El-Awady Raafat A, Semreen Mohammad H, Saber-Ayad Maha M, Cyprian Farhan, Menon Varsha, Al-Tel Taleb H
Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates; College of Pharmacy, University of Sharjah, Sharjah, United Arab Emirates; Cancer Biology Department, National Cancer Institute and College of Medicine, Cairo University, Cairo, Egypt.
Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates; College of Pharmacy, University of Sharjah, Sharjah, United Arab Emirates.
DNA Repair (Amst). 2016 Jan;37:1-11. doi: 10.1016/j.dnarep.2015.10.004. Epub 2015 Nov 4.
DNA damage response machinery (DDR) is an attractive target of cancer therapy. Modulation of DDR network may alter the response of cancer cells to DNA damaging anticancer drugs such as doxorubicin. The aim of the present study is to investigate the effects of a newly developed imidazopyridine (IAZP) derivative on the DDR after induction of DNA damage in cancer cells by doxorubicin. Cytotoxicity sulphrhodamine-B assay showed a weak anti-proliferative effect of IAZP alone on six cancer cell lines (MCF7, A549, A549DOX11, HepG2, HeLa and M8) and a normal fibroblast strain. Combination of IAZP with doxorubicin resulted in synergism in lung (A549) and breast (MCF7) cancer cells but neither in the other cancer cell lines nor in normal fibroblasts. Molecular studies revealed that synergism is mediated by modulation of DNA damage response and induction of apoptosis. Using constant-field gel electrophoresis and immunofluorescence detection of γ-H2AX foci, IAZP was shown to inhibit the repair of doxorubicin-induced DNA damage in A549 and MCF7 cells. Immunoblot analysis showed that IAZP suppresses the phosphorylation of the ataxia lelangiectasia and Rad3 related (ATR) protein, which is an important player in the response of cancer cells to chemotherapy-induced DNA damage. Moreover, IAZP augmented the doxorubicin-induced degradation of p21, activation of p53, CDK2, caspase 3/7 and phosphorylation of Rb protein. These effects enhanced doxorubicin-induced apoptosis in both cell lines. Our results indicate that IAZP is a promising agent that may enhance the cytotoxic effects of doxorubicin on some cancer cells through targeting the DDR. It is a preliminary step toward the clinical application of IAZP in combination with anticancer drugs and opens the avenue for the development of compounds targeting the DDR pathway that might improve the therapeutic index of anticancer drugs and enhance their cure rate.
DNA损伤反应机制（DDR）是癌症治疗的一个有吸引力的靶点。DDR网络的调节可能会改变癌细胞对阿霉素等DNA损伤抗癌药物的反应。本研究的目的是研究一种新开发的咪唑并吡啶（IAZP）衍生物在阿霉素诱导癌细胞DNA损伤后对DDR的影响。细胞毒性磺罗丹明-B试验表明，IAZP单独对六种癌细胞系（MCF7、A549、A549DOX11、HepG2、HeLa和M8）和一种正常成纤维细胞系具有微弱的抗增殖作用。IAZP与阿霉素联合使用在肺癌（A549）和乳腺癌（MCF7）细胞中产生协同作用，但在其他癌细胞系和正常成纤维细胞中均未产生协同作用。分子研究表明，协同作用是由DNA损伤反应的调节和细胞凋亡的诱导介导的。使用恒场凝胶电泳和γ-H2AX焦点的免疫荧光检测，IAZP被证明可以抑制阿霉素诱导的A549和MCF7细胞中的DNA损伤修复。免疫印迹分析表明，IAZP抑制共济失调毛细血管扩张症和Rad3相关（ATR）蛋白的磷酸化，ATR蛋白是癌细胞对化疗诱导的DNA损伤反应中的一个重要参与者。此外，IAZP增强了阿霉素诱导的p21降解、p53、CDK2、caspase 3/7的激活以及Rb蛋白的磷酸化。这些作用增强了阿霉素在两种细胞系中诱导的细胞凋亡。我们的结果表明，IAZP是一种有前途的药物，可能通过靶向DDR增强阿霉素对某些癌细胞的细胞毒性作用。这是IAZP与抗癌药物联合临床应用的初步步骤，并为开发靶向DDR途径的化合物开辟了道路，这些化合物可能提高抗癌药物的治疗指数并提高其治愈率。
