DOWN-REGULATION OF COLLAGEN-XII IN TRANSFORMED MESENCHYMAL CELLS

Collagen XII is a complex multidomain protein associated with the surf ace of interstitial collagen fibrils. This protein is produced in larg e amounts by fibroblasts cultivated in vitro. However, it is completel y absent from cells transformed by the oncogene v-myc or v-src and fro m cells derived from a methylcholanthrene-induced fibrosarcoma. Since all these cells lack any mRMA for collagen XII, it seems likely that t he synthesis is blocked at the transcriptional level. Experiments with a temperature-sensitive mutant of Rous sarcoma virus demonstrated tha t a single oncogene product is sufficient to inhibit the synthesis. A reduction in the expression of collagen XII might have profound effect s on the stability of the extracellular matrix of transformed cells. ( C) 1995 Wiley-Liss, Inc.