Shankar Sharmila, Singh Thiyam Ramsing, Srivastava Rakesh K
Department of Pharmaceutical Sciences, University of Maryland, 20 N. Pine Street, Baltimore, MD 2120-1180, USA.
Prostate. 2004 Sep 15;61(1):35-49. doi: 10.1002/pros.20069.
We assessed the influence of sequential treatment of ionizing radiation followed by tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) on intracellular mechanisms of apoptosis of prostate tumor cells in vitro and in vivo.
Prostate normal and cancer cells were exposed to irradiation and TRAIL. Four- to 6-week-old athymic nude mice were injected s.c. with PC-3 tumor cells. Tumor bearing mice were exposed to irradiation and TRAIL, either alone or in combination (TRAIL after 24 hr of irradiation), and tumor growth, apoptosis, and survival of mice were examined. Expressions of death receptors, Bcl-2 family members, and caspase were measured by Western blotting, ELISA, and ribonuclease protection assay; tumor cellularity was assessed by H&E staining; inhibition of p53 was performed by RNA interference (RNAi) technology, and apoptosis was measured by annexin V/propidium iodide staining, and terminal deoxynucleotidyltransferase-mediated nick end labeling assay.
Irradiation significantly augmented TRAIL-induced apoptosis in prostate cancer cells through upregulation of DR5, Bax, and Bak, and induction of caspase activation. Dominant negative FADD and p53 siRNA inhibited the synergistic interaction between irradiation and TRAIL. The pretreatment of cells with irradiation followed by TRAIL significantly enhanced more apoptosis than single agent alone or concurrent treatment. Furthermore, irradiation sensitized TRAIL-resistant LNCaP cells to undergo apoptosis. The sequential treatment of xenografted mice with irradiation followed by TRAIL-induced apoptosis through activation of caspase-3, induction of Bax and Bak, and inhibition of Bcl-2, and completely eradicated the established tumors with enhanced survival of nude mice.
The sequential treatment with irradiation followed by TRAIL can be used as a viable option to enhance the therapeutic potential of TRAIL in prostate cancer.
我们评估了电离辐射序贯肿瘤坏死因子（TNF）相关凋亡诱导配体（TRAIL）对前列腺肿瘤细胞体外和体内凋亡细胞内机制的影响。
将前列腺正常细胞和癌细胞暴露于辐射和TRAIL中。给4至6周龄的无胸腺裸鼠皮下注射PC-3肿瘤细胞。对荷瘤小鼠单独或联合（辐射24小时后给予TRAIL）进行辐射和TRAIL处理，检测肿瘤生长、凋亡及小鼠存活情况。通过蛋白质免疫印迹法、酶联免疫吸附测定法和核糖核酸酶保护试验检测死亡受体、Bcl-2家族成员和半胱天冬酶的表达；通过苏木精和伊红染色评估肿瘤细胞密度；采用RNA干扰（RNAi）技术抑制p53，通过膜联蛋白V/碘化丙啶染色和末端脱氧核苷酸转移酶介导的缺口末端标记试验检测凋亡情况。
辐射通过上调DR5、Bax和Bak并诱导半胱天冬酶激活，显著增强TRAIL诱导的前列腺癌细胞凋亡。显性负性FADD和p53小干扰RNA抑制了辐射与TRAIL之间的协同相互作用。先进行辐射预处理再给予TRAIL的细胞处理方式比单独使用单一药物或同时处理显著增强了更多的细胞凋亡。此外，辐射使对TRAIL耐药的LNCaP细胞对凋亡敏感。对异种移植小鼠先进行辐射再给予TRAIL的序贯处理通过激活半胱天冬酶-3、诱导Bax和Bak以及抑制Bcl-2诱导凋亡，并完全根除已形成的肿瘤，同时提高了裸鼠的存活率。
辐射序贯TRAIL治疗可作为增强TRAIL在前列腺癌治疗潜力的可行选择。
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