Objective: Curcumin has been shown to have significant protective effects against cancer and induction of apoptosis is a crucial strategy for cancer therapy, so we have now evaluated the mechanisms involved in two novel asymmetric curcumin analogues induced cell death in MCF -7 cells.
Methods:The cytotoxicity of two curcumin analogues towards tumor cells was investigated by MTT assays. The morphological analysis using a laser scanning confocal microscope. Futher cell cycle analysis, reactive oxygen species (ROS), mitochondrial transmembrane potentials (Δφm), intracellular Ca 2+ levels analysis and apoptosis assays via a flow cytometry (FCM). We used western blot assays to determine the expressions of apoptosis-related factors and p38MAPK at protein level.Results: MCF -7 cells showed a significant loss of viability, reduced mitochondrial membrane potential (Δφm), increased intracellular Ca 2+ levels, and increased production of ROS, which activated the pro-apoptotic p38 mitogen-activated protein kinase. Pretreatment with the antioxidant, N-acetylcysteine, inhibited both two curcumin analogues mediated ROS production and cytotoxicity. Western blotting revealed that the loss of Δφm inhibited Bcl-2, and induced Bax and Bak expression; this promoted release of cytochrome c and apoptosis inducing factor from the mitochondria to the cytosol, activation of caspase-9 and caspase-3 in the cytosol, and induction of apoptosis.
Conclusion:The two curcumin analogues displays strong antitumor effect through ROS-dependent mitochondria apoptosis pathway in MCF -7 cells, and has promising potential to be developed as antitumor compounds.
Camptothecin-20(s)-O-glycine ester-[N-(3'α, 12'α-dihydroxy-24'-carbonyl-5'β-cholan)] (A2), 10-(3'α,12'α-dihydroxy-5'β-cholan-24'-carboxyl)-(20 s)-camptothecin (C2), and 10-O-(3-O-(3'α, 12'α-dihydroxy-24'-carbonyl-5'β-cholan)-propyl)-(20S)-camptothecin (D2) are novel camptothecin-deoxycholic acid analogues. MTT assays were performed to assess the anticancer activity of these compounds against hepatocellular carcinoma SMMC-7721, breast carcinoma MCF-7, and colorectal carcinoma HCT-116 cells. A2 had a high killing ability on SMMC-7721 cells selectively, but C2 and D2 did not exhibit selectivity with regard to SMMC-7721 killing. Uptake assays were performed in an effort to elucidate the transport mechanisms of A2 into SMMC-7721 cells. A2 increased the mRNA expression of OATP1B3 (an organic anion-transporting polypeptide) and uptake of A2 was inhibited by rifampin (inhibitor of OATP1B3), which indicated that the transporter-mediated transport of A2 was mediated by OATP1B3. In addition, according to the western blot and apoptosis assays, we found that A2 killed SMMC-7721 cells by inducing cell apoptosis mainly via an AIF (apoptosis-inducing factor) pathway and a caspase-dependent mitochondria apoptosis pathway.
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