NFAT、ATF2、STAT3信号通路与介导的炎性因子在砷诱导膀胱上皮细胞恶性转化中的作用机制研究

Our studies found that over expression of ATF2, NFAT, STAT3 gene transcripts and COX-2 were induced by NaAsO2 in human uroepithelial cell line (SV-HUC-1). COX-2 is an important mediator for inflammation and tumor promotion, and a joinase between cancer and inflammation. Some proteins and cytokines correlated with tumor progression (COX-2,Cyclin D1,c-myc,MMP,Bcl-2,VEGF）and in?ammation （TNF-α,TGF,COX-2,IL-6,IL-8） could be regulated by ATF2, NFAT and STAT3. Bladder cancer development might be linked with inflammatory stimuli. Therefore, we presume that cellular signaling pathways of ATF2, NFAT and STAT3 and relative in?ammatory cytokines may involve malignant transformation of SV-HUC-1 cells treated by NaAsO2. In this study, ATF2, NFAT and STAT3 gene transcripts and relative cellular signaling pathways, as well as inflammatory factors (TNF-α,TGF, IL-6,IL-8) will be studied in arsenic-treated SV-HUC-1 cells, in order to understand the effects of arsenic on ATF2, NFAT and STAT3 signaling pathways and inflammation. The interaction among ATF2, NFAT and STAT3 and in?ammatory cytokines will be studied in arsenic-treated SV-HUC-1 cells. Besides, cell survival, proliferation, angiogenesis and invasion also are determined. These will help us to understand possible mechanism for the induction of malignant transformation of SV-HUC-1 cells by arsenic. In addition, urine samples are collected from arsenic exposed individuals. ATF2, NFAT and STAT3 expressions in exfoliated bladder urothelial cells, and in?ammatory cytokines and arsenicals in urine will be measured. The relationship between arsenicals concentrations and ATF2, NFAT and STAT3 expressions as well as in?ammatory cytokines will be analysised to screen biomarkers of bladder damage induced by arsenic. The systemic studies will not only help to reveal the molecular mechanism of bladder cancer induced by arsenic on the point of view of tumorigenesis and inflammation, but also provide a feasible project for bladder cancer prevention and screening in earlier period in arsenic exposure population.

我们前期研究发现砷诱导人正常膀胱上皮细胞COX-2和NFAT、ATF2、STAT3转录因子表达升高。COX-2是重要的炎症和肿瘤促进调节子， ATF2、NFAT、STAT3三个转录因子均能调节与肿瘤发生和炎症有关的蛋白，而膀胱癌又是与炎症有关的肿瘤之一。由此推测，ATF2、NFAT、STAT3信号通路及所涉及的炎性因子可能参与了砷诱导的膀胱上皮细胞恶性转化。因此，本研究以ATF2、NFAT、STAT3转录因子为切入点，研究砷对人膀胱上皮细胞三个转录因子信号通路和炎性因子分泌的影响，探索三个转录因子和炎症在砷诱导膀胱上皮细胞恶性转化中的作用机制。此外，检测高砷暴露人群尿膀胱脱落细胞三种转录因子的表达水平和尿中炎性因子含量，筛选砷致膀胱损伤的生物标志物。本研究项目不仅能够从炎症与肿瘤发生的角度揭示砷诱发膀胱癌的机制，而且可为高砷暴露人群膀胱癌的预防和早期筛查提供可行的方案。

砷是广泛存在于环境中的类金属元素，能够诱发膀胱癌。但对砷致膀胱癌机制不清楚。我们先前的研究已证明低浓度砷能够引起人正常膀胱上皮细胞COX-2表达水平增高，COX-2是重要的炎症和肿瘤促进调节子，而膀胱癌是与炎症有关的肿瘤之一。因此，我们从炎症因子及其相关信号通路角度探究砷促进膀胱上皮细胞恶性转化的机制，为砷致膀胱癌的防治提供依据。.本项目开展了以下研究：（1）砷对人膀胱上皮细胞ATF2、NFAT、STAT3和NF-κB转录因子信号通路的影响，以及这些信号通路在砷促进膀胱上皮细胞增殖、迁移和肿瘤相关生物学特征因子表达中的调控机制；（2）与肿瘤发生密切相关的炎性因子在砷处理的膀胱上皮细胞的表达水平，及其调控通路，炎性因子在砷处理的膀胱上皮细胞促增殖因子表达中的作用；（3）亚慢性二甲基砷暴露大鼠膀胱上皮细胞NF-κB信号通路活化情况，增殖因子表达和促炎性因子表达情况，调查高砷暴露人群尿中炎性因子和各种砷化物水平，分析砷化物暴露对炎性因子分泌的影响；（4）揭示ATF2、NFAT2、STAT3和NF-κB在砷诱导膀胱上皮细胞增殖、转化和致癌过程中的作用。我们的研究发现砷暴露能够增加膀胱上皮细胞增殖和迁移，促进炎性因子分泌，诱导细胞恶性转化。砷可通过刺激细胞产生ROS，激活MAPK信号通路，并经JNK/MAPK和P38/MAPK信号通路诱导ATF2表达；经ERK/MAPK信号通路激活NFAT2和NF-κB信号，从而增加促增殖因子和促炎因子的表达。砷也可诱导JAK2/STAT3信号通路活化。这些信号通路均与肿瘤发生和炎性因子分泌有关。这些结果在大鼠砷化物暴露模型和高砷暴露人群调查进一步得到证实。本项目研究结果使我们了解ATF2、NFAT、STAT3、NF-κB信号通路和炎症在砷致膀胱上皮细胞恶性转化中的作用，为砷中毒的预防提供新思路，加快和促进本学科领域的发展。