SPARC acts as a mediator of TGF-β1 in promoting epithelial-to-mesenchymal transition in A549 and H1299 lung cancer cells

Abstract

Migration and metastasis of tumor cells greatly contributes to the failure of cancer treatment. Recently, the extracellular protein secreted protein acidic and rich in cysteine (SPARC) has been reported closely related to tumorigenesis. Some articles have suggested that SPARC promoted metastasis in several highly metastatic tumors. However, there are also some studies shown that SPARC acted as an antitumor factor. SPARC-induced epithelial-to-mesenchymal transition (EMT) in melanoma cells and promoted EMT in hepatocellular carcinoma. Therefore, the role of SPARC in tumorigenesis and its relationship with EMT is still unclear. In this study, we investigated the expression change of SPARC in A549 and H1299 lung cancer cells undergoing EMT process. Our study indicated that SPARC was upregulated in A549 and H1299 cells EMT process. We further investigated the function of SPARC on proliferation, migration, and EMT process of A549 and H1299 cells. Overexpression of SPARC promoted the migration and EMT of A549 and H1299 cells. Knockdown SPARC inhibited the EMT of A549 cells. Overexpression of SPARC induced the increased expression of p-Akt and P-ERK. Furthermore, exogenous SPARC peptide promoted transforming growth factor (TGF)-β1-induced EMT of A549 and H1299 cells. SPARC knockdown partially eliminated TGF-β1 function in inducing EMT of A549 cells. SPARC follistatin-like functional domain reduced the expression of E-cadherin, but had no effect on the expression of p-Akt and p-ERK. In conclusion, we elucidated that SPARC contributes to tumorigenesis by promoting migration and EMT of A549 and H1299 lung cancer cells. These results will provide some new suggestion for lung cancer treatment. © 2018 BioFactors, 44(5):453-464, 2018.

Keywords: SPARC; TGF-β1; epithelial-to-mesenchymal transition; migration.