The clinical significance of circulating GPC1 positive exosomes and its regulative miRNAs in colon cancer patients

Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide. Recent study found an increased level of glypican-1 positive (GPC1(+)) plasma exosomes in patients with stage II CRC, but decreased levels of plasma miR-96-5p and miR-149. This study further investigated the clinical significance of plasma GPC1(+) exosomes and plasma miR-96-5p and miR-149 levels in stage III CRC patients. To study the effect of these microRNAs on GPC1(+) plasma exosomes, we isolated and purified exosomes and overexpressed human GPC1 and the microRNAs miR-96-5p and miR-149 by adenovirus vectors. Overexpression of GPC1 activated epithelial-mesenchymal transition (EMT) which then increased invasion and migration in HT29 and HCT-116 colon cancer cells. In contrast, silencing GPC1 expression and overexpressing miR-96-5p and miR-149 significantly inactivated EMT and decreased invasion and migration of HT29 and HCT-116 cells. miR-96-5p and miR-149 inhibitors significantly increased invasion and migration of HT29 and HCT-116 cells. Our results indicate that high levels of circulating GPC1 positive exosomes before and after surgery as well as low circulating miR-96-5p and miR-149 before surgery indicated a severe clinical status and poor prognosis in stage III colon cancer patients. We conclude that GPC1 can be a biomarker for relapse of stage III CRC and may be involved in EMT activation, invasion, and migration of colorectal cancer cells.