Mutational analysis of the CDKN2 (MTS1/p16ink4A) gene in primary B-cell lymphomas

Abstract

The CDKN2 gene located on chromosome 9p21 encodes the cyclin-dependent kinase-4 inhibitor p16. This gene is a putative tumor-suppressor gene because of its frequent alterations in many kinds of tumor cell lines. We analyzed the CDKN2 gene to evaluate its alterations in 52 primary specimens of non-Hodgkin's lymphoma (NHL) or chronic lymphocytic leukemia (CLL) of B-cell origin by Southern blot analysis, polymerase chain reaction-mediated single-strand conformation polymorphism (PCR-SSCP) analysis, and direct sequencing. By Southern blot analysis, we showed homozygous deletion of the CDKN2 gene in 3 of 42 patients with B-NHL (7.1%). After screening by PCR-SSCP analysis, direct sequencing identified one missense mutation at codon 72 (nucleotide 233) and two frameshifts due to a 35-bp deletion arising at codon 49 (nucleotides 163 to 175) in patients with B-NHL (3 of 42, 7.1%). In the patient carrying the missense mutation, hemizygous deletion of the CDKN2 gene was also suspected. In this study, we detected alterations in CDKN2 in 6 of 42 patients (14.3%) with B-NHL and in none of 10 patients with B-CLL. Our results suggest that the CDKN2 alterations contribute in tumorigenesis in some patients with B-NHL.

The CDKN2 gene alterations in various types of adult T‐cell leukaemia

“…Alterations in the CDKN2 gene have frequently been found in acute lymphocytic leukaemia (ALL) (Cayuela et al, 1996;Ogawa et al, 1995;Ohnishi et al, 1995;Quesnel et al, 1995), especially the T-cell phenotype (Schröder et al, 1995;Siebert et al, 1995), but rarely in acute myelogenous leukaemia Nakamaki et al, 1995). Furthermore, we found, as did other investigators, that changes in the CDKN2 gene may contribute to tumourigenesis in some patients with non-Hodgkin's lymphoma (NHL) (Koduru et al, 1995;Uchida et al, 1995).…”

“…In lymphoid malignancies, the CDKN2 gene is inactivated mainly by homozygous deletions (Ogawa et al, 1995). However, we reported some point mutations in B-cell type non-Hodgkin's lymphomas (Uchida et al, 1995), and other investigators have also reported point mutations in acute lymphocytic leukaemia (Cayuela et al, 1996;Ohnishi et al, 1995;Quesnel et al, 1995) and chronic lymphocytic leukaemia (Haider et al, 1995;Otsuki et al, 1995). Thus, the CDKN2 gene appears to be inactivated by point mutations in some patients with lymphoid malignancies.…”

“…Southern blot analysis. Southern blotting was performed as described previously (Uchida et al, 1995). Briefly, DNA was digested with EcoRI (Boehringer Mannheim, Mannheim, Germany), separated by electrophoresis through 0 .…”

“…As exon 2 is too long for PCR-SSCP analysis, we divided it into three fragments, designated CDKN2-exon 2A, CDKN2-exon 2B and CDKN2-exon 2C. To make these fragments, we used published primer sequences (Kamb et al, 1994;Uchida et al, 1995). PCR-SSCP analysis was performed using these four fragments, respectively.…”

“…PCR-SSCP analysis was performed using these four fragments, respectively. PCR-SSCP analysis has been described previously (Uchida et al, 1995).…”