Benzyl isothiocyanate induces protective autophagy in human prostate cancer cells via inhibition of mTOR signaling
Benzyl isothiocyanate induces protective autophagy in human prostate cancer cells via inhibition of mTOR signaling
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DOI：
10.1093/carcin/bgs359
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发表时间：
2013-02-01
期刊：
影响因子：
4.7
通讯作者：
Hwang, Thomas I-Sheng
中科院分区：
文献类型：
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作者：
Lin, Ji-Fan;Tsai, Te-Fu;Hwang, Thomas I-Sheng
异硫氰酸苄酯（Benzyl isothiocyanate， BITC）是一种膳食化学预防剂，通过引起细胞凋亡来抑制人类各种癌细胞的生长。在这项研究中，我们证明了BITC不仅可以诱导人类激素敏感（Rv1）和难治（PC3）前列腺癌细胞凋亡，还可以诱导自噬。在bitc处理的细胞中，通过监测自噬标记蛋白微管相关蛋白1轻链3 （LC3）的加工、LC3聚集成颗粒结构和酸性细胞器的形成来检测自噬的诱导。3-甲基腺嘌呤抑制自噬增加了bitc诱导的细胞凋亡，而caspase抑制剂抑制了bitc诱导的细胞死亡。我们的数据还显示，BITC以剂量依赖的方式抑制哺乳动物雷帕霉素靶蛋白（mTOR）激酶活性。在bitc处理的细胞中，mTOR内在催化活性指标phospho-mTOR （Ser2481）和mTOR直接底物phospho- unc -51样激酶1 （Ser757）的表达降低。然而，在BITC处理后期，仅在PC3细胞中检测到phospho-mTOR （Ser2448）、phospho-AKT （Ser473）和抗凋亡Bcl-2的表达增加。总之，我们的研究结果表明，BITC通过抑制mTOR信号通路在Rv1和PC3细胞中诱导保护性自噬反应。AKT存活通路的激活仅在PC3细胞中观察到，这代表了晚期前列腺癌在BITC治疗后的耐药机制。这些发现可能有助于BITC在前列腺癌治疗中的有益作用。
Benzyl isothiocyanate (BITC) is a dietary chemopreventive agent that inhibits the growth of various human cancer cells by causing apoptotic cell death. In this study, we demonstrate that BITC not only induces apoptosis but also induces autophagy in human hormone-sensitive (Rv1) and -refractory (PC3) prostate cancer cells. In BITC-treated cells, the induction of autophagy was detected by monitoring the processing of an autophagy marker protein, microtubule-associated protein 1 light chain 3 (LC3), the aggregation of LC3 into granular structures and the formation of acidic organelles. Inhibition of autophagy using 3-methyladenine increased BITC-induced apoptosis, whereas the administration of caspase inhibitor suppressed BITC-induced cell death. Our data also showed that BITC inhibits mammalian target of rapamycin (mTOR) kinase activity in a dose-dependent manner. The expression of phospho-mTOR (Ser2481), an indicator of mTOR intrinsic catalytic activity, and phospho-UNC-51-like kinase 1 (Ser757), a direct substrate of mTOR, were decreased in BITC-treated cells. However, the increased expression of phospho-mTOR (Ser2448), phospho-AKT (Ser473) and antiapoptotic Bcl-2 were detected only in PC3 cells at later stages of BITC treatment. Collectively, our results show that BITC induces a protective autophagy response in Rv1 and PC3 cells through inhibition of the mTOR signaling pathway. Activation of the AKT survival pathway was only observed in PC3 cells, representing a resistance mechanism of advanced prostate cancer upon BITC treatment. These findings could potentially contribute to the beneficial effect of BITC in prostate cancer treatments.