Dietary Turmeric Post-Treatment Decreases DMBA-Induced Hamster Buccal Pouch Tumor Growth by Altering Cell Proliferation and Apoptosis-Related Markers

Abstract

In the present study, post-treatment effects of dietary turmeric on markers related to apoptosis, cell proliferation, and inflammation in 7,12-dimethylbenz(a)anthracene (DMBA)-induced hamster buccal pouch (HBP) tumors were investigated. Tumors were induced by applying 0.5% DMBA topically to the HBP three times per week for 12 weeks. After tumor development, half of the animals continued on the control diet and the other half were shifted to a 1% turmeric diet for 4 weeks. To rule out DMBA discontinuation as a cause of inhibition in tumor growth, DMBA treatment was continued during dietary exposure of turmeric in another set of animals until the end of the experiment. The turmeric diet inhibited tumor growth in animals with or without DMBA carcinogen treatment compared to the animals on the control diet. When compared to hamsters bearing tumors that remained on the control diet, the buccal pouches of hamsters bearing tumors receiving turmeric showed the following results: (1) decreased cell proliferation (diminished PCNA, cyclin D1, and Bcl-2) and PCNA labelling index, (2) enhanced apoptosis (increased Bax, caspase-3, caspase-9, and cytochrome c, and decreased survivin) and apoptotic index, (3) decreased inflammation (decreased Cox-2), and (4) decreased MAPK activation (p-ERK and p-p38). These data indicate that tumor growth decreased due to the modulation of cellular pathways associated with cell proliferation and apoptosis.