Expression of PCNA, cytokeratin, Bcl-2 and p53 during chemoprevention of hamster buccal pouch carcinogenesis by ethanolic neem (Azadirachta indica) leaf extract.

OBJECTIVES

To evaluate the effect of ethanolic neem leaf extract (ENLE) on cell proliferation, differentiation and apoptosis associated proteins during 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis.

DESIGN AND METHODS

Hamsters were divided into four groups. The right buccal pouches of animals in group 1 were painted with 0.5% DMBA three times a week. Animals in group 2 painted with DMBA as in group 1, received in addition, intragastric administration of ENLE (200 mg/kg bw) on days alternate to DMBA application. Group 3 animals were given ENLE (200 mg/kg bw) alone. Animals in group 4 served as control. All the animals were sacrificed after an experimental period of 14 weeks. The expression of proliferating cell nuclear antigen (PCNA), cytokeratin, Bcl-2 and p53 in the buccal pouch tissues were investigated using immunohistochemical staining. In addition, the expression of p53 was confirmed by Western blot analysis.

RESULTS

Topical application of DMBA for 14 weeks induced buccal pouch carcinomas associated with increased expression of PCNA, mutant p53 and Bcl-2 and decreased expression of cytokeratin. Administration of ENLE significantly inhibited the development of HBP carcinomas as revealed by decreased expression of PCNA, mutant p53 and Bcl-2 and overexpression of cytokeratin.

CONCLUSION

These findings suggest that ENLE exerts its anticancer properties by inhibiting cell proliferation and inducing differentiation and apoptosis.