Gene expressions in experimental carcinogenesis of rat submandibular gland and salivary gland tumors of human being

应用RT-PCR-SSCP技术研究了含2%DMBA海绵颗粒的大鼠下颌下腺（SMG）癌变过程。应用免疫组化和DNA芯片技术对涎腺肿瘤和阻塞性涎腺炎的临床病例进行了研究，结果表明：在实验性涎腺肿瘤的发生过程中，正常SMG和所有实验性病例中均存在H-ras mRNA。15例DMBA治疗后5周、6周、9周和12周标本中分别有1例、5例、13例和15例出现H-ras基因突变。H-ras基因第12外显子第1密码子发生点突变，GGA变为GAA。有报道称，H-ras原癌基因的甘氨酸取代维生素A的点突变可能激活其致瘤性。结果提示：H-ras基因的点突变可能诱发实验性涎腺癌的恶变。本文应用免疫组织化学方法对正常涎腺和阻塞性涎腺炎组织中Cal和金属蛋白（MT）进行了定位研究。在正常腺体中，Cal定位于肌上皮细胞，MT定位于导管基底细胞。涎腺炎的反应性肌上皮细胞和导管样结构的外层细胞同时表达Cal和MT。这些细胞在阻塞性涎腺炎中可能同时具有肌上皮钟状细胞和导管基底细胞的特征。在这些肿瘤中，观察到转录因子和凋亡抑制因子的mRNA扩增。在涎腺炎中，免疫球蛋白和血小板衍生生长因子的某些组分的mRNA扩增。然而，这些mRNA的扩增对肿瘤发生和发展的影响仍然不清楚。

A process of carcinogenesis in rat submandibular gland (SMG), following the 2%DMBA containing sponge pellet insertion, was studied by the use of RT-PCR-SSCP. Furthermore, clinical cases of salivary gland tumors and obstructive sialoadenitis were studied by the use of immunohistochemistry and DNA array.In the experimental carcinogenesis, presence of H-ras mRNA was demonstrated in normal SMG and all experimental cases. Mutant H-ras gene was observed by PCR-SSCP in 1 of 15 cases at 5 weeks after DMBA treatment, 5 cases at 6 weeks specimen, 13 cases at 9 weeks and all 15 cases at 12 weeks specimen. Point mutation of H-ras gene was found cordon 1 exon 12 and GGA was changed to GAA. It has been reported that the point mutation substitutes glysine for glutamin may activate oncogenicity of H-ras proto-oncogene. These results suggested that the point mutation of H-ras gene might induce malignant transformation of experimental carcinoma.Immunohistochemical localization of Cal and metaltyonein (MT) was examined in normal salivary gland and obstructive sialoadenitis. In the normal gland, Cal was localized in myioepithelial cells and MT was found in ductal basal cells. Reactive myoepithelial cells and outer layer cells of duct-like structures in sialoadenitis expressed both Cal and MT staining. These cells in obstructive sialoadenitis may demonstrate cellular characteristics of both myoepithelial bells and ductal basalcells.DNA array analysis for obstructive sialoadenitis, pleomorphic adenoma and cyst adenoma was carried out. In these neoplasms, amplification of mRNA of transcription factors and apoptosis inhibitors was observed. In sialoadenitis, amplification of mRNA of some component of immunoglobulin and platelet derived growth factor. Though, the influences of amplification of these mRNA to the tumor genesis and tumor progression are still unclear.