Department of Biology, Cancer Research Unit, University of York, York YO10 5DD, UK.
Department of Molecular Oncology, Barts Cancer Institute, Queen Mary University of London, London EC1M 6BQ, UK.
Br J Cancer. 2018 Jan;118(2):189-199. doi: 10.1038/bjc.2017.391. Epub 2017 Nov 14.
Phospholipases D1 and D2 (PLD1/2) hydrolyse cell membrane glycerophospholipids to generate phosphatidic acid, a signalling lipid, which regulates cell growth and cancer progression through effects on mTOR and PKB/Akt. PLD expression and/or activity is raised in breast, colorectal, gastric, kidney and thyroid carcinomas but its role in prostate cancer (PCa), the major cancer of men in the western world, is unclear.
PLD1 protein expression in cultured PNT2C2, PNT1A, P4E6, LNCaP, PC3, PC3M, VCaP, 22RV1 cell lines and patient-derived PCa cells was analysed by western blotting. PLD1 protein localisation in normal, benign prostatic hyperplasia (BPH), and castrate-resistant prostate cancer (CRPC) tissue sections and in a PCa tissue microarray (TMA) was examined by immunohistochemistry. PLD activity in PCa tissue was assayed using an Amplex Red method. The effect of PLD inhibitors on PCa cell viability was measured using MTS and colony forming assays.
PLD1 protein expression was low in the luminal prostate cell lines (LNCaP, VCaP, 22RV1) compared with basal lines (PC3 and PC3M). PLD1 protein expression was elevated in BPH biopsy tissue relative to normal and PCa samples. In normal and BPH tissue, PLD1 was predominantly detected in basal cells as well in some stromal cells, rather than in luminal cells. In PCa tissue, luminal cells expressed PLD1. In a PCa TMA, the mean peroxidase intensity per DAB-stained Gleason 6 and 7 tissue section was significantly higher than in sections graded Gleason 9. In CRPC tissue, PLD1 was expressed prominently in the stromal compartment, in luminal cells in occasional glands and in an expanding population of cells that co-expressed chromogranin A and neurone-specific enolase. Levels of PLD activity in normal and PCa tissue samples were similar. A specific PLD1 inhibitor markedly reduced the survival of both prostate cell lines and patient-derived PCa cells compared with two dual PLD1/PLD2 inhibitors. Short-term exposure of PCa cells to the same specific PLD1 inhibitor significantly reduced colony formation.
A new specific inhibitor of PLD1, which is well tolerated in mice, reduces PCa cell survival and thus has potential as a novel therapeutic agent to reduce prostate cancer progression. Increased PLD1 expression may contribute to the hyperplasia characteristic of BPH and in the progression of castrate-resistant PCa, where an expanding population of neuroendocrine-like cells express PLD1.
磷脂酶 D1 和 D2（PLD1/2）水解细胞膜甘油磷脂生成磷脂酸，这是一种信号脂质，通过对 mTOR 和 PKB/Akt 的影响来调节细胞生长和癌症进展。在乳腺癌、结直肠癌、胃癌、肾癌和甲状腺癌中，PLD 的表达和/或活性升高，但在前列腺癌（PCa）中的作用尚不清楚，PCa 是西方世界男性的主要癌症。
通过 Western blot 分析培养的 PNT2C2、PNT1A、P4E6、LNCaP、PC3、PC3M、VCaP、22RV1 细胞系和患者来源的 PCa 细胞中 PLD1 蛋白的表达。通过免疫组织化学检查正常、良性前列腺增生（BPH）和去势抵抗性前列腺癌（CRPC）组织切片以及 PCa 组织微阵列（TMA）中 PLD1 蛋白的定位。使用 Amplex Red 法测定 PCa 组织中的 PLD 活性。使用 MTS 和集落形成测定法测量 PLD 抑制剂对 PCa 细胞活力的影响。
与基底细胞系（PC3 和 PC3M）相比，PLD1 蛋白在腔细胞系（LNCaP、VCaP、22RV1）中的表达较低。BPH 活检组织中 PLD1 蛋白的表达相对于正常和 PCa 样本升高。在正常和 BPH 组织中，PLD1 主要在基底细胞中检测到，也在一些基质细胞中检测到，而不是在腔细胞中检测到。在 PCa 组织中，腔细胞表达 PLD1。在 PCa TMA 中，每个 DAB 染色的 Gleason 6 和 7 组织切片的平均过氧化物酶强度显着高于 Gleason 9 分级的组织切片。在 CRPC 组织中，PLD1 在基质区室中表达明显，在偶尔的腺体中在腔细胞中表达，在表达嗜铬粒蛋白 A 和神经元特异性烯醇化酶的扩展细胞群中表达。正常和 PCa 组织样本中的 PLD 活性水平相似。一种特定的 PLD1 抑制剂与两种双重 PLD1/PLD2 抑制剂相比，显着降低了前列腺细胞系和患者来源的 PCa 细胞的存活。PCa 细胞短期暴露于相同的特定 PLD1 抑制剂可显着减少集落形成。
一种新型的 PLD1 特异性抑制剂，在小鼠中耐受性良好，可降低 PCa 细胞的存活率，因此具有作为降低前列腺癌进展的新型治疗剂的潜力。PLD1 表达增加可能导致 BPH 的增生特征，并导致去势抵抗性 PCa 的进展，其中扩展的神经内分泌样细胞表达 PLD1。
