Effects Of Inositol Hexaphosphate (IP₆) On Cell Cycle And Related Regulatory Factors In Human Heptoma Cell Line HepG₂

Objective:To investigate the effects and mechanisms of IP6 on cell cycle and related regulatory factors protein expression of human heptoma cell line HepG2. Explore the growth inhibition of human hepatoma cell line HepG2 mechanism for the anti-tumor effect of IP6 provide a theoretical basis for application development.Methods:Will group is divided into low dose group (1.0mmol/L), dose group (2.0 mmol/L), high dose group (3.0 mmol/L) IP6,respectively in the role of HepG2 cells cultured in vitro.to IP6 role 24h without the same cultivation time HepG2 cells as control group. Its effects on the cells were evaluated by following indexes: 1 Flow cytometry analysis was performed for cell cycle progression. 2 Immunocytochemical stain was used to test the expression of cyclinD1, Rb and p27 3 RT-PCR was used to test the expression of cyclinDl and CDK4 in HepG2 cells.Results:1 Flow cytometric analysis showed that IP6 could cause G1 cell cycle arrest in HepG2 cells (p<0.05)2 The immunocytochemical stain showed that different concentrations of IP6 decreased the expression of cyclinDl (F=225.02, q=15.20-25.35, p<0.05) and strongly increased the expression of Rb (F=63.31,q=2.77—13.06, p<0.05) and p27 (F=254.75,q=4.71—25.71, p<0.05).And along with dosage increase, the expression of each IP6 group Rb (q=2.02—10.29, p<0.05) and p27 (q=8.52—21.00, p<0.05) elevates gradually.3 Reverse transcription polymerase chain reaction (RT-PCR) showed that compared with the control group, the expression of cyclinDl (F=672.34,q=16.41—41.99, p<0.05) and CDK4mRNA(F=108.35,q=5.32—16.27, p<0.05) was significantly decreased at all IP6 concentrations. And along with dosage increase, the expression of each IP6 function group cyclinDl mRNA (q=10.25—25.62,P<0.05) and CDK4 mRNA(q=3.32—10.95,P<0.05) reduces gradually.Conclusion:1 IP6 inhibited human hepatoma cell line HepG2 cells through the cell cycle and the associated regulatory factors achieved;2 IP6 to G1 phase cell cycle arrest and thus inhibit the growth of hepatoma cell line HepG2;3 Its mechanism may be through regulation of cell cycle factor expression, make the cell block in G1 phase:IP6 may be by reducing CyclinDl, CDK4 levels, thereby reducing CDK compound concentration, interference-CDK4 activation, restrain the Rb protein products, make E2F active reduce phosphorylation synthesis of making, DNA is restrained, make cell block in G1 phase; IP6 may raise p27 level that by combining the cyclinD1/CDK4/competitive cyclin-CDK complex, restrain CDK4 activity, enables E2F activity decreases, inhibit DNA synthesis, stopping cells into people S period, making the cell block in G1 phase; By IP6may raise level Rb protein, enhance the Rb protein and the combination of E2F, make the cell block in G1 phase. (?)...