Relation between Tetraspanin- Associated and Tetraspanin- Non- Associated Exosomal Proteases and Metabolic Syndrome in Colorectal Cancer Patients

Abstract

Purpose: Exosomal proteases are important in regulation of molecular signaling from growth factor receptors and<br />adhesion molecules and also the regulation of cell motility and protein folding. The aim of this study was to evaluate<br />the level of ADAM10, ADAM17 and 20S proteasomes in exosomes isolated from colorectal cancer patients (CRCPs)<br />in relation with clinical and histopathological parameters. Methods: Blood plasma exosomes of 60 CRCPs at stage<br />T2-4N0-2M0-1 and 10 control subjects (CSs) with colorectal polyps were isolated using ultrafiltration in combination<br />with ultracentrifugation. The level of tetraspanin-associated (ADAM20 and ADAM17) and tetraspanin-non-associated<br />(20S proteasome) proteases were evaluated by flow cytometry and western blot analysis. Results: The ADAM10-/<br />ADAM17- population predominated in plasma exosomes of CRCPs and the level of ADAM10+ exosomes was<br />significantly higher in exosomes of CSs compared with CRCPs. No difference was found between subpopulations<br />of ADAM10/ADAM17 exosomes and level of exosomal 20S proteasomes in terms of sex, age and tumor grade.<br />Simultaneous decrease of ADAM10+/ADAM17-subpopulation of exosomes and level of exosomal 20S proteasomes in<br />patients with metastatic CRC was observed compared with patients with non-metastatic CRC. The level of ADAM17+<br />exosomes significantly reduced in exosomes of CRCPs with metabolic syndrome compared to CRCPs without<br />metabolic syndrome( 3.97±0.71 (%) vs. 13.04±1.34 (%), respectively (p<0.05). A decrease in the 20S proteasomes<br />level in plasma exosomes was revealed in CRCPs with metabolic syndrome compared with CRCPs without metabolic<br />disorders ( 1.90±0.25 (r.u.) vs. 2.92±0.42 (r.u.) respectively( (p<0.05). Conclusion: According to findings of this study,<br />it seems that exosomal proteases can be promising molecular predictors of hematogenous metastasis in patients with<br />non-metastatic CRC. Further studies on subpopulation composition of exosomes CRCPs are need for elucidating the<br />role of tetraspanin-associated and tetraspanin-non-associated exosomal proteases in CRC development and progression.