Role of free Radicals

Cancer

Millions of patients throughout the world suffer from cancer. Recent evidence suggests regional variance of cancer with lung, breast, colon, uterus and prostate cancers being prevalent in developed countries compared to cervical, mouth/pharynx, esophageal and liver cancers being prevalent in the developing world. Evidence suggests that cancer development occurs in two stages, initiation and promotion. Initiation involves a permanent, irreversible genetic change in the cell’s DNA. This generally causes DNA strand brakes, which can lie dormant in the cell but do not alone cause cancer. Promotion elicits the second stage of carcinogenesis, which stimulates the cell infiltration, transforming it to a cancerous cell. This process is reversible and may require continued stimulation to promote mutations. Many components have both initiating and promoting activities, however, free radicals are thought to act principally as promoting agents. Superoxide radicals and many peroxides are tumor promoters whereas some antioxidants act as anti-promoters and anti-carcinogens. Free radicals have been associated with gross chromosomal damage and also inhibition of the biological natural repair system. Free radicals and ROS can alter gene expression by mobilization of calcium stores, which activate a variety of cellular kinases, phosphatases and transcription factors. Lipid peroxidation by free radicals and ROS has also been implicated as a causative factor in cancer development.

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