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Telomerase Potential Cancer Biomarker

Telomerase Potential Cancer Biomarker

SEATTLE—Telomerase may be an early biomarker of pancreatobiliary
malignancies, and telomerase enzyme immunostaining represents a potential
breakthrough in screening for and diagnosing cancer in patients with biliary
strictures, Tarun Mullick, MD, said at the president’s plenary session of the
67th Annual Meeting of the American College of Gastroenterology (ACG abstract

Current methods of screening for and diagnosing cholangiocarcinomas are
inadequate, with endoscopic retrograde cholangiopancreatography (ERCP) brush
cytology only 30% to 70% effective, Dr. Mullick said in an interview with ONI.
"But having a biomarker may enhance your technique to something that is
closer to 90% to 100% sensitive. Using a bio-marker is such a leap in
concept; this is the first real study that looked at the possibility of doing

Telomerase is a reverse transcriptase. It synthesizes telomeric DNA, and
its upregulation confers immortality to cancer cells, said Dr. Mullick,
instructor of clinical internal medicine, Division of Gastroenterology and
Hepatology, University of Virginia, Charlottesville.

At the ACG meeting, Dr. Mullick and his colleagues presented preliminary
data on telomerase as a potential biomarker of cancer. These preliminary
findings showed that 15 of 15 pancreatobiliary malignancies, including two
cholangio-carcinomas, were telomerase positive, while 5 of 5 benign
pancreatic ducts were telomerase negative.

In the current study, the investigators sought to determine the role of
telomer-ase in differentiating benign bile ducts from cholangiocarcinoma in
surgical resection specimens, and to determine the feasibility of utilizing
telomerase enzyme detection with ERCP brush cytology in patients with benign
and malignant biliary strictures.

Telomerase staining was performed on surgical resection specimens from 10
patients with cholangiocarcinoma and 10 with benign bile ducts. The
researchers also assessed for telomerase enzyme in seven patients with
biliary stricture—four who progressed to or were diagnosed with cancer and
three with benign ducts—using ERCP brush cytology.

Dr. Mullick explained that telomerase antibody immunostaining is performed
by first deparaffinizing and rehydrating tissues, and then retrieving the
telomerase enzyme antigen. Primary and secondary antibody incubation are then
performed, and the enzyme is visualized using AEC chromagen, which stains


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