A variety of foods that make up a healthy diet contain compounds that researchers now believe could turbocharge the growth of tumors.
Eggs, tofu, seed oils, and nuts contain essential Omega 6 fatty acids that the body cannot make on its own. Maintaining a balance of omega-6 fatty acids and omega-3s is crucial for brain development, bone health, metabolism regulation, and other vital bodily processes.
The body only needs these heart-healthy fatty acids in small quantities, and doctors recommend taking in more omega-3s in the form of salmon and other oily fish and nuts. Omega-6s, though, generally come in the form of vegetable oils used in cooking, processed foods, and fast food, and Americans consume a lot of them.
The Western diet is packed with an omega-6 called linoleic acid, which has been linked to higher levels of inflammation and cancer growth. Now, researchers at Weill Cornell Medicine believe it could help cancer cells grow and multiply.
In the lab, researchers deliberately gave mice breast cancer cells and fed one group of them safflower oil, which is high in linoleic acid. The mice fed the oil had faster-growing tumors than the placebo group that did not consume linoleic acid.
Their research revealed linoleic acid can activate mTORC1 — the ‘control center’ in cells that decides whether they grow, divide or make proteins. In aggressive breast cancer, excess linoleic acid overstimulates mTORC1, fueling tumor growth.
Dr John Blenis, the study’s senior author and a cancer researcher at Weill Cornell Medicine, said: ‘We now know that linoleic acid feeds cancer cell growth in a very specific way.
‘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.’
Doctors recommend taking in more omega-3s in the form of salmon and other oily fish and nuts. Omega-6s, though, generally come in the form of vegetable oils used in cooking, processed foods, and fast food
Excess linoleic acid is delivered throughout the body by a protein called FABP5, which overstimulates the mTORC1 in cells, promoting tumor growth.
Researchers measured levels of FABP5 across various kinds of cancer before deciding to test the acid’s impact on triple-negative breast cancer (TNBC) cells, which produce much higher levels of FABP5 than other types of cancers.
Before inserting the cancer cells into the mice, researchers conducted experiments in lab petri dishes.
They grew human breast cancer cells, both TNBC and hormone-positive, and added pure linoleic acid.
Once the acid was introduced, the mTORC1 ‘control center’ was activated only in the triple-negative breast cancer cells.
Further experiments showed linoleic acid only overactivated mTORC1 when FABP5 was present.
Then for the mice experiment, one group was fed a high-linoleic acid diet, while the other group ate their normal diet.
One group had triple-negative breast cancer cells that naturally produced too much FABP5, while the other group had non-TNBC tumors.
They found that linoleic acid fueled the growth of tumors only in mice with cancers that had higher levels of FABP5.
The research team tested their findings in mice with triple-negative breast cancer. When fed a high-linoleic-acid diet, these mice showed more tumor growth
The study marks the first time a precise biological mechanism has been shown to connect linoleic acid from food to cancer growth.
Dr Nikos Koundouros, the study’s first author, said: ‘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.’
Previous research has long debated whether omega-6 fats, such as linoleic acid, contribute to cancer, but conflicting findings left the question unresolved. Most studies focused on broad correlations without uncovering the underlying biology.
The latest study cuts through the confusion.
By identifying a pathway that is active only in specific aggressive cancers (like FABP5-positive TNBC) the team of researchers revealed diet can directly influence tumor growth, but only when conditions are right; in this case, when FABP5/mTORC1 is present.
Dr Blenis said: ‘There is a real opportunity here to tailor nutrition in a smarter way.
‘We’ve gone beyond population-level guesses and into the biology of each patient’s disease.’
The study was published in the journal Science.
The Western diet is packed with an omega-6 called linoleic acid, which has been linked to higher levels of inflammation and cancer growth
TNBC accounts for about 15 percent of all breast cancer cases and most commonly occurs in women under 40.
TNBC ‘differs from other types of invasive breast cancer in that it tends to grow and spread faster, has fewer treatment options, and tends to have a worse prognosis,’ according to the American Cancer Society.
Survival rates vary depending on the cancer’s stage. For stages two and three, 60 percent of patients live past five years of diagnosis, the Cleveland Clinic reported.
However, once stage four is reached, the chances of surviving after five years plummet to just 10 percent.
