癌前病变Caspase-3表达下调与胃黏膜癌变的关联

目的观察Caspase-3蛋白在胃癌及其癌前病变组织中的表达,分析它与细胞凋亡和细胞增殖的关系,探讨Caspase-3蛋白在胃癌发生过程中的生物学意义及相关分子病理学机制。方法选取184例胃黏膜活检和手术切除组织标本,其中胃癌20例,慢性萎缩性胃炎6例,萎缩性胃炎伴肠上皮化生(简称肠上皮化生)31例,萎缩性胃炎伴不典型增生(简称不典型增生)114例;正常对照13 例。采用SABC法检测Caspase-3蛋白的表达;通过图像域值分析计算其阳性指数,分析其与细胞增殖(Ki67蛋白阳性指数)和凋亡(TUNEL指数)的相关关系。结果 Caspase-3蛋白在重度不典型增生组织中的阳性指数(29．8％±3．9％)显著低于轻度(58．3％±4．2％)和中度不典型增生(50．4％± 4．8％)及萎缩性胃炎(68．3％±3．3％)或肠上皮化生(70．9％±4．3％),差异有统计学意义(P<0．05); 而与胃癌(26．9％±3．0％)相比,差异无统计学意义(P>0．05)。Caspase-3蛋白表达与细胞凋亡呈显著正相关(r=0．94,P<0．05),Caspase-3蛋白阳性组细胞增殖指数(18．3％±2．2％)显著低于阴性组(48．9％±3．1％;P<0．05)。结论 Caspase-3蛋白在萎缩性胃炎、肠上皮化生和(或)轻中度不典型增生黏膜中表达上调,而在重度不典型增生及胃癌组织中表达下调,且这种变化与细胞凋亡呈显著正相关。Caspase-3失活或表达下调相关的细胞凋亡和增殖紊乱可能在胃黏膜损伤及癌变过程中起某种作用。

Down-regulation of Caspase-3 expression in precancerous lesions and its relation to gastric carcinogenesis

OBJECTIVE: To study the level of expression of Caspase-3 protein in precancerous lesions of stomach and its relation to gastric carcinogenesis. METHODS: Formalin-fixed paraffin embedded tissues from 184 cases of gastric mucosa biopsy and surgically removed specimens, including gastric cancer (GC, N = 20), chronic atrophic gastritis (CAG, N = 6), atrophic gastritis with intestinal metaplasia (IM, N = 31), atrophic gastritis with dysplasia (DYS, N = 114) and normal controls (N = 13) were examined for expression of Caspase-3 protein and Ki-67 index by SABC immunohistochemistry, and for apoptosis by TdT-mediated dUTP biotin nick end labeling (TUNEL) method. Caspase-3, Ki-67 and TUNEL index were compared in different stages of gastric precancerous lesions and their correlation was analyzed. RESULTS: The positive index of Caspase-3 protein in severe DYS (29.8% +/- 3.9%) showed no significant difference compared with that in GC (26.9% +/- 3.0%, P > 0.05), but was significantly lower than that in low (58.3% +/- 4.2%) and moderate grade DYS (50.4% +/- 4.8%), CAG (68.3% +/- 3.3%) and IM (70.9% +/- 4.3%, P < 0.05). Caspase-3 positive index was significantly correlated with that of apoptosis detected by TUNEL (r = 0.94, P < 0.05). Ki-67 index in Caspase-3 protein positive group (18.3% +/- 2.2%) was significantly lower than that in Caspase-3 negative group (48.9% +/- 3.1%, P < 0.05). CONCLUSION: Caspase-3 protein expression was upregulated in CAG with or without IM and low or moderately low in DYS, while down-regulated in severe DYS and gastric carcinoma, and significantly positively correlated with cell apoptosis. It is suggested that down-regulated expression of Caspase-3 protein somehow contributes to gastric carcinogenesis through an imbalance between cell apoptosis and proliferation.