27-Hydroxycholesterol acts on myeloid immune cells to induce T cell dysfunction, promoting breast cancer progression.

Breast cancer remains one of the leading causes of cancer mortality in the US. Elevated cholesterol is a major risk factor for breast cancer onset and recurrence, while cholesterol-lowering drugs, such as statins, are associated with a good prognosis. Previous work in murine models showed that cholesterol increases breast cancer metastasis, and the pro-metastatic effects of cholesterol were due to its primary metabolite, 27-hydroxycholesterol (27HC).