Supplementation with Spirulina platensis probably has a protective effect against breast cancer in women. Researchers from Sultan Qaboos University in Oman write about this in the American Journal of Pathology. The researchers caused rats to develop breast cancer by injecting them with a carcinogenic compound, and then observed that spirulina supplementation reduced the chance of tumour formation by a factor of seven.
Phycocyanin – Plants contain hundreds of substances that may have a protective effect against cancer, and the cyanobacteria Spirulina platensis contains lots. Phycocyanin, for example [structural formula on the right]. Or selenium, or chlorophyll, or carotenoids. Or gamma-linolenic acid [structural formula below].
There are indications that substances such as the components of Spirulina platensis can inhibit cancer cell development or activate the immune system that kills cancer cells. But scientists had never looked at whether Spirulina platensis can protect lab animals against cancer.
The researchers injected 20 young female rats with the carcinogenic 7,12-dimethylbenz[a]anthracene [DMBA], and gave another 20 rats injections that did not contain carcinogenic substances. Half of both groups were given normal food and the other half were given food that contained 1 percent spirulina powder. The human equivalent of the dose would be 5-8 g Spirulina platensis per day.
Of the rats that had been injected with DMBA and that ate standard food, 87 percent developed tumours during the course of the experiment. Of the rats that had been injected with DMBA and had been given spirulina, 13 percent developed tumours. Supplementation with spirulina increased the survival chances of the rats that had been injected with DMBA.
Spirulina activated suicide genes in the cancer cells, the researchers discovered. In addition, spirulina reduced the number of estradiol alpha-receptors, and the concentration of the protein Ki-67.
Estradiol can make hormone-sensitive cancer cells grow faster via the alpha-receptor. Ki-67 is a marker for cell division.
“In conclusion, Spirulina platensis exhibited remarkable antitumor activity by inhibiting cell proliferation induced by DMBA in rats”, the researchers write. “Although the direct mode of action and in-depth molecular mechanisms of Spirulina platensis have yet to be established, we plan to use microarray gene expression profiling to investigate the molecular pathways underlying the mode of action of its main ingredients that might act in synergy.”
Chemoprevention of rat mammary carcinogenesis by spirulina.
Spirulina (SP) (Arthrospira platensis; previously Spirulina platensis) is a filamentous blue-green microalga (cyanobacterium) with potent dietary phytoantioxidant and anticancerous properties. We investigated the chemopreventive effect of SP against 7,12-dimethylbenz[a]anthracene (DMBA)-induced rat breast carcinogenesis, and further studied its underlying mechanisms of action in vitro. Remarkably, SP cleared DMBA-induced rat mammary tumors, which was clearly confirmed by morphological and histological methods. SP supplementation reduced the incidence of breast tumors from 87% to 13%. At the molecular level, immunohistochemical analysis revealed that SP supplementation reduced expression of both Ki-67 and estrogen ?. More interestingly, molecular analysis in the in vitro experiments indicated that SP treatment inhibited cell proliferation by 24 hours, which was accompanied by increased p53 expression, followed by increased expression of its downstream target gene, Cdkn1a (alias p21 or p21(Waf1/Cip1)). In addition, SP increased Bax and decreased Bcl-2 expression, indicating induction of apoptosis by 48 hours after SP treatment. To our knowledge, this is the first report of in vivo chemopreventive effect of SP against DMBA-induced breast carcinogenesis in rat, supporting its potential use in chemoprevention of cancer.
Copyright © 2014 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.
PMID: 24269837 [PubMed - in process]