Proteasome inhibitor MG132 sensitizes HPV-positive human cervical cancer cells to rhTRAIL-induced apoptosis
Proteasome inhibitor MG132 sensitizes HPV-positive human cervical cancer cells to rhTRAIL-induced apoptosis
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DOI：
10.1002/ijc.21580
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发表时间：
2006-04-15
影响因子：
6.4
通讯作者：
de Jong, S
中科院分区：
文献类型：
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作者：
Hougardy, BMT;Maduro, JH;de Jong, S
在宫颈癌发生过程中，p53 肿瘤抑制途径被 HPV（人乳头瘤病毒）E6 癌基因表达破坏。 E6 以 p53 为目标，进行蛋白酶体介导的快速降解。因此，我们研究了 MG132 的蛋白酶体抑制是否可以恢复野生型 p53 水平并使 HPV 阳性宫颈癌细胞系对细胞凋亡刺激物（如 rhTRAIL（重组人 TNF 相关细胞凋亡诱导配体））敏感。在一组宫颈癌细胞系中，CaSki 对 rhTRAIL 诱导的细胞凋亡高度敏感，HeLa 中等，SiHa 对 rhTRAIL 诱导的细胞凋亡不敏感。 MG132 以 caspase 依赖性和时间依赖性方式使 HeLa 和 SiHa 对 rhTRAIL 诱导的细胞凋亡强烈敏感。 MG132 在 HeLa 中大量诱导 TRAIL 受体 DR4 和 DR5 膜表达，而在 SiHa 中，只有 DR5 膜表达从几乎不可检测到高水平上调。拮抗性 DR4 抗体部分抑制了 HeLa 中 rhTRAIL 和 MG132 诱导的细胞凋亡，但对 SiHa 中的细胞凋亡没有影响。 MG132 对 E6 介导的 p53 蛋白酶体降解的抑制导致活性 p53 水平升高，p53 小干扰 RNA (siRNA) 敏感的 p21 上调证明了这一点。尽管 p53 siRNA 部分抑制了 HeLa 和 SiHa 中 MG132 诱导的 DR5 上调，但未观察到对 rhTRAIL 诱导的细胞凋亡的影响。 MG132 加 rhTRAIL 增强了 caspase 8 和 caspase 3 的激活以及 X 连锁凋亡抑制剂 (XIAP) 的伴随裂解，特别是在 HeLa 中。此外，仅在 HeLa 中观察到 caspase 9 激活。使用 siRNA 与 rhTRAIL 组合下调 XIAP 会诱导 HeLa 中高水平的细胞凋亡，而必须将 MG132 添加到 XIAP siRNA 加 rhTRAIL 的组合中才能诱导 SiHa 中的细胞凋亡。总之，蛋白酶体抑制使 HPV 阳性宫颈癌细胞系对 rhTRAIL 敏感，与 p53 无关。我们的结果表明，不仅 DR4 和 DR5 上调，而且 XIAP 失活也有助于 MG132 在宫颈癌细胞系中对 rhTRAIL 致敏。将蛋白酶体抑制剂与 rhTRAIL 联合使用可能对宫颈癌治疗有用。 (c) 2005 年 Wiley-Liss, Inc.
In cervical carcinogenesis, the p53 tumor suppressor pathway is disrupted by HPV (human papilloma virus) E6 oncogene expression. E6 targets p53 for rapid proteasome-mediated degradation. We therefore investigated whether proteasome inhibition by MG132 could restore wild-type p53 levels and sensitize HPV-posi- tive cervical cancer cell lines to apoptotic stimuli such as rhTRAIL (recombinant human TNF-related apoptosis inducing ligand). In a panel of cervical cancer cell lines, CaSki was highly, HeLa intermediate and SiHa not sensitive to rhTRAIL-induced apoptosis. MG132 strongly sensitized HeLa and SiHa to rhTRAIL-induced apoptosis in a caspase-dependent and time-dependent manner. MG132 massively induced TRAIL receptor DR4 and DR5 membrane expression in HeLa, whereas in SiHa only DR5 membrane expression was upregulated from almost undetectable to high levels. Antagonistic DR4 antibody partially inhibited apoptosis induction by rhTRAIL and MG132 in HeLa but had no effect on apoplosis in SiHa. Inhibition of E6-mediated p53 proteasomal degradation by MG132 resulted in elevated levels of active p53 as demonstrated by p53 small interfering RNA (siRNA) sensitive p21 upregulation. Although p53 siRNA partially inhibited MG132-induced DR5 upregulation in HeLa and SiHa, no effect on rhTRAIL-induced apoptosis was observed. MG132 plus rhTRAIL enhanced caspase 8 and caspase 3 activation and concomitant cleavage of X-linked inhibitor of apoptosis (XIAP), particularly in HeLa. In addition, caspase 9 activation was only observed in HeLa. Downregulation of XIAP using siRNA in combination with rhTRAIL induced high levels of apoptosis in HeLa, whereas MG132 had to be added to the combination of XIAP siRNA plus rhTRAIL to induce apoptosis in SiHa. In conclusion, proteasome inhibition sensitized HPV-positive cervical cancer cell lines to rhTRAIL independent of p53. Our results indicate that not only DR4 and DR5 upregulation but also XIAP inactivation contribute to rhTRAIL sensitization by MG132 in cervical cancer cell lines. Combining proteasome inhibitors with rhTRAIL may be therapeutically useful in cervical cancer treatment. (c) 2005 Wiley-Liss, Inc.