Pericyte-fibroblast transition promotes tumor growth and metastasis

Vascular pericytes, an important cellular component, in the tumor microenvironment, are often associated with tumor vasculatures and their functions in cancer invasion and metastasis are poorly understood. Here we show that PDGF-BB induces pericyte fibroblast transition (designated as PFT), which significantly contributes to tumor invasion and metastasis. Gain- and loss-of-function experiments demonstrate that the PDGF-BB-PDGFRβ signaling promotes PFT in vitro and in in vivo tumors. Genome-wide expression analysis indicates that PDGF-BB-activated pericytes acquire mesenchymal progenitor features. Pharmacological inhibition and genetic deletion of PDGFRβ ablate the PDGF-BB-induced PFT. Genetic tracing of pericytes with two independent mouse strains, i.e., TN-AP-CreERT2:R26R-tdTomato and NG2:R26R-tdTomato, shows that PFT cells gains stromal fibroblast and myofibroblast markers in tumors. Importantly, co-implantation of PFT cells with less-invasive tumor cells in mice markedly promotes tumor dissemination and invasion, leading to an increased number of circulating tumor cells (CTCs) and metastasis. Our findings reveal a novel mechanism of vascular pericytes in PDGF-BB-promoted cancer invasion and metastasis by inducing PFT and thus targeting PFT may offer a new treatment option of cancer metastasis. Pericytes were isolated and treated with PDGF-BB or control for 1 or 5 days