IDENTIFICATION OF THE CELLS EXPRESSING COT PROTOONCOGENE MESSENGER-RNA

The cell types expressing cot proto-oncogene mRNA were identified by i n situ hybridization (ISH) histochemistry. Among a variety of adult mo use tissues examined, four types of glandular cells expressing cot gen e were identified: (1) granular duct cells in the submandibular and su blingual glands; (2) serous cells in the parotid gland; (3) peptic (ch ief) cells in gastric glands; and (4) goblet cells in colonic glands. Investigation of the developmentally regulated expression of cot mRNA using tissues of 14-day and 18-day embryos, newborn and weanling mice showed that cot gene is expressed only in morphologically differentiat ed and functionally activated cells of these four types. No other type s of cells showing ISH signals were observed. Based on these results, cot gene expressions in cultured cells of colonic adenocarcinomas and gastric adenocarcinomas were examined. SW 480 and WiDr cells showed hi gh expression of this gene and so should be useful for functional anal ysis of Cot kinase. The expression patterns of cot gene in tumor tissu es of the parotid gland, and gastric and colonic glands were investiga ted. Two of the tissues overexpressed this gene markedly, suggesting t hat overproduction of Cot kinase may be one cause of their transformat ion.