Prostate-specific antigen-activated thapsigargin prodrug as targeted therapy for prostate cancer
Prostate-specific antigen-activated thapsigargin prodrug as targeted therapy for prostate cancer
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DOI：
10.1093/jnci/95.13.990
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发表时间：
2003-07-02
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影响因子：
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通讯作者：
Isaacs, JT
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作者：
Denmeade, SR;Jakobsen, CM;Isaacs, JT
背景：标准抗增殖化疗对转移部位内缓慢增殖的雄激素非依赖性前列腺癌细胞相对无效。相比之下，亲脂性细胞毒素毒胡萝卜素通过破坏细胞内游离 Ca2+ 水平引起细胞凋亡，对增殖细胞和静止细胞（即 G(0) 停滞）均有效。然而，毒胡萝卜素的作用机制表明它不太可能对癌细胞或前列腺细胞具有选择性。方法：我们将化学修饰形式的毒胡萝卜素 L12ADT 与作为前列腺特异性抗原 (PSA) 蛋白酶底物的肽载体偶联，产生可溶性、细胞不渗透性的潜在前药，该前药在转移性前列腺癌位点内被 PSA 在细胞外特异性激活。我们分析了该前药的PSA水解动力学、该前药对产生PSA的LNCaP人前列腺癌和不产生PSA的HCT-116人结肠癌细胞的体外细胞毒性，以及该前药在小鼠体内的药代动力学。我们还分析了前药在前列腺癌（使用 LNCaP 细胞）和肾癌（使用人 SN12C 细胞）裸鼠异种移植模型中的抗肿瘤功效。结果：L12ADT肽前药可被PSA高效水解，在体外对产生PSA的前列腺癌细胞具有选择性毒性，并且在人血浆中稳定。 7 mg/kg 的单剂量导致血清前药峰值浓度为 15.4 +/- 1.1 muM，半衰期约为 2.8 小时。 24 小时内，血浆中观察到的游离 L12ADT 含量低于 0.5%。前列腺癌异种移植肿瘤中前药和释放的L12ADT水平分别比体外LD(50)高约八倍和六倍。通过静脉内施用前药治疗的小鼠中的前列腺癌异种移植肿瘤的生长受到抑制，且没有显着的宿主毒性。对小鼠进行连续皮下注射前药可完全抑制已建立的产生 PSA 的前列腺癌异种移植肿瘤的生长，但对不产生 PSA 的肾癌异种移植肿瘤没有影响。结论：有必要进一步开发 PSA 激活的毒胡萝卜素前药作为转移性前列腺癌的治疗方法。
Background: Standard anti-proliferative chemotherapy is relatively ineffective against slowly proliferating androgen-independent prostate cancer cells within metastatic sites. In contrast, the lipophilic cytotoxin thapsigargin, which causes apoptosis by disrupting intracellular free Ca2+ levels, is effective against both proliferative and quiescent (i.e., G(0)-arrested) cells. However, thapsigargin's mechanism of action indicates that it is unlikely to be selective for cancer cells or prostate cells. Methods: We coupled a chemically modified form of thapsigargin, L12ADT, to a peptide carrier that is a substrate for the prostate-specific antigen (PSA) protease to produce a soluble, cell-impermeant latent prodrug that is specifically activated extracellularly within metastatic prostate cancer sites by PSA. We analyzed the kinetics of PSA hydrolysis of the prodrug, the in vitro cytoxicity of the prodrug against PSA-producing LNCaP human prostate cancer and PSA non-producing HCT-116 human colon cancer cells, and the in vivo pharmacokinetics of the prodrug in mice. We also analyzed antitumor efficacy of the prodrug in nude mice xenograft models of prostate cancer (using LNCaP cells) and renal carcinoma (using human SN12C cells). Results: The L12ADT peptide prodrug was hydrolyzed efficiently by PSA, was selectively toxic to PSA-producing prostate cancer cells in vitro, and was stable in human plasma. A single dose of 7 mg/kg resulted in a peak serum prodrug concentration of 15.4 +/- 1.1 muM and a half-life of approximately 2.8 hours. Over 24 hours, less than 0.5% of free L12ADT was observed in plasma. Levels of prodrug and liberated L12ADT in prostate cancer xenograft tumors were approximately eightfold and sixfold, respectively, higher than the in vitro LD(50)s. Prostate cancer xenograft tumors in mice treated with prodrug by intravenous administration were growth-inhibited without substantial host toxicity. Continuous subcutaneous prodrug administration in mice produced complete growth inhibition of established PSA-producing prostate cancer xenograft tumors but had no effect on PSA non-producing renal carcinoma xenograft tumors. Conclusion: Further development of PSA-activated thapsigargin prodrugs as therapy for metastatic prostate cancer is warranted.