higher expression in all these CRC cell lines. In addition, its knockdown inhibited not only the cell growth of SW480 and HT29 cells, but also the cell migration and invasion. Further analysis of its molecular mechanism suggested that the expression of four crucial proteins of Wnt/β-catenin pathway, including β-catenin, TCF4, MMP2 and MMP9 was reduced as a result of USP39 knockdown. Taken together, all these findings demonstrated that USP39 protein plays an important role in the growth and metastasis of colorectal cancer mainly through Wnt/β-catenin pathway.