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Abstract- Silibinin a natural flavonoid has been reported to induce cell death in various types of cancers and also in endothelial cells which shows its anti-angiogenesis effect. However, its molecular mechanism is not clearly defined. In this article, we provided evidence for one of the mechanisms by which Silibinin induces apoptosis in HUVEC. For this purpose, HUVECs were grown on 96 well plates and cell viability was measured by MTT assay and IC50 was determined as 143μM after 24 hr of treatment by Silibinin. Caspase-9 activity in dose dependent (100-300μM) and time dependent (24,48 and 72hr) treatment by Silibinin was assessed using chromogenic substrate LEHD-pNA. Maximum activity of caspase 9 was in 100 μM of silibinin after 48 hours of treatment. DNA fragmentation was analyzed by gel electrophoresis. Cells were incubated with different concentrations of silibinin (100-400μM) and DNA that was extracted from cells which were incubated by 400 μM of silibinin formed a smear on agarose gel. Data obtained from this study showed the ability of Silibinin to inhibit HUVEC cell proliferation through apoptosis induction which indicates the anti-angiogenesis effect of this compound.

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Objective: Prostate cancer is one of the most common cancer in the developed countries. Most of cancer deaths are due to development of metastasis. Hence, prevention of metastasis is critical. Silibinin is a flavonoid component that inhibits cell proliferation and causes cell death of human prostate cancer. In this study, the expression of CD82 gene in PC-3 cells treated with escalating concentrations of silibinin was evaluated which can result in new view for prostate cancer therapy. Materials and Methods: In this study, PC-3 cells were treated with different concentrations of silibinin for 24h. The LD50 was determined. RNA was extracted by trizol, then cDNA was synthesized. Precise primers were designed for CD82 and GAPDH genes by specific software. Quantity of CD82 gene expression compare to GAPDH gene in different concentrations of silibilin was analyzed using very sensitive quantitative Real-time PCR. Results: CD82 gene expression in PC-3 cells treated with 100, 150 and 200μg/ml of silibinin at 24h was increased by 1.97±0.26 (P<0.05), 3.00±0.26 and 3.43±0.43 (P<0.01), respectively. Conclusion: The results of quantitative Real-time PCR indicated that silibinin can probably decrease metastasis, by up-regulation of CD82 metastasis suppressor gene in PC-3 cells.