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Telomerase activity and in situ telomerase RNA expression in malignant and non-malignant lymph nodes. 1997

K Yashima, and M A Piatyszek, and H M Saboorian, and A K Virmani, and D Brown, and J W Shay, and A F Gazdar
Hamon Centre for Therapeutic Oncology Research, UT Southwestern Medical Centre, Dallas 75235-8593, USA.

OBJECTIVE Telomerase, an enzyme associated with cellular immortality, is expressed by most malignant tumours, but is inactive in normal somatic cells except for male germ cells and proliferating stem cells. Thus, the measurement of telomerase activity in tissue samples may provide useful diagnostic and prognostic information. The aim of this study was to determine whether telomerase expression is useful for the detection of occult malignant cells in lymph nodes. METHODS Telomerase activity was compared with histological findings in 123 surgically removed lymph nodes submitted for routine or frozen section diagnosis. Telomerase activity was measured using a modified, semi-quantitative PCR-based telomeric repeat amplification protocol (TRAP). The assay was adapted for single 5 microns OCT embedded cryostat sections. In either fresh tissues or cryostat sections, normalised activity was linear when compared with protein concentration. Furthermore, using an in situ hybridisation method, the human telomerase RNA (hTR) component was measured in a subset of negative and positive nodes. RESULTS Most (96%) of the 97 histologically negative nodes expressed low levels of activity (mean value of positive samples = 3.0 units/microgram protein) which may be derived from activated lymphocytes that express telomerase activity. All 26 malignant nodes (17 metastases, nine lymphomas) expressed telomerase (mean value = 17.8 units/microgram protein). The rank order levels between the two groups differed significantly (p = 0.0002). In situ results showed clearly that the hTR was expressed relatively highly in metastatic cancer cells and at lower levels in germinal centres of secondary follicles. CONCLUSIONS Although expression of telomerase by activated lymphocytes may limit its usefulness, measurement of enzyme activity combined with detection of hTR using in situ hybridisation may assist in the histopathological diagnosis of lymph nodes.

UI MeSH Term Description Entries
D008198 Lymph Nodes They are oval or bean shaped bodies (1 - 30 mm in diameter) located along the lymphatic system. Lymph Node,Node, Lymph,Nodes, Lymph
D008206 Lymphatic Diseases Diseases of LYMPH; LYMPH NODES; or LYMPHATIC VESSELS. Lymphatism,Status Lymphaticus,Disease, Lymphatic,Diseases, Lymphatic,Lymphatic Disease
D008207 Lymphatic Metastasis Transfer of a neoplasm from its primary site to lymph nodes or to distant parts of the body by way of the lymphatic system. Lymph Node Metastasis,Lymph Node Metastases,Lymphatic Metastases,Metastasis, Lymph Node
D008223 Lymphoma A general term for various neoplastic diseases of the lymphoid tissue. Germinoblastoma,Lymphoma, Malignant,Reticulolymphosarcoma,Sarcoma, Germinoblastic,Germinoblastic Sarcoma,Germinoblastic Sarcomas,Germinoblastomas,Lymphomas,Lymphomas, Malignant,Malignant Lymphoma,Malignant Lymphomas,Reticulolymphosarcomas,Sarcomas, Germinoblastic
D005629 Frozen Sections Thinly cut sections of frozen tissue specimens prepared with a cryostat or freezing microtome. Frozen Section,Section, Frozen,Sections, Frozen
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D012261 Ribonucleoproteins Complexes of RNA-binding proteins with ribonucleic acids (RNA). Ribonucleoprotein
D012313 RNA A polynucleotide consisting essentially of chains with a repeating backbone of phosphate and ribose units to which nitrogenous bases are attached. RNA is unique among biological macromolecules in that it can encode genetic information, serve as an abundant structural component of cells, and also possesses catalytic activity. (Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed) RNA, Non-Polyadenylated,Ribonucleic Acid,Gene Products, RNA,Non-Polyadenylated RNA,Acid, Ribonucleic,Non Polyadenylated RNA,RNA Gene Products,RNA, Non Polyadenylated
D016133 Polymerase Chain Reaction In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships. Anchored PCR,Inverse PCR,Nested PCR,PCR,Anchored Polymerase Chain Reaction,Inverse Polymerase Chain Reaction,Nested Polymerase Chain Reaction,PCR, Anchored,PCR, Inverse,PCR, Nested,Polymerase Chain Reactions,Reaction, Polymerase Chain,Reactions, Polymerase Chain
D017403 In Situ Hybridization A technique that localizes specific nucleic acid sequences within intact chromosomes, eukaryotic cells, or bacterial cells through the use of specific nucleic acid-labeled probes. Hybridization in Situ,Hybridization, In Situ,Hybridizations, In Situ,In Situ Hybridizations

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