Expression of Human Telomerase RNA Is an Early Event of Stomach Carcinogenesis

Expression of human telomerase RNA (hTR) and telomerase activity in gastric cancer and corresponding non‐cancerous mucosa were studied. Telomerase activity was detected in 23 (88%) of 26 carcinoma tissues. Although all tumor specimens and non‐cancerous mucosa expressed various levels of hTR, 21 (81%) of 26 cases expressed hTR at a higher level in the tumor than that in the corresponding mucosa. All 8 gastric carcinoma cell lines also expressed hTR at high levels. Nine (35%) of 26 non‐cancerous mucosa showed telomerase activity and all of them contained intestinal metaplasia. The incidence of telomerase‐positive mucosa in grade 2 intestinal metaplasia was significantly higher than that in grade 0 or grade 1 intestinal metaplasia, whereas hTR overexpression was found in grade 0 or grade 1 intestinal metaplasia as well as grade 2 intestinal metaplasia. The degree of Heticobacter pylori infection increased in parallel with the level of hTR expression and telomerase positivity. These results overall suggest that Helicobacter pylori infection may he a strong trigger for hTR overexpression in intestinal metaplasia, and this may lead to telomerase reactivation.