Alterations in small leucine-rich proteoglycans in right-sided colorectal cancer.
652 Background: Colorectal cancer (CRC) is a heterogeneous disease, and there are anatomic, functional and molecular differences between the tumors of the proximal and distal colorectum. Various molecular phenotypes have been associated with aggressive subtypes in these pathologies, and several of these markers show a relationship with proteoglycans, which in turn show significant alterations in colon tumors, which affect both their core proteins and their glycosaminoglycan chains. Small leucine-rich proteoglycans (SLRPs) constitute a family of molecules encoded by 18 distinct genes. They are grouped into five classes and may appear coupled to different glycosaminoglycan chains ––including chondroitin/dermatan sulfate or keratan sulphate–– or not, depending on the specific species. They are ubiquitously expressed in extracellular matrices, and have been found involved in the regulation of organ size and shape during embryonic development. In this study we investigate the expression patterns of SLRPs in right-sided CRCs. Methods: A transcriptomic approach was used, employing qPCR to analyze SLRP core protein transcriptions. Immunohistochemical techniques were also used to analyze tissue expression of particular genes showing significant expression differences of potential interest. Results: Only two proteins displayed significant alterations: biglycan appeared overexpressed approximately 4 fold (p = 0.015), and osteoglycin decreased about 4 fold (p = 0.05). Transcripts for epiphycan, opticin, nyctalopin and podocan-like 1 were not detected in most patients, while chondroadherin was detected in 50% of healthy tissues but not in CRCs. Expression of lumican, decorin, keratocan, asporin, ECM2, fibromodulin, PRELP, tsukushi, podocan and osteoadherin was detected, but with no significant differences compared to healthy tissue. Conclusions: Normal mucosa of the large bowel expresses most SLRPs, and two, biglycan and osteoglycin, appeared altered in right-sided CRCs. These alterations could be related to binding of different ligands and modulation of homeostasis.