Li Xue-Mei, Su Jing-Ran, Yan Shi-Ping, Cheng Zhao-Ling, Yang Ting-Ting, Zhu Qiang
Department of Gastroenterology, Provincial Hospital Affiliated to Shandong University, Jinan, Shandong, China.
Medical School of Shandong University, Jinan, Shandong, China.
Cancer Biomark. 2014;14(4):233-40. doi: 10.3233/CBM-140402.
TIPE2 is a novel inflammation regulator, and the role of TIPE2 in colitis-induced colon cancer is not clear. The aim of this study was to test whether TIPE2 inhibits TLR4 pathway in colon cancer patients and to explore potential mechanism of TIPE2 in colon cancer by caspase-8.
Expression of TIPE2 and TLR4 in human colon cancer tissues and cell line HT-29 was detected by immunohistochemistry or real-time PCR. TIPE2 mRNA was suppressed by siRNA transfection and the transfection efficiency was proved by fluorescence microscopy and real-time PCR. TLR4 pathway was activated by treating the cells with 1 μg/ml LPS for 4 h. Caspase-8 activities were tested by colorimetric assay in four HT-29 cell groups.
TIPE2 was expressed in the cytoplasm of colon cancer tissues and HT-29 cells. TIPE2 expression was more pronounced in colon cancer tissues compared to normal controls and it was related with lymph node metastasis and Dukes stage of colon cancer. TIPE2 expression was positively correlated with that of TLR4 in colon cancer (r=0.7354). TIPE2 expression was knocked down successfully by siRNA transfection. Caspase-8 activity was elevated both in TIPE2 knockdown cells and in TLR4 activated cells compared to wild-type cells (P< 0.05). And the caspase-8 activity was further increased in TIPE2 knockdown cells after TLR4 was activated (P < 0.05).
TIPE2 can inhibit caspase-8 activity in colon cancer cells. TIPE2 can regulate TLR4 inflammatory effect and inhibit further amplification of cascade reaction via caspase-8, which provides one new therapeutic target for clinical treatment schedule.
TIPE2是一种新型炎症调节因子，其在结肠炎相关结肠癌中的作用尚不清楚。本研究旨在检测TIPE2是否在结肠癌患者中抑制TLR4信号通路，并通过半胱天冬酶-8探索TIPE2在结肠癌中的潜在作用机制。
采用免疫组织化学或实时PCR检测人结肠癌组织和细胞系HT-29中TIPE2和TLR4的表达。通过小干扰RNA（siRNA）转染抑制TIPE2 mRNA表达，并通过荧光显微镜和实时PCR验证转染效率。用1μg/ml脂多糖（LPS）处理细胞4小时以激活TLR4信号通路。采用比色法检测四个HT-29细胞组中的半胱天冬酶-8活性。
TIPE2在结肠癌组织和HT-29细胞的细胞质中表达。与正常对照相比，TIPE2在结肠癌组织中的表达更明显，且与结肠癌的淋巴结转移和Dukes分期相关。在结肠癌中，TIPE2表达与TLR4表达呈正相关（r=0.7354）。通过siRNA转染成功敲低了TIPE2表达。与野生型细胞相比，TIPE2敲低细胞和TLR4激活细胞中的半胱天冬酶-8活性均升高（P<0.05）。在激活TLR4后，TIPE2敲低细胞中的半胱天冬酶-8活性进一步增加（P<0.05）。
TIPE2可抑制结肠癌细胞中的半胱天冬酶-8活性。TIPE2可调节TLR4的炎症效应，并通过半胱天冬酶-8抑制级联反应的进一步放大，为临床治疗方案提供了一个新的治疗靶点。
