Expression of cyclin-dependent kinase inhibitor p27kip1 in malignant lymphomas

p27(kip1) is a cyclin-dependent kinase inhibitor that regulates progression from G1 into S phase. Aberrations in cell cycle control are often observed in tumors and might even be necessary in tumor development, Recent reports showed that low p27(kip1) expression is associated with poor prognosis in several tumors and leukemia. To investigate the expression of p27(kip1) in malignant lymphomas and elucidate the role of p27(kip1) as a possible prognostic indicator, the authors performed an immunohistochemical staining of p21(kip1) correlated with Ki-67 labelling index and clinical parameters, p27(kip1) expression was reduced variably in most malignant lymphomas and inversely correlated with Ki-67 labelling index (p=0.0151). Regarding chemotherapeutic response, p21(kip1) expression in the complete remission group showed statistically significant difference in expression compared to the progressive disease group (p=0.0021), There were significant differences in survival between cases with low and high p27(kip1) expression (p=0.0071). In a multivariate Cox analysis, p27(kip1) expression was independent prognostic factors as well as other known prognostic factors including age, grade, stage and chemotherapeutic response. In conclusion, the study suggests that reduced expression of p21(kip1) protein may play a role in the pathogenesis and biologically aggressive behavior of malignant lymphomas.