title: Refined mapping of genomic rearrangements involving the short arm of chromosome 9 in acute lymphoblastic leukemias and other hematologic malignancies.
abstract: Deletions of chromosomal band 9p21 have been detected in various tumor types as well as in more than 20% of acute lymphoblastic leukemia (ALL). These deletions frequently include the entire interferon (IFN) gene cluster as well as the methylthioadenosine phosphorylase (MTAP) gene. Recently, the CDKN2 gene (p16INK4A, MTS I, CDK41) was proposed as a candidate tumor-suppressor gene on 9p21 because it is frequently deleted in cell lines derived from multiple tumor types. To determine if CDKN2 or another closely related gene on 9p is the target of 9p deletions in ALL and other hematologic malignancies, we analyzed 20 primary patient samples (13 ALL, 2 acute myeloid leukemias [AML], and 5 non-Hodgkin's lymphomas [NHL]) with 9p rearrangements using Southern blot analysis, fluorescence in situ hybridization (FISH), and single-strand conformation polymorphism (SSCP) for alterations of CDKN2. Homozygous deletions of the CDKN2/CDKN2B (p15) region were detected in 10 cases (50%; 6 ALL, 2 AML, and 2 NHL). In 1 additional case, the intensity of the Southern blot band was significantly reduced, suggesting a CDKN2 deletion in a subpopulation of the malignant cells. No CDKN2 or CDKN2B rearrangements were seen. The IFN gene cluster was homozygously deleted in 2 of 15 (13%) analyzed cases, whereas the MTAP gene was deleted in 6 of 15 cases (40%). In addition, hemizygous deletions of the CDKN2 region were identified in 6 ALL cases using interphase FISH. No point mutation of the coding region of CDKN2 was detected by SSCP in these cases. We conclude that CDKN2 is the most frequently homozygously deleted marker on 9p. The absence of point mutations in the coding region of CDKN2 in cases with hemizygous 9p deletions and the frequent codeletion of MTAP, CDKN2B, and other yet unidentified neighboring genes suggest that the simultaneous deletion of these genes may be necessary for the selective growth advantage of malignant cells.
authors.affiliation: Department of Medicine, University of Chicago, IL 60637, USA.
authors.forename: M H
authors.initials: MH
authors.lastname: Dreyling
authors.forename: S K
authors.initials: SK
authors.lastname: Bohlander
authors.forename: M M
authors.initials: MM
authors.lastname: Le Beau
authors.forename: O I
authors.initials: OI
authors.lastname: Olopade
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015139:Blotting, Southern; D001853:Bone Marrow / Q000473:pathology; D001854:Bone Marrow Cells; D002352:Carrier Proteins / Q000097:blood / Q000235:genetics*; D002478:Cells, Cultured; D002675:Child, Preschool; D002869:Chromosome Aberrations; D002872:Chromosome Deletion; D025063:Chromosome Disorders; D002874:Chromosome Mapping; D002899:Chromosomes, Human, Pair 9; D019941:Cyclin-Dependent Kinase Inhibitor p16; D005260:Female; D017353:Gene Deletion; D015321:Gene Rearrangement; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007372:Interferons / Q000235:genetics; D007621:Karyotyping; D015470:Leukemia, Myeloid, Acute / Q000097:blood / Q000235:genetics* / Q000473:pathology; D008228:Lymphoma, Non-Hodgkin / Q000097:blood / Q000235:genetics* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000473:pathology; D005810:Multigene Family; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000097:blood / Q000235:genetics* / Q000473:pathology; D011683:Purine-Nucleoside Phosphorylase / Q000235:genetics
chemical_list: D002352:Carrier Proteins; D019941:Cyclin-Dependent Kinase Inhibitor p16; D007372:Interferons; D011683:Purine-Nucleoside Phosphorylase; C021784:5'-methylthioadenosine phosphorylase