Correlation of DNA damage in epidemic dropsy patients to carcinogenic potential of argemone oil and isolated sanguinarine alkaloid in mice

In recent times, a higher incidence of gall bladder carcinoma in the Indo-Gangetic basin has been linked with the consumption of contaminated mustard oil. Consumption of mustard oil contaminated with argemone oil (AO) is well known to cause clinical manifestation referred to as "epidemic dropsy." Because sanguinarine, an active alkaloid of AO, has been shown to intercalate DNA, a possible correlation of DNA damage in epidemic dropsy patients to tumorigenic potential of AO and isolated sanguinarine alkaloid in mice was investigated in the present study. Single topical application of AO (0.15-0.3 ml) or isolated sanguinarine (4.5-18 micromol) followed by twice-weekly application of tetradecanoylphorbolmyristate acetate (TPA) for 25 weeks resulted in formation of tumors. Histopathologically these tumors were of squamous cell carcinoma type and similar to those found in the positive control group using dimethylbenzanthracene (DMBA)/TPA. The activities of cutaneous gamma-glutamyl transpeptidase (GGT) and glutathione-S-transferase P (GST-P), marker enzymes of tumorigenesis, were found to exhibit higher expression in AO or isolated sanguinarine/TPA treated groups when compared to control. The higher expression of p53 and p21/WAF1 in skin after single topical application of AO or isolated sanguinarine further confirms the tumorigenic response. Single topical application of AO or isolated sanguinarine alkaloid to mice showed significant DNA damage in terms of Olive tail moment (89-129%), tail length (54%) and tail DNA (153-205%) using Comet assay in skin cells. Further, the extent of DNA damage in blood cells of epidemic dropsy patients in alkaline Comet assay was found to be significantly higher as compared to normal population, indicating the genotoxic response of AO exposure. Although the genotoxic lesions may be repaired to some extent on withdrawal of consumption of AO contaminated mustard oil and the residual genotoxic effects caused by AO may not be expressed as signs of carcinogenesis. Environmental factors or hormonal changes during aging process may lead to stimulate/promote the genetically altered latent cells to form neoplastic lesions and can act as one of the etiological factors responsible for higher incidence of gall bladder carcinoma in the population of Indo-Gangetic basin.