胃癌前病变APC抑癌基因原位杂交光镜及电镜观察

APC gene expression in precancerous lesions of stomach examined by light and electron microscopic in situ hybridization

目的 探讨胃癌前病变APC基因异常表达及其意义。方法 应用光镜及电镜原位杂交对胃癌前病变APC基因进行细胞和超微水平观察。结果 (1)APC基因阳性率以正常胃黏膜最高 ,为 83 3% ;轻、中、重度异型增生分别为 77 8%、6 2 5 %和 2 5 9% ,重度者明显低于前两者 ,癌组织则更低 ,为 6 7%～ 8 0 %。 (2 )肠上皮化生中 ,APC基因阳性率大肠型高于小肠型 ,不完全性高于完全性 ,大肠型不完全性最高。 (3)电镜下APC基因杂交信号位于正常胃黏膜壁细胞、异型增生及癌细胞胞浆基质内 ,其信号逐渐减弱直至阴性。结论 APC基因表达异常主要位于胃癌前病变———重度异型增生上皮中 ,系胃癌发生过程中的早期事件。检测胃黏膜APC基因可预测其癌变倾向 。

Objective To study the significance of abnormal expression of APC gene in gastric cancer and its precancerous lesions.Methods The expression of APC gene was examined in 119 cases of precancerous lesions and 40 cases of gastric cancers by light and electron microscopic in situ hybridization technique.Results 1. The positive rate of APC gene expression in normal gastric mucosa, mild dysplasia, moderately severe dysplasia, severe dysplasia and gastric cancer was 83.3%, 77.8%, 62.5%, 25.9%, and 6.7%～8.0%, respectively. 2. In 4 types of intestinal metaplasia (IM), APC gene expressed much more frequently in colonic type than in small intestinal type ( P <0.05), more frequently in incomplete type of IM than in complete type ( P >0.05). The positive rate of incomplete colonic type was the highest. 3. Under electron microscope, the APC positive signals were located in the cytoplasm matrix of gastric mucosa cells. They decreased gradually from normal parietal cells, dysplasia cells to cancer cells till negative.Conclusion Abnormal expression of APC gene occurs mainly in precancerous lesion severe dysplasia. It is considered as an early event during gastric carcinogenesis. Detecting APC gene in gastric mucosa helps predict the trend of dyplasia to become malignant, and diagnose gastric cancer in early stage.