USP22 promotes proliferation in renal cell carcinoma by stabilizing survivin.

Renal cell carcinoma (RCC) is one of the commonest urological tumors. The incidence of RCC ranks third among urological tumors, after prostate cancer and bladder tumors. However, the etiology of RCC remains unclear. Ubiquitin-specific protease 22 (USP22), a potential marker of cancer stem cells, is associated with the occurrence and progression of numerous tumors. However, the roles of USP22 in RCC have not yet been investigated. Survivin is a member of the inhibitor of apoptotic protein family involved in RCC progression. The present study first detected the expression of USP22 and survivin in RCC tissues using immunohistochemistry and western blotting. It was revealed that the protein levels of USP22 and survivin in RCC tissues were higher than those in adjacent normal renal tissue. Subsequently, it was demonstrated that USP22 knockdown inhibited the growth of an RCC cell line ACHN and downregulated the protein level of survivin, accompanied by an increased level of cleaved-caspase-3. By contrast, overexpression of USP22 promoted the growth of ACHN cells, upregulated the expression of survivin and decreased the level of cleaved-caspase-3. Notably, the changes in USP22 expression did not affect the SURVIVIN mRNA level. Finally, it was confirmed that USP22 interacted with survivin and stabilized it by downregulating its ubiquitination. The present results indicate that USP22 may regulate survivin via deubiquitination, thereby promoting the proliferation of RCC cells. The results of the current study suggest that USP22 may represent a novel therapeutic target for patients with RCC.