Low cyclin F expression in hepatocellular carcinoma associates with poor differentiation and unfavorable prognosis

Cyclin F, capable of forming Skp1‐Cul1‐F‐box protein ubiquitin ligase complex, is implicated in controlling centrosome duplication and preventing genome instability. Cyclin F oscillates during cell cycle with a similar pattern to cyclin A. However, its expression and significance in cancer remain obscure. In this study, we showed that cyclin F was noticeably decreased in 16 pairs of tissue samples of hepatocellular carcinoma (HCC) compared to paracarcinoma tissues, at both mRNA and protein levels. Immunohistochemical staining data revealed that in 71.8% (176/245) of HCC cases, cyclin F expression in tumor tissue was much lower than that in nontumorous tissue. Low cyclin F expression, defined by receiver operating characteristic curve analysis, was present in 69.0% of HCC patients. Low expression of cyclin F was significantly correlated with tumor size, clinical stage, serum alpha‐fetoprotein level and tumor multiplicity. Further study showed that cyclin F expression was reversely associated with tumor differentiation in HCC. Kaplan–Meier analysis indicated that low cyclin F expression was related to poor overall survival and recurrence‐free survival. The prognostic impact of cyclin F was further confirmed by stratified survival analysis. Importantly, multivariate analysis revealed that low cyclin F expression was an independent poor prognostic marker for overall survival. We conclude that cyclin F is downregulated in HCC and is a promising prognostic marker for patients suffering from this deadly disease.