Authors' Affiliation: Genentech, Inc., South San Francisco, California.
Clin Cancer Res. 2013 Dec 15;19(24):6912-23. doi: 10.1158/1078-0432.CCR-13-1186. Epub 2013 Oct 4.
We sought to identify predictive biomarkers for a novel nicotinamide phosphoribosyltransferase (NAMPT) inhibitor.
We use a NAMPT inhibitor, GNE-617, to evaluate nicotinic acid rescue status in a panel of more than 400 cancer cell lines. Using correlative analysis and RNA interference (RNAi), we identify a specific biomarker for nicotinic acid rescue status. We next determine the mechanism of regulation of expression of the biomarker. Finally, we develop immunohistochemical (IHC) and DNA methylation assays and evaluate cancer tissue for prevalence of the biomarker across indications.
Nicotinate phosphoribosyltransferase (NAPRT1) is necessary for nicotinic acid rescue and its expression is the major determinant of rescue status. We demonstrate that NAPRT1 promoter methylation accounts for NAPRT1 deficiency in cancer cells, and NAPRT1 methylation is predictive of rescue status in cancer cell lines. Bisulfite next-generation sequencing mapping of the NAPRT1 promoter identified tumor-specific sites of NAPRT1 DNA methylation and enabled the development of a quantitative methylation-specific PCR (QMSP) assay suitable for use on archival formalin-fixed paraffin-embedded tumor tissue.
Tumor-specific promoter hypermethylation of NAPRT1 inactivates one of two NAD salvage pathways, resulting in synthetic lethality with the coadministration of a NAMPT inhibitor. NAPRT1 expression is lost due to promoter hypermethylation in most cancer types evaluated at frequencies ranging from 5% to 65%. NAPRT1-specific immunohistochemical or DNA methylation assays can be used on archival formalin paraffin-embedded cancer tissue to identify patients likely to benefit from coadministration of a Nampt inhibitor and nicotinic acid.
我们试图确定一种新型烟酰胺磷酸核糖转移酶（NAMPT）抑制剂的预测生物标志物。
我们使用 NAMPT 抑制剂 GNE-617 来评估超过 400 种癌细胞系中烟酸挽救状态。通过相关分析和 RNA 干扰（RNAi），我们确定了烟酸挽救状态的特定生物标志物。接下来，我们确定了表达标志物的调控机制。最后，我们开发了免疫组织化学（IHC）和 DNA 甲基化检测，并评估了各种适应症癌症组织中该标志物的流行情况。
烟酰胺磷酸核糖转移酶（NAPRT1）是烟酸挽救所必需的，其表达是挽救状态的主要决定因素。我们证明，NAPRT1 启动子甲基化导致癌细胞中 NAPRT1 缺乏，并且 NAPRT1 甲基化可预测癌细胞系中的挽救状态。NAPRT1 启动子的亚硫酸氢盐下一代测序图谱鉴定了肿瘤特异性的 NAPRT1 DNA 甲基化位点，并开发了一种适用于存档福尔马林固定石蜡包埋肿瘤组织的定量甲基化特异性 PCR（QMSP）检测。
NAPRT1 肿瘤特异性启动子甲基化使两种 NAD 补救途径之一失活，导致与 NAMPT 抑制剂联合给药的合成致死性。在所评估的大多数癌症类型中，由于启动子甲基化，NAPRT1 表达丧失，频率范围为 5%至 65%。NAPRT1 特异性免疫组织化学或 DNA 甲基化检测可用于存档福尔马林石蜡包埋的癌症组织，以识别可能受益于 NAMPT 抑制剂和烟酸联合给药的患者。
