Involvement of autophagy in oncogenic K-Ras-induced malignant cell transformation.
Involvement of autophagy in oncogenic K-Ras-induced malignant cell transformation.
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自噬参与致癌K-RAS诱导的恶性细胞转化。
DOI：
10.1074/jbc.m110.138958
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发表时间：
2011-04-15
期刊：
影响因子：
--
通讯作者：
Lee SJ
中科院分区：
文献类型：
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作者：
Kim MJ;Woo SJ;Yoon CH;Lee JS;An S;Choi YH;Hwang SG;Yoon G;Lee SJ
自噬最近被认为与癌症的预防和进展有关。然而，自噬诱导与恶性肿瘤初始获得之间关系的分子基础目前尚不清楚。在这里，我们提供了第一个证据，证明自噬对于致癌的K-Ras （K-RasV12）诱导的恶性细胞转化是必不可少的。逆转录病毒表达K-RasV12诱导人乳腺上皮细胞自噬液泡形成和恶性转化。有趣的是，自噬的药理抑制完全阻断了k - rasv12诱导的、不依赖于锚定的细胞在软琼脂上的生长。过表达K-RasV12的细胞中，ATG5和ATG7（分别为自噬特异性基因5和7）的mRNA和蛋白水平均升高。短发夹（sh） RNA靶向抑制ATG5或ATG7的表达可抑制裸鼠软琼脂细胞生长和肿瘤形成。此外，抗氧化剂抑制活性氧（ROS）可以明显减弱k - rasv12诱导的ATG5和ATG7诱导、自噬和恶性细胞转化。MAPK通路组分在过表达K-RasV12的细胞中被激活，JNK的抑制减弱了ATG5和ATG7的诱导以及随后的自噬。此外，抗氧化剂预处理完全抑制k - rasv12诱导的JNK活化。我们的研究结果提供了新的证据，证明自噬在致癌K-Ras的恶性转化中起着关键作用，并表明活性氧介导的JNK激活通过上调ATG5和ATG7在自噬诱导中起因果作用。
Autophagy has recently been implicated in both the prevention and progression of cancer. However, the molecular basis for the relationship between autophagy induction and the initial acquisition of malignancy is currently unknown. Here, we provide the first evidence that autophagy is essential for oncogenic K-Ras (K-RasV12)-induced malignant cell transformation. Retroviral expression of K-RasV12 induced autophagic vacuole formation and malignant transformation in human breast epithelial cells. Interestingly, pharmacological inhibition of autophagy completely blocked K-RasV12-induced, anchorage-independent cell growth on soft agar. Both mRNA and protein levels of ATG5 and ATG7 (autophagy-specific genes 5 and 7, respectively) were increased in cells overexpressing K-RasV12. Targeted suppression of ATG5 or ATG7 expression by short hairpin (sh) RNA inhibited cell growth on soft agar and tumor formation in nude mice. Moreover, inhibition of reactive oxygen species (ROS) with antioxidants clearly attenuated K-RasV12-induced ATG5 and ATG7 induction, autophagy, and malignant cell transformation. MAPK pathway components were activated in cells overexpressing K-RasV12, and inhibition of JNK blunted induction of ATG5 and ATG7 and subsequent autophagy. In addition, pretreatment with antioxidants completely inhibited K-RasV12-induced JNK activation. Our results provide novel evidence that autophagy is critically involved in malignant transformation by oncogenic K-Ras and show that reactive oxygen species-mediated JNK activation plays a causal role in autophagy induction through up-regulation of ATG5 and ATG7.