Abstract
Background:
Curcumin, an active ingredient of turmeric with no discernable toxicity, inhibits the growth of transformed cells and the development and progression of colon carcinogenesis in experimental animals. Recent data from one of our laboratories demonstrated that a crude skin extract or a purified crystalline compound (Bufo melanostictus-antineoplastic factor 1, BM-ANF1) from Indian common toad (Bufo melanostictus, Schneider) skin inhibits the growth of human leukemic cells. The present investigation was undertaken to determine whether combining BM-ANF1 with curcumin would be a better therapeutic strategy for colon cancer.
Materials and methods:
Colon cancer HCT-116 cells were used. Changes in growth, apoptosis, growth factor receptor signaling and events of the cell cycle were analyzed.
Results:
Curcumin together with BM-ANF1 produced a greater inhibition of HCT-116 cells growth than either agent alone, attributable to the inhibition of proliferation and stimulation of apoptosis, as evidenced by suppression of proliferating cell nuclear antigen (PCNA) expression, cell cycle arrest at the G2/M-phase and caspase-3 activation. There was also a marked reduction of cyclin-dependent kinase (CDK)2, CDK4 and cyclin B expression and up-regulation of CDK inhibitors (p21, p27) and p53, accompanied by attenuation of Akt signaling and nuclear factor-kappa B (NF-kappaB) activation.
Conclusion:
BM-ANF1 in combination with curcumin causes a marked inhibition of growth of colon cancer cells and could be an effective therapeutic strategy for colon cancer.
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