Codeletion of CDKN2 and MTAP genes in a subset of non-Hodgkin's lymphoma may be associated with histologic transformation from low-grade to diffuse large-cell lymphoma.
Identifying the various genetic alterations that contribute to lymphomagenesis is key to our improved understanding of the biological behavior of the disease. Recently, we and others have defined a tumor suppressor region on the short arm of chromosome 9 harboring a cluster of genes, including MTAP, CDKN2A (p16INK4a), and CDKN2B (p15INK4B), which is frequently deleted in a variety of tumor types. To determine whether this region is involved in a particular subset of malignant lymphomas, we have examined 16 cases of diffuse large-cell lymphoma (DLCL) (including three cases that evolved from low-grade non-Hodgkin lymphoma (NHL) (transformed DLCL)), and nine cases of low-grade NHL that had subpopulations of large cells with a diffuse growth pattern (seven follicular NHL, one chronic lymphocytic leukemia, one mycosis fungoides). Interphase fluorescence in situ hybridization was performed on these samples using a 250-kb cosmid contig (COSp16), which encompasses MTAP, CDKN2A, and CDKN2B. Six of the 16 DLCLs and one of nine low-grade NHLs had deletions of COSp16. COSp16 was homozygously deleted in four cases; two cases had hemizygous deletions, and one case had a partial homozygous deletion of the cosmid contig. Three of 13 cases of de novo DLCL, all three transformed DLCLs, and one of nine low-grade NHL had COSp16 deletions. Although the numbers are small, COSp16 deletion was associated with transformed DLCL in contrast to de novo DLCL (P < 0.04, Fisher's exact test) or low-grade NHL (P < 0.02). The COSp16 deletion was mostly submicroscopic and was not observed in association with any specific recurring cytogenetic abnormalities. These results suggest that targeted deletion of the CDKN2A region occurs in a subset of non-Hodgkin's lymphomas, and may be associated with transformed lymphomas.
Dreyling
M H
MH
Department of Medicine, The University of Chicago, Illinois 60637, USA.
Roulston
D
D
Bohlander
S K
SK
Vardiman
J
J
Olopade
O I
OI
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000473:pathology; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics*; D005260:Female; D017353:Gene Deletion; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D016403:Lymphoma, Large B-Cell, Diffuse / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D008228:Lymphoma, Non-Hodgkin / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011683:Purine-Nucleoside Phosphorylase / Q000235:genetics*
D019941:Cyclin-Dependent Kinase Inhibitor p16; D011683:Purine-Nucleoside Phosphorylase; C021784:5'-methylthioadenosine phosphorylase