"Telomerase" TUMOR TIDBITS, A BIWEEKLY EMAIL NEWSLETTER FROM GULF COAST VETERINARY ONCOLOGY Number 97; April 25, 2003. ======================================================================= Free Cancer Therapy for 4 months! Dogs without lymphoma having a hematocrit between 19% and 37% and a creatinine <1.8 may be eligible for this anemia study. The qualification examination is provided at no cost and eligible dogs may have all services provided at no charge (including any appropriate surgery, radiation, or chemotherapy) for 4 months. Call our offices in Houston (713.693.1166, Ms. Kelly Griffice) or San Antonio (210.822.1913, Ms. Waynette Wheeler) for additional information. Want a copy of our latest Oncology Handbook? It's available as a pdf file (careful, it's a 2MB file). Email us from http://www.gcvs.com/oncology/emailonc.htm to request a copy. ======================================================================= THIS WEEK'S TUMOR TIDBIT: Telomerase ======================================================================= A single enzyme, telomerase, appears to be responsible for the unchecked growth of cells seen in human cancers, report researchers from the University of Texas. The finding could offer researchers an entirely new approach to the diagnosis and treatment of cancer. Telomeres are DNA sequences found at the ends of eukaryotic chromosomes which maintain the fidelity of genetic information during replication. Under normal circumstances the telomeres become shorter and shorter with each cycle of cell division. A sufficiently short telomere is believed to signal the cells to stop dividing. The telomerase enzyme is a ribonucleic protein that synthesizes telomeric DNA on chromosome ends. After conducting research indicating that telomerase was involved in telomere maintenance, a team of researchers at the University of Texas developed a highly sensitive assay for telomerase. The assay technique utilizes PCR to increase the sensitivity, speed and efficiency of previous assays. An evaluation of cell lines from 18 different human tissues revealed the presence of telomerase in 98 of 100 immortal cell lines. Telomerase was not found in any of 22 mortal cell lines. Subsequent assays of tumor biopsies revealed the presence of telomerase in 90 of 101 specimens representing 12 different tumor types. None of 50 normal somatic tissue specimens tested positive for telomerase. Telomerase appears to be stringently repressed in normal human somatic tissues but reactivated in cancer, where immortal cells are likely required to maintain tumor growth. The assay developed by the University of Texas researchers, called TRAP (telomeric repeat amplification protocol), makes analysis of telomerase activity in primary tumor specimens feasible. The fact that telomerase appears to be expressed in virtually all advanced malignancies should lead to new diagnostic and therapeutic applications. Assays for telomerase could help determine the status of suspect tumors, while a drug that block telomerase could have significant anti-cancer effects. The Oncology Program at the University of Illinois School of Veterinary Medicine has had a similar experience noting that over 90% of spontaneously occurring tumors of dogs have an overexpression of telomerase. Clinical studies involving drugs that block telomerase are in the early phases of study. To watch an animation of telomerase activity, visit http://faculty.plattsburgh.edu/donald.slish/Telomerase.html ======================================================================= As always, we hope this info helps and don't hesitate to call or email us Gulf Coast Veterinary Oncology! Kevin A. Hahn, DVM, PhD, Diplomate ACVIM (Oncology), drhahn@gcvs.com Janet K. Carreras, VMD, Diplomate ACVIM (Oncology), drcarreras@gcvs.com Glen K. King, DVM, MS, Diplomate ACVR (Radiology & Radiation Therapy), drking@gcvs.com Gulf Coast Veterinary Diagnostic Imaging & Oncology 1111 West Loop South, Suite 150, Houston, TX 77027 P: 713.693.1166 F: 713.693.1167 W: www.gcvs.com ======================================================================= Copyright © 2003, Gulf Coast Veterinary Oncology