Zhou Xiao-Dong, Yu Jie-Ping, Liu Jin, Luo He-Sheng, Chen Hong-Xia, Yu Hong-Gang
Department of Gastroenterology, Renmin Hospital of Wuhan University, Jiefang Road 238, 430060 Wuhan, China.
Clin Sci (Lond). 2004 Apr;106(4):397-405. doi: 10.1042/CS20030238.
The aim of the present study was to investigate the prevalence of c-FLIP [cellular FLICE-inhibitory protein, where FLICE is Fas-associated death domain (FADD)-like interleukin-1beta-converting enzyme] expression in gastric adenocarcinoma and its possible implications for the progression of the cancer. Expression of c-FLIP in 48 gastric adenocarcinomas and their normal counterparts was analysed by reverse transcriptase PCR, Western blotting and immunohistochemistry. In situ cell apoptosis was detected by TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling) assay. As a result, c-FLIP transcripts were constitutively expressed in gastric adenocarcinomas and their levels were significantly higher than those in matched normal tissues ( P < 0.01). Immunohistochemically, the c-FLIP protein was also found to be expressed in all gastric adenocarcinomas (48/48), and 68.8% (33/48) showed an intense immunostaining; in contrast, only 75% (36/48) of normal gastric mucosa showed positive staining and none of them immunostained intensely. The abundance of c-FLIP protein was significantly higher in carcinoma than in normal gastric mucosa (6.93 +/- 0.58 versus 3.19 +/- 0.26, P < 0.01) and showed a reverse correlation with apoptotic index in adenocarcinoma, but not in normal mucosa. In addition, abundance of c-FLIP was significantly associated with lymph node metastasis at both mRNA level ( P < 0.05) and protein level ( P < 0.01). Western-blot analysis showed that the expression levels of the long form of c-FLIP and the short form of c-FLIP in adenocarcinomas were 2.6-fold and 2.8-fold ( P < 0.01) higher than those in normal tissues respectively. However, no significant difference was found between the expression levels of the two isoforms in both adenocarcinomas or normal tissues. In conclusion, overexpression of c-FLIP is tumour specific, which may be one of the in vivo mechanisms by which tumour cells escape from apoptotic death during the malignant transformation, and plays an important role in lymph node metastasis of gastric adenocarcinoma, which ultimately contributes to the tumour progression.
本研究旨在调查c-FLIP[细胞FLICE抑制蛋白，其中FLICE是Fas相关死亡结构域（FADD）样白细胞介素-1β转换酶]在胃腺癌中的表达情况及其对癌症进展的可能影响。通过逆转录聚合酶链反应、蛋白质免疫印迹法和免疫组织化学分析了48例胃腺癌及其相应正常组织中c-FLIP的表达。采用末端脱氧核苷酸转移酶介导的dUTP缺口末端标记法检测原位细胞凋亡。结果显示，c-FLIP转录本在胃腺癌中组成性表达，其水平显著高于配对的正常组织（P<0.01）。免疫组织化学检测发现，c-FLIP蛋白也在所有胃腺癌中表达（48/48），68.8%（33/48）显示强免疫染色；相比之下，正常胃黏膜仅75%（36/48）呈阳性染色，且均无强免疫染色。c-FLIP蛋白在癌组织中的丰度显著高于正常胃黏膜（6.93±0.58对3.19±0.26，P<0.01），且与腺癌的凋亡指数呈负相关，但在正常黏膜中无此相关性。此外，c-FLIP丰度在mRNA水平（P<0.05）和蛋白质水平（P<0.01）均与淋巴结转移显著相关。蛋白质免疫印迹分析显示，腺癌中c-FLIP长形式和短形式的表达水平分别比正常组织高2.6倍和2.8倍（P<0.01）。然而，两种异构体在腺癌和正常组织中的表达水平均无显著差异。总之，c-FLIP的过表达具有肿瘤特异性，这可能是肿瘤细胞在恶性转化过程中逃避凋亡死亡的体内机制之一，并且在胃腺癌的淋巴结转移中起重要作用，最终促进肿瘤进展。
