ANALYSIS OF CYCLIN-DEPENDENT KINASE INHIBITOR GENES (CDKN2A, CDKN2B, AND CDKN2C) IN CHILDHOOD RHABDOMYOSARCOMA

p16(INK4A), p15(INK48), and p18 proteins are highly specific inhibitor s of cyclin-dependent serine/threonine kinase (CDK) activities require d for GI-S transition in the eukaryotic cell division cycle. Mutations , mainly homozygous deletions, of the CDKN2A (p16(INK4A)/MTSI) gene ha ve been recently found in tumor cell lines and in many primary tumors. We looked for homozygous deletions of CDKN2A, CDKN2B (p15(INK4B)), an d CDKN2C (p18) in 12 primary rhabdomyosarcoma (RMS) specimens and in f ive cell lines established from this cancer type. By means of polymera se chain reaction (PCR) and PCR-single strand conformation polymorphis m (PCR-SSCP), we analyzed the presence of biallelic gene deletion or p oint mutation causing gene function loss. All the examined tumor cell lines (100%) and three of 12 (25%) primary tumors showed homozygous de letion of CDKN2A. Furthermore, no aberrant bands in primary tumors wer e detected via SSCP, suggesting the absence of mutations in the coding region. In all cases the deleted area at 9p21 also involved the CDKN2 B gene. Conversely, no homozygous deletion or point mutations were det ected when CDKN2C was analyzed. Our results strongly indicate that the p16(INK4A) (and/or p15(INK4B)) protein plays a key role in the develo pment and/or progression of childhood rhabdomyosarcoma and suggest tha t this CDK-inhibitor protein might control proliferation and/or differ entiation of human muscle cells. Moreover, alteration of CDKN2C does n ot appear to be involved in the genesis of rhabdomyosarcoma. (C) 1996 Wiley-Liss, Inc.