Role of endothelial cells in the regulation of mechanical microenvironment on tumor progression

Majority of cancer patients die from cancer metastases. The physical stimulation produced by microenvironment regulates invasive behavior of cancer cells. Blood vessel is one of the "pathways" for cancer to metastasize, in which tumor cells need to cross the endothelial barrier for intravasation and extravasation. Tumor vessels are arranged in untraditional hierarchies and characterized with rupture, bend, swell and high permeability that are beneficial to intravasation of cancer cell. Abnormal vessels are accompanied with uneven blood flow, increased compression and interstitial fluid pressure. Meanwhile, excessive proliferation of tumor leads to low oxygen pressure in solid tumor. The aberrant tumor mechanical microenvironment changes the biochemical and mechanical signal transduction of endothelial cells and participates in tumor progression. Many current researches focus on how chemical signals regulate endothelial cell function while the role of physical cues is unclear. In this review, the role of endothelial cells in the regulation of shear stress, intercellular force, extracellular matrix and pressure on tumor progression is summarized.