Prediction of malignant transformation of oral precancerous lesions by analyzing gene expression profiles and gene polymorphism.

为了初步研究致癌过程中基因表达谱的变化，观察了给予致癌物、4NQO或苯并[a]芘后小鼠舌上皮组织中基因表达谱和形态变化的变化。用基因芯片系统进一步比较了正常口腔上皮、口腔白斑和口腔癌组织中的基因表达谱，并对显著上调的基因进行了蛋白表达的免疫组织化学检测。结果表明：1)给予致癌剂后6周，舌上皮细胞出现异型增生；2)致癌剂作用后，63个基因表达上调，6个基因表达下调。其中，SPRR2A、SPRR2E、SPRR2B和SPRR3基因发生了特征性变化。3)口腔白斑组织中有8个基因表达上调，10个基因表达下调。4)在口腔白斑癌变过程中，与口腔白斑相比，口腔白斑癌变组织中角蛋白10、角蛋白10和角蛋白10的基因表达明显下调。5)免疫组织化学检测显示，角蛋白10蛋白的表达显著降低，仅定位于癌小叶中心。6)激肽释放酶蛋白也轻微定位于癌小叶中心。基因多态分析(SNP)目前正在进行中，导致恶性转化的SNP尚未确定。

To basically investigate changes in gene expression profiles during carcinogenesis, changes in gene expression profiles and morphological changes were examined in the tongue epithelial tissues of the mice after administrating carcinogens, 4NQO or benzo 【a】 pyrene. Further gene expression profiles were compared among human normal epithelia, oral leukoplakias and oral cancers using GeneChip system, and as to markedly up-regulated genes, their protein expression in those tissues was examined immunohistochemically.The results obtained were as follows :1) Epithelial dysplasia was observed in the tongue epithelia at 6 weeks after administration of carcinogens.2) Expression of 63 genes was up-regulated, while that of 6 genes was down-regulated by the administration of carcinogens. Especially, characteristic changes were observed in SPRR2A, SPRR2E, SPRR2B and SPRR3 genes. Of these genes up-regulation of SPRR2A mRNA was confirmed by RT-PCR method.3) In oral leukoplakia, 8 genes were up-regulated and 10 genes were down-regulated when compared with normal epithelial tissues. Of these genes, loricrin, keratin 2E and keratin10 genes were markedly down-regulated in oral cancer tissues.4) In cases developing cancers from oral leukoplakias, gene expression in cancer tissues of loricrin, karatin10 and kallikrein was markedly down-regulated in comparison with oral leukoplakias.5) Immunohistochemical examination revealed that expression of keratin10 protein was markedly decreased and it was only localized at the center of cancer lobules.6) Kallikrein protein was also slightly localized at the center of cancer lobules.These results indicates that changes in loricrin, karatin10 and kallikrein may be predictive markers of malignant transformation from oral leukoplakia. Analysis of gene polymorphism (SNP) is now undergoing and SNPs responsible for malignant transformation were not yet determined.