Shariat S F, Desai S, Song W, Khan T, Zhao J, Nguyen C, Foster B A, Greenberg N, Spencer D M, Slawin K M
The Matsunaga-Conte Prostate Cancer Research Center, Scott Department of Urology, Baylor College of Medicine, Houston, Texas 77030, USA.
Cancer Res. 2001 Mar 15;61(6):2562-71.
In patients with localized prostate cancer, radical prostatectomy and radiation therapy, although effective in controlling localized disease, are often associated with significant side effects attributable to injury of adjacent tissues. Moreover, patients with metastatic disease eventually fail systemic hormonal or chemotherapy because of the development of progressive, refractory disease. In this study, we evaluated the safety and efficacy of a novel suicide gene therapy that could potentially spare normal tissue while bypassing molecular mechanisms of apoptosis resistance by using chemically inducible effector caspases to trigger apoptosis in prostate cancer cells. Initially, we compared the ability of a panel of inducible Fas signaling intermediates to kill human and murine prostate cancer cell lines. On the basis of the superior killing by downstream caspase-1 and caspase-3, replication-deficient adenoviral vectors expressing conditional caspase-1 (Ad-G/iCasp1) or caspase-3 (Ad-G/iCasp3), regulated by nontoxic, lipid-permeable, chemical inducers of dimerization (CID), were constructed. Upon vector transduction followed by CID administration, aggregation and activation of these recombinant caspases occur, leading to rapid apoptosis. In vitro, both human (LNCaP and PC-3) and murine (TRAMP-C2 and TRAMP-C2G) prostate cancer cell lines were efficiently transduced and killed in a CID-dependent fashion. In vivo, direct injection of Ad-G/iCasp1 into s.c. TRAMP-C2 tumors caused focal but extensive apoptosis without evidence for a bystander effect at the maximal viral dose (i.e., 2.5 x 10(10) viral particles/25 microl) in host animals that also received CID compared with control animals. Treatment with Ad-G/iCasp1 plus CID resulted in a transient, yet significant, reduction both in tumor growth and volume compared with tumors treated with vector but not CID (P < 0.035) or vector-diluent plus CID (P < 0.022), both of which grew more rapidly. These results demonstrate that CID-regulated, caspase-based suicide gene therapy is safe and can inhibit the growth of experimental prostate cancer in vitro and in vivo through potent induction of apoptosis, providing a rationale for further development.
在局限性前列腺癌患者中，根治性前列腺切除术和放射治疗虽能有效控制局部疾病，但常因邻近组织损伤而伴有显著副作用。此外，转移性疾病患者最终会因进行性难治性疾病的发展而导致全身激素治疗或化疗失败。在本研究中，我们评估了一种新型自杀基因疗法的安全性和有效性，该疗法通过使用化学诱导效应半胱天冬酶触发前列腺癌细胞凋亡，有可能使正常组织免受损伤，同时绕过凋亡抵抗的分子机制。最初，我们比较了一组可诱导的Fas信号中间体杀死人及小鼠前列腺癌细胞系的能力。基于下游半胱天冬酶-1和半胱天冬酶-3的更强杀伤作用，构建了由无毒、可透过脂质的化学二聚化诱导剂（CID）调控的、表达条件性半胱天冬酶-1（Ad-G/iCasp1）或半胱天冬酶-3（Ad-G/iCasp3）的复制缺陷型腺病毒载体。载体转导后给予CID，这些重组半胱天冬酶会发生聚集和激活，导致快速凋亡。在体外，人（LNCaP和PC-3）及小鼠（TRAMP-C2和TRAMP-C2G）前列腺癌细胞系均能被有效转导，并以CID依赖的方式被杀死。在体内，将Ad-G/iCasp1直接注射到皮下TRAMP-C2肿瘤中，在最大病毒剂量（即2.5×10¹⁰病毒颗粒/25微升）下，与对照动物相比，在接受CID的宿主动物中引起了局部但广泛的凋亡，且无旁观者效应的证据。与仅用载体但未用CID处理的肿瘤（P < 0.035）或载体稀释剂加CID处理的肿瘤（P < 0.022）相比，Ad-G/iCasp1加CID处理导致肿瘤生长和体积出现短暂但显著的减小，后两者生长更快。这些结果表明，CID调控的、基于半胱天冬酶的自杀基因疗法是安全的，并且通过强力诱导凋亡可在体外和体内抑制实验性前列腺癌的生长，为进一步开发提供了理论依据。
