Methylation is an inactivating mechanism of the p16 gene in multiple myeloma associated with high plasma cell proliferation and short survival

Abstract

Summary. In order to gain further insights into the role of the p16 gene in cell cycle regulation and the prognostic implications of its inactivation, we investigated the methylation status of the p16 gene in 98 untreated patients using a polymerase chain reaction assay based on the inability of some restriction enzymes to digest methylated sequences. Forty-one patients showed a p16 methylated gene (42%). The percentage of S-phase plasma cells (PC) in these patients was almost three times higher than in those with an unmethylated p16 gene (4AE16% ± 3AE37% vs 1AE5% ± 1AE41%, P < 0AE001). The presence of p16 methylation also correlated with both elevated b2-microglobulin serum levels and high C-reactive protein values. Patients with a p16 methylated gene had shorter overall and progression-free survival than those patients without p16 methylation. However, this feature did not retain independent prognostic influence on multivariate analysis, probably due to its association with the S-phase PC, which had more potent statistical significance in the Cox model. These findings showed methylation of the p16 gene was a frequent event in MM patients at diagnosis, and was associated with an increased proliferative rate of plasma cells and a poor prognosis, indicating an important role for p16 gene in the cell cycle regulation of multiple myeloma tumour cells, and thus in the clinical outcome of the disease.

DNA methylation changes in multiple myeloma

“…Previous reports have already shown that hypermethylation of p16 is a common phenomenon in MM and MGUS. [6][7][8][9]35 While two studies found a correlation of aberrant p16 methylation with a poorer outcome, 8,9 Guillerm Figure 1 Representative MSP analysis of patient samples. Lanes U: amplified products with primers recognizing the unmethylated gene sequence.…”

“…This epigenetic event acts as an alternative to mutations and deletions to disrupt tumor suppressor gene function. 4,5 It was reported previously that hypermethylation of the cell cycle inhibitors p15 and p16, [6][7][8][9] the apoptosis regulator DAP kinase 10 and the tumor suppressor RASSF1A 11 may occur in MM patients. Additionally, we have recently identified hypermethylation-associated silencing of the suppressor of cytokine signaling-1 (SOCS-1) gene to be a frequent epigenetic aberration in MM.…”

p16/INK4a gene methylation is a frequent finding in pulmonary MALT lymphomas at diagnosis

“…p16 gene methylation has been considered to be a molecular event associated with the progression of MALT lymphoma to its high-grade counterpart. [15][16][17][18][19] However, our findings suggest that p16 gene methylation is not associated with the tumor progression but rather may contribute to the 35,36 and by the frequent p16 gene methylation found in monoclonal gammopathy of undetermined significance, in the plaque phase of mycosis fungoides, and in other premalignant lesions. [20][21][22]37 Several MALT lymphoma-specific or -associated gene alterations have been reported, such as translocations between the immunoglobulin heavy chain gene and BCL10 gene or MALT1 gene, trisomy 3, and trisomy 18, as well as API2-MALT1 fusion.…”

“…10,11 In lymphoid malignancies, p16 gene silencing, mainly induced by gene methylation, is frequently found in Hodgkin and non-Hodgkin lymphomas, [12][13][14] and has been associated with tumor progression. [15][16][17][18][19] However, it has also been suggested that the methylation of this gene is one of the early events in the development of lymphoid malignancies. [20][21][22] MALT lymphoma constitutes more than 80% of all primary lung lymphomas.…”

Primary cutaneous marginal zone B-cell lymphoma: a molecular and clinicopathological study of cases from Asia, Germany, and the United States

“…In other B-cell malignancies, DAPK and p16 gene methylation has been associated with tumor progression. [40][41][42] However, recent studies have shown that methylation of these genes may be an early event in lymphomagenesis: DAPK and p16 gene methylation is frequently found in premalignant and low-grade lymphoid disorders, not associated with tumor progression, and their methylation status is maintained in higher-grade or advanced lymphoid neoplasms. [43][44][45][46][47][48] In line with these findings, methylation of DAPK and p16 is a common, early epigenetic phenomenon that allows tumor cells to promote cellcycle progression and escape the normal apoptosis of a non-antigen-stimulated expanded B-cell population.…”