Semi - quantitative Comparison of Terminal Restriction Fragment Length and Telomerase in Breast Cancer for Biotherapy

Rha, Sun Young; Park, Kyu Hyun; Kim, Tae Soo; Kim, Joo Hang; Roh, Jae Kyung; Min, Jin Sik; Lee, Kyung Shik; Kim, Byung Soo; Chung, Hyun Cheol

Abstract

PURPOSE
We determined the clinical significance of telomerase activity and telomere length in breast cancer patients and also developed the measuring system of telomerase activity change with RNAse A pre-treatment.
MATERIALS AND METHODS
We measured the telomerase activity in 71 breast cancer tissues and paired normal tissues with TRAP (Telomeric Repeat Amplification Protocol) assay. Telomerase activity was calculated by computer-assisted densitometry compared to telomerase activity of the 293 control cell line. To develop the measuring system of telomerase activity modulation, we measured the telomerase activity after the treatment with RNAse A, 150microgram/ml, which inhibited 70% of telomerase activity compared to control in the 293 control cell line. In 59 paired tissues with telomerase activity, terminal restriction fragment (TRFs) length were measured using Southern blotting.
RESULTS
Sixty-three out of 71 cancer tissues showed telomerase activity (88.7%), while no telomerase activity was detected in their paired normal tissues. Telomerase activity was correlated to the node metastasis (p=0.02) and stage (p=0.005), but not to the tumor size or the hormonal receptor status. TRFs were neither specific to tumor tissues nor related to any of the clinical parameters. However, changes of TRFs of the tumor tissues from their paired normal tissues were correlated to the telomerase activities. Also the patients with different TRFs between cancer and normal tissues were in more advanced stage. After pre-treatment with the 150microgram/ml of RNAse A, telomerase activity in the tumor tissues showed variable inhibition. Relative inhibition, the ratio of inhibited telomerase activity in each tumor tissue compared to the inhibition of 293 control cell line, was proportional to the telomerase activity.
CONCLUSION
In breast cancer, telomerase activity was specific to the tumor tissues and correlated to tumor progression. A combination of telomerase activity and TRFs changes can be used as a guidline in detecting a better candidate for telomerase inhibition. Semi-quantitative assay with RI system can be used in evaluating the changes of telomerase activity after treatment with a new telomerase inhibitor with TRAP assay.