Institute of Cytology and Genetics, Russian Academy of Sciences, Lavrentieva 10, Novosibirsk 630090, Russia.
Department of Genetic Technologies, Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia.
Int J Mol Sci. 2024 Sep 27;25(19):10405. doi: 10.3390/ijms251910405.
Targeting DNA repair pathways is an important strategy in anticancer therapy. However, the unrevealed interactions between different DNA repair systems may interfere with the desired therapeutic effect. Among DNA repair systems, BER and NHEJ protect genome integrity through the entire cell cycle. BER is involved in the repair of DNA base lesions and DNA single-strand breaks (SSBs), while NHEJ is responsible for the repair of DNA double-strand breaks (DSBs). Previously, we showed that BER deficiency leads to downregulation of NHEJ gene expression. Here, we studied BER's response to NHEJ deficiency induced by knockdown of NHEJ scaffold protein XRCC4 and compared the knockdown effects in normal (TIG-1) and hTERT-modified cells (NBE1). We investigated the expression of the , and genes of BER and ; the / genes of NHEJ at the mRNA and protein levels; as well as , and . We found that, in both cell lines, XRCC4 knockdown leads to a decrease in the mRNA levels of both BER and NHEJ genes, though the effect on protein level is not uniform. XRCC4 knockdown caused an increase in p53 and Sp1 proteins, but caused G1/S delay only in normal cells. Despite the increased p53 protein, p21 did not significantly increase in NBE1 cells with overexpressed hTERT, and this correlated with the absence of G1/S delay in these cells. The data highlight the regulatory function of the XRCC4 scaffold protein and imply its connection to a transcriptional regulatory network or mRNA metabolism.
靶向 DNA 修复途径是癌症治疗的重要策略。然而，不同 DNA 修复系统之间未被揭示的相互作用可能会干扰预期的治疗效果。在 DNA 修复系统中，BER 和 NHEJ 通过整个细胞周期保护基因组完整性。BER 参与 DNA 碱基损伤和 DNA 单链断裂 (SSBs) 的修复，而 NHEJ 负责修复 DNA 双链断裂 (DSBs)。此前，我们表明 BER 缺陷导致 NHEJ 基因表达下调。在这里，我们研究了 BER 对由 NHEJ 支架蛋白 XRCC4 敲低引起的 NHEJ 缺陷的反应，并比较了在正常 (TIG-1) 和 hTERT 修饰细胞 (NBE1) 中的敲低效应。我们研究了 BER 的 、 和 基因以及 NHEJ 的 / 基因在 mRNA 和蛋白质水平上的表达；以及 、 和 。我们发现，在两种细胞系中，XRCC4 敲低导致 BER 和 NHEJ 基因的 mRNA 水平均降低，尽管对蛋白质水平的影响并不一致。XRCC4 敲低导致 p53 和 Sp1 蛋白增加，但仅在正常细胞中导致 G1/S 延迟。尽管 p53 蛋白增加，但在过表达 hTERT 的 NBE1 细胞中 p21 没有显著增加，这与这些细胞中没有 G1/S 延迟相关。这些数据强调了 XRCC4 支架蛋白的调节功能，并暗示其与转录调节网络或 mRNA 代谢有关。
