Study uncovers how fat cells may fuel aggressive breast cancer tumours

Fat cells could play a crucial role in fuelling certain breast cancer tumours, according to new research which may open the door to future treatments for one of the disease’s most aggressive forms.

Scientists have long observed that living with overweight or obesity is linked to a higher risk of developing or dying from breast cancer. The latest study, published in Nature Communications, suggests a possible explanation that the tumours may directly draw energy from neighbouring fat cells.

The findings are particularly significant for triple-negative breast cancer, a form which accounts for about 15 per cent of all breast cancers. This type is more likely to recur than other forms, has lower survival rates and is disproportionately common among black women and women under 40.

Researchers at the University of California, San Francisco, discovered that tumour cells appear to extract energy by extending straw-like structures, known as gap junctions, into adjacent fat cells. These structures allow cancer cells to siphon off lipids – fatty compounds such as cholesterol that the body uses to store energy.

Jeremy Williams, the study’s lead author and a postdoctoral scholar at the university, explained: “Aggressive cancer cells can co-opt different nutrient sources to help them grow, including by stimulating fat cells in the breast to release their lipids. In the future, new treatments might starve the tumour cells by preventing their access to lipids from neighbouring cells.”

The team carried out experiments using both human breast tissue and mouse models. In samples taken from individuals, fat cells located close to tumours were found to be significantly depleted of lipids. When researchers blocked the tumour cells’ ability to form gap junctions, the cancers stopped growing.

Similar results were seen in mice implanted with genetically altered tumour tissue that lacked the capacity to produce these straw-like structures. “Knocking out a single gene impaired the formation and progression of the tumour,” Williams said.

Several drugs that inhibit gap junction formation are already in early-stage clinical trials for other purposes, raising hopes that they could eventually be repurposed for breast cancer treatment.

Dr Julia McGuinness, a breast cancer specialist at Columbia University, said the research offered the first clear evidence of a mechanism linking fat cells to tumour growth. “It’s suggesting one pathway to treat aggressive cancers for which we don’t have any good therapies,” she said. “We already know that obese women with these cancers have worse outcomes. Slimming down could be protective.”

Justin Balko, professor of cancer research at Vanderbilt University Medical Center, called the study “a new way cancer grows and feeds itself”. He cautioned, however, that more evidence was needed to confirm whether this mechanism plays a major role in human cancers.

While further research is required, the findings may help explain why obesity is such a significant risk factor for breast cancer, and point towards new strategies to cut off tumours from one of their potential energy sources.