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

为了初步研究致癌物、4NQO和苯并【a】芘对小鼠舌上皮组织基因表达谱和形态学的影响，对致癌物发生过程中基因表达谱的变化进行了研究。应用GeneChip系统进一步比较人正常上皮、口腔白斑和口腔癌的基因表达谱，并对明显上调的基因进行免疫组织化学检测其蛋白表达。结果表明：1)给药6周后，舌上皮出现上皮发育不良。2) 63个基因表达上调，6个基因表达下调。尤其是SPRR2A、SPRR2E、SPRR2B和SPRR3基因的特征性变化。通过RT-PCR方法证实了这些基因中SPRR2A mRNA的上调。3)与正常上皮组织相比，口腔白斑中有8个基因上调，10个基因下调。其中，loricrin、角蛋白2E和角蛋白10基因在口腔癌组织中明显下调。4)口腔白斑癌变病例中，与口腔白斑相比，loricrin、karatin10和kallikrein在癌组织中的基因表达明显下调。5)免疫组化检查显示，角化蛋白10表达明显降低，且仅局限于癌小叶中心。6) Kallikrein蛋白也轻微定位于癌小叶的中心。这些结果提示loricrin、karatin10和kallikrein的变化可能是口腔白斑恶性转化的预测指标。目前正在进行基因多态性（SNP）分析，但尚未确定与恶性转化有关的SNP。

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.