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Abstract:
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Retinoids refer to natural and synthetic derivatives of vitamin A, which play multiple roles in embryogenesis, development, vision, homeostasis as well as proliferation and apoptosis. In the current study, a panel of 13 retinoids was screened to detect their apoptosis inducing effect on a human hepatoma cell line Huh-7. Huh-7 cells were treated with each retinoid (10 µM) for 72 hours in serum free medium. After every 24 hours, floating cells were collected and fresh medium plus retinoids were added. Attached cells were harvested after 72 hours followed by cell number counting. Proteins extracted from floating cells and attached cells were subjected to Western blot analysis to detect the cleavage/activation of caspase-3, which is a hallmarker of on-going apoptosis. After 72 hours treatment, except β-carotene, 12 out of 13 retinoids tested caused cell number decrease. Among those 12 retinoids, fenretinide and 13-cis-retinol decreased cell number most markedly, 68% and 62% respectively. Western blot results indicated that there was strong caspase-3 cleavage in fenretinide- and 9-cis-retinoic acid-treated cells, although weak caspase-3 cleavage was also detected in other retinoids treated cells. Hoechst 33342 and Propidium Iodide double staining also suggested there was nuclear DNA condensation in fenretinide-treated Huh-7 cells after 24 hour. Based on those results, we conclude that fenretinide and 9-cis-retinoic acid decreased cell number by causing apoptosis mediated by caspase-3 activation in human hepatoma cell line Huh-7. The same screening will be conducted on different hepatoma cell lines and the underlying molecular mechanism will be further pursued. |
