涎腺腺样囊性癌细胞凋亡的诱导与P53基因的修复

Mutation of P53 gene sequence in adenoid cystic carcinoma and its rep air induced by TNF-α

目的 探讨涎腺腺样囊性癌 (salivaryadenoidcysticcarcinoma) p5 3基因的突变以及重组人肿瘤坏死因子α(recombinedhumantumornecrosisfactor-α ,rhTNF -α)诱导凋亡过程中 p5 3基因的修复。 方法 ①在裸鼠移植瘤模型上 ,采用TNF -α 10 0× 10 4IU/kg或 10× 10 4IU/kg瘤体内注射 ,诱导腺样囊性癌移植瘤细胞凋亡 ;②采用DNA核酸序列测定方法 ,对移植瘤及凋亡诱导后的肿瘤分别进行 p5 3基因 6、7、8外显子的测定。 结果 发现腺样囊性癌移植瘤 p5 3基因第 8外显子的第 2 73、2 80号位点有点突变 ,其中 2 73位点为GCA→GCG ;2 80位点为GAG→GAC。第 6、7外显子未见突变。采用TNF -α治疗后 ,第 8外显子的第 2 80号突变位点得以修复正常 ,GAC→GAG ;而 2 73号突变位点未被修复。第 6、7外显子序列无变化。结论 ①涎腺腺样囊性癌发生中 p5 3基因的第2 73、2 80号密码子有点突变 ;②TNF -α可以修复p5 3基因突变中的C :G配对的点突变 ,不能修复A :G碱基的突变 ;③TNF -α对正常基因序列没有影响。

Objective To study the original mutat io n of p53 gene in salivary adenoid carcinoma SACC-83 cells and to analyze the rep air of the gene in the apoptosis induced by recombined human tumor necrosis fact or alpha (rhTNF-α).Methods ①Twelve Balb/c nude mice (SPF grade, 4-5 weeks o ld female) were contributed to this study. Zero point two milliliter cell suspe nsion with 6×107 concentration of SACC-83 cells (offered by School of Stomato logy, Peking University) were collected to injected subcutaneously on the back o f each nude mice. The 12 Balb/c nude mice were divided into 3 groups with 4 in e ach group. The mice in group A and B were given 100×104 IU/kg or 10×104 IU /kg TNF-α to each respectively. Those in group C were given saline only as the controls. The treatment was given for 8 times and conducted every the other day . ② Polymerase chain reaction (PCR) and DNA sequencing analysis were performed to study the original mutation of the tumor and the repair of p53 gene sequence after TNF-α treatment.Results The point mutations of p53 exon 8 were found at t he codon 273 GCA→GCG and 280 GAG→GAC. No any mutation was found in both exon 6 and exon 7. After treatment by TNF-α at two different dose, apoptosis was obse rved microscopically, the codon 280 was repaired GAC→GAG, but the codon 273 was not. No any change of both exon 6 and exon 7 sequence was found.Conclusion ① The point mutations of p53 exon 8 were exis ted in SACC-83 cells. ② TNF-α may repair the G:C mutative gene,but could not repair A:G mutation; ③ TNF-α does not affect the normal gene squences of p53.