Cyclin D1 overexpression in hepatocellular carcinoma

Background/Aims. Cyclin D1 gene amplification and cyclin D1 protein overexp ression have been reported in various human tumors, including hepatocellula r carcinoma (HCC). However, their significance is still controversial. In t he present study, we examined the expression of cyclin D1 and its relations hips to p53 and Ki-67 in HCCs. Methods. The expression and topological dist ribution of cyclin DI, p53 and Ki-67 in 50 cases of HCC were examined immun ohistochemically, and the relationship between the expression of these prot eins and their pathologic features was investigated. Results: Overexpressio n of cyclin D1 was noted in 58% of the HCC cases, and significantly associa ted with a well-differentiated histology and a low Ki-67 labeling index (LI ). Cyclin DI overexpression was also observed in all (7 of 7) dysplastic no dules and in non-neoplastic hepatocytes. On the other hand, aberrant p53 ex pression was detected in 36% of the cases, which showed positive relationsh ips with poor differentiation, portal vein invasion, and KI-67 LI. Only eig ht of the 50 cases examined (16%) were positive for both cyclin D1 and p53, which showed only a small number of cyclin D1-positive cells. There was no significant relationship between the expressions of cyclin D1 and p53. Con clusions: Our results suggest that cyclin D1 overexpression may be an early event in hepatocarcinogenesis and that it plays a role in tumor differenti ation. In addition, cyclin DT expression is not correlated with tumor cell proliferation in HCCs.