Gene expression during Experimental Carcinogenesis of Rat Submandibular Gland DNA Array Study

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A model study for salivary carcinogenesis was made by implantation of a sponge pellet, which containing DMBA/olive oil solution into the rat submandibular gland. Twelve weeks after implant operation, adeno-squamous cell carcinoma histologically consisting of both hyper keratinized squamous epithelium and tubulo-duct-like structures.Gene expression of experimental carcinoma and normal submandibular gland were examined using DNA array method (Atras TM Rat 1.2 Clontech). Cut off ratio and differences were decided as twice and background intensity level (=4) respectively.Up regulated genes in all experimental carcinoma were 48 genes and down regulated were 25 genes. Most enhanced gene in the cancer tissue was for epidermal fatty acid-binding protein, which usually found in dysplastic keratinocytes and the next was for heat shock proteins as known one of the famous stress proteins. Some house keeping genes such as beta-actin also increased in cancer tissue. In the group of protoncogenes and their signal conduction pass way ; although, there are no evidence of increasing of mRNAs of growth factors and their receptors. G-proteins mRNA such as H-ras and ras-related gene were increased dramatically and some messages which cording important factors acting on Raf-MEK-MRK growth signaling pass way. Point mutation of H-ras gene also found in this model study that a guanine at exon 1, corden 12 changes into an adenine. This mutation could change amino-acid sequence and had been reported that one of the accelerate factor in cell proliferation.H-ras mutation and overexpression may play an important role for experimental carcinogenesis in rat submandibular gland.