Immunohistochemical detection of telomerase (hTERT) protein in human cancer tissues and a subset of cells in normal tissues

We examined human telomerase reverse transcriptase (hTERT) protein distribu tion by immunohistochemistry in cultured cells and tissue sections. Cells w ith telomerase activity had nuclear positive signals whereas cells without telomerase activity did not, In most normal epithelial tissues, hTERT expre ssion was prominent in the early proliferative descendent progenitor cells. In cancers with high telomerase activity, hTERT expression was detected in almost ail neoplastic cells and correlated with telomerase activity levels , whereas cancers with low telomerase activity had fewer hTERT-positive can cer cells. In pediatric neuroblastomas with a favorable outcome, both the p ercentage of positive cells and the signal intensity of each hTERT-expressi ng cell decreased. These studies indicate that detection of telomerase at t he cellular level is achievable and may have utility in cancer diagnostics.