TMEM205 promotes M2-like macrophage polarization and advances the progression of triple-negative breast cancer.

[INTRODUCTION] Triple-negative breast cancer (TNBC) is a highly aggressive subtype and lacks effective targeted therapies. Transmembrane protein 205 (TMEM205) has been implicated in tumor progression and immune resistance, but its precise role and mechanism in TNBC remain unclear. This study aims to explore the function and mechanism of TMEM205 in TNBC progression, as well as its impact on the tumor immune microenvironment.

[METHODS] The expression and prognostic significance of TMEM205 in breast cancer were analyzed using datasets, such as TCGA and UALCAN. TMEM205 was overexpressed and knocked down in TNBC cell lines (MDA-MB-231 and BT-549), and the effects on cell biological activity were verified by functional assays, including CCK-8, colony formation, wound healing, and Transwell assays. A coculture system of tumor cells and THP-1-derived macrophages was established. Key signaling molecules of TNBC cells were detected by Western blot, and cytokine levels by ELISA, so as to study tumor cell-macrophage interactions. The role of TMEM205 in tumor growth and angiogenesis was further validated through xenograft mouse models and endothelial tube formation assays.

[RESULTS] TMEM205 was significantly upregulated in breast cancer tissues and associated with a poor prognosis. TMEM205 overexpression promoted the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of TNBC cells, while TMEM205 knockdown inhibited their biological functions. Furthermore, TMEM205 overexpression not only increased the secretion of IL-6 but also activated the JAK2/STAT3 signaling axis, showing a positive correlation with M2 macrophage infiltration. The TNBC cell-conditioned medium with TMEM205 overexpression significantly promoted endothelial cell angiogenesis.

[CONCLUSION] TMEM205, as a multifunctional oncoprotein in TNBC, jointly drives tumor progression by promoting cell proliferation, metastasis, angiogenesis, and fostering an immunosuppressive microenvironment via M2 macrophage polarization. TMEM205 may be a promising therapeutic target for TNBC.