鼻咽癌中p53基因突变的研究

p53 mutation in nasopharyngeal carcinoma

目的：探讨鼻咽癌中ｐ５３基因突变情况。方法：用非同位素不对称ＰＣＲ－单链构象多态性技术（ａＰＣＲ－ＳＳＣＰ），分析了鼻咽癌活检组织、细胞株和裸鼠移植瘤中ｐ５３基因第５、６、７和８外显子（ｅｘｏｎ）的基因突变，并对其中ｅｘｏｎ８突变的ＳＵＮＥ－１和ＳＵＮＴ－１进行ＤＮＡ测序。结果：在２０例鼻咽癌活检组织中没有发现突变；但在鼻咽癌细胞株ＣＮＥ１、ＣＮＥ２、ＳＵＮＥ－１和瘤株ＳＵＮＴ－１中存在第８外显子突变，而ＨＫ１为第５外显子突变。ＤＮＡ测序发现ＳＵＮＥ－１和ＳＵＮＴ－１的突变点在ｅｘｏｎ８的密码子（ｃｏｄｏｎ）２８０上，由ＡＧＡ（精氨酸）→ＡＣＡ（苏氨酸）。结论：ｐ５３基因突变热点的ｅｘｏｎ５、６、７和８可能在鼻咽癌变过程中没有重要意义，而在裸鼠移植瘤和细胞株建立过程中起重要作用。ＥＢＶ由于和鼻咽癌的关系密切，在鼻咽癌中可能存在ＥＢＶ编码蛋白与ｐ５３结合或蛋白表达被ＥＢＶ抑制等其他途径使ｐ５３失活。

Purpose:To study p53mutation in nasopharyngeal carcinoma.Method:a nonradioactive protocol for asymmetric PCR-single stand conformation polymorphisms(aPCR-SSCP)was applied to screen p53 mutations in exon 5,6,7and8.The exon8 of SUNE-1 and SUNT-1 were sequenced.Results:Among 20 biopsy specimens of NPC,mutations were not found.However,a mutation was found in exon8 of p53 in the NPC cell lines of CNE1,CNE2,SUNE-1 and newly established nude mice tumor SUNT-1 and a mutation was also found in exon 5 of NPC cell line of HK1.DNA sequence revealed that both SUNE-1 and SUNT-1 harbored a heterozygous mutation:AGA(arginime)→ACA (threonine) in codon 280. Conclusion:the results suggest that p53 mutation conserved sequences exon 5,6,7 and 8 might not be important in the carcinogensis of NPC but it may play a important role in the establishment of nude mice and cell lines.Because of the close relation ship between EBV and NPC,there might be other ways of p53 inactivation than mutation,such as binding with EBV encoded protein,or down regulation by EBV.