Introduction: Prevention of cancer remains a primary need and new chemopreventive agents must be developed for this purpose. It is well known that the radiotherapy is associated with severe side effects and offers no firm expectation for a cure. Thus, there is a constant need for the investigation of other potentially useful options. One of the widely sought approaches is cancer chemoprevention that uses natural agents. Curcumin, a natural plant product, has been shown to have anti-inflammatory and antioxidant properties and which, thus, may be a potential anticancer drug.
Material and Methods: The inhibitory effects of dietary curcumin (0.6 % in diet) on colonic precancerous lesions in rats treated with 1,2-dimethylhydrazine, (DMH, 20 mg/kg, s.c. once weekly for 6 weeks) or exposed to γ-radiation (6.5 Gy) alone or in combination were evaluated histologically and histochemically.
Results: The results showed clear features of colonic dysplasia with DMH treatment. The dysplastic crypts exhibited marked hyperchromatism, loss of polarity besides nuclear and cellular stratification. Whereas, γ-irradiation revealed marked crypt dilatation accompanied by disorganized crypt structure and alteration of surface epithelium. The results also demonstrate an apparent synergy between the radiation and the chemical carcinogen in the induction of augmentation of mucosal abnormalities accompanied with increased total DNA content and cell proliferation. Consistent with these observations, changes in the type of mucous secretion with predominance of sialomucins were observed in the areas of mild to moderate dysplasia whilst the surrounding normal epithelium produced sulphated material. Mucus depletion was a common feature in areas of severe dysplasia.
Addition of curcumin to the diet remarkably reduced the amount and severity of dysplastic lesions with DMH-induced colon preneoplasia without appreciable toxicity. Moreover, curcumin could prevent or improve the disruption of colonic architecture caused by γ- irradiation. Such improvement was also investigated but to a lesser extent with the combined radiation and DMH.
Conclusion: These results indicated that curcumin is potent in inhibiting the preneoplastic lesions and other cellular events relevant to colon and was, therefore, of value as a safe chemotherapeutic agent.