This study indicated that human normal rectum (HNR) and human rectum
carcinoma (HRC) contained three populations of
proteoglycans (PGs). About 63% of the HNR PGs, in terms of
uronic acid, were
heparan sulfate proteoglycans (HSPGs) of M(r) 500,000 with HS side-chains of M(r) 35,000. The other two populations were
versican (29%) and
decorin (8%) of M(r) 715,000 and 90,000, respectively, bearing mainly
dermatan sulfate (DS) (73%) and
chondroitin sulfate (CS) (27%) chains of M(r) 24-26,000 and 20-22,000, respectively. In contrast, in terms of
uronic acid, HRC contained 2-fold amounts of PGs. The majority of these PGs (87%) were
versican and
decorin of lower hydrodynamic size (500,000 and 70,000, respectively) than in HNR, with CS as prominent GAG (70%) in both types of PG. The M(r) of CS and DS chains in these PGs was 12-14,000 and 14-16,000, respectively. The remaining portion (13%) of PG was HSPGs of lower hydrodynamic size (300,000) with smaller HS chains (29,000) than HSPGs of HNR. Moreover, the molar concentrations of
versican and
decorin estimated from PG-derived
protein contents represented a significant, but disproportionate increase, about 5-fold and 8-fold, respectively. The sulfation pattern of rectum
carcinoma-associated
versican and
decorin was significantly altered mainly in containing (62%) 6-sulfated
disaccharides and a significant proportion (10%) of non-sulfated
disaccharides. DS chains of the
tumor-associated
versican and
decorin contained decreased amounts of
iduronic acid. On the metabolic level, the abnormally high production of
versican and
decorin in this malignant
tumor suggests a dramatic modification in their biosynthetic steps at both translational and posttranslational levels.