Effects of cyclohexanone analogues of curcumin on growth, apoptosis and NF-κB activity in PC-3 human prostate cancer cells

Abstract

Abstract. Curcumin is a non-nutritive yellow pigment found in the spice turmeric, which is derived from the rhizome of the plant Curcuma longa Linn. Six cyclohexanone analogues of curcumin (A 1 -A 6 ) were investigated for their effects on growth and apoptosis in PC-3 human prostate cancer cells. The ability of these compounds to inhibit NF-κB activity in PC-3 cells was also determined. Five out of the six curcumin analogues (A 2 -A 6 ) had stronger inhibitory effects compared to curcumin on the growth of cultured PC-3 cells. Compounds A 2 -A 6 also had stronger stimulatory effects on apoptosis in PC-3 cells than curcumin, and these curcumin analogues more potently inhibited NF-κB activity than curcumin. The inhibitory effects of these compounds on NF-κB activity correlated with their effects on growth inhibition and apoptosis stimulation in PC-3 cells. The results of the present study provide a rationale for in vivo studies with A 2 -A 6 using suitable animal models of prostate cancer. IntroductionCurcumin is a non-nutritive yellow pigment found in the spice turmeric, which is derived from the rhizome of the plant Curcuma longa Linn. Curcumin lacks toxicity in humans (1), and extensive research over several decades has revealed that curcumin possesses anticancer, anti-inflammatory, antioxidant, antiviral and anti-bacterial activities (2,3). Curcumin suppressed cell proliferation or induced apoptosis in cultured prostate cancer cells and other types of cancer cells (4-10). Curcumin also inhibited prostate carcinogenesis (11). Studies from our laboratory and those of other authors have demonstrated enhanced anticancer activities of curcumin when combined with other anticancer agents (12-14). Findings of earlier studies showed that curcumin exerts a wide range of anticancer effects by modulating a diversity of signaling pathways, including nuclear factor-κB (NF-κB) and other pathways (15)(16)(17)(18)(19)(20). Curcumin has entered clinical trials for certain types of human cancer (21-23). However, the clinical efficacy of curcumin is limited, which is likely to be due to its low bioavailability (21-23). It was suggested that the β-diketone moiety of curcumin causes instability and poor metabolic properties (24-26). Enhanced stability was found in curcumin analogues by deleting the β-diketone moiety of the molecule (27). Recently, it was demonstrated that the cyclohexanone analogues of curcumin have enhanced stability in biological medium compared to curcumin (28). The cyclohexanone-containing curcumin analogue 2,6-bisp[(3-methoxy-4-hydroxyphenyl)methylene)]-cyclohexanone was found to be more potent than curcumin for inhibiting NF-κB in human breast cancer cells in vitro (29).In an earlier study, we synthesized a series of cyclohexanone curcumin analogues and determined their inhibitory effect on the activity of aldose reductase (30). In the present study, we investigated the effects of these curcumin analogues on the growth and apoptosis of human prostate cancer PC-3 cells. We also determined the inhibitory effect ...

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Anticancer Activity of Acanthopanax trifoliatus (L) Merr Extracts is Associated with Inhibition of NF-κB Activity and Decreased Erk1/2 and Akt Phosphorylation

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“…A minimum of 200 cells were counted to determine the percentage of apoptotic cells in each sample. Caspase-3 activation was measured using an EnzoLyte AMC Caspase-3 Assay Fluorimetric kit (AnaSpec, Fremont, CA, USA) following the manufacturer's instructions (Wei et al, 2012). Fluorescence intensity was measured using a Tecan Infinite M200 plate reader (Tecan US Inc., Durham, NC, USA).…”