J Korean Med Sci.  2000 Apr;15(2):167-172. 10.3346/jkms.2000.15.2.167.

Change of telomerase activity in rectal cancer with chemoradiation therapy

• Kim HR
• Kim YJ
• Kim HJ
• Kim SK
• Lee JH

• KMID: 648118
• DOI: http://doi.org/10.3346/jkms.2000.15.2.167

Abstract

Telomerase, an enzyme associated with cellular immortality, is expressed by most malignant cells and is inactive in most normal somatic cells, with the exception of proliferative stem cells, germ cells and activated lymphocytes. Measuring telomerase activity clinically may provide useful diagnostic and prognostic information of cancer. The purpose of this study was to investigate the change in telomerase activity following chemoradiation in rectal cancer, which almost always produces positive enzymatic activity. A total of 24 tumor tissue samples were used in this study, consisting of 12 paired specimens before and 4 week after chemoradiation. Telomerase activity was determined by PCR-based telomeric repeat amplification protocol (TRAP) assay. The telomerase activity was positive in 10 out of 12 patients (83%) in pre-irradiated and post-irradiated states. The levels of telomerase activity was decreased in 8 out of 10 patients after chemoradiation (80%) and two cases showed no change in enzymatic activity. One case showed no activity in either sample. The other case showed no enzymatic activity in the pre-irradiated sample, but showed weak activity in the post-irradiated sample. These data indicate that telomerase activity in rectal cancer is reduced after neoadjuvant chemoradiation therapy, possibly suggesting a mechanism of downstaging following chemoradiation therapy in cancer.

Keyword

Telomerase; Rectal Neoplasms; Drug Therapy; Radiotherapy

MeSH Terms

Adult
Aged
Antimetabolites, Antineoplastic/administration & dosage
Antineoplastic Agents/administration & dosage
Cisplatin/administration & dosage
Combined Modality Therapy
Enzyme Activation/radiation effects
Enzyme Activation/drug effects
Female
Fluorouracil/administration & dosage
Gene Amplification
Human
Male
Middle Age
Rectal Neoplasms/radiotherapy*
Rectal Neoplasms/enzymology*
Rectal Neoplasms/drug therapy
Telomerase/metabolism*