The Effects Of Inositol Hexaphosphate (IP₆) On Proliferation Of HT-29 Human Colon Carcinoma Cell Line And Its Mechanisms

Objective: To investigate the effects of inositol hexaphosphate on proliferation of HT-29 human colon carcinoma cell line and its mechanisms .Methods: Cells were exposed to various concentrations ( 0mM, 1.8 mM, 3.3 mM , 5.0 mM, 8.0 mM, 13.0 mM )of IP6 for certain time. Its effects on the cells were evaluated by detecting follow indexes:(1) Cells were treated continuously and uncontinuously respectively with IP6.The effect of IP6 on cells proliferation was evaluated by MTT assay.(2) Immunocytochemical stain was used to detect the expression of P53 protein,P21 protein and proliferating cell nuclear antigen(PCNA).(3) Oncogene mdm2 mRNA expression state in cells were determined by reverse transcription polymerase chain reaction (RT-PCR).Results: 1 Continuous treatment with IP6 had an inhibition effect on the proliferation of HT-29 cells. The OD Value of each IP6 group was lower than that of control group (P<0.05).At the same time point, the OD Value decreased with IP6 concentration rising. Meanwhile, in contrast to the Oday of exposure to IP6 ,the OD Values of 8.0mM and 13.0mM groups decreased significantly (P<0.05) on the 6th day.The results showed that the inhibition effects of IP6 was both concentration-dependent and time-dependent. The experiment of uncontinuous treatment with IP6 also showed a time-dependent inhibition .2 The immunocytochemical stain showed that different concentration of IP6 decreased the abnormal expression of p53 gene and PCNA (P<0.05) and induced the expression of p21 gene (P<0.05).3 The expression of mdm2 mRNA was decreased by 3.3mM~8.0mM IP6 (P<0.05) .Conclusion: IP6 had an inhibition effect on proliferation of HT-29cells. The mechanisms of the effect might be related to many links, such as inhibiting the expression of oncogene mdm2 and the abnormal expression of p53 gene; inducing the expression of cell cycle inhibitor p21 thus blocking the cell cycle; decreasing the expression of PCNA (the coenzyme of DNA polymerase) ,so that decrease DNA synthesis and inhibit cell proliferation.