Obesity reprograms immune cells in breasts to promote tumor formation

Smoking has long been the biggest cause of cancer in the United States, but obesity, now the second leading cause, has been gaining ground. A new study from researchers at the University of Chicago finds that women with breast cancer, the most common cancer among women, are at even higher risk from obesity.

Breast cancers occur in adipose tissue, better known as fat. Triple-negative breast cancer (TNBC) is a type of breast cancer that is particularly difficult to treat. None of the three most appealing drug targets — the estrogen receptor, the progesterone receptor and human epidermal growth factor receptor 2 — are present on TNBC cells.

“These cancers can be particularly aggressive,” said study author Lev Becker, PhD, an assistant professor in the metastatic cancer have higher levels of IL-6 in their blood, which is correlated with poor survival rates.

Obesity, the study authors wrote, is a pathological state that “facilitates tumorigenesis by creating tumor permissive conditions in multiple tissues.” This suggests that chronic inflammation and its effects on tumorigenesis may be reversed by targeted anti-inflammatory therapies or by weight loss. Indeed, the researchers found that inducing weight loss in obese mice by feeding them a healthier low-fat diet reversed macrophage inflammation and TNBC tumor formation in mammary fat, even though their body weight remained elevated. These findings highlight the potential value of weight loss, not only as a preventive intervention but even after patients develop breast cancer.

This research was supported by grants from the National Institutes of Health, the Cancer Research Foundation, the Avon Foundation, the Bernice Goldblatt Endowment Fellowship, the University of Chicago, and the Department of Health via a National Institute for Health Research Biomedical Research Centre award to Guy’s and St Thomas’ NHS Foundation Trust and King’s College, London.

Additional authors of the study were Payal Tiwari, Ariane Blank, Chang Cui, Kelly Schoenfelt, Guolin Zhou, Galina Khramtsova and Funmi Olopadefrom the University of Chicago Medicine; Ajay M. Shah from King’s College, London; and Yanfei Xuand Seema A. Khan from Northwestern University.