The Expression of p16 in Diffuse Large B-cell Lymphoma and Its Prognostic Implications

Abstract

Background: The molecular mechanisms that are responsible for the initiation and progression of diffuse large B-cell lymphoma are largely unknown. p16 is an inhibitor of cyclin-dependent kinase and its inactivation by methylation has been reported as a major tumorigenic mechanism in malignant tumors. The aim of this study was to analyze the correlation between the clinical data and the p16 protein expression in diffuse large B-cell lymphomas. Methods: Tumor samples were obtained from 62 patients who were suffering with diffuse large B-cell lymphoma. To investigate the role of p16 in the pathogenesis and progression of diffuse large B-cell lymphoma, 62 cases of diffuse large B-cell lymphoma were examined for their expression of p16 via performing immunohistochemistry. The correlation of the p16 expression with the various clinico- pathologic findings was also analyzed. Results: p16 was expressed in all the cases of reactive lymphoid hyperplasia (100%) and in 40 cases (64.5%) out of the 62 cases of diffuse large B-cell lymphoma that we studied. The expression rate of p16 was 31.8% in the high risk group and 82.5% in the low risk group of diffuse large B-cell lymphoma. The expression rate of p16 in the fatal cases was 12.5%. For our results, the loss of a p16 expression in diffuse large B-cell lymphoma was noted, and especially in the high risk group (P=0.04). Conclusion: The loss of p16 appeared to be involved in the genesis or progression of diffuse large B-cell lymphoma. In addition, the loss of the p16 expression may play important roles for patients' progression into the high risk group and it may cause more mortality for those patients with diffuse large B-cell lymphoma. Deranged expressions and loss of the p16 expression may play an important role in the pathogenesis of diffuse large B-cell lymphoma. (Korean J Hematol 2007;42:129-135.)