Sirisena Nirmala D, Samaranayake Nilakshi, Dissanayake Vajira H W
Human Genetics Unit, Faculty of Medicine, University of Colombo, No. 25 Kynsey Road, Colombo 8, 00800, Sri Lanka.
Department of Parasitology, Faculty of Medicine, University of Colombo, Colombo 8, 00800, Sri Lanka.
BMC Res Notes. 2019 Aug 1;12(1):476. doi: 10.1186/s13104-019-4512-9.
A previous study undertaken at our centre to identify common genetic variants associated with sporadic breast cancer in Sri Lankan women showed that the T allele of rs3218550, located in the 3'untranslated region of X-ray repair cross-complementing gene-2 (XRCC2), increased breast cancer risk by 1.5-fold. Dual luciferase reporter assays performed in MCF-7 breast cancer cells showed a putative transcriptional repressor effect exerted mainly by the T allele. Electrophoretic mobility shift assays were conducted to further investigate the interaction of this variant with DNA-binding protein, using nuclear protein extracts derived from MCF-7 cells.
An allele-specific differential binding was observed. The T allele resulted in differential DNA-protein complex binding as evidenced by the presence of multiple bands of increased intensity compared to the wild-type C allele. This implies possible alteration in binding of regulatory proteins by the variant allele. These results implicate XRCC2:rs3218550C>T as a potential low-penetrant susceptibility allele for sporadic breast cancer. XRCC2 is known to play an essential role in homologous recombination repair of DNA double-strand breaks. It is plausible that this variant may be exerting regulatory effects on XRCC2 gene expression leading to altered DNA repair capacity. Further functional studies are warranted to validate this finding.
我们中心之前进行的一项研究旨在确定与斯里兰卡女性散发性乳腺癌相关的常见基因变异，结果显示位于X射线修复交叉互补基因2（XRCC2）3'非翻译区的rs3218550的T等位基因使乳腺癌风险增加了1.5倍。在MCF-7乳腺癌细胞中进行的双荧光素酶报告基因检测显示，主要由T等位基因发挥推定的转录抑制作用。使用来自MCF-7细胞的核蛋白提取物进行电泳迁移率变动分析，以进一步研究该变异与DNA结合蛋白的相互作用。
观察到等位基因特异性差异结合。与野生型C等位基因相比，T等位基因导致DNA-蛋白质复合物结合出现差异，表现为强度增加的多条条带。这意味着变异等位基因可能改变了调节蛋白的结合。这些结果表明XRCC2:rs3218550C>T是散发性乳腺癌的一个潜在低 penetrance 易感等位基因。已知XRCC2在DNA双链断裂的同源重组修复中起重要作用。这个变异可能对XRCC2基因表达发挥调节作用，导致DNA修复能力改变，这似乎是合理的。需要进一步的功能研究来验证这一发现。
