Something fishy: How a component of fish oil may counteract the effects of some chemotherapy

Cancer is an incredibly broad group of diseases characterized by similar features, the most notable being uncontrolled cell growth. Although researchers have made great strides in understanding the molecular mechanisms behind various cancers, they are still working on creating effective therapies that specifically target these mechanisms. This means that many therapies rely on relatively old-fashioned treatments: chemo or radiation, which kill the tumor cells faster or more effectively than they kill normal cells. As might be expected from such harsh therapies for such serious diseases, many of these cancer therapies are associated with severe side effects.

To address these side effects (and possibly as a result of newfound interest in their health), many patients turn to dietary remedies, including a variety of supplements. Fish oil is one of the most popular choices, and it is used by an estimated 20% of cancer patients^[1]. However, relatively little work has been done to assess fish oil’s interactions with common cancer treatments like chemotherapy.

Fish oil is a common supplement, but its sources and processing can vary greatly. It can come from any oily fish, including eel, herring, and mackerel. The specific fatty acids components in fish oil can vary, depending on the species and diet of the source fish. Since the benefits of fish oil supplementation and oily fish consumption have been widely researched for decades, scientists are now beginning to assess the components of fish oil in more detail, especially as they pertain to specific populations or interactions with medications.

The group who conducted this study was the first group to identify certain fatty acids called platinum-induced fatty acids (PIFAs) ^[2]that can induce resistance to chemotherapy in mice. Specifically, they identified 12S-HHT and 16:4(n-3) as two fatty acids that can cause resistance to chemotherapy by altering DNA damage repair mechanisms. Figure 1 depicts how PIFAs may interact with macrophages to ultimately induce some level of chemoresistance. This study is a follow-up to the previous mouse-based report and aims to examine the fish oil supplementation habits of cancer patients, as well as further clarify the effects of fish oil supplementation on chemotherapy resistance.

Figure 1: Possible mechanism for PIFA-induced chemoresistance

Reference: Houthuijzen et al. Nat Commun. 2014 Nov.

Fish oil supplementation is relatively common in cancer patients. The researchers conducting this study recently identified certain components of fish oil (especially platinum-induced fatty acid 16:4) that can promote chemotherapy resistance in mice, so they sought to understand whether these effects could also be seen in human tumors.