该研究采用rmhTNF- MKN-45裸鼠皮下移植瘤模型，观察p53异构体Δ133p53表达的生物学意义，为胃癌的治疗提供新的依据。

以人胃癌MKN-45细胞为研究材料，建立裸鼠皮下移植瘤模型，随机分成3组，空白对照组肌注生理盐水，实验1组肌注rmhTNF 16.7 IU，实验2组肌注rmhTNF 33.3 IU，均为0.1 mL，1次/d，连续注射10 d。14天后，处死裸鼠，剥离肿瘤组织，记录肿瘤体积和抑瘤率，采用NRT-PCR检测Δ133p53、p53、MDM2mRNA表达水平。

rmhTNF对MKN-45裸鼠移植瘤有抑制作用(F＝937.773，P<0.01)，剂量为16.7 IU、33.3 IU的rmhTNF，作用10 d后，裸鼠移植瘤抑制率分别为14.10%、29.04%；作用14 d后，裸鼠移植瘤抑制率分别为36.09%、57.50%，而且具有量效及时效依赖关系。nRT-PCR结果示，随着rmhTNF剂量的增加，MKN-45裸鼠移植瘤中，Δ133p53mRNA的相对表达量分别为1.021、0.602、0.372(F＝105.735，P<0.01)，MDM2mRNA的相对表达量分别为1.087、0.826、0.617(F＝27.028，P<0.01)，p53mRNA的相对表达量分别为0.321、0.580、0.872(F＝25.963，P<0.01)，Δ133p53表达水平逐渐下降，与MDM2呈正相关(r＝0.913，P<0.01)，与p53呈负相关(r＝-0.903，P<0.01)。Δ133p53蛋白的表达量：0.714、0.496、0.348，MDM2蛋白的表达量：0.747、0.630、0.531，并且随rmhTNF剂量增加而降低：Δ133p53蛋白(F＝38.755，P<0.01)、MDM2蛋白(F＝18.897，P<0.01)；实验组p53蛋白的表达量：0.338、0.525、0.713，并且随rmhTNF剂量增加而增高(F＝17.596，P<0.01)。Pearson直线相关分析结果示：Δ133p53表达水平逐渐下降，与MDM2呈正相关(r＝0.961，P<0.01)，与p53呈负相关(r＝-0.891，P<0.01)。

rmhTNF对人胃癌细胞MKN-45裸鼠移植瘤的抑制效应中，Δ133p53与野生型p53发生拮抗作用，其抗肿瘤途径可能与调节p53-MDM2表达途径有关，Δ133p53可能是胃癌治疗的重要靶点。

To observe the biological significance of p53 isoforms Δ133p53 expression by using subcutaneous xenograft tumor model of rmhTNF-MKN-45 in nude mice, and provide a new basis for the treatment of gastric cancer.

The subcutaneous xenograft model of nude mice was established with human gastric cancer MKN-45 cells.The mice were randomly divided into three groups: blank control group was intramuscular injected with normal saline, experimental group 1 was intramuscular injected with rmhTNF 16.7 IU, and experimental group 2 was intramuscular injected with rmhTNF 33.3 IU, 0.1 ml once a day, for 10 days continuously.After 14 days, the nude mice were sacrificed, the tumor tissue was removed, the tumor volume and tumor inhibition rate were recorded, and the mRNA expression levels of Δ133p53, p53 and MDM2 were detected by NRT-PCR.

rmhTNF had an inhibitory effect on MKN-45 nude mice(F=937.773, P<0.01). The inhibitory rates of 16.7 IU and 33.3 IU rmhTNF were 14.10% and 29.04% after treating 10 d; the inhibitory rates of 16.7 IU and 33.3 IU rmhTNF were 36.09% and 57.50% after treating 14 d, and showed dose-effect and time-dependent relationships.The nRT-PCR results showed that with the increase of rmhTNF dose, the relative expression levels of Δ133p53 mRNA in MKN-45 nude mice transplanted tumor were 1.021, 0.602 and 0.372(F=105.735, P<0.01). The relative expression levels of MDM2 mRNA were 1.087, 0.826 and 0.617(F=27.028, P<0.01), and the relative expression levels of p53 mRNA were 0.321, 0.580 and 0.872(F=25.963, P<0.01). The Δ133p53 expression level decreased gradually, which was positively related to MDM2(r=0.913, P<0.01), and negatively related to p53(r=-0.903, P<0.01). Δ133p53 protein expression levels: 0.714, 0.496, 0.348(F=38.755, P<0.01), MDM2 protein expression levels: 0.747, 0.630, 0.531(F=18.897, P<0.01), and decreased with the increase of rmhTNF dose.The expression level of p53 protein in the experimental group was 0.338, 0.525, 0.713, and increased with the increase of rmhTNF dose(F=17.596, P<0.01). Pearson linear correlation analysis results showed that Δ133p53 expression level decreased gradually, which was positively correlated with MDM2(r=0.961, P<0.01), and negatively correlated with p53(r=-0.891, P<0.01).

In the inhibitory effect of rmhTNF on human gastric cancer cell line MKN-45 xenograft tumor in nude mice, Δ133p53 antagonizes wild-type p53, and its anti-tumor pathway may be related to the regulation of p53-MDM2 expression pathway, and it may be an important target of gastric cancer therapy.