Wong Benjamin Chun-Yu, Jiang Xiao Hua, Lin Marie C m, Tu Shui Ping, Cui Jian Tao, Jiang Shi Hu, Wong Wai Man, Yuen Man Fung, Lam Shiu Kum, Kung Hsiang Fu
Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong.
Gastroenterology. 2004 Jan;126(1):136-47. doi: 10.1053/j.gastro.2003.10.063.
Aspirin exerts antitumor effect partly through blocking tumor promoter-induced activator protein-1 (AP-1) activation. The aim of this study is to determine how specific COX-2 inhibitor SC-236 mediates antitumor effect by modulation of AP-1-signaling pathway.
AP-1 transcriptional activity and DNA-binding activity were detected by luciferase reporter assay and gel shift assay, separately. Mitogen-activated protein kinase (MAPK) activation was determined by Western blot and in vitro kinase assay. Antisense oligonucleotide against c-Jun-N-terminal kinase (JNK) was used to suppress JNK expression.
We showed that SC-236 inhibited 12-O-tetradecanoylphorbol-13-acetate (PMA)-induced cell transformation in a dose-dependent manner in JB6 cells. At a dose range (12.5-50 micromol/L) that inhibited cell transformation, SC-236 also inhibited anchorage-independent cell growth and AP-1-activation in 3 gastric cancer cells, independent of COX-prostaglandin synthesis. SC-236 down-regulated c-Jun-NH2-terminal kinase phosphorylation and activity. Suppression of JNK activity reversed the inhibitory effect on AP-1 activity by SC-236 and suppressed gastric cancer cell growth, indicating that the inhibitory effect of SC-236 on AP-1 activation and cell growth was through interaction with JNK.
The inhibitory effect on JNK-c-Jun/AP-1 activation contributes to the antitumor effect of COX-2-specific inhibitor, and inhibition of JNK activation may have a therapeutic benefit against gastric cancer.
阿司匹林部分通过阻断肿瘤启动子诱导的活化蛋白-1（AP-1）激活发挥抗肿瘤作用。本研究旨在确定特异性环氧化酶-2（COX-2）抑制剂SC-236如何通过调节AP-1信号通路介导抗肿瘤作用。
分别采用荧光素酶报告基因检测法和凝胶迁移试验检测AP-1转录活性和DNA结合活性。通过蛋白质免疫印迹法和体外激酶试验测定丝裂原活化蛋白激酶（MAPK）的激活情况。使用针对c-Jun氨基末端激酶（JNK）的反义寡核苷酸抑制JNK表达。
我们发现SC-236在JB6细胞中以剂量依赖的方式抑制12-O-十四酰佛波醇-13-乙酸酯（PMA）诱导的细胞转化。在抑制细胞转化的剂量范围（12.5 - 50 μmol/L）内，SC-236还抑制3种胃癌细胞的非贴壁依赖性细胞生长和AP-1激活，且不依赖于COX-前列腺素合成。SC-236下调c-Jun氨基末端激酶的磷酸化水平和活性。抑制JNK活性可逆转SC-236对AP-1活性的抑制作用，并抑制胃癌细胞生长，表明SC-236对AP-1激活和细胞生长的抑制作用是通过与JNK相互作用实现的。
对JNK-c-Jun/AP-1激活的抑制作用有助于COX-2特异性抑制剂的抗肿瘤作用，抑制JNK激活可能对胃癌具有治疗益处。
