Role of cyanotoxins in the development and promotion of cancer

Cyanotoxins are primarily produced by different species of cyanobacteria, also known as blue-green algae, and have appeared to be environmental poisons that have various toxic effects on animal health, including humans. Cyanotoxins have been linked to the development and promotion of multiple cancers in recent studies. Important cyanotoxins, such as microcystins, nodularins, and cylindrospermopsin, have been found to play significant roles in developing and promoting various cancers. These toxins are generally responsible for oxidative stress, DNA damage, and disrupt cellular signaling pathways thus the development of cancers in various cells. Cancer is a multistep process caused by multiple mutations in normal cells. Microcystin-LR inhibits protein phosphatases (PP1 and PP2A), which leads to abnormal cell proliferation and tumor development. Similar inhibition of PP1 and PP2A is shown by nodularin, and in fact, their mechanism of carcinogenesis is the same as that of microcystins to some extent. Cylindrospermopsin inhibits protein synthesis and thus has genotoxic effects and may promote the development of cancer. Anatoxin-a and saxitoxins are well-known neurotoxins but, are thought to have indirect carcinogenic effects based on the fact that they can induce oxidative stress and DNA damage in cells by producing reactive oxygen species, thus further studies are needed to fully elucidate their role in the development and promotion of cancer. This review provides a detailed account of how different cyanotoxins play a role in the development and promotion of cancer.