Multiple sites of highly amplified DNA sequences detected by molecular cytogenetic analysis in HS-RMS-2, a new pleomorphic rhabdomyosarcoma cell line.

A molecular cytogenetic analysis was performed on HS-RMS-2, a cell line established in this laboratory from a rare pleomorphic type of rhabdomyosarcoma. G-banding and multicolor-FISH analyses revealed that the cells have a complex chromosomal composition. Comparative genomic in situ hybridization (CGH) detected eight highly amplified regions at 1p36.1-p36.2, 1p31-p32, 1q21-q31, 8q12-q21, 8q24-qter, 11q12-q13, 12q13-q14 and 18q12-q22, suggesting the co-existence of multiple amplified oncogenes in these tumor cells. Reverse chromosome painting, using a probe regenerated by microdissection of a long marker chromosome, revealed the native location of three of eight possible genes to be on chromosomes 1p31-32, 12q14 and 18q21. FISH using BAC and cosmid probes revealed amplification of JUN (1p31), MYC (8q24), CCND1 (11q13), INT2 (11q13.3), MDM2 (12q14.3-q15) and MALT (18q21). These findings indicate that at least eight amplified oncogenes may contribute to the pathogenesis of a rare pleomorphic type of rhabdomyosarcoma. This new cell line should prove useful for in vitro preclinical studies of molecularly targeted therapies.