Abstract
Background: Our previous study demonstrated that overexpression of multiple epidermal growth factor-like domains 11 was involved the recurrence mechanism of triple negative breast cancer (TNBC) via up-regulation of cytokines and chemokines, including IL-17A signaling pathway. However, information concerning the role of IL-17A in tumor behavior or cancer microenvironment remains lacking. The aim of this study was to investigate the role of IL-17A on TNBC recurrent mechanisms, including tumor behavior, circulating tumor cells (CTCs), and cancer microenvironment. Methods: Using human TNBC MDA-MB-231 and MDA-MB-468 lines, the role of IL17-A was elucidated by knocked down IL-17A (DIL-17A) or administration of different dose of IL-17A in the culture medium. Cell proliferation, migration assay, Western blot analysis and Real-time PCR for IL-17A related signaling were evaluated. Three groups of implanted 4T1 cells in BALB/c mice were designed, namely, wild type (WT), DIL-17A, and WT + neutralizing IL-17 antibody (WT+Ab). Tumor weight, necrosis area, and the number of CTCs were measured. Immunohistochemistry or Western blot for CD34, CD8, and TGF-b1 were evaluated. Anoikis resistance was analyzed by live/dead stain and flow cytometry. Finally, clinic-pathological correlation between IL-17A expression and patients’ outcome such as disease free survival (DFS) and overall survival (OS) was performed by Kaplan-Meier’s method.Results: Our results demonstrated that IL-17A stimulated migratory activity, but not growth rate, of MDA-MB-231/468 cells via increased Src, Rho, and COX2 expression. In vivo, there was an increased necrosis area, a decreased tumor CD34 expression and CTCs in DIL-17A group; while there was a decreased tumor CD34 expression, CD8(+) cells, and CTCs, but an increased TGF-b1 expression in WT+Ab group, compared to the WT group. Knocked down-IL-17A also decreased anoikis resistance in human TNBC and murine 4T1 cell lines. Kaplan-Meier’s analysis disclosed a negative correlation between tumor IL-17A expression and OS in TNBC patients. Conclusion: We conclude that IL-17A promotes migratory and angiogenic activity in the tumors, enhances anoikis resistance, and modulates the immune landscape of tumor microenvironment favoring subsequent cancer metastasis. The blockade of IL-17A might provide a co-treatment target to prevent tumor metastasis or recurrence in TNBC patients.
A 9-kDa matricellular SPARC fragment released by cathepsin D exhibits pro-tumor activity in the triple-negative breast cancer microenvironment