Abstract

p27(kip1) protein, a cyclin-dependent kinase inhibitor, has been reported to be a powerful negative prognostic marker in patients with breast carcinoma. However, to this day, studies on p27(kip1) protein expression in ductal carcinoma in situ (DCIS) have been extremely limited. We studied the immunohistochemical expression of p27(kip1) protein in 49 cases of the DCIS and compared the findings to the clinicopathologic parameters, cyclin D1, p53 and estrogen receptor (ER). Positive nuclear staining of p27(kip1) protein was identified in 23 (46.9%) cases. The p27(kip1) protein expression correlated positively with the cyclin D1 immunopositivity (p<0.005) and ER expression (p<0.005). No significant associations were seen in the p27(kip1) protein expression and clinicopathologic parameters. The overexpression of cyclin D1 (59.2% of the cases) correlated positively with ER expression (p<0.001). The p53 protein expression was identified in 30.6% and seemed to be correlated inversely with ER expression (p=0.06). The DCISs with high grade nuclei were more likely to be p53-positive (p<0.05). Our data suggest that the expression of p27(kip1) protein as well as cyclin D1 and p53 protein may be influenced by the ER status in DCIS. The significantly positive correlation of p27(kip1) protein and cyclin D1 expression (p<0.005) supports the theory that the balance of the two opposing signals is important in determining the cell proliferation in breast cancers. Therefore, a comprehensive understanding of loop reaction of p27(kip1)-cyclin D1-ER may be necessary for the treatment of DCIS.

• Keywords: p27(kip1);Cyclin D1;p53;Breast;Ductal carcinoma in situ;