| Abstract: | 空氣污染中存在許多致癌物質，NOx（NO、NO/sub 2/、NO/sub 3/…）是其中一種。過去有研究指出，NO及NO/sub 2/會造成哺乳類動物肺部的損傷；此外也有研究指出NO及NO/sub 2/與細胞的增生分化也有相關。而這兩者都癌化有關。本篇實驗發現，暴露氣體性NOx（1μM）之下會引起人類肺纖維細胞（MRC-5）的增生，利用流式細胞儀與細胞毒性測試方法發現，細胞週期中的S期及細胞數目都有增加。許多研究證實NO在細胞訊息傳遞中是一重要因子。在本篇研究中我們想了解氣體性NOx促使MRC-5細胞增生的訊息傳遞路徑，利用西方墨點法結果發現：(1)iNOS被活化；(2)活化MAPK cascade（MEKK1、MKK4、JNK、p38MAPK）；(3)一些轉錄因子被活化（NF-κB、phospho-ATF2、c-Jun／c-Fos）；(4)細胞週期蛋白表現增加（Cyclins、Cdks）；(5)細胞週期的抑制蛋白表現下降（p27、p21、p16）。此外，本實驗中發現氣體性NOx與MRC-5細胞的抗凋謝死亡也有相關，利用西方墨點法結果發現：(1)抗凋謝死亡蛋白表現增加（IAP、phospho-Bad）；(2)促使細胞凋謝死亡蛋白表現下降（Cytochrome c、Caspase 3）。因此我們推論氣體性氮氧化物可能經由促使人類肺纖維細胞增生與抑制人類肺纖維細胞凋謝死亡來導致肺癌的產生。
There are many carcinogen in air pollution, including NOx (NO, NO/sub 2/, NO/sub 3/). Several data have suggested that NO and NO/sub 2/ could induce injury in mammalian lung cells. Formation of NO and NO/sub 2/ have been shown to stimulate cells proliferation and differentiation. These are contributing to multistage carcinogenesis. We demonstrated that exposure of human lung fibroblast cells (MRC-5) to gaseous NOx saturation solution (1μM) would induce cell poliferation. We used flow cytometry and MTT assay to clarify the gaseous NOx induced cell poliferation. In this study, we found that gaseous NOx can increase cell cycle at S phase and cell number. Many studies have identified NOx as having a critical role in cellular signaling. In this study, we focused on elucidating the mechanism of gaseous NOx signaling in MRC-5 cells. We found that Nox-induced activation of (1)inducible nitric oxide synthase (iNOS), (2)MAPK cascade (MEKK1, MKK4, JNK, p38MAPK), (3)transcription factors (NF-κB, phospho-ATF2, c-Jun/c-Fos), (4)cell cycle proteins (Cyclins, Cdks), and decreasing of cell cycle inhibitors (p27, p21, p16). We also found that gaseous Nox could activate anti-apoptotic factors (IAP, phospho-Bad) and decrease expression of apoptotic proteins (Cytochrome c, Caspase 3). In conclusion, we suggest that gaseous NOx could play an important role in carcingogenesis by inducing human lung fibroblast cells proliferation and anti-apoptosis. |
