Obesity and elevated circulating cholesterol are risk factors for breast cancer recurrence, while the use of statins, cholesterol biosynthesis inhibitors widely used for treating hypercholesterolemia, is associated with improved disease-free survival. Here, we show that cholesterol mediates the metastatic effects of a high-fat diet via its oxysterol metabolite, 27-hydroxycholesterol. Ablation or inhibition of CYP27A1, the enzyme responsible for the rate-limiting step in 27-hydroxycholesterol biosynthesis, significantly reduces metastasis in relevant animal models of cancer. The robust effects of 27-hydroxycholesterol on metastasis requires myeloid immune cell function, and it was found that this oxysterol increases the number of polymorphonuclear-neutrophils and γδ-T cells at distal metastatic sites. The pro-metastatic actions of 27-hydroxycholesterol requires both polymorphonuclear-neutrophils and γδ-T cells, and 27-hydroxycholesterol treatment results in a decreased number of cytotoxic CD8+T lymphocytes. Therefore, through its actions on γδ-T cells and polymorphonuclear-neutrophils, 27-hydroxycholesterol functions as a biochemical mediator of the metastatic effects of hypercholesterolemia.

Clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated (Cas

No abstract

Aberrant fibroblast growth factor (FGF) and FGF receptor (FGFR) system have been associated with breast cancer. The objectives of our study were to investigate the effects and mechanisms of FGFR inhibition on tumor growth and metastasis on breast cancer. Our studies showed that the FGFR inhibitor PD173074 decreased the viability of several human breast cancer cells, as well as 4T1 murine mammary tumor cells. Therefore, we chose 4T1 cells to study PD173074's antitumor mechanism. Flow cytometry showed that PD173074 induced 4T1 cell apoptosis in a concentration-dependent manner. Western blot demonstrated that PD173074-induced apoptosis was correlated with the inhibition of Mcl-1 and survivin. Moreover, PD173074 also significantly increased the ratio of Bax/Bcl-2. PD173074 could also block 4T1 cell migration and invasion in vitro. In 4T1 tumor-bearing mice, PD173074 significantly inhibited tumor growth without obvious side effects. Meanwhile, PD173074 functionally reduced microvessel density and proliferation index and induced tumor apoptosis. Importantly, we found that FGFR inhibition by PD173074 reduced myeloid-derived suppressor cells (MDSCs) in the blood, spleens and tumors, accompanied by the increased infiltration of CD4(+) and CD8(+) T cells in the spleens and tumors. Furthermore, PD173074 significantly inhibited breast tumor metastasis to the lung of inoculated 4T1 breast cancer cells, which was accompanied by a reduction in MDSCs. Our findings suggested that FGFR inhibition could delay breast tumor progression, impair lung metastasis and break immunosuppression by effecting on tumor microenvironment, which may provide a promising therapeutic approach for breast cancer patient.