Specific changes in the collagen phenotype of BALB 3T3 cells as a result of transformation by sarcoma viruses or a chemical carcinogen

Abstract

Radioactive proline-labeled procollagen, accumulated during a 3 h incubation of normal and transformed BALB 3T3 cultures, was treated with pepsin and the resulting collagen components were analyzed by carboxymethyl-cellulose chromatography and sodium dodecyl sulfate/polyacrylamide gel electrophoresis in the presence or absence of reducing agent. Collagen in the medium of 3 subclones of BALB 3T3 A-31 that exhibited contact inhibition of growth at confluence, as well as in the medium of one that did not, consisted of .alpha.1 and .alpha.2 subunits in the ratio of 3:1, suggesting that 3T3 cells synthesize type I collagen, [.alpha.1(I)]2.alpha.2, and another type designated X, composed of .alpha.1 chains, which may or may not be identical to .alpha.1(I). Culture medium from 3T3 transformed by Kirsten or Moloney sarcoma virus contained type I collagen and another type differing from I and X and designated type Y. The latter appeared to be similar to type III collagen [.alpha.1(III)]3, since it contained intrahelical disulfide bonds. Analysis of intracellular collagen also demonstrated the presence of type III in Ki-3T3 and its absence from 3T3 cells. Collagen components from the medium of an SV 40 transformant were identical to those of the contact inhibited clones, while the collagen from a 4-nitroquinoline-1-oxide-induced transformant was composed of 2 components differing from .alpha.1(I), .alpha.2, and .alpha.1(III). The type of collagen accumulated in transformed cell cultures may be specifically related to the transforming agent.