Clinical Significance of AR-V567es in Prostate Cancer-Letter.
Clinical Significance of AR-V567es in Prostate Cancer-Letter.
复制标题
AR-V567es 在前列腺癌中的临床意义。
DOI：
10.1158/1078-0432.ccr-19-1400
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Plymate,StephenR
中科院分区：
文献类型：
--
作者：
Uo,Takuma;Plymate,StephenR
关于前列腺癌中通过 PCR 检测到的 ARv567es 发生率存在相互矛盾的结果，显示频率范围从转移性肿瘤细胞中的 3% 到循环肿瘤细胞中的 70% 以上（CTC；参考文献 1、2）。为了解决这个问题，Bernemann 及其同事对 ARv567es 报道的不同 PCR 检测策略进行了全面比较 (1)。荧光信号的光学读出是 SYBR Green 和 TaqMan 方法的基础，这些方法允许在指数阶段定量测量总 PCR 扩增子。然而，当引物设计不当时，PCR 与引物二聚体和错误引发产物的存在相关，导致对基于扩增子的荧光信号（即假阳性信号）衍生的数据的误解。许多已发表的检测方法均基于使用两种寡核苷酸的 PCR，其中一种寡核苷酸跨越外显子 4 至外显子 8 的外显子连接处 (2, 3)。然而，外显子 4 和外显子 7 的 50 个边缘之间以及外显子 5 和外显子 8 的 30 个边缘之间存在序列相似性。因此，Bernemann 及其同事证明，在没有 ARv567es 的情况下，跨外显子寡核苷酸的非特异性结合可能会与 AR-FL 发生，从而为基于 SYBR Green 和 TaqMan 的检测提供假阳性信号。此外，他们还表明，之前报道的 PCR 引物和检测方法导致 ARv567es 检测在癌细胞系、患者来源的异种移植物、前列腺肿瘤样本和 CTC 中出现高假阳性率 (1,2,3)。另一方面，Bernemann 及其同事证实，特定的基于 TaqMan 的检测 (1, 4) 通过了严格的标准化检查表。这些经过验证的检测通常包括外显子 4 和 8 内的 PCR 引物以及跨越外显子 4 至 8 连接处的小沟结合剂。这些检测仅在 45 个样本中的三个中检测到 ARv567es (1)，而最近的报告表明该变异在 CTC 中的发生率很高（78%；参考文献 2）。我们之前的研究也观察到这种相对较低的检出率：在转移性前列腺癌队列中，15 名患者中只有 1 名 ARv567es 呈阳性（mCRPC；参考文献 4）。事实上，在 mCRPC 中，通过 RNA-seq 进行的特定外显子-外显子连接读取表明 ARv567es 的流行率较低（4%），而 AR-V7 是最常见的变体（89%；参考文献 5）。 Bernemann 及其同事指出了临床样本（包括作为潜在生物标志物的血液）中基于 PCR 的 ARv567es 检测的具体问题。由于没有确凿的 AR 基因序列和/或蛋白质验证，ARv567es 的发病率和作用尚未确定。
There are conflicting results regarding incidence of ARv567es detected by PCR in prostate cancer, displaying frequencies ranging from 3% in metastatic to more than 70% in circulating tumor cells (CTC; refs. 1, 2). To resolve this issue, Bernemann and colleagues performed a comprehensive comparison of the different reported PCR detection strategies for ARv567es (1). Optical readout of fluorescence signals is the basis of SYBR Green and TaqMan approaches that permit quantitative measurements of the total PCR amplicons during the exponential stages. However, when primers are not well designed, PCR is associated with the presence of primer dimer and mis-priming product, leading to misinterpretation of the data derived from amplicon-based fluorescence signals (ie, false-positive signals). Many published assays are based on PCR with two oligonucleotides, one of which spans the exon junction of exon 4 to exon 8 (2, 3). However, sequence similarity exists between the 50 edges of exon 4 and exon 7, as well as the 30 edges of exon 5 and exon 8. Thus, Bernemann and colleagues demonstrated nonspecific binding of exon spanning oligonucleotides might occur with AR-FL in the absence ofARv567es, providing false-positive signals for both SYBR Greenand TaqMan-based assays. Furthermore, they have shown that previously reported PCR primers and detection methods resulted in ARv567es detection with high false-positive rates in cancer cell lines, patient-derived xenografts, prostate tumor samples, and CTCs (1, 2, 3). On the other hand, Bernemann and colleagues confirmed that the specified TaqMan-based assays (1, 4) passed the rigorous standardized checklist. These validated assays commonly include PCR primers within exons 4 and 8 in combination with a minor groove binder spanning the junction of exon 4 to 8. These assays detected ARv567es in only three of 45 samples (1) as opposed to the recent report with a high incidence rate of this variant in CTC (78%; ref. 2). This, relatively low detection rate is also observed in our previous study: only 1 of 15 patients was ARv567es positive across the cohort of metastatic prostate cancer (mCRPC; ref. 4). Indeed, in mCRPC, specified exon–exon junction reads by RNA-seq demonstrated low prevalence (4%) of ARv567es, whereas AR-V7 was the most frequent variant (89%; ref. 5). Bernemann and colleagues points to the specific problems of PCR-based ARv567es detection in clinical samples including blood as a potential biomarker. Without confirmatory AR gene sequence and/or protein verification, the incidence and role of ARv567es has yet to be determined.