FOLFOX4联合1-MT对胃癌小鼠皮下移植瘤的抑制作用

Inhibitory effect of FOLFOX4 combined with 1-MT on subcutaneous xenografts of gastric cancer in mice

目的:观察FOLFOX4联合1-甲基-色氨酸(1-methyl tryptophan,1-MT)对荷胃癌小鼠皮下移植瘤生长的抑制作用,以及对胃癌组织吲哚胺-2,3-双加氧酶(indoleamine-2,3-dioxygenase,IDO)表达的影响。方法:将IDO真核表达质粒(pcDNA3.1-IDO)转染小鼠胃癌细胞MFC,建立稳定表达IDO的细胞株,RT-PCR与Westernblot法检测细胞中IDO的表达。小鼠皮下接种转染pcDNA3.1-IDO的MFC细胞悬液,建立高表达IDO的小鼠胃癌皮下移植瘤模型(32只),同时设空白对照(8只,接种未转染的MFC细胞)和阴性对照(8只,接种转染pcDNA3.1质粒的MFC细胞),观察各组小鼠成瘤情况。将32只模型小鼠随机分为1-MT治疗组、FOLFOX4治疗组、FOLFOX4+1-MT联合治疗组和未治疗组(阳性对照组),每组8只。治疗组分别注射给予1-MT、FOLFOX4或FOLFOX4+1-MT,阳性对照组给予生理盐水。观察各组小鼠一般情况及肿瘤质量差异。注射细胞悬液后第12天处死所有小鼠,剥离瘤体并称重,计算各组小鼠平均瘤质量及抑瘤率,另取肿瘤标本采用免疫组织化学染色法检测胃癌组织中IDO的表达。结果:RT-PCR与Westernblot均检测到pcDNA3.1-IDO转染细胞中IDO的表达。高表达IDO的胃癌皮下移植瘤模型小鼠肿瘤质量大于空白对照组和阴性对照组小鼠(P<0.05),且其胃癌组织IDO的表达亦较空白对照组和阴性对照组明显增加(P<0.05)。给予1-MT、FOLFOX4和FOLFOX4+1-MT治疗后,模型小鼠进食量均不同程度增加,行动较之前灵活,嗜睡也有不同程度好转,FOLFOX4+1-MT联合治疗组小鼠症状基本缓解。1-MT治疗组、FOLFOX4治疗组和FOLFOX4+1-MT联合治疗组小鼠肿瘤质量均小于未治疗组(P<0.05),其抑瘤率分别为8.91%、80.20%、86.13%,FOLFOX4+1-MT联合治疗组小鼠肿瘤质量小于1-MT治疗组和FOLFOX4治疗组(P<0.05)。1-MT治疗组、FOLFOX4治疗组和FOLFOX+1-MT联合治疗组小鼠胃癌组织中IDO的表达均低于未治疗组(P<0.05);FOLFOX4+1-MT联合治疗组胃癌组织中IDO的表达低于1-MT治疗组和FOLFOX4治疗组(P<0.05)。结论:1-MT对胃癌小鼠皮下移植瘤的生长和胃癌组织IDO的表达具有抑制作用,并能与FOLFOX4发挥协同抗肿瘤作用。

OBJECTIVE： To observe the inhibitory effect of FOLFOX4 combined with 1-MT on subcutaneous xenografts of gastric cancer in mice, and its influence on the expression of indoleamine-2, 3-dioxygenase （IDO） in gastric cancer tissue. METHODS： Transfect the IDO eukaryotic expression plasmids （pcDNA3.1-IDO） into mice gastric cancer cell line MFC. The cell line expressing IDO stably was established. Expression of IDO was detected by reverse transcription polymerase chain reaction （RT-PCR） and Western blot. Suspension of the MFC cells transfected with pcDNA3.1-IDO plasmid were inoculated subcutaneously in mice. Mice gastric carcinoma subcutaneous xenografts model expressing IDO highly was established （n=32）. Blank control （n=8, untransfected MFC cells） and negative control （n=8, transfected MFC cells） were set up. The 32 model mice were randomly divided into 1-MT treatment group, FOLFOX4 treatment group, FOLFOX4＋1-MT combined treatment（saline） group and non-treatment group （positive control group）. There were eight mice in each group. The general condition of the mice and the differences in tumor quality were observed. Twelve day after cell suspension injection, all of the mice were sacrificed. The tumors were excised and weighed. Average tumor size and the tumor inhibitory rates of each group were calculated. The expression of IDO in gastric carcinoma tissues was evaluated by immunohistochemistry. RESULTS： Tumor of mice gastric carcinoma subcutaneous xenografts model expressing IDO highly was greater than blank control and negative control groups （P〈0.05） and the expression of IDO in gastric carcinoma tissue was also increased significantly（P〈0.05）. After given 1-MT, FOLFOX4 and FOLFOX4＋I-MT treatments, the food intake of model mice increased to varying degrees, more agile than before, and lethargy was also improved to different extents. The symptoms of FOLFOX4＋I-MT combined treatment group were basically resolved. The tumors of 1-MT treatment, FOLFOX4 treatment and FOLFOX4＋I-MT combined treatment group were smaller than no treatment group （P〈0.05）. The turnout inhibitory rates were 8.91%, 80.20%, 86.13%, respectively. FOLFOX4＋I-MT combined treatment group tumor was less than 1-MT treatment group and FOLFOX4 treatment groups （P〈0.05）. The expressions of IDO in gastric carcinoma tissue of 1-MT treatment, FOLFOX4 treatment and FOLFOX＋I- MT combined groups were lower than non-treatment group （P〈0.05）. The expression of IDO in gastric cancer tissue of FOLFOX4＋I-MT combined treatment group was lower than 1-MT treatment group and FOLFOX4 treatment groups （P〈0.05）. CONCLUSION： 1-MT could inhibit the growth of subcutaneous xenografts of gastric carcinoma and the expression of IDO in gastric carcinoma tissue in mice. It could play synergistic antitumor role together with FOLFOX4.