An ingredient in common cooking oil linked to aggressive breast cancer

Breast cancer is one of the most common cancers found in women in the United States. About 1 in 3 of all new female cancer diagnoses each year is breast cancer, according to the American Cancer Society. This year, an estimated 316,950 new cases of invasive breast cancer are expected. A new study has now shed light on a potential dietary link to one of the most aggressive and difficult-to-treat subtypes of breast cancer.
A fat commonly found in cooking oils and animal products may accelerate the growth of a particularly aggressive type of breast cancer, according to a new preclinical study led by researchers at Weill Cornell Medicine. The study is published in the Science journal. Linoleic acid, an omega-6 fatty acid found in cooking oil derived from seeds such as soybean and safflower oil, and also in animal products including pork and eggs, is linked with enhancing the growth of the aggressive ‘triple negative’ breast cancer subtype. This study could lead to new dietary and pharmaceutical strategies in the battle against breast and other cancers.

Researchers found that linoleic acid activates a major cancer growth pathway in triple-negative tumor cells by binding to a protein called FABP5. Compared to other hormone-sensitive breast cancer types, this protein is abundant in TNBC. The interaction leads to the activation of the mTORC1 pathway, which regulates cell growth and metabolism.

“This discovery helps clarify the relationship between dietary fats and cancer, and sheds light on how to define which patients might benefit the most from specific nutritional recommendations in a personalized manner,” study’s senior author Dr. John Blenis, the Anna-Maria and Stephen Kellen Professor of Cancer Research in the Department of Pharmacology and a member of the Sandra and Edward Meyer Cancer Center at Weill Cornell Medicine said in a statement.

Omega-6 linoleic acid is a nutrient essential in mammals for supporting multiple bodily processes. However, the abundance of this fat in ‘Western-style’ diets has increased significantly since the 1950s, leading to increased usage of seed oils in fried and ultra-processed foods. The excessive intake of Omega-6 might be one of the reasons for the spike in breast cancer rates and some other diseases. Previous studies have suggested mixed and inconclusive results, and have not really explained the biological mechanism tying omega-6s to cancers. Some of the factors that increase the risk includes age, genetic mutations, reproductive history, dense breasts, personal history of breast cancer or certain noncancerous breast diseases, family history of breast or ovarian cancer, exposure to the drug (diethylstilbestrol - DES).

The new study, however, sought to resolve this confusion by initially looking at breast cancer, which has been linked to modifiable factors such as obesity. The researchers studied the ability of omega-6 fatty acids, particularly linoleic acid’s to drive an important, nutrient-sensing growth pathway called the mTORC1 pathway.

They studied mice with triple-negative breast cancer that were fed a diet rich in linoleic acid. Researchers observed that it enhanced tumor growth, increased FABP5 expression, and elevated activation of the mTORC1 pathway. The blood and tumor samples from newly diagnosed triple-negative breast cancer patients also showed higher levels of FABP5 and linoleic acid.

The study stresses the role of linoleic acid in breast cancer. This is also the first research to establish a specific mechanism through which this common dietary ingredient influences disease.
“There may be a broader role for FABP5-mTORC1 signaling in other cancer types and even in common chronic diseases such as obesity and diabetes,” study’s first author, Dr. Nikos Koundouros, a postdoctoral research associate in the Blenis laboratory, added.