Huang Haishan, Pan Xiaofu, Jin Honglei, Li Yang, Zhang Lin, Yang Caili, Liu Pei, Liu Ya, Chen Lili, Li Jingxia, Zhu Junlan, Zeng Xingruo, Fu Kai, Chen Guorong, Gao Jimin, Huang Chuanshu
Zhejiang Provincial Key Laboratory for Technology & Application of Model Organisms, School of Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China. Nelson Institute of Environmental Medicine, New York University School of Medicine, Tuxedo, New York.
Zhejiang Provincial Key Laboratory for Technology & Application of Model Organisms, School of Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China.
Clin Cancer Res. 2015 Aug 15;21(16):3783-93. doi: 10.1158/1078-0432.CCR-14-2829. Epub 2015 May 14.
The carcinogenic capacity of B[a]P/B[a]PDE is supported by epidemiologic studies. However, the molecular mechanisms responsible for B[a]P/B[a]PDE-caused lung cancer have not been well investigated. We evaluated here the role of novel target PHLPP2 in lung inflammation and carcinogenesis upon B[a]P/B[a]PDE exposure.
We used the Western blotting, RT-PCR, [(35)S]methionine pulse and immunohistochemistry staining to determine PHLPP2 downregulation following B[a]P/B[a]PDE exposure. Both B[a]PDE-induced Beas-2B cell transformation model and B[a]P-caused mouse lung cancer model were used to elucidate the mechanisms leading to PHLPP2 downregulation and lung carcinogenesis. The important findings were also extended to in vivo human studies.
We found that B[a]P/B[a]PDE exposure downregulated PHLPP2 expression in human lung epithelial cells in vitro and in mouse lung tissues in vivo. The ectopic expression of PHLPP2 dramatically inhibited cell transformation upon B[a]PDE exposure. Mechanistic studies showed that miR-205 induction was crucial for inhibition of PHLPP2 protein translation by targeting PHLPP2-3'-UTR. Interestingly, PHLPP2 expression was inversely associated with tumor necrosis factor alpha (TNFα) expression, with low PHLPP2 and high TNFα expression in lung cancer tissues compared with the paired adjacent normal lung tissues. Additional studies revealed that PHLPP2 exhibited its antitumorigenic effect of B[a]P/B[a]PDE through the repression of inflammatory TNFα transcription.
Our studies not only first time identify PHLPP2 downregulation by lung carcinogen B[a]P/B[a]PDE, but also elucidate a novel molecular mechanisms underlying lung inflammation and carcinogenesis upon B[a]P/B[a]PDE exposure.
流行病学研究证实了苯并[a]芘/苯并[a]芘二酮（B[a]P/B[a]PDE）的致癌能力。然而，B[a]P/B[a]PDE导致肺癌的分子机制尚未得到充分研究。我们在此评估了新型靶点PHLPP2在B[a]P/B[a]PDE暴露后肺部炎症和致癌作用中的作用。
我们使用蛋白质免疫印迹法、逆转录-聚合酶链反应、[35S]甲硫氨酸脉冲标记和免疫组织化学染色来确定B[a]P/B[a]PDE暴露后PHLPP2的下调情况。利用B[a]PDE诱导的Beas-2B细胞转化模型和B[a]P诱导的小鼠肺癌模型来阐明导致PHLPP2下调和肺癌发生的机制。重要发现还扩展到了人体体内研究。
我们发现，B[a]P/B[a]PDE暴露在体外下调了人肺上皮细胞中PHLPP2的表达，在体内下调了小鼠肺组织中PHLPP2的表达。PHLPP2的异位表达显著抑制了B[a]PDE暴露后的细胞转化。机制研究表明，miR-205的诱导通过靶向PHLPP2-3'-UTR对抑制PHLPP2蛋白翻译至关重要。有趣的是，PHLPP2的表达与肿瘤坏死因子α（TNFα）的表达呈负相关，与配对的相邻正常肺组织相比，肺癌组织中PHLPP2表达低而TNFα表达高。进一步研究表明，PHLPP2通过抑制炎症性TNFα转录发挥其对B[a]P/B[a]PDE的抗肿瘤作用。
我们的研究不仅首次确定了肺癌致癌物B[a]P/B[a]PDE可下调PHLPP2，还阐明了B[a]P/B[a]PDE暴露后肺部炎症和致癌作用的一种新的分子机制。
