Objective: To develop monoclonal antibodies against the catalytic subunit of human telomerase hTERT for its expression detection of human tumors.
Methods: A dominant epitope in hTERT (peptide hTERT(9))was automatically synthesized based on Fmoc method, and was used to immunize BALB/c mice. Hybridomas were generated and screened by ELISA for specific monoclonal antibodies, and the characterization of which were performed by Western blotting and immunohistochemical staining.
Results: Antigenic peptide hTERT(9) was synthesized and confirmed by MALDI-TOF-MS and HPLC analysis. Three hybridoma cell lines secreting anti-hTERT(9) antibodies designated as H4, G8 and A11 were established after primary screening and consequent three rounds of limited dilution. Both of H4 and G8 were IgM, while A11 was IgG1 in isotyping. The competitive assay showed that the antibodies were hTERT(9) specific, and the affinity of G8 was stronger than that of H4 and A11 assayed by affinity ranking. However, in Western blotting, both of H4 and G8 stained an about 123 000 protein band with HeLa and 293 cell extracts but not with normal 2BS cells. Besides, positive staining presented in the nucleus of HeLa, while 2BS was non-reactive immunohistochemically. The sections from paraffin-embedded blocks of 127 cases of human cancer, 40 of precancerous and 19 of benign tumors were in situ stained by G8 antibody, the results showed that the human cancer tissues were 80.31% (102/127) positive in specific nuclear reaction, on the contrary, only a minority of precancerous lesions present weak positive (17.5%, 7/40), and negative in benign tumors (0/19).
Conclusions: The monoclonal antibodies developed against synthetic peptide were hTERT-specific and could recognize both the native and the denatured form. Thus their use in immunoblotting or immunohistochemistry for detecting the telomerase hTERT expression of cancer cell and tissues was promising.