Protein expression of cell cycle regulator, p27(Kip1), correlates with histopathological grade of non-Hodgkin's lymphoma

The protein p27(Klp1) is one of the cyclin-dependent kinase inhibitors that are known to play important roles in the regulation of cell-circle progres sion. Low. levels of p27 expression in malignant cells are associated with poor prognosis in patients with breast. lung, colorectal and gastric cancer s, To determine the relation of cyclin-dependent kinase inhibitors to histo pathological grades of B-cell non-Hodgkin's lymphomas, the expression of p2 7, cyclin Df and cyclin E in lymph node tissues was investigated in 56 pati ents with B-cell non-Hodgkin's lymphomas by western blotting and immunohist ochemical techniques. High levels of p27 expression were observed in most l ymph node tissue samples (93%) obtained from patients with low grade B-cell non-Hodgkin's lymphomas, while expression was low in lymph node tissue tak en from all patients with intermediate and high grade B-cell non-Hodgkin's lymphomas. The difference in p27 expression in lymphoma tissues was signifi cant among the different histopathological grades of B-cell non-Hodgkin's l ymphomas (P<0.01), The analysis of the survival time of patients showed tha t the reduction of p27 expression correlated with poor prognosis. Cyclin DI . showed a high level of expression in mantle cell lymphomas and high grade B-cell non-Hodgkin's lymphomas. Cyclin E showed limited expression in Ig o f 31 lymphoma tissues, Both cyclin D1 and E protein expression were not sig nificantly different among the grades of B-cell non-Hodgkin's lymphomas. Th ese results demonstrate that the level of p27 expression in lymphoma tissue is an important parameter in the classification of B-cell non-Hodgkin's ly mphomas and in the prediction of prognosis.