Glycosylation changes occur widely in colon tumours, suggesting glycosylated molecules as potential
biomarkers for
colon cancer diagnostics. In this study,
proteoglycans (PGs) expression levels and their transcriptional patterns are investigated in human colon tumours in vivo and
carcinoma cells in vitro. According to RT-PCR analysis, normal and
cancer colon tissues expressed a specific set of PGs (
syndecan-1,
perlecan,
decorin,
biglycan,
versican, NG2/CSPG4,
serglycin,
lumican, CD44), while the expression of
glypican-1,
brevican and
aggrecan was almost undetectable. Overall transcriptional activity of the PGs in normal and
cancer tissues was similar, although expression patterns were different. Expression of
decorin and
perlecan was down-regulated 2-fold in colon tumours, while
biglycan and
versican expression was significantly up-regulated (6-fold and 3-fold, respectively). Expression of collagen1A1 was also increased 6-fold in colon tumours. However, conventional HCT-116 colon
carcinoma and AG2
colon cancer-initiating cells did not express
biglycan and
decorin and were
versican-positive and -negative, respectively, demonstrating an extracellular origin of the PGs in
cancer tissue. Selective expression of
heparan sulfate (HS)
proteoglycans syndecan-1 and
perlecan in the AG2
colon cancer-initiating cell line suggests these PGs as potential
biomarkers for cancer stem cells. Overall transcriptional activity of the HS biosynthetic system was similar in normal and
cancer tissues, although significant up-regulation of extracellular
sulfatases SULF1/2 argues for a possible distortion of HS sulfation patterns in colon tumours. Taken together, the obtained results suggest
versican,
biglycan, collagen1A1 and SULF1/2 expression as potential microenvironmental
biomarkers and/or targets for
colon cancer diagnostics and treatment.