Anticancer effect of dentatin and dentatin-hydroxypropyl-P-cyclodextrin complex on human colon cancer

Introduction: Dentatin (DEN) (5-methoxy-2, 2-dimethyl-10-(1, 1-dimethyl-2propenyl) dipyran-2-one), a natural compound present in the roots of Clausena excavata Burm f, possesses pro-apoptotic and antiproliferative effects in various cancer cells. Because of its hydrophobicity, it is believed that its complexation with hydroxy-[beta]-cyclodextrin (HP[beta]CD) will make it a potent inhibitor of cancer cell growth. In the current work, the molecular mechanisms of apoptosis induced by DEN and DEN-HP[beta]CD complex were demonstrated in human colon HT-29 cancer cells. Materials and methods: After the human colon HT-29 cancer cells were treated with DEN and DEN-HP[beta]CD complex, their effects on the expression of apoptotic-regulated gene markers in mitochondria-mediated apoptotic and death receptor pathways were detected by Western blot analysis and reverse transcription polymerase chain reaction. These markers included caspases-9, 3, and 8, cytochrome c, poly (ADP-ribose) polymerase, p53, p21, cyclin A as well as the Bcl-2 family of proteins. Results: At 3, 6, 12, and 24 [micro]g/mL exposure, DEN and DEN-HP[beta]CD complex significantly affected apoptosis in HT-29 cells through the down-regulation of Bcl-2 and cyclin A in turn, and up-regulation of Bax, p53, p21, cytochrome c at both protein and mRNA levels. DEN and DEN-HP[beta]CD complex also decreased cleaved poly (ADP-ribose) polymerase and induced caspases-3, -8, and -9. Conclusion: Results of this study indicate that the apoptotic pathway caused by DEN and DEN-HP[beta]CD complex are mediated by the regulation of caspases and Bcl-2 families in human colon HT-29 cancer cells. The results also suggest that DEN-HP[beta]CD complex may have chemotherapeutic benefits for colon cancer patients. Keywords: natural products, HP[beta]CD, apoptosis, pro-apoptotic proteins, anti-apoptotic proteins