cd4 + regulatory T (Treg) cells are associated with immune tolerance and antitumor immunosuppression. The aim of the present study was to investigate the role and molecular mechanism of c-c motif chemokine ligand 11 (ccl11) in the regulation of Treg cells from patients with breast cancer (Bc) and healthy individuals in vitro, and from tumor-bearing mice in vivo. cd4 + T cells isolated from patients with Bc or healthy individuals were incubated with anti-ccl11 neutralizing antibodies or recombinant human ccl11 protein, in the presence or absence of a STaT5 inhibitor. The serum ccl11 level and proportion of Treg cells characterized as cd4 + cd25 + forkhead box P3 + (Foxp3) among the cd4 + T cells in patients with Bc and healthy individuals were analyzed by eliSa and flow cytometry, respectively. CCL11, C-C motif chemokine receptor 3 (ccr3), Foxp3, phosphorylated-STaT5 and STaT5 expression levels were determined by western blotting. The serum ccl11 level and the proportion of cd4 + cd25 + Foxp3 + Treg cells were significantly increased in patients with BC compared with healthy individuals. ccl11 blockade reduced the proportion of cd4 + cd25 + Foxp3 + Treg cells, the expression of ccr3 and Foxp3, and the level of STaT5 activation in tumor-associated cd4 + T cells, in a dose-dependent manner. ccl11 blockade also reduced the proportion of cd4 + cd25 + Foxp3 + Treg cells and the serum levels of interleukin (il)-2 and transforming growth factor (TGF)-β1 in tumor-bearing mice. The recombinant human ccl11 protein increased the proportion of cd4 + cd25 + Foxp3 + Treg cells, the expression of ccr3 and Foxp3, and the release of il-2 and TGF-β1 in non-tumor-associated cd4 + T cells via the STaT5 signaling pathway. The results of the present study may aid in identifying therapeutics that could further modulate the immune system during Bc.

Breast cancer is the most common cancer in women. Novel mechanisms and targets are urgently needed to understand and treat this disease due to the complexity of breast cancer. I n this study, we evaluated the expression level of tripartite motif-containing (TRIM) 35 in various breast cancer cell lines by qPCR and immunoblot. Cell proliferation assay a nd flow cytometry were performed upon overexpression and depletion of TRIM35. Xenograft tumor model was applied to validate the findings observed in vitro. The correlation between TRIM35 and outcomes of breast cancer patients was investigated by analyzing The Cancer Genome Atlas (TCGA) database. We observed differential expression of TRIM35 in various breast cancer cell lines. Overexpression of TRIM35 significantly inhibited cell proliferation and promoted cell apoptosis. On the contrary, depletion of TRIM35 exerted the opposite effects on cell proliferation and apoptosis. Mechanistically, TRIM35 reduced PDK1 by ubiquitination, resulting in the degradation of PDK1. Overexpression of TRIM35 significantly suppressed ZR7530 cell line-derived xenograft tumor growth by inducing apoptosis. Finally, a lower level of TRIM35 was associated with a poor prognosis in patients. In conclusion, TRIM35 functions as a tumor suppressor to suppress breast cancer proliferation by inactivating AKT signaling through the increased ubiquitination of PDK1, resulting in the promotion of apoptosis.