Abstract
Cancer-associated fibroblasts (CAFs) plays an important role in the tumor microenvironment. The heterogeneity of CAFs affects the effect of CAFs on promoting or inhibiting tumors, which can be regulated by other cells in the tumor microenvironment through paracrine methods. The urokinase-type plasminogen activator (PLAU) system mediates cell proliferation, migration, adhesion, and other functions through the proteolytic system, intracellular signal transduction, and chemokine activation. PLAU promotes tumor progression in many tumors. We explored the function of PLAU in ESCC and the influence of PLAU secreted by tumor cells on the heterogeneity of CAFs. We found that PLAU is highly expressed in ESCC, which is related to poor prognosis and can be used as a prognostic marker for ESCC. Through loss-of function and gain-of function experiments, we found that PLAU promoted ESCC proliferation and clone formation via MAPK pathway, and promotes migration by upregulating Slug and MMP9, which can be reversed by the MEK 1/2 inhibitor U0126. At the same time, through sequencing, cytokine detection, and RT-qPCR verification, we found that tumor cells secreted PLAU promoted the conversion of fibroblasts to inflammatory CAFs, which upregulated expression and secretion of IL8 via the uPAR/Akt/NF-κB pathway. The IL8 secreted by CAFs in turn promotes the high expression of PLAU in tumor cells and further promoted the progression of ESCC. In summary, PLAU was not only a prognostic marker of ESCC, which promoted tumor cell proliferation and migration, but also promoted the formation of inflammatory CAFs by the PLAU secreted by tumor cells.