Comparison of human tenascin expression in normal, Simian‐virus‐40‐transformed and tumor‐derived cell lines

Tenascin is a polymorphic high-molecular-mass extracellular-matrix glycoprotein composed of six similar subunits. Using two-domain-specific anti-tenascin monoclonal antibodies, we have studied the expression and distribution of tenascin in four cultured normal human fibroblasts, two simian-virus-40-(SV40)-transformed and three tumor-derived (melanoma, rhabdomyosarcoma and fibrosarcoma) cell lines. We found that (a) cultured normal human fibroblasts accumulate considerable amounts of tenascin and retain 60-90% in the extracellular matrix, while they release the remainder into the tissue-culture medium; (b) of the two SV40-transformed counterparts we have tested, the AG-280 cell line accumulates no detectable amounts of tenascin and the WI-38-VA cell line accumulates about 10-times less tenascin than its normal counterpart and releases about 90% of it into the culture medium; (c) some tumor-derived cell lines accumulate considerable amounts of tenascin, but in these cases, more than 90% is released into the culture media; (d) in normal human fibroblasts, two major tenascin isoforms, generated by alternative splicing of the mRNA precursor, are detectable (280 kDa and 190 kDa, respectively) and the lower-molecular-mass tenascin isoform is accumulated preferentially in the extracellular matrix; (e) in SV40-transformed or tumor-derived cell lines, only the higher-molecular-mass isoform is detectable and it is more sialylated than the tenascin produced by the normal human fibroblast cell lines.