Telomerase activity in touch-imprint cell preparations from fresh prostate needle biopsy specimens

To evaluate whether it is possible to detect telomerase activity in cells exfoliated from prostate biopsies immediately before fixation.

A total of 115 transrectal biopsies of prostate tissue from 49 patients were touch-imprinted on an RNase-free microscope slide and then fixed. Touch imprints were immediately frozen and used to extract telomerase. Telomerase activity was determined by a telomeric repeat amplification protocol (TRAP) using a PCR-ELISA method. Inflammation and epithelial cells in each biopsy were quantitated by image cytometry.

A total of 90/115 extracts had a proteic content suitable for analysis. Telomerase activity was detected in 18/26 (70%) carcinomas, 2/9 (22%) low-grade prostatic intraepithelial neoplasia (PIN) lesions, and 1/3 (33%) high-grade PIN lesions. In 4 of 7 patients with telomerase-positive tumors, telomerase activity was also found in a distant site devoid of morphologically detectable cancer cells. Telomerase activity was detected in touch imprints from fragments with less than 1 mm(2) of epithelial tissue, and was not associated with the extent of inflammation.

From the technical stand point, the touch-imprint method may provide a useful adjunct for telomerase detection in prostate biopsies. With this procedure the bioptic fragment is left intact for histological examination. Diagnostically, the presence of telomerase activity in sites distant from the original tumor might suggest the presence of tumor cells that are morphologically undetectable.