Background & objective: Telomerase is a ribonucleoprotein enzyme, which plays an important role in cell immortalization and carcinogenesis. Recent studies on the association of telomerase activity with prognostic factors of breast cancer were controversial due to different methods. This study was to establish a feasible assay of quantitative detection of telomerase activity based on silver staining, and investigate possible association between telomerase activity and clinicopathological prognostic factors in primary breast cancer.
Methods: Highly sensitive silver-staining telomeric repeat amplification protocol assay (SS-TRAP) was used to quantify telomerase activity in 52 frozen human breast cancer samples and their adjacent breast tissues, 32 benign lesions, and 14 normal mammary gland lesions. The association between telomerase activity and clinicopathological data was analyzed.
Results: Telomerase activity was detected in 47 of the 52 breast cancer samples (90.38%), and in 10 of the 32 benign lesions, whereas no activity was detected in 37 of 52 adjacent nonmalignant breast tissues, and all 14 normal mammary gland tissues. The telomerase activity levels were 36.91+/-15.35, 8.27+/-4.37, 14.10+/-5.28, 0 (unit: TPG) in breast cancer, adjacent tissue of cancer, benign lesion, and normal tissue, respectively. The difference of telomerase activity was significant between breast cancer and the other 3 groups by using ANVOA (all P< 0.01). A strong correlation was found between telomerase activity and pathological category, and differentiation degree by logistic regression analysis, i.e. with ongoing tumor progression, telomerase activity appeared to increase in primary breast cancer (P=0.003, and P=0.004). No correlation was seen between telomerase activity and disease course, age, and menopause status of patients (all P >0.05). Telomerase activity level of invasive non-special cancer was higher than that of invasive special cancer(P< 0.05). Telomerase activity level of moderately/poorly differentiated carcer was higher than that of highly differentiated cancer (P< 0.05), while no obvious difference was found between moderately and poorly differentiated cancer (P >0.05).
Conclusions: The activation of telomerase might occur early in breast cancer,and plays a critical role in carcinogenesis and tumor development. Telomerase may serve as a specific marker of early diagnosis and prognosis in mammary gland neoplasm.