Bernemann Christof, Humberg Verena, Thielen Barbara, Steinestel Julie, Chen Xin, Duensing Stefan, Schrader Andres J, Boegemann Martin
Department of Urology, University Hospital Muenster, Muenster, Germany.
Department of Urology, University Hospital Augsburg, Augsburg, Germany.
Clin Cancer Res. 2019 Jul 1;25(13):3856-3864. doi: 10.1158/1078-0432.CCR-18-4276. Epub 2019 Apr 16.
Androgen receptor splice variants are known to facilitate resistance of prostate cancer cells toward antihormonal therapies. However, detection of the most prominent variant, AR-V7, on its own, is not sufficiently accurate for prediction of response. Thus, simultaneous detection of other variants might improve prediction. AR-V567es has been shown to be expressed in late stages of prostate cancer. Yet, there have been discrepant results regarding incidence of AR-V567es. We therefore aimed to perform a comprehensive comparison of different detection approaches for AR-V567es mRNA.
We compared a custom-made, probe-based PCR assay with 6 published AR-V567es detection PCR assays in distinct samples, that is, cancer cell lines, LuCaP xenografts, primary and metastatic tumor samples, and circulating tumor cells (CTC).
Using distinct approaches, we concordantly detected expression of AR-V567es in only three of 45 samples (LuCaP xenografts 86.2 and 136s2 as well as one CTC sample). We observed varying results in all other samples. Specificity analysis displayed nonspecific binding of 5 previously published PCR assays to AR full-length mRNA in the absence of AR-V567es.
Validation of biomarker detection approaches is one of the most critical steps before transfer into clinical application. By performing comparative analysis of different detection approaches, we revealed eminent variability among previously described systems. Furthermore, we demonstrate an overestimation of AR-V567es in prostate cancer, presumably due to nonspecific detection of AR-FL mRNA. Therefore, any correlation between AR-V567es expression and clinical responses is highly doubtful and does not reflect the biological nature of the disease.
已知雄激素受体剪接变体可促进前列腺癌细胞对抗激素疗法产生耐药性。然而，单独检测最主要的变体AR-V7，对于预测反应的准确性不足。因此，同时检测其他变体可能会改善预测效果。AR-V567es已被证明在前列腺癌晚期表达。然而，关于AR-V567es的发生率存在不一致的结果。因此，我们旨在对AR-V567es mRNA的不同检测方法进行全面比较。
我们将一种定制的基于探针的PCR检测方法与6种已发表的AR-V567es检测PCR方法在不同样本中进行比较，这些样本包括癌细胞系、LuCaP异种移植瘤、原发性和转移性肿瘤样本以及循环肿瘤细胞（CTC）。
使用不同的方法，我们仅在45个样本中的3个样本（LuCaP异种移植瘤86.2和136s2以及一个CTC样本）中一致检测到AR-V567es的表达。在所有其他样本中，我们观察到了不同的结果。特异性分析显示，在没有AR-V567es的情况下，5种先前发表的PCR检测方法与AR全长mRNA存在非特异性结合。
生物标志物检测方法的验证是转化为临床应用之前最关键的步骤之一。通过对不同检测方法进行比较分析，我们揭示了先前描述的系统之间存在显著差异。此外，我们证明了前列腺癌中AR-V567es的高估，可能是由于AR-FL mRNA的非特异性检测。因此，AR-V567es表达与临床反应之间的任何相关性都非常值得怀疑，并且不能反映该疾病的生物学本质。
