ISOLATION OF GENES DIFFERENTIALLY EXPRESSED IN HUMAN PRIMARY MYOBLASTS AND EMBRYONAL RHABDOMYOSARCOMA

Using a subtractive hybridization method, we have cloned 48 cDNAs whic h are expressed in human primary myoblasts but down-regulated in the e mbryonal-rhabdomyosarcoma (RMS) cell line RD. Twenty-nine sequences co uld be identified as coding for previously known gene products, while 19 encode unknown proteins. Twelve clones coding for known proteins th at were highly down-regulated in the RD cells were chosen for further analysis on Northern blots containing additional normal and RMS cells. The expression pattern of TGF-beta-induced gene product-3 (beta igH3) , inhibitory G-protein alpha sub-unit (G alpha(12)), osteoblast-specif ic factor-2 (OSF-2), 22-kDa smooth-muscle protein (SM22), clone A3351 (homologous to mouse talin), testican, thrombospondin-1 and thrombospo ndin-2 suggests involvement of these proteins in the genesis of the ne oplastic phenotype. Among the clones with unknown sequence, several ar e identical or homologous to expressed sequence tags or known cDNA5, s uch as integrins or laminin. These results suggest that several isolat ed clones might have an important role in the determination or mainten ance of the normal phenotype, and thus their loss is possibly involved in the progression of malignancy. (C) 1996 Wiley-Liss, Inc.