目的:已发现DNA修复基因及其变体可改变口腔癌的风险。
方法:20例口腔癌中XRCC3、NBS1和OGG1基因的表达水平,6口腔癌前,50例健康对照者进行RT-PCR检测。所有受试者的基因分型为XRCC3rs861539C>T,NBS1rs1805794C>G,通过PCR-RFLP方法,OGG1rs1052133C>G多态性;它们的基因型与其表达水平相关。Further,使用RNAfold对所研究的SNP周围的mRNA序列进行局部折叠结构分析.
结果:结果显示XRCC3,NBS1和OGG1转录本在口腔癌中的表达增加(4.49倍,3.45折,和3.27倍)以及口腔癌前(3.04倍,5.32折,和1.74倍),与对照组相比。发现OGG1的转录水平显着增加(6.68倍,与CC基因型相比,GG基因型的p值0.009)。XRCC3的C>T多态性和OGG1的C>G多态性导致其mRNA二级结构的明显变化。XRCC3C>T多态性的C等位基因折叠能量低于T等位基因(MFECvsT:-50.20kcal/molvs-48.70kcal/mol)。在OGG1C>G多态性的情况下,C等位基因的MFE(-23.30kcal/mol)高于G等位基因(-24.80kcal/mol)。
结论:我们的结果显示XRCC3、NBS1和OGG1水平在口腔癌和口腔癌前疾病中均升高,这表明它们作为口腔癌和癌前病变的前瞻性生物标志物的作用。这些基因中的SNP改变了它们的表达水平,可能是通过改变转录本的二级结构。然而,由于样本量较小,我们的研究只能提供一个提示性的结论,并警告未来的研究用大样本量来验证我们的发现。
OBJECTIVE: DNA repair genes and their variants have been found to alter the risk of oral cancer.
METHODS: The level of expression of XRCC3, NBS1, and OGG1 genes among 20 cases of oral cancer, 6 pre-oral cancer, and 50 healthy control subjects was measured with RT-PCR. All the subjects were also genotyped for XRCC3 rs861539 C>T, NBS1 rs1805794 C>G, and OGG1 rs1052133 C>G polymorphisms by the PCR-RFLP method; their genotypes were correlated with their level of expression. Further, a localized fold structure analysis of the mRNA sequence surrounding the studied SNPs was performed with RNAfold.
RESULTS: Results showed increased expression of XRCC3, NBS1, and OGG1 transcripts among oral cancer (4.49 fold, 3.45 fold, and 3.27 fold) as well as pre-oral cancer (3.04 fold, 5.32 fold, and 1.74 fold) as compared to control subjects. The transcript level of OGG1 was found to be significantly increased (6.68 fold, p-value 0.009) with the GG genotype compared to the CC genotype. The C>T polymorphism of XRCC3 and the C>G polymorphism of OGG1 result in an apparent change in its mRNA secondary structure. Folding energy with the C allele for XRCC3 C>T polymorphism was lower than that of the T allele (MFE C vs T: -50.20 kcal/mol vs -48.70 kcal/mol). In the case of OGG1 C>G polymorphism MFE for the C allele was higher (-23.30 kcal/mole) than with the G allele (-24.80 kcal/mol).
CONCLUSIONS: Our results showed elevated levels of XRCC3, NBS1, and OGG1 both in oral cancer and pre-oral cancer conditions, which indicates their role as prospective biomarkers of oral cancer and pre-cancerous lesions. SNPs in these genes alter their level of expression, possibly by altering the secondary structure of their transcript. However, due to the small sample size our study can only provide a suggestive conclusion and warned future study with large sample size to verify our findings.