de Mello Martins Antonio G Gomes, Allegretta Giuseppe, Unteregger Gerhard, Haupenthal Jörg, Eberhard Jens, Hoffmann Michael, van der Zee Jill A, Junker Kerstin, Stöckle Michael, Müller Rolf, Hartmann Rolf W, Ohlmann Carsten-H
Department of Drug Design and Optimization (DDOP), Helmholtz Institute for Pharmaceutical Research Saarland, Campus E8.1, 66123 Saarbrücken, Germany.
Saarland University, Department of Urology and Pediatric Urology, 66424 Homburg/Saar, Germany.
J Steroid Biochem Mol Biol. 2017 Nov;174:183-191. doi: 10.1016/j.jsbmb.2017.09.006. Epub 2017 Sep 7.
CYP17A1-independent intratumoral steroid hormone synthesis is regarded as one possible explanation for resistance to treatment with the CYP17-inhibitor Abiraterone (Abi). The aim of our study was therefore to investigate the steroid metabolism of prostate cancer cells under serum starvation and the effects of Abi treatment. We assessed steroid metabolism in a panel of prostate cancer cells under serum starvation by radioactivity detector-coupled HPLC and HPLC-ESI-ToF-mass spectrometry after treatment with pregnenolone, progesterone and allopregnanolone. We further evaluated the effects of Abi on steroid metabolism of testosterone, dihydrotestosterone (DHT) and dehydroepiandrosterone (DHEA) by enzyme immunoassays (EIAs). Androgen-responsive cell lines metabolized pregnenolone primarily to mitogenic steroid 5α-pregnan-3β,6α-diol-20-one under serum starvation. Co-administration of Abi lead to detectable concentrations of the Abi metabolite Δ-Abi (D4A), known to inhibit enzymes other than CYP17A1 in steroid metabolism. In addition, co-administration of Abi abrogated pregnenolone metabolism and resulted in a CYP17A1-independent significant increase of DHEA (13- to >100-fold) and DHT (2.5-fold) in androgen-responsive cells. Our results demonstrate the CYP17A1-independent formation of 5α-pregnan-3β,6α-diol-20-one by androgen-responsive prostate cancer cells under serum starvation and its inhibition by Abi. Its metabolism from pregnenolone suggests a major steroidogenesis shift in these cells, hinting at a neuroendocrine transdifferentiation phenomenon. The marked increase of DHEA levels by Abi resembles the steroidogenic pathways in nervous tissue, in a manner that precludes CYP17A1 activity. To which extent these processes are responsible or involved in the development of resistance to Abi, needs to be further elucidated.
不依赖细胞色素P450 17A1（CYP17A1）的肿瘤内类固醇激素合成被认为是对CYP17抑制剂阿比特龙（Abi）治疗产生耐药性的一种可能解释。因此，我们研究的目的是调查血清饥饿状态下前列腺癌细胞的类固醇代谢以及Abi治疗的效果。我们在用孕烯醇酮、孕酮和别孕烷醇酮处理后，通过放射性检测器耦合高效液相色谱法（HPLC）和HPLC-电喷雾电离飞行时间质谱法，评估了血清饥饿状态下一组前列腺癌细胞中的类固醇代谢。我们还通过酶免疫测定法（EIA）进一步评估了Abi对睾酮、二氢睾酮（DHT）和脱氢表雄酮（DHEA）类固醇代谢的影响。雄激素反应性细胞系在血清饥饿状态下主要将孕烯醇酮代谢为有丝分裂类固醇5α-孕烷-3β,6α-二醇-20-酮。联合使用Abi导致可检测到Abi代谢物Δ-Abi（D4A）的浓度，已知该代谢物在类固醇代谢中可抑制CYP17A1以外的酶。此外，联合使用Abi消除了孕烯醇酮的代谢，并导致雄激素反应性细胞中DHEA（13至>100倍）和DHT（2.5倍）在不依赖CYP17A1的情况下显著增加。我们的结果表明，雄激素反应性前列腺癌细胞在血清饥饿状态下可独立于CYP17A1形成5α-孕烷-3β,6α-二醇-20-酮，并受到Abi的抑制。其从孕烯醇酮的代谢表明这些细胞中主要的类固醇生成转变，暗示着神经内分泌转分化现象。Abi使DHEA水平显著升高，其方式类似于神经组织中的类固醇生成途径，排除了CYP17A1的活性。这些过程在多大程度上导致或参与了对Abi的耐药性发展，有待进一步阐明。
