TTPAL inhibits the progression of breast cancer and reprograms tumor-associated macrophages by inhibiting JAK2/STAT3 signaling pathway.

backgroundBreast cancer remains a major disease that poses a significant threat to the health of women worldwide. Identifying new targets and formulating effective treatment strategies is particularly crucial for breast cancer patients. Tocopherol alpha transfer protein like (TTPAL) promotes tumor development, but its precise role and underlying mechanisms in breast cancer progression remain unclear. This study aims to investigate the role of TTPAL in breast cancer progression and explore its potential mechanisms.

methodsWe analyzed TTPAL expression using data from the Gene Expression Omnibus (GEO) datasets and The Cancer Genome Atlas (TCGA) database. TTPAL expression levels were examined in breast cancer tissue and normal breast tissue by immunohistochemistry staining (IHC), and western blotting assay. Further CCK‑8 assay, colony formation assay, wound healing, transwell assay and tumor xenograft experiments were used to detect the effect of TTPAL on breast cancer progression. RNA sequencing was performed to explore the underlying mechanisms. Co-immunoprecipitation (Co-IP) and rescue experiments were conducted to elucidate the interaction between TTPAL and the JAK2/STAT3 signaling pathway. Additionally, the effects of TTPAL on M2 polarization of tumor-associated macrophages (TAMs) were explored through co-culture experiments and analysis of tumor tissue.

resultsTTPAL mRNA and protein levels were significantly downregulated in breast cancer tissue and breast cancer cell lines. Ectopic TTPAL expression potently suppressed breast cancer cell proliferation, colony formation, migration in vitro, and tumor growth in vivo. Mechanistically, TTPAL interacts with JAK2, inhibiting JAK2 phosphorylation (Tyr1007/1008) without altering the total JAK2 protein level; subsequently reduces STAT3 phosphorylation (Tyr705), thereby attenuating the oncogenic JAK2/STAT3 signaling pathway. Rescue experiments with Colivelin reversed the effect of TTPAL on tumor suppressive. Crucially, TTPAL-overexpressing breast cancer cells attenuated M2 polarization of TAMs in vitro and suppressed infiltration of CD206+ TAMs in vivo. Clinically, low TTPAL expression strongly correlated with high CD163⁺ TAMs infiltration in breast cancer patient tissues.

conclusionsTTPAL acts as a potent tumor suppressor in breast cancer by inhibiting JAK2/STAT3 signaling and impeding M2 polarization of TAMs within the tumor microenvironment (TME). Restoration of TTPAL function presents a promising dual-targeting therapeutic strategy to inhibit tumor cell growth and remodel the immunosuppressive TME.