How omega-3 fatty acids help beta-carotene to better protect against cancer
A high intake of carotenoids such as beta-carotene in the form of fruit and vegetables reduces the risk of breast cancer. Carotenoids also protect breast cancer patients who have been successfully treated against the recurrence of the disease. [Am J Clin Nutr. 2015 Jun;101(6):1197-205.] In 2007, researchers at Zhengzhou University in China published an in vitro study that shows how carotenoids control breast cancer cells. And how you can perhaps strengthen this anti-carcinogenic effect...
The researchers exposed MCF-7 cells to beta-carotene. MCF-7 cells are human breast cancer cells that need hormones such as estradiol and progesterone for their growth. Oncologists use MCF-7 as a model for the most common forms of breast cancer.
Beta-carotene killed some breast cancer cells. The higher the concentration, the stronger the effect. You can see this below. The anticancer effect of beta-carotenen became stronger als exposure lasted longer.
Beta-carotene increased the production of the PPAR gamma protein in breast cancer cells. PPAR-gamma is a receptor for fatty acids, and especially for polyunsaturated omega-3 fatty acids.
Activation of PPAR-gamma enables cells to absorp fatty acids, but also inhibit CDK enzymes. A relatively new group of cancer drugs inhibits CDK4 and CDK6 enzymes. However, stimulation of PPAR-gamma inhibits all CDK enzymes to a certain degree.
GW9662 sabotages the PPAR gamma protein. Administration of GW9662 nullified the effect of beta-carotene. You would expect that the administration of omega-3 fatty acids will have the opposite effect, but will actually strengthen the cancer-inhibiting effect of beta-carotene. The researchers have not studied whether this is the case.
The researchers discovered another mechanism by which beta-carotene kills breast cancer cells. Beta-carotene increased the activity of free radicals in the cancer cells. The figure below shows that this effect disappeared if the researchers also exposed the MCF-7 cells to glutathione, a substance that detoxifying enzymes need to neutralize aggressive substances.
Above you can see that both glutathione and GW9662 eliminate the cancer cell killing effect of beta-carotene.
"Our results demonstrated that beta-carotene can regulate cell apoptosis through pleiotropic mechanisms", write the researchers. "Both PPAR-gamma activation and reactive oxygen species production are involved in the apoptosis pathway. Beta-carotene increases the PPAR-gamma mRNA and protein level in a time-dependent manner."
"In addition, beta-carotene acts as prooxidant to increase intracellular reactive oxygen species, which may be responsible for mitochondrial dysfunction."
Other cancer types
Activating PPAR-gamma not only inhibits the growth of breast cancer cells, but according to test tube and animal studies may also inhibit stomach cancer [Cancer Res. 2005 Jun 1;65(11):4769-74.], prostate cancer [Cancer Res. 1998 Aug 1;58(15):3344-52.], colon cancer [Int J Oncol. 2004 Sep;25(3):631-9.], pancreatic cancer [Biochem Biophys Res Commun. 2003 Jan 31;301(1):50-3.] and melanoma [Cancer Lett. 2006 May 8;236(1):133-41.].
More coming soon.
Eur J Cancer. 2007 Nov;43(17):2590-601.
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