Study Of Melittin On Tumor Inhibition And Part Of Mechanism Of Human Gastric Cancer SGC-7901 Cell Xenografts In Nude Mice

Stomach cancer is one of common malignant tumors, which incidence is on the top of all of cancer in China. However, there is no significant effect of treatment now. Therefore, exploring new drugs of gastric cancer is very important. Melittin which is the main active ingredients of bee venom, is a non-specific cytotoxic peptide. The changes of immunity and inhibition rate of SGC-7901 tumor-bearing mice were observed by this experiment, providing the basis for further clinical trials. The main contents are summarized as follows:1Effect of melittin on tumor growth of human gastric cancer SGC-7901 tumor–bearing miceCaged animals points to adapt to the environment, after sevev days, started the experiment. SGC-7901 cells in logarithmic growth pahse were prepared at a concentration 2.5×10¹⁰ cells/L and were subcutaneously inoculated into the right flank of nude mice with 0.2ml cancer cells. When the implanted tumor grew to about 100 mm³, it was beginning to inject drug into abdominal every other day. After seven times, melittin (2,4mg/kg) could inhibit tumor growth compared with model group. Besides, melittin (2,4mg/kg) could prolong the survival time of SGC-7901 tumor-bearing mice. Melittin(1,2,4mg/kg) could make tumor mortified which determined by morphology. While the range of necrocis was increased with the dose increased.2Effect of melittin on immune function of human gastric cancer SGC-7901 tumor–bearing mice2.1Effect of melittin on spleen index of human gastric cancer SGC-7901tumor–bearing miceUnder the sterile conditions, removing the spleen and liver, then weighted them. The organ index of tumor-bearing mice was calculated as follows: Organ index=Organ weight / body weight. Melittin (2,4mg/kg) could reinforce spleen index but not liver index obviously compared with model group.2.2 Effect of melittin on phagocytosis in peritoneal macrophage of tumor-bearing micePhagocytosis of peritoneal macrophage was measured by neutral red method. Melittin (1,2,4mg/kg) could improve phagocytosis of peritoneal macrophage obviously compared with model group.2.3 Effect of melittin on activity in NK cell of tumor-bearing miceNK cell activity was detected by improved MTT assay. Melittin (2,4mg/kg) could reinforce NK cell activity compared with model group.2.4 Effects of melittin on IL-2, TNF-αand IL-1 formation of human gastric SGC-7901 tumor-bearing miceThe content of IL-2, TNF-αand IL-1 in serum was determined by ELISA method. Melittin (4mg/kg) could reinforce the content of IL-2, TNF-αandIL-1.2.5 Effects of the melittin on the mRNA expression of IL-2,TNF-α,IL-1βin tumorThe mRNA expression of IL-2, TNF-αand IL-1βin tumor was determined by RT-PCR method. Melittin (2,4mg/kg) could reinforce the mRNA expression of IL-2, TNF-αand IL-1βcompared with model group.2.6 Effect of the melittin on the protein expression of TNF-αin tumorThe protein expression of TNF-αin tumor was determined by western-blot method. Melittin (4mg/kg) could reinforce the protein expression of TNF-αcompared with model group.