Simbulan-Rosenthal C M, Rosenthal D S, Luo R, Li J H, Zhang J, Smulson M E
Department of Biochemistry and Molecular Biology, Georgetown University School of Medicine, 3900 Reservoir Road NW, Washington, DC 20007, USA.
Nucleic Acids Res. 2001 Feb 1;29(3):841-9. doi: 10.1093/nar/29.3.841.
Poly(ADP-ribose) polymerase (PARP) knockout mice are resistant to murine models of human diseases such as cerebral and myocardial ischemia, traumatic brain injury, diabetes, Parkinsonism, endotoxic shock and arthritis, implicating PARP in the pathogenesis of these diseases. Potent selective PARP inhibitors are therefore being evaluated as novel therapeutic agents in the treatment of these diseases. Inhibition or depletion of PARP, however, increases genomic instability in cells exposed to genotoxic agents. We recently demonstrated the presence of a genomically unstable tetraploid population in PARP(-/-) fibroblasts and its loss after stable transfection with PARP cDNA. To elucidate whether the genomic instability is attributable to PARP deficiency or lack of PARP activity, we investigated the effects of PARP inhibition on development of tetraploidy. Immortalized wild-type and PARP(-/-) fibroblasts were exposed for 3 weeks to 20 microM GPI 6150 (1,11b-dihydro-[2H:]benzopyrano[4,3,2-de]isoquinolin-3-one), a novel small molecule specific competitive inhibitor of PARP (K(i) = 60 nM) and one of the most potent PARP inhibitors to date (IC(50) = 0.15 microM). Although GPI 6150 initially decreased cell growth in wild-type cells, there was no effect on cell growth or viability after 24 h. GPI 6150 inhibited endogenous PARP activity in wild-type cells by approximately 91%, to about the residual levels in PARP(-/-) cells. Flow cytometric analysis of unsynchronized wild-type cells exposed for 3 weeks to GPI 6150 did not induce the development of tetraploidy, suggesting that, aside from its catalytic function, PARP may play other essential roles in the maintenance of genomic stability.
聚（ADP - 核糖）聚合酶（PARP）基因敲除小鼠对诸如脑缺血、心肌缺血、创伤性脑损伤、糖尿病、帕金森症、内毒素休克和关节炎等人类疾病的小鼠模型具有抗性，这表明PARP参与了这些疾病的发病机制。因此，强效选择性PARP抑制剂正作为治疗这些疾病的新型治疗药物进行评估。然而，抑制或耗尽PARP会增加暴露于基因毒性剂的细胞中的基因组不稳定性。我们最近证明了在PARP（-/-）成纤维细胞中存在基因组不稳定的四倍体群体，并且在用PARP cDNA稳定转染后该群体消失。为了阐明基因组不稳定性是归因于PARP缺乏还是PARP活性缺失，我们研究了PARP抑制对四倍体发育的影响。将永生化的野生型和PARP（-/-）成纤维细胞暴露于20μM GPI 6150（1,11b - 二氢 - [2H：]苯并吡喃并[4,3,2 - de]异喹啉 - 3 - 酮）3周，GPI 6150是一种新型的PARP特异性竞争性小分子抑制剂（K（i）= 60 nM），也是迄今为止最有效的PARP抑制剂之一（IC（50）= 0.15μM）。虽然GPI 6150最初会降低野生型细胞的生长，但24小时后对细胞生长或活力没有影响。GPI 6150将野生型细胞中的内源性PARP活性抑制了约91％，达到了PARP（-/-）细胞中的残留水平。对暴露于GPI 6150 3周的未同步化野生型细胞进行流式细胞术分析未诱导四倍体的发育，这表明除了其催化功能外，PARP可能在维持基因组稳定性中发挥其他重要作用。
