Cancer-associated fibroblasts induce epithelial-mesenchymal transition of esophageal squamous cell carcinoma through paracrine TGFβ1 signalling

Abstract

Abstract BackgroundConcurrent chemoradiotherapy is the standard treatment regimen for unresectable advanced patients with esophageal squamous cell carcinoma. CAFs (cancer-associated fibroblasts), one major component of tumor microenvironment were involved in tumor initiation and progression. However, the mechanisms by which CAFs enhanced the malignance of ESCC have remained most unknown. Epithelial-to-mesenchymal transition(EMT) is a process which promoted the mobility, resistance to chemoradiotherapy, cancer stemness and ability of immune evasion of cancer cells.MethodsCAFs and NFs (normal fibroblasts) were isolated from tumor tissues and matched normal esophageal epithelial tissues, respectively. The EMT characteristics induced by CAFs were analyzed by detection of related genes and protein expressions in esophageal cancer cells. The CAFs-induced drug resistance was evaluated by MTT assay. The influences of CAFs on the migration and invasion were investigated by wound healing and transwell assay. The mechanisms by which CAFs promoted EMT of esophageal cancer cells was investigated by Western blotting.ResultsIn our study, we had successfully isolated CAFs and NFs from tumor tissues and matched normal esophageal epithelial tissues, respectively. We found paracrine TGFβ1 signaling from CAFs induced esophageal cancer cells to display EMT characteristics with the epithelial markers down-regulated and the mesenchymal markers up-regulated. CAFs-induced EMT enhanced the migration and invasion, drug resistance and cancer stemness traits of esophageal cancer cells. Mechanism studies revealed that paracrine TGFβ1 signaling promoted EMT of esophageal cancer cells in a phos-smad2/3-slug-dependent manner. Furthermore, paracrine TGFβ1 signaling induced the activation of NF-κB signaling pathway, which was reported to be significantly associated with aggressive clinical biology and poor treatment outcome after chemoradiotherapy in ESCC patients. ConclusionsTogether, our study highlighted CAFs’ tumor-promoting role in esophageal cancer and and provide potential anti-cancer targets by reversing EMT.