Investigation on the mechanisms for angiogenesis regulatory-miRNA expression in colorectal cancer and endothelial cell interactions

Abstract

Angiogenesis is an essential step in cancer progression and metastasis. Accumulating evidence has shown that changes in miRNA expression profiles of endothelial cells (ECs) elicited by cancer cells promote angiogenesis. In particular, the vascular endothelial growth factor (VEGF), a key pro-angiogenic factor, is known to influence miRNA expression in ECs

however, quantitative aspects of VEGF’s role in miRNA regulation during angiogenesis are poorly defined. Here, I demonstrate differential angiogenic effects on the human umbilical vein endothelial cells (HUVECs) by five different colorectal cancer (CRC) cell lines via in vitro HUVEC migration and angiogenesis assays in response to CRC conditioned medium (CM). Among the tested CMs, LoVo was most effective for eliciting HUVEC angiogenic phenotypes, at least partially due to its high VEGF level. Furthermore, I found that pro-angiogenesis regulatory-miRNAs (pro-angio-miRNAs, miR-296, miR-132, miR-105, and miR-200) were upregulated in VEGF-rich LoVo CM treated HUVECs relative to VEGF-scarce SW620 treated control. In addition, VEGFR inhibitor treatment downregulated these pro-angio-miRNAs but not miR-132, suggesting VEGF and additional signaling functions in angio-miRNA expression. Quantitative analyses on angio-miRNAs’ target mRNA expression also suggested independent pathways may account for their regulated expression. Taken together, these data indicate that multiple paracrine factors including VEGF secreted by CRCs effectively modulate angio-miRNA expression, impacting their target expression and HUVEC angiogenic phenotypes. Quantitative analytic schemes on miRNA and mRNA expression as well as cellular phenotypes are expected to provide valuable insights into identifying new paracrine factors supporting angiogenesis.