Allelic loss of chromosomes 8 and 19 in MENX-associated rat pheochromocytoma.
Pheochromocytomas are neoplasias of neural crest origin that arise from the chromaffin cells of the adrenal medulla. Pheochromocytomas arise with complete penetrance in rats homozygous for a germ-line frameshift mutation of Cdkn1b, encoding the cell cycle inhibitor p27KIP1 (MENX syndrome). We performed a genome-wide scan for allelic imbalance comparing 20 rat pheochromocytoma DNAs with normal rat DNA to better understand the pathobiology of the tumors and to correlate the findings with human pheochromocytoma. We identified allelic imbalance (AI) at candidate regions on rat chromosomes 8 and 19. Interestingly, the regions often lost in rat tumors are syntenic to regions involved in human pheochromocytomas. Fluorescence in situ hybridization analysis further validated the AI data. Sdhd and Rassf1a were analyzed in detail as they map to regions of AI on chromosome 8 and their homologues are implicated in human pheochromocytoma: we found no genetic mutations nor decreased expression. We also analyzed additional candidate genes, that is, rat homologues of genes predisposing to human pheochromocytoma and known tumor-suppressor genes, but we found no AI. In contrast, we observed frequent overexpression of Cdkn2a and Cdkn2c, encoding the cell cycle inhibitors p16INK4a and p18INK4c, respectively. The relative small number of allelic changes we found in rat pheochromocytoma might be related to their nonmalignant status and losses at chromosomes 8 and 19 are events that precede malignancy. Because of the high concordance of affected loci between rat and human tumors, studies of the MENX-associated pheochromocytomas should facilitate the identification of novel candidate genes implicated in their human counterpart.
Shyla
Alena
A
Institute of Pathology, Helmholtz Zentrum München-German Research Center for Environment and Health, Neuherberg, Germany.
Hölzlwimmer
Gabriele
G
Calzada-Wack
Julia
J
Bink
Karin
K
Tischenko
Oleg
O
Guilly
Marie-Noëlle
MN
Chevillard
Sylvie
S
Samson
Elenore
E
Graw
Jochen
J
Atkinson
Michael J
MJ
Pellegata
Natalia S
NS
D000310:Adrenal Gland Neoplasms / Q000235:genetics* / Q000473:pathology; D000818:Animals; D002888:Chromosomes, Human, Pair 19; D002898:Chromosomes, Human, Pair 8; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics*; D018450:Disease Progression; D016368:Frameshift Mutation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D019656:Loss of Heterozygosity; D018895:Microsatellite Repeats; D010673:Pheochromocytoma / Q000235:genetics* / Q000473:pathology; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D015854:Up-Regulation
C493962:Cdkn1b protein, rat; D050760:Cyclin-Dependent Kinase Inhibitor p27