Differentiation induction in the human rhabdomyosarcoma cell line TE-671. A morphological, biochemical and molecular analysis.

In the clonal human rhabdomyosarcoma cell line TE-671-1A, the expression of genes implicated in myogenic differentiation was determined before and after exposure to the differentiation inducers retinoic acid (RA), sodium butyrate (NaBut) and N-monomethylformamide (NMF). Exposure to NaBut or RA resulted in a significant (NaBut: p < 0.0001; RA: p < 0.05) increase in biochemical differentiation paralleled by a significant (NaBut: p < 0.0001; RA: p < 0.0002) inhibition of proliferation. An increase in the relative number of myotube-like giant cells was observed after exposure to NaBut. Exposure to NMF proved to be least effective and produced a significant (p < 0.0001) inhibition of proliferation without increase in differentiation. On the molecular level, exposure to RA resulted in a moderate increase in RAR a mRNA expression, whereas CRABP mRNA remained constant. RAR beta and RAR gamma mRNA were not expressed. mRNA expression of c-raf, c-myc and c-Ki-ras remained constant before and after exposure to all inducers of differentiation. C-fos mRNA was not expressed. In summary, differentiation can successfully be induced in the human rhabdomyosarcoma cell line TE-671-1A by various inducers of differentiation. In contrast to other myogenic cell lines, however, the proto-oncogenes myc, fos and raf are not involved in the transmission of myogenic differentiation signals in TE-671-1A cells.