Aberrant expression of USP22 is associated with liver metastasis and poor prognosis of colorectal cancer.

BACKGROUND

The present study was aimed at clarifying the expression of ubiquitin carboxyl-terminal hydrolase 22 (USP22), a novel deubiquitinating enzyme gene, in colorectal cancer (CRC) and its clinical significance.

METHODS

USP22 expression was detected with quantitative RT-PCR, Western blot, and immunohistochemistry (IHC) in 43 CRCs and non-cancerous matched tissues. Furthermore, USP22 protein expression was analyzed in 192 CRC tumors by IHC to evaluate the association with survival.

RESULTS

In 43 paired fresh tissues, the expression level of USP22 was significantly higher in primary CRCs than that in the paired non-cancerous tissues at both mRNA and protein levels (P < 0.0001). Nuclear USP22 expression significantly increased from normal mucosa through adenoma to primary carcinoma (P < 0.0001) and from primary carcinoma to liver metastasis (P = 0.021). The incidence of positive USP22 expression was 54.16% in 192 conventional CRC tissues. Notably, high USP22 expression was significantly associated with shorter disease-specific survival (P < 0.0001) and shorter disease-free survival (P < 0.0001). Cox regression analysis showed USP22 was an independent prognostic parameter for CRC patients.

CONCLUSION

USP22 might be an independent predictive factor for CRC prognosis and aberrant expression of USP22 may play an essential role in colorectal carcinogenesis and liver metastasis.