Apoptosis in the process of carcinogenesis of oral precancerous lesions

我们用免疫组化方法对口腔白斑、口腔白斑继发癌和口腔鳞状细胞癌标本中lewis^y （le^y）抗原、tgf - α、P53蛋白、bcl-2蛋白和PCNA的表达进行了研究。采用Tunel法检测DNA片段，研究细胞凋亡的发生情况。此外，我们在体外研究了抗肿瘤药物和硝普钠（SNP）是否能诱导口腔上皮细胞凋亡。我们还检测了细胞凋亡过程中基因表达的变化。实验结果如下：1。Le^y抗原和bcl-2蛋白在口腔癌组织中的表达较白斑组织弱。相反，tgf - α、P53蛋白和PCNA在口腔癌中的表达强于在白斑中的表达。在白斑中，Le^y抗原和bcl-2蛋白的表达随上皮异常增生的分级而降低，而tgf - α、P53蛋白和PCNA的表达随上皮异常增生的分级而升高。Le^y抗原和bcl-2蛋白的表达随恶性转化而降低。Tunel法检测的DNA片段在口腔白斑中较口腔癌多发。5-Fu、顺铂和SNP均可诱导口腔上皮细胞（NA）凋亡，凋亡过程中c-myc、c-myb、p53 mRNA表达下调。

We investigated the expression of lewis^y (le^y) antigen, TGF-alpha, P53 protein, bcl-2 protein and PCNA immunohistochemically in the specimens which were obtained from patients with leukoplakia, cancer developed from leukoplakia and oral squamous cell carcinoma. Further, occurrence of apoptosis in those specimens was studied by detecting the fragmentation of DNA using Tunel method. In addition, we examined in vitro whether apoptosis could be induced in oral epithelial cells by anticancer drugs and sodium nitroprusside (SNP). We also examined the changes in the expression of genes during apoptosis.The results obtained were as follows :1.Le^y antigen and bcl-2 protein in oral cancer were expressed more weakly than those in leukoplakia. On the contrary, TGF-alpha, P53 protein and PCNA in oral cancer were expressed more strongly than those in leukoplakia.2.The expression of Le^y antigen and bcl-2 protein decreased with the grade of epithelial dysplasia in leukoplakia, whereas the expression of TGF-alpha, P53 protein and PCNA increased with the grade of epithelial dysplasia.3.The expression of Le^y antigen and bcl-2 protein decreased with malignant transformation.4.DNA fragmentation detected by Tunel method occurred more frequently in leukoplakia than in oral cancer.5-Fu, cisplatin and SNP could induced apoptosis in oral epithelial cells (NA) and mRNA expression of c-myc, c-myb, p53 was downregulated during apoptosis.