ABSENCE OF REGULAR ALPHA(2)(I) COLLAGEN CHAINS IN COLON-CARCINOMA BIOPSY FRAGMENTS

The extracellular matrix (ECM) is known to play an active role in nume rous biological processes such as differentiation, apoptosis and cance r, Extensive alterations of epithelial basement membranes and of inter stitial ECM are known to occur during the progression of most invasive carcinomas. Collagen, which represents the major component of the int erstitial ECM, is primarily involved in the stromal changes at the sit e of tumor cell invasion. We have previously described the occurrence in breast and colon cancer ECM of an oncofetal form of collagen, chara cterized by an acidic chain distinct from those of type I and III coll agen. In the present paper, we bring evidence that alpha(2)(I) collage n chains in colon cancer tissues expressing the acidic chains, are eit her overmodified or absent, both as protein and as regular mRNA transc ripts, The results obtained strongly suggest that: i) the disorganisat ion of the collagen architecture and the phenomenon of fibril dispersi on, which accompanies the lysis of basement membrane, is not only due to the enzymatic degradation of the collagen fibres, but presumably al so to changes of the collagen molecules deposited in the stroma; ii) t he neosynthesis of collagen occurring at tumor-host interface is deepl y deregulated, and therefore to be considered the result of altered co llagen gene expression correlated with the tumor progression, rather t han as a mere defensive reaction of the host cells.