Department of Anatomy and Cell Biology, Queen's University, Kingston, ON, Canada.
World J Urol. 2013 Apr;31(2):325-30. doi: 10.1007/s00345-012-0848-7. Epub 2012 Mar 2.
Phosphodiesterases (PDEs) play a role in controlling cyclic nucleotide action, including cyclic guanosine monophosphate (cGMP). Previous studies have ascribed a protective role of cGMP signaling on hypoxia-mediated cancer progression. Herein, we determine their potential role in hypoxia-mediated chemoresistance and immune escape.
Phosphodiesterase assays were used to measure PDE activity in prostate cancer cell lines (DU145, PC3). Immunoblots were performed to determine the presence of PDEs in human prostate tissue samples. The effect of PDE inhibition on hypoxia-induced chemoresistance (compared to normoxic controls, 20% O2) was determined using clonogenic assays. Flow cytometry was used to determine the effects of PDE inhibition on surface MHC class I-related chain A (MICA), a natural killer (NK) cell-activating ligand. A mouse model was used to evaluate the in vivo effects of PDE inhibition on the growth of human prostate cancer cells.
PDE5 and PDE11 were the most prominent PDEs in the cell lines, representing between 86 and 95% of the total cGMP-specific PDE activity. Treatment of DU-145 cells with a PDE inhibitor significantly reduced the hypoxia-associated acquisition of resistance to doxorubicin, with a mean 51% reduction in surviving fraction compared to controls (p < 0.001, ANOVA). As well, PDE inhibition completely reversed (p = 0.02, ANOVA) hypoxia-induced shedding of the immune stimulatory molecule, MICA, and attenuated the growth of human prostate tumor xenografts in an NK cell-competent murine model (p = 0.03, Wilcoxon, Mann-Whitney).
These results suggest a rationale for future studies on the potential therapeutic applications of PDE inhibitors in men with prostate cancer.
磷酸二酯酶（PDEs）在控制环核苷酸作用中发挥作用，包括环鸟苷酸单磷酸（cGMP）。先前的研究将 cGMP 信号传导归因于缺氧介导的癌症进展的保护作用。在此，我们确定它们在缺氧介导的化学抗性和免疫逃逸中的潜在作用。
使用磷酸二酯酶测定法测量前列腺癌细胞系（DU145、PC3）中的 PDE 活性。免疫印迹用于确定人前列腺组织样本中 PDE 的存在。使用集落形成测定法确定 PDE 抑制对缺氧诱导的化学抗性（与常氧对照相比，20%O2）的影响。流式细胞术用于确定 PDE 抑制对表面 MHC Ⅰ类相关链 A（MICA）的影响，MICA 是一种自然杀伤（NK）细胞激活配体。使用小鼠模型评估 PDE 抑制对人前列腺癌细胞生长的体内影响。
PDE5 和 PDE11 是细胞系中最突出的 PDE，占总 cGMP 特异性 PDE 活性的 86%至 95%。用 PDE 抑制剂处理 DU-145 细胞可显著降低与缺氧相关的对阿霉素的耐药性获得，与对照组相比，存活分数降低了 51%（p<0.001，ANOVA）。此外，PDE 抑制完全逆转（p=0.02，ANOVA）缺氧诱导的免疫刺激分子 MICA 的脱落，并在 NK 细胞功能正常的小鼠模型中减弱人前列腺肿瘤异种移植物的生长（p=0.03，Wilcoxon，Mann-Whitney）。
这些结果为未来研究 PDE 抑制剂在患有前列腺癌的男性中的潜在治疗应用提供了依据。
