The Spectrum of Microvasculature Basal Microvilli in Human Solid Tumors: A Pilot Study

Abstract

In our pervious study, we had reported that basal microvilli with cellular trafficking ability exist in pancreatic ductal adenocarcinoma (PDAC) and murine PDAC models, which a remarkable example of how endothelial plasticity in tumor blood vessels feed tumor cells. As human solid tumors in different organs are driven by similar oncogenic mutations, basal microvilli may exist in other human solid tumors. Here we have done a small pilot study in human solid tumors to see whether other solid tumors take this approach, and surprisingly found that basal microvilli-like structure observed in human cholangiocarcinoma, metastatic nonfunctional pancreatic neuroendocrine tumor (panNET) and breast cancer, but not human hepatocellular carcinoma, glioblastoma, renal clear cell carcinoma and oral squamous cell carcinoma. Consistent with characteristics of basal microvilli in PDAC, immuno-staining results showed that the expression of VEGFR2 was down-regulate in the microvasculature with basal microvilli in panNET. This finding indicates that basal microvilli might be a common way to get nutrients from or clear waste to the microvasculature in aggressive and metastatic tumors.