| Summary: | 碩士 === 國立高雄海洋科技大學 === 水產食品科學研究所 === 101 === Pterostilbene (3, 5-dimethoxy-4′-hydroxystilbene, PSB), a natural dimethylated analog of resveratrol, is known to have diverse pharmacological activities including anti-proliferation, anti-metastasis,and anti-inflammation activities. Previous studies demonstrated the effects of in vitro and in vivo studies of a potential anti-colon cancer agent of PSB. 3′-hydroxypterostilbene (3, 5-dimethoxy-3′, 4′-dihydroxystilbene, HPSB ) is the part metabolite of PSB in mice urine. HPSB is the presence of an additional hydroxyl group in position 3′ by hydroxylation. HPSB has been demonstrated to induce apoptosis. Here, we comparison with the ability of PSB and HPSB in inducing mechanisms of inhibiting proliferation of human colon cancer cells. MTT analysis demonstrated that PSB and HPSB was able to inhibit number of colon cancer cell growth and induce apoptosis. Biological activity of HPSB showed more potent in the growth inhibition in COLO205 cancer cells than PSB. Furthermore, HPSB show more potent antioxidant activity than PSB. We evaluate the ability of PSB and HPSB induced apoptosis in COLO205 cancer cells. Flow cytometry analysis show that PSB treatment increased sub-G1 cell population whereas HPSB with stronger apoptosis-inducing activity. PSB and HPSB induced apoptosis in COLO 205 cell through modulation of mitochondrial functions regulated by reactive oxygen species (ROS). PSB and HPSB induced caspase-3 activation, which is associated with the degration of DFF-45 (DNA fragmentation factor) and PARP (poly (ADP-riobse) polymerase). Indded, HPSB showed more strong inducing apoptosis than PSB. Flow cytometry analysis show that PSB treatment increased autophagy marker acidic vascular organelles (AVOs) formation whereas HPSB with stronger autophagy-inducing activity. Pretreatment Chloroquine (CQ an autophagy inhibitor) also significantly induce apoptosis in PSB or HPSB-treated cells. PSB and HPSB induced autophagy may play suppression role in apoptosis. The mechanisms of HPSB induced autophagy was through down-regulated PI3K-Akt and MAPKs signaling including decreased the phosphorylation of mTOR and p70S6K in COLO 205 cells. In a xenograft model, we evaluate the ability of PSB and HPSB inhibits the growth of colon cancer tumor xenografts in vivo. HPSB significantly decreased tumor growth, volume and weight of COLO 205 xenografts. In a AOM/DSS model, we evaluate the ability of PSB and HPSB biological activity inhibits the growth of colon cancer tumor and the underlying molecular mechanism in vivo. Our results shown that feeding HPSB (250 ppm and 500 ppm) for 10 weeks significantly reduced the tumor number and incidence in mouse colon. At the molecular levels, the results from western blot analysis showed that dietary HPSB exhibited the anti-inflammatory by decreasing the levels of iNOS and COX-2. Moreover, HPSB significantly decreased tumor growth through down-regulation of cyclin D1, MMP-9 and VEGF protein expression. In conclusion, we demonstrated that HPSB displayed more potent activity in inducing of apoptosis and autophagy than PSB. In addition, HPSB significantly decreased tumor growth, volume and weight through down-regulation of iNOS , COX-2, cyclin D1, MMP-9 and VEGF protein expression. HPSB displayed more potent activity on antioxidant activity than PSB.These results provide insight into might establish a molecular basis for the development of colon cancer therapeutic agents.
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