TELOMERASE ACTIVITY IN NORMAL AND NEOPLASTIC BREAST

Telomerase activity is detected in the majority of human tumors and pr ovides a mechanism to escape from proliferative limitations due to tel omere loss, Similar to other studies, telomerase activity was detected with a modified telomeric repeat amplification protocol in the majori ty (76%) of 49 human breast cancer specimens, including most (75%) duc tal carcinoma in situ specimens. There were no correlations between te lomerase activity and tumor stage or estrogen/progesterone receptor st atus, In four of seven invasive tumors, telomerase expression seemed t o be heterogeneous because not all microdissected regions were telomer ase positive, Low levels of telomerase activity were also detected in a minority (17%) of breast specimens from patients without evidence of cancer, These findings suggest that telomerase activation can occur e arly in breast cancer progression and may be periodically down-regulat ed during subsequent progression.