FBJ Virus-Induced Osteosarcoma Contains Type I, Type I Trimer, Type III as Well as Type V Collagens

Abstract

The FBJ osteosarcoma (a virus-induced osteosarcoma named after its discoverers, Finkel, Biskis, and Jinkins) contains an extensive extracellular matrix. Collagens were extracted by digestion with pepsin in dilute acetic acid from tumors grown in lathyritic mice and fractionated by differential salt precipitation, yielding five fractions. Fraction 1 (precipitated at acidic 0.7M and neutral 2.0M NaCl) gave rise mainly to α1 (III) chain on phosphocellulose column chromatography. The α1 (III) chain was identified by its typical behavior on interrupted electrophoresis and analysis of the CNBr-cleaved peptides. The α1 (III) chain of the FBJ tumor had a high content of hydroxylysine and neutral saccharide. Fraction 2 (precipitated at acidic 0.7M and neutral 4.5M NaCl) yielded α1 (I) and α2 (I) chains on the phosphocellulose column from which α1 (I) was eluted as a broad peak, conceivably reflecting a high content of hydroxylysine and neutral saccharide. Fraction 4 (precipitated at acidic 1.2M and neutral 4.5M NaCl) yielded type V collagen, which also featured an exceptionally high content of neutral saccharide (Yamagata, S., et al. (1982) Biochem. Biophys. Res. Commun. 105, 1208-1214). The proportions of type I, type I trimer, type III, and type V collagens extracted by pepsin digestion from FBJ tumor were calculated to be 33, 29, 26, and 12%, respectively.
The FBJ tumor is free from invasion by blood vessels, shows no deposition of calcium, and thus has the appearance of cartilage. But type II collagen, a specific gene product of cartilage, could not be identified in any of the fractions analyzed. Contrary to its appearance, collagen type analyses indicate that FBJ osteosarcoma is literally induced from osteogenic cells.