Hypermethylation of the p15 INK4B gene promoter in B‐chronic lymphocytic leukemia

The p15 gene is a putative tumor suppressor gene that encodes a member of the cyclin dependent kinase inhibitors. Inactivation of p15 by promoter hypermethylation has been postulated as a possible way by which tumor suppressor genes are inactivated in cancer. In this study, we examined the methylation status of the p15 gene promoter in 34 patients with B‐Chronic Lymphocytic Leukemia (B‐CLL), by the Methylation‐Specific Polymerase Chain Reaction. Selective methylation of the p15 gene promoter was found in 4/34 cases (11.8%). According to Rai staging, the four patients with methylated p15 were staged on diagnosis as: 1 on Stage 0, 1 in Stage I, 1 in Stage III, and 1 in Stage IV. Our results suggest that methylation of the p15 gene promoter can be detected in a small subset of B‐CLL patients, at all stages of the disease. Am. J. Hematol., 2007. © 2007 Wiley‐Liss, Inc.