Vogel U, Dybdahl M, Frentz G, Nexo B A
National Institute of Occupational Health, Lerso Parkalle 105, Dk-2100, Copenhagen, Denmark.
Mutat Res. 2000 Nov 9;461(3):197-210. doi: 10.1016/s0921-8777(00)00051-3.
We have previously shown that high DNA repair capacity protects psoriasis patients against chemically induced basal cell carcinoma [Dybdahl et al. Mutat. Res. 433 (1999) 15-22]. We have used the same study persons to investigate the correlation between expression of eight genes involved in nucleotide excision repair and DNA repair capacity. mRNA levels of XPA, XPB, XPC, XPD, XPF, XPG, CSB and ERCC1 in primary lymphocytes from 33 individuals were quantified by dot-blots and normalized to beta-actin. ERCC1 and XPD mRNA quantities were highly correlated (r=0.89; P<10(-11)) while XPA, XPB, XPC, XPG, XPFand CSB mRNAs were moderately correlated (r=0.2-0.7). Thus, the mRNA expressions seem to fall in at least two groups. There was a three to sevenfold variation in the expression levels of the mRNAs. This is in contrast to the more than a hundredfold variation in mRNA levels reported in cancer patients.DNA repair capacity was measured in a host cell reactivation assay, where primary lymphocytes were transfected with an UV-irradiated plasmid encoding firefly-luciferase. Only ERCC1 and XPD mRNA levels correlated with the DNA repair capacity (P<0.03). In order to see if ERCC1 or XPD activity was limiting for DNA repair, we cotransfected with plasmids encoding NER genes, thus over-expressing either XPB, XPC, XPD, CSB or ERCC1 in the host cell reactivation assay. Only XPB over-expression increased DNA repair capacity. Thus, there is no indication that neither XPD nor ERCC1 limits the DNA repair capacity. However, our results indicate that ERCC1 and XPD mRNA levels may be used as a proxy for DNA repair capacity in lymphocytes.
我们之前已经表明，高DNA修复能力可保护银屑病患者免受化学诱导的基底细胞癌的侵害[Dybdahl等人，《突变研究》433（1999年）15 - 22页]。我们使用相同的研究对象来调查参与核苷酸切除修复的八个基因的表达与DNA修复能力之间的相关性。通过斑点印迹法定量测定了33名个体原代淋巴细胞中XPA、XPB、XPC、XPD、XPF、XPG、CSB和ERCC1的mRNA水平，并以β - 肌动蛋白进行标准化。ERCC1和XPD的mRNA量高度相关（r = 0.89；P < 10⁻¹¹），而XPA、XPB、XPC、XPG、XPF和CSB的mRNA则中度相关（r = 0.2 - 0.7）。因此，mRNA表达似乎至少分为两组。这些mRNA的表达水平存在三到七倍的差异。这与癌症患者中报道的mRNA水平超过一百倍的差异形成对比。在宿主细胞再激活试验中测量DNA修复能力，其中用编码萤火虫荧光素酶的紫外线照射质粒转染原代淋巴细胞。只有ERCC1和XPD的mRNA水平与DNA修复能力相关（P < 0.03）。为了查看ERCC1或XPD的活性是否限制DNA修复，我们在宿主细胞再激活试验中与编码核苷酸切除修复基因的质粒共转染，从而使XPB、XPC、XPD、CSB或ERCC1中的任何一个过表达。只有XPB的过表达增加了DNA修复能力。因此，没有迹象表明XPD或ERCC1限制了DNA修复能力。然而，我们的结果表明，ERCC1和XPD的mRNA水平可作为淋巴细胞中DNA修复能力的替代指标。
