MHY451 induces cell cycle arrest and apoptosis by ROS generation in HCT116 human colorectal cancer cells.

Colorectal cancer (CRC) is the third most frequently diagnosed cancer and cause of cancer-related deaths. Despite advancements in conventional therapeutic approaches to CRC, most patients with CRC die of their disease. There is a need to develop novel therapeutic agents for this malignancy. Therefore, the present study aimed to examine the anticancer effects and elucidate the underlying mechanism of MHY451 in HCT116 human colorectal cancer cells. Treatment with MHY451 inhibited cell growth in a time- and concentration-dependent manner. MHY451 increased the accumulation of cell cycle progression at the G2/M phase. This agent decreased the protein level of cyclin B1 and its activating partners, Cdc25c and Cdc2, whereas it increased the cell cycle inhibitor p21WAF/CIP. The induction of apoptosis was observed by decreased viability, cleavage of poly(ADP-ribose) polymerase (PARP), alteration in the ratio of Bax/Bcl-2 protein expression and reduction of procaspase-8 and -9. Pretreatment with Z-VAD-FMK, a pan-caspase inhibitor, inhibited MHY451-induced apoptosis, indicating that apoptotic cell death by MHY451 was mediated through caspases. Moreover, the apoptotic effect of MHY451 was reactive oxygen species (ROS)-dependent, evidenced by the inhibition of MHY451-induced PARP cleavage and ROS generation by N-acetylcysteine-induced ROS scavenging. Taken together, these results demonstrate that MHY451 exerts anticancer effects by regulating the cell cycle, inducing apoptosis through caspase activation and generating ROS. These results suggest that MHY451 has considerable potential for chemoprevention or treatment of CRC or both.

HS-1793, a resveratrol analogue, downregulates the expression of hypoxia-induced HIF-1 and VEGF and inhibits tumor growth of human breast cancer cells in a nude mouse xenograft model.

A synthetic analogue of resveratrol, 4-(6-hydroxy-2-naphtyl)-1,3-benzenediol (HS-1793), with improved photosensitivity and stability profiles, has been recently reported to exert anticancer activity on various cancer cells. However, the molecular mechanism of action and in vivo efficacy of HS-1793 in breast cancer cells have not been fully investigated. In the present study, we evaluated the effect of HS-1793 on hypoxia-inducible factor-1α (HIF-1α), which drives angiogenesis and the growth of solid tumors, in addition to the in vivo therapeutic effects of HS-1793 on breast cancer cells. HS-1793 was found to inhibit hypoxia (1.0% oxygen)-induced HIF-1α expression at the protein level, and its inhibitory effect was more potent than that of resveratrol in MCF-7 and MDA-MB-231 breast cancer cells. Furthermore, HS-1793 reduced the secretion and mRNA expression of vascular endothelial growth factor (VEGF), a key mediator of HIF-1-driven angiogenesis, without affecting cell viability. To evaluate the anticancer effects of HS-1793 in vivo, triple-negative MDA-MB-231 breast cancer xenografts were established in nude mice. HS-1793 significantly suppressed the growth of breast cancer tumor xenografts, without any apparent toxicity. Additionally, decreases in Ki-67, a proliferation index marker, and CD31, a biomarker of microvessel density, were observed in the tumor tissue. Expression of HIF-1 and VEGF was also downregulated in xenograft tumors treated with HS-1793. These in vivo results reinforce the improved anticancer activity of HS-1793 when compared with that of resveratrol. Overall, the present study suggests that the synthetic resveratrol analogue HS-1793 is a potent antitumor agent that inhibits tumor growth via the regulation of HIF-1, and demonstrates significant therapeutic potential for solid cancers.