Scientists at the University of California, Davis have discovered that docosahexaenoic acid (DHA)—a fatty acid commonly found in fish and fish oil supplements—may be beneficial in the treatment of kidney cancer.
Their study found that DHA reduces renal cell carcinoma invasiveness, growth rate, and blood vessel growth when combined with the anti-cancer therapy regorafenib. Regorafenib works to fight cancer by attacking tyrosine kinases, which are enzymes that activate other proteins. However, kidney cancers mutate to resist these therapies.
“Most renal cell carcinomas learn to escape therapy after a couple of years,” says Robert Weiss, professor of medicine at UC Davis, chief of nephrology at Sacramento VA Medical Center, and head of the kidney cancer working group at the UC Davis Comprehensive Cancer Center. “A simple additive, which is completely nontoxic, could have a positive effect on disease, even rescuing regorafenib and similar therapies from resistance.”
Going into the study, Weiss and his associates knew that DHA metabolites, called epoxydocosapentaenoic acid (EDP), have the potential to restrain the ability of cancers to invade and grow blood vessels. Unfortunately, an enzyme called soluble epoxide hydrolase (sEH) usually breaks down and inactivates EDP.
“We knew that regorafenib blocks sEH,” said Weiss. “If you add more DHA and block sEH, all that DHA goes towards creating EDP, which contributes to the anti-cancer effect.”
The team tested the combination against both cancer cell lines and human tumors in mice, finding that the compound killed kidney cancer cells in both models.
Although the results are promising, these benefits are quite narrow, says Weiss—there’s still no proof that fish oil supplements could have any impact against kidney cancer on their own.
“We don’t have any evidence for that so far,” he notes. “It would be premature to make that assumption.” However, these findings do offer a simple way for patients with advanced kidney cancer to increase the effectiveness of their treatments.
