Iniparib Nonselectively Modifies Cysteine-Containing Proteins in Tumor Cells and Is Not a Bona Fide PARP Inhibitor
Iniparib Nonselectively Modifies Cysteine-Containing Proteins in Tumor Cells and Is Not a Bona Fide PARP Inhibitor
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DOI：
10.1158/1078-0432.ccr-11-1973
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发表时间：
2012-01-15
影响因子：
11.5
通讯作者：
Shoemaker, Alexander R.
中科院分区：
文献类型：
--
作者：
Liu, Xuesong;Shi, Yan;Shoemaker, Alexander R.
目的：PARP抑制剂正被开发为癌症的治疗剂。目前已有超过6种化合物进入临床试验。这些化合物中的大多数是β-烟酰胺腺嘌呤二核苷酸（NAD（+））竞争性抑制剂。一个例外是iniparib，它被认为是一种非竞争性PARP抑制剂。在这项研究中，我们比较了两种不同结构类型的NAD（+）-竞争性化合物与iniparib及其C-亚硝基代谢物的生物活性。实验设计：在酶和细胞测定中分析了两种化学系列的NAD（+）-竞争性PARP抑制剂，iniparib及其C-亚硝基代谢物。在MDA-MB-436（BRCA 1缺陷型）和DLD 1（-/-）（BRCA 2缺陷型）细胞以及BRCA有效MDA-MB-231和DLD 1（+/+）细胞中进行活力试验。Capan-1和B16 F10异种移植模型用于在体内比较iniparib和veliparib。结果：所有NAD（+）竞争性抑制剂在PARP细胞分析中均表现出强活性，强增强替莫唑胺的活性，并在体内外诱导BRCA缺陷肿瘤细胞的强杀伤作用。细胞杀伤与DNA损伤的诱导有关。相比之下，iniparib及其C-亚硝基代谢产物均未抑制PARP酶或细胞活性，增强替莫唑胺，或在BRCA缺陷环境中显示活性。我们发现，iniparib的亚硝基代谢产物与许多含半胱氨酸的蛋白质形成加合物。此外，iniparib和它的亚硝基代谢产物形成蛋白加合物nonspecifically在tumor cells.Conclusions：Iniparib非选择性地修饰肿瘤细胞中的含半胱氨酸蛋白，iniparib的主要作用机制可能不是通过抑制PARP活性。临床癌症研究; 18（2）; 510-23。(C)2011年AACR。
Purpose: PARP inhibitors are being developed as therapeutic agents for cancer. More than six compounds have entered clinical trials. The majority of these compounds are beta-nicotinamide adenine dinucleotide (NAD(+))-competitive inhibitors. One exception is iniparib, which has been proposed to be a noncompetitive PARP inhibitor. In this study, we compare the biologic activities of two different structural classes of NAD(+)-competitive compounds with iniparib and its C-nitroso metabolite.Experimental Design: Two chemical series of NAD(+)-competitive PARP inhibitors, iniparib and its C-nitroso metabolite, were analyzed in enzymatic and cellular assays. Viability assays were carried out in MDA-MB-436 (BRCA1-deficient) and DLD1(-/-) (BRCA2-deficient) cells together with BRCA-proficient MDA-MB-231 and DLD1(+/+) cells. Capan-1 and B16F10 xenograft models were used to compare iniparib and veliparib in vivo. Mass spectrometry and the H-3-labeling method were used to monitor the covalent modification of proteins.Results: All NAD(+)-competitive inhibitors show robust activity in a PARP cellular assay, strongly potentiate the activity of temozolomide, and elicit robust cell killing in BRCA-deficient tumor cells in vitro and in vivo. Cell killing was associated with an induction of DNA damage. In contrast, neither iniparib nor its C-nitroso metabolite inhibited PARP enzymatic or cellular activity, potentiated temozolomide, or showed activity in a BRCA-deficient setting. We find that the nitroso metabolite of iniparib forms adducts with many cysteine-containing proteins. Furthermore, both iniparib and its nitroso metabolite form protein adducts nonspecifically in tumor cells.Conclusions: Iniparib nonselectively modifies cysteine-containing proteins in tumor cells, and the primary mechanism of action for iniparib is likely not via inhibition of PARP activity. Clin Cancer Res; 18(2); 510-23. (C) 2011 AACR.