Azadirachta indica exerts chemopreventive action against murine skin cancer: studies on histopathological, ultrastructural changes and modulation of NF-kappaB, AP-1, and STAT1.

The present study reports the histopathological, ultrastructural changes and modulation of NF-kappaB, AP-1, and STAT 1 during skin carcinogenesis in LACA mice and its intervention with Azadirachta indica. Skin tumors were induced by topical application of 7,12-dimethylbenz(a)anthracene (DMBA) (500 nmol/100 microl for 2 weeks) followed by 12-O-tetradecanoylphorbol-13-acetate (TPA) (1.7 nmol/100 microl of acetone, twice weekly) as a promoter. Male LACA mice were divided into four groups: Control, DMBA/TPA, aqueous Azadirachta indica leaf extract (AAILE), and AAILE + DMBA/TPA. AAILE was administered orally at a dose level of 300 mg/kg body weight three times a week for 20 weeks. Topical application of DMBA/ TPA to the skin resulted in well-developed squamous cell carcinomas characterized by hyperproliferation, hyperkeratosis, and corrugation of the epidermis. Degenerative changes were observed in the tumors of AAILE + DMBA/TPA-treated animals. Scanning electron microscopy revealed surface disruptions and certain rounded structures on the skin tumors of DMBA/TPA-treated animals. Topographical changes were also observed in the tumors of AAILE + DMBA/TPA-treated animals, which resembled regions of degeneration. Tumors obtained in DMBA/TPA group were associated with enhanced expression of NF-kappaB and AP-1 when compared to the control counterparts. Inhibition in tumorigenesis in response to A. indica treatment was accompanied by an overexpression of STAT 1 and AP-1 and decrease in NF-kappaB expression. The results of the present study provide a basis for the chemopreventive potential of A. indica against murine skin carcinogenesis.