The omega-3 fatty acid, DHA, regulates dangerous molecular activity in breast cancer cells

Breast cancer is most widespread in the western countries, and it is the leading cause of cancer-related deaths among women. Diet and lifestyle play a key role in the development of the disease. Earlier studies have shown that eating more oily fish or taking fish oil supplements that contain the omega-3 fatty acids, EPA and DHA, lowers the risk. A new study has shown that DHA supplements can be used as an adjuvant in cancer therapy. This particular omega-3 fatty acid inhibits the formation of some harmful molecules that stimulate the growth of breast cancer cells.

Breast cancer normally occurs in the glandular tissue or in the milk ducts. The cancer may be encapsulated in the glandular tissue, and it normally takes several years for the cancer cells to spread into the surrounding tissue. When this happens, the cancer has become invasive with the risk of cancer cells spreading to the adjacent lymph nodes and traveling through the bloodstream to other parts of the body, where it metastasizes.
Around 80 percent of breast cancer nodules are hormone-sensitive, and 13 percent of them carry a surface protein (HER2 ). These subtypes, also known as triple-positive breast cancer (TPBC) account for around 40 percent of cancer-related deaths. If the breast cancer is neither hormone-sensitive nor sensitive to HER2 antibodies, it is called triple-negative breast cancer (TNBC). This subtype accounts for around 15 percent of breast cancers. The TNBC subtype is also known to be the most aggressive one and has a high rate of recurrence within the first year after treatment. This results in a higher mortality rate, which is why there is an urgent need for new strategies for preventing and treating the different types of breast cancer.

The link between immune defense, molecules, and cancer

In the introduction to their study, the authors describe how the immune defense is tasked with destroying abnormal cells such as cancer cells. It is also important to have the right balance between the inflammatory and anti-inflammatory processes of the immune defense to prevent damage to healthy body tissues. This balance is called immune homeostasis. However, it appears that most types of cancer are characterized by disturbances in this delicate balance, including chronic low-grade inflammation.
It also appears that cancer cells are able to express so-called immune checkpoint molecules that prevent cancer cells from being attacked by the immune system. It is sort of like laying out a smoke screen that enables the cancer cells to hide from the immune defense.
Cancer cells can also develop disruptions in the regulation of miRNA (micro-RNA) that has importance for the cellular DNA expression and mobility. Micro-RNAs also have a role in helping worn-out or abnormal cells to carry out apoptosis, which is programmed self-destruction. In other words, cancer cells make use of several mechanisms to divert the immune defense and to proliferate uncontrollably.
In vivo studies (human studies) and in vitro studies (typically lab tests) have shown that omega-3 fatty acids, DHA in particular, counteract breast cancer. However, very few studies have looked at DHA’s potential in the treatment of breast cancer through regulation of the immune defense, the self-destructive immune reactions, and miRNA.

New insight into DHA’s potential in the treatment and prevention of breast cancer

In the new study, the researchers used two different breast cancer cell cultures (BT-474 and MDA-MB-231), which they obtained from the National Cell Bank of Iran. These cultures, which represented the TPBC and TNBC subtypes were cultivated using special methods at 37 degrees Celsius. Afterwards, they were treated with DHA for 24 hours. The study also included breast cancer cell cultures that were not treated with DHA. These served as a control group.
All the different cell cultures, which were initially cultivated in a special way, significantly expressed the so-called immune checkpoint molecules that protect cancer cells against being attacked by the immune system. However, the subsequent exposure to DHA resulted in a significant drop in immune checkpoint molecules, and the cells’ normal miRNA expression was upregulated.
Based on their findings, the scientists concluded that supplementation with DHA is useful as part of the treatment of breast cancer because DHA helps regulate several different molecules that are relevant for the pathogenic development of the disease.
The new study is published in BMC Nutrition, and the authors say their results provide new insight into DHA’s potential in breast cancer therapy.
EPA and DHA, which are found in oily fish and fish oil supplements, also help to prevent breast cancer.

• Far fewer women in Northern Europe and USA get breast cancer compared with Asia and Africa
• This is primarily because of western diets and lifestyles. If Asians and Africans move to Europe or the US, their risk of breast cancer increases correspondingly
• Western diets contain too little omega-3 from oily fish and too much omega-6 from plant oils, margarine, deep-fried food, and ready meals. This increases the risk of chronic inflammation and other metabolic disturbances.
• The omega-3 fatty acid, DHA, which is found in oily fish and fish oil supplements, has a preventative and therapeutic effect

Vitamin D, selenium, and iodine have other preventative mechanisms

Breast cancer seems to be a result of being deficient in one or several nutrients that are important for cellular gene expression, regulation of inflammation, hormone balance, and antioxidant defense.

Read more:
»Breast cancer: Common deficiencies of a few nutrients increase the risk of breast cancer and lethal metastases«

References:

Sepideh Maralbashi et al. Docosahexaenoic acid (DHA) impairs hypoxia-induced cellular and exosomal overexpression of immune-checkpoints and immunomodulatory molecules in different subtypes of breast cancer cells. BMC Nutrition 2024

Dorota Dydjow-Bendek and Pawel Zagozdzon. Total Dietary, Fatty Acids, and omega-3/omega-6 Ratio as Risk Factors of Breast Cancer in the Polish Population – a Case-Control study. In Vivo January-February 2020

Sarawoti Khadge et al. Long-chain omega-3 polysaturated fatty acids decrease mammary tumor growth, multiorgan metastatis and enhance survival. Clin Exp Metastasis. 2018