| Research Abstract |
Telomerase is essential for the indefinite proliferation of human cells, and is repressed in most normal human somatic cells. So we have tried various strategies of gene therapy for cancer targeting telomerase. First, an adenovirus vector expressing antisense mRNA against a part of telomerase gene, hTERT, was constructed to induce growth inhibition after critical shortening of telomeres. Telomerase activities in various human cell lines, such as HeLa, LoVo, A549, SW403, and VMRC-LCD, infected with the vector were evaluated by TRAP assay. While the viability of the cells decreased in LoVo and VMRC-LCD, telomerase activity was not significantly repressed. Further investigation on the construct of the vector seems to be necessary.
Then we next tried to repress the TRF2 function, which is essential to maintain the D and T loop of telomere structure, by dominant-negative manner, expecting to induce apotosis of cancer cells without delay. We obtained the wild and mutant-TRF2 expressing vectors and introduced them into human cancer cell lines. However, no significant difference in cell proliferation was shown between the wild and dominant negative TRF2 expressing cells. We considered that inactivation of p53 in cancer cell lines may be associated with this result.
From these data, we speculated the possibility that even above strategies were effective for some population, it was not detected by oveall analysis. So we tried to establish the method to evaluate the telomerase activity level in each. By immunohistochemical detection of hTERT expression using anti-hTERT antibody, the telomerase activity in each cell could be evaluated in situ. This method would promote the further investigation to establish the gene therapy targeting telomerase.
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