Expression of telomerase subunits in normal and neoplastic prostate epithelial cells isolated by laser capture microdissection

BACKGROUND. Vertebrates have special structures at the ends of their chromo somes, known as telomeres, which may provide the chromosomes with stability and protect them from exonucleolytic degradation. The shortening of telome ric DNA with each cell division may lead to cell cycle arrest and/or apopto sis of a normal human somatic cell. Telomerase, an RNA-dependent DNA polyme rase, elongates the 3'-ends of telomeric DNA. Thus, the presence of telomer ase activity may reflect a cell's potential immortal state. The telomerase complex is comprised of several subunits. In the current study, the authors describe the use of laser capture microdissection (LCM) to procure pure ma tched tumor and normal cell populations from histologic sections and to det ermine the expression of telomerase subunits in these purified samples. METHODS. Pure matched tumor and normal prostate epithelial cells were procu red by LCM using fresh frozen tissue samples obtained from patients undergo ing radical prostatectomy. RNA was extracted from LCM captured cells, and t he subunits for telomerase were assayed by reverse transcriptase-polymerase chain reaction. RESULTS. In 18 samples that were captured with LCM, only the catalytic subu nit of telomerase, or hTERT, was found to be discriminatory between tumor c ells (17 of 18 specimens, 94.4%) and nontumor cells (none of 18 specimens). TP1, a protein that has been shown to be associated with telomerase activi ty, was expressed in 3 of 18 normal cells (16.7%) and 15 of 18 tumor cells (83.3%). The RNA subunit of telomerase, or hTR, was expressed in 10 of 18 n ormal cells (55.6%) and 18 of 18 tumor cells (100%). There was no apparent correlation between telomerase subunit(s) expression and Gleason sum score. CONCLUSIONS. Molecular analyses of LCM cells from prostate carcinoma patien t samples demonstrated transcriptional up-regulation of all telomerase subu nits in the prostatic epithelium. However, only the catalytic subunit of te lomerase, hTERT, was found to be discriminatory between neoplastic versus n ormal cells (94.4% vs. 0%). This finding suggests that (he hTERT subunit ma y be a useful marker for the detection of prostate carcinoma and/or a poten tial target for therapy. (C) 2001 American Cancer Society.