Carcinogenesis promotion stage

Carcinogenesis develops in three stages initiation, promotion, and progression. Chem-ical substances can act at the initiation stage or at the promotion stage. Moreover, some chemicals have both initiating and promoting activities. 

Continuous feeding of rats with 1% fenugreek seed powder (FSP) and 0.05% and 0.10% diosgenin suppressed total colonic aberrant crypt foci (ACF) by up to 32, 24 and 42%, respectively, in azoxymethane-induced carcinogenesis in rats. During the promotional stages, FSP inhibited total ACF. 

Murakoshi, M. et al.. Potent preventive action of a-carotene against carcinogenesis spontaneous liver carcinogenesis and promoting stage of lung and skin carcinogenesis in mice are suppressed more effectively by a-carotene than by P-carotene, Cancer Res., 52, 6583, 1992. 

Inano, H., Onoda, M., Inafuku, N., Kubota, M., Kamada, Y., Osawa, T., Kobayashi, H., and Wakabayashi, K., Chemoprevention by curcumin during the promotion stage of tumorigenesis of mammary gland in rats irradiated with gamma-rays. Carcinogenesis, 20, 1011, 1999. 

The tumor-promoting activity of OA can be also partially related to other actions at cellular level, such as oxidation of different substrates, methylation of DNA bases, and inhibitory mechanisms of gap intracellular communication, which is believed to be of importance in the promotion stage of carcinogenesis. An additional factor hypothesized to contribute to the tumor promotion by OA is amplification of genes conferring multidrug resistance to cells. ... 

The subsequent stage of carcinogenesis has been referred to as the "promotion" stage which has been extensively studied originally in the experimental induction of skin cancer and later with respect to the induction of other cancers. (, 7)... 

In a study by Harada et al. (1991), Syrian golden hamsters were used as a carcinogenesis model. The hamsters were treated with N-nitroso-bis(2-oxopropyl)amine and fed with a protein-deficient diet consisting of DL-ethionine and L-methionine for tumor promotion. In this study, the dietary supplementation with GTP (500mg/kg per day) during the promotion stage was found to reduce pancreatic tumorigenesis as compared with non-GTP supplemented animals (Harada et al., 1991). 

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