中文摘要：

目的研究鼻咽癌中是否存在DNA聚合酶β（DNA polymerasβ，polβ）的突变及变异情况。方法采用RT-PCR法（逆转录-DNA聚合酶链反应）、PCR-SSCP（聚合酶链-单链构象多态性分析）、DNA序列分析法对26例鼻咽癌组织进行polβ基因突变研究。结果鼻咽癌组织中存在polβ基因突变，且基因突变率与癌组织的病理分级有关，高分化（G1）、中度分化（G2）、低分化及未分化（G3）鼻咽癌组织中polβ基因突变率分别为12.5％（2／16）、21．4％（3／14）、80％（8／10）。G1与G2比较，差异无统计学意义（P〉0．01），G1与G3、G2与G3比较，差异均有统计学意义（P〈0．005）。测序结果表明，polβ基因的第454位核苷酸由T变为C，其氨基酸变异为第114位氨基酸由Phe变为Ser；第466位核苷酸由G变为A，其氨基酸变异为第118位氨基酸由Gly变为Glu；第148位核苷酸由A变为G，其氨基酸变异为第28位氨基酸由Asn变为Ser。结论发现在鼻咽癌组织中存在多种形式的polβ突变，导致氨基酸序列、空间结构的改变，可能与鼻咽癌的发生、发展相关。

英文摘要：

Objective To study DNA polymerasβ（polβ） gene mutation in human nasopharyngeal cancer. Methods 40 cases of nasopharyngeal carcinoma （NPC） tissues were collected to study DNA polβgene mutation with PT-PCR, PCR-SSCP and DNA sequence analyzing technique, the 40 cases of NPC were divided into three groups according to pathology differentiation, 16 cases of grade Ⅰ （G1） , 14 cases of grade Ⅱ （G2） , 10 cases of grade Ⅲ （G3）. Results Polβgene mutation was detected by SSCP in 13 of 40 NPC tissues （with mutation rate 32. 5%） and Many kinds of mutation were found by DNA sequencing, the mutation rate of G1, G2, G3 was 12. 5%, 21.4%, 80% respectively. The sequencing of the PCR product showed an T to C chang at nucleotide 454 , which resulted in a substitution of the amino acid from Phe to Ser at site 114; 466nt G→A resulting in Gly→Glu at 118 site ; 148nt A→G resulting in Asn→Ser at 28 site. Conclusion The study proves there is polβ alternation in human nasopharyngeal carcinorna, this induces change in amino acid and spatial structure. The mutation rate in low differentiated cancer was significantly higher than those in moderate and high ones. These mutations may be related with the development of NPC.