Expression and distribution of human telomerase catalytic component, hTERT, in human breast tissues.

BACKGROUND

Activation of telomerase is essential in a variety of malignant tumors. However, the regulation of its activation and the expression of human telomerase reverse transcriptase (hTERT) are not fully understood in breast tissues.

MATERIALS AND METHODS

In order to clarify this point, the telomerase activity was examined by telomeric repeat amplification protocol (TRAP) assay and quantified by hybridization protection assay (HPA) and, moreover, the expressions of hTERT mRNA and protein were examined by RT-PCR and immunohistochemistry, respectively.

RESULTS

Telomerase activity and the expression of hTERT mRNA were detected in 41(75%) and 37(67%) cases among 55 breast carcinomas, respectively. However, the telomerase ZV activity was detected in only 14(40%) among 35 benign breast tumors. Strong correlation was observed between telomerase activity and hTERT mRNA expression, as described previously. Moreover, the strong expression of hTERT protein in the nucleus of the cell was detected in 30 (57%) cases among 53 breast carcinomas and weak expression of the protein was also detected in 11 (35%) cases among 31 benign breast tumors by immunohistochemistry. There were 12 breast carcinomas which had no telomerase activity. Three of them had hTERT mRNA and protein and in 3 other cases, only hTERT protein was detected. Five cases had the expression of mRNA but not the protein and it was only one case which had no activity and expression of hTERT mRNA and protein. However, in benign tumors, 14 (87.5%) cases among 16 TRAP-negative tumors had no mRNA and protein expression.

CONCLUSION

These results indicate that complicated regulation might be involved in the regulation of telomerase activity and also the activation of the gene may be important in the carcinogenesis of human breast carcinomas.