Study On Effects By Inositol Hexaphosphate (IP₆) For The Treatment Of Subcutaneous Transplantable Tumor Of Human Colorectal Cancer In Nude Mice

Objective:To investigate the effect and explore the related mechanism of IP6(Inositol Hexaphosphate, IP6) on the treatment of human colorectal cancer in nude mice subcutaneous xenograft model, for the clinical treatment of colon cancer to provide experimental basis.Methods:Models of human colorectal cancer xenografts in nude mice were established and divided randomly into four groups. Each group included six mice.Control group:injected normal saline; 5-FU group:injection according to 20 mg/kg; IP6 groups: divided into low-does IP6 group (40mg/kg) and high-does group (100mg/kg); 0.5ml reagent was given to each mouse by intraperitoneal injection once a day. After continuous administration of 28d, the mice were killed by broking necks. During the experiment, we observed the general state of nude mice and detected transplanted tumors'size, weight. After the experiment, tumor, liver and kidney were got to do pathological detection. Fluorescence microscopy and electron microscopy were used to detect the changes of tumor tissues and cells.Hoechst staining and TUNEL were applied to assay apoptosis of tumor cells; the methods of immunohistochemistry, PT-PCR and westem-blot were adopted to detect the expression of PCNA, P53, bcl-2, and bax.Results:All of 24 models of HT-29 cell xenografts were formed after subcutaneous injection of a certain concentration of human colon cancer HT-29 cells; tumor formation rate was 100%. All of mice were in good condition during the experiment, no adverse reactions occur, except the mice in 5-FU group. Mice in 5-FU group were in poor state, even that one was dead. The growth curve of subcutaneous tumor showed that compared with control group, the growth of subcutaneous tumors in IP6 groups and 5-FU group slowed down. The changes of control group, low-dose IP6 group, high-dose IP6 group and 5-FU group respectively were (0.66±0.15) cm3,(0.45±0.06) cm3,(0.41±0.08) cm3 (0.26±0.54) cm3.There was no significant difference between low-dose IP6 group and high-dose IP6 group. The differences between IP6 groups and control groups were significant (P<0.05).Compared with 5-FUgroup, IP6 groups also had significant differences (P<0.05).Howere, there was no significant difference between low-dose IP6 group and high-dose IP6 group. The tumor weights of control groups,low-dose IP6 group, high-dose IP6 group and 5-FU group respectively were (0.80±0.22) g,(0.50±0.10) g,(0.46±0.13) g,(0.25±0.92) g. Compared with control group, the weight of tumors in IP6 groups and 5-FU group decreased significantly (P<0.05); there was no significant difference (P>0.05) between IP6 groups; the difference between IP6 groups and 5-FU group was significant (P<0.05).Hoechst staining and TUNEL assay showed cell apoptosis increased significantly in IP6 groups (P<0.05), comparing with control group. Immunohistochemistry showed PCNA and P53 protein expression was significantly lower in IP6 groups (P<0.05); RT-PCR and Western-blot showed that compared with the control group, the expression of bax significantly increased (P<0.05), bcl-2 expression significant ly decreased (P<0.05).Conclusion:IP6 has significant effects to inhibit the growth of tumor. And IP6 has fewer side effects, comparing with 5-FU. IP6 can reduce the expression of PCNA and P53 and regulate the expression of gene bcl-2 and bax, affecting signal transduction within cancer cells to inhibit cancer cell proliferation and promote apoptosis.