Frederiksen Lisa J, Siemens D Robert, Heaton Jeremy P, Maxwell Lori R, Adams Michael A, Graham Charles H
Department of Anatomy and Cell Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6.
J Urol. 2003 Sep;170(3):1003-7. doi: 10.1097/01.ju.0000081126.71235.e0.
Tumor hypoxia has been correlated with metastasis and resistance to chemotherapy. Hypoxia is also associated with human prostate cancers, which are highly resistant to chemotherapy. We hypothesized that hypoxia contributes to chemoresistance in prostate cancer cells and this hypoxia induced chemoresistance can be inhibited by low concentrations of nitric oxide (NO) mimetics.
Human PC-3 and mouse TRAMP-C2 prostatic adenocarcinoma cells were incubated in 20% or 0.5% O(2) for 12 hours with or without glyceryl trinitrate (GTN) (0.1 nM). This treatment was followed by a 1-hour incubation with doxorubicin and survival was assessed by clonogenic assays. Western blot analysis was used to measure NO synthase levels. The effect of hypoxia and GTN on cell cycle distribution was determined by flow cytometry.
Hypoxic pre-incubation of the 2 cell lines resulted in increased survival following exposure to doxorubicin. Co-incubation of PC-3 and TRAMP-C2 cells with GTN (0.1 nM) inhibited the hypoxia induced resistance to doxorubicin. Each cell line expressed all 3 NO synthase isoforms at levels that were not significantly affected by O(2) concentrations. Cell cycle analysis revealed that there was no significant difference in the distribution of PC-3 cells at each stage of the cycle. However, incubation under hypoxia resulted in a small decrease in the number of TRAMP-C2 cells in S-phase.
These findings indicate that NO may have an important role in the regulation of chemosensitivity in prostate cancer cells. Furthermore, the results suggest that GTN administration may represent a means of chemosensitizing prostatic carcinomas.
肿瘤缺氧与转移及化疗耐药相关。缺氧也与对化疗高度耐药的人类前列腺癌有关。我们推测缺氧促成前列腺癌细胞的化疗耐药，且这种缺氧诱导的化疗耐药可被低浓度一氧化氮（NO）模拟物抑制。
将人PC-3和小鼠TRAMP-C2前列腺腺癌细胞在20%或0.5% O₂环境中培养12小时，添加或不添加硝酸甘油（GTN）（0.1 nM）。之后用阿霉素孵育1小时，通过克隆形成试验评估细胞存活情况。采用蛋白质印迹分析来检测NO合酶水平。通过流式细胞术确定缺氧和GTN对细胞周期分布的影响。
对这两种细胞系进行缺氧预孵育导致暴露于阿霉素后细胞存活率增加。PC-3和TRAMP-C2细胞与GTN（0.1 nM）共同孵育可抑制缺氧诱导的对阿霉素的耐药性。每个细胞系均表达所有三种NO合酶同工型，其水平不受O₂浓度的显著影响。细胞周期分析显示，PC-3细胞在细胞周期各阶段的分布没有显著差异。然而，在缺氧条件下孵育导致TRAMP-C2细胞S期数量略有减少。
这些发现表明NO可能在调节前列腺癌细胞的化学敏感性中起重要作用。此外，结果表明给予GTN可能是使前列腺癌化疗增敏的一种方法。
