In Situ Detection of mRNA and RNA Component of Human Telomerase in Proliferative Lesions of the Stomach

ABSTRACT

BACKGROUND: Proliferative lesions of the stomach were investigated by in situ hybridization using RNA probes for telomerase components and compared with the results by TRAP (telomeric repeat amplification protocol) assay. METHODS: RNA probes for hTR (human telomerase RNA component) and hTERT (mRNA coding for a catalytic subunit of human telomerase) were made by cloning and in vitro transcription. The probes were applied for in situ hybridization in 23 cases of adenocarcinoma of the intestinal type and adjacent dysplasia, and in the normal and metaplastic mucosa of the stomach. RESULTS: Telomerase activity by TRAP was positive in all cases of adenocarcinoma, most cases of dysplasia, and many cases of normal mucosa. hTR in situ hybridization showed positive staining in the adenocarcinoma cells, dysplastic cells, a few cells in the proliferation zone of the normal mucosa, and a few infiltrated lymphocytes. hTERT showed positive staining in the same cells. CONCLUSIONS: Telomerase is expressed in most cases of dysplastic lesions and is thought to be acquired in the early steps of carcinogenesis. The expression is noted in a few cells of the normal proliferative zones and the infiltrated lymphocytes, emphasizing the importance of in situ detection of telomerase at the cell level.