Inhibition of human telomerase in MKN-45 cell line by antisense hTR expression vector induces cell apoptosis and growth arrest.
OBJECTIVE
To investigate the effects of antisense human telomerase RNA (hTR)on the biologic behavior of human gastric cancer cell line: MKN-45 by gene transfection and its potential role in the gene therapy of gastric cancer.


METHODS
The hTR cDNA fragment was cloned from MKN-45 through RT-PCR and subcloned into eukaryotic expression vector (pEF6/V5-His-TOPO) in cis-direction or trans-direction by DNA recombinant methods. The constructed sense, antisense and empty vectors were transfected into MKN-45 cell lines separately by lipofectin-mediated DNA transfection technology. After drug selection, the expression of antisense hTR gene in stable transfectants and normal MKN-45 cells was detected by RT-PCR, the telomerase activity by TRAP, the apoptotic features by PI and Hoechst 33258 staining, the cell cycle distribution by flow cytometry and the population doubling time by cell counting. Comparison among the stable transfectants and normal MKN-45 cells was made.


RESULTS
The sense, antisense hTR eukaryotic expression vectors and empty vector were successfully constructed and proved to be the same as original design by restriction endonuclease analysis and sequencing. Then, they were successfully transfected into MKN-45 cell lines separately with lipofectin. The expression of antisense hTR gene was only detected in MKN-45 cells stably transfected with antisense hTR vector (named as MKN-45-ahTR) but not in the control cells. In MKN-45-ahTR, the telomerase activity was inhibited by 75%, the apoptotic rate was increased to 25.3%, the percentage of cells in the G0/G1 phase was increased to 65%, the proliferation index was decreased to 35% and the population doubling time was prolonged to 35.3 hours. However, the telomerase activity, the apoptotic rate, the distribution of cell cycle, the proliferation index and the population doubling time were not different among the control cells.


CONCLUSIONS
Antisense hTR can significantly inhibit telomerase activity and proliferation of MKN-45 cells and induce cell apoptosis. Antisense gene therapy based on telomerase inhibition can be a potential therapeutic approach to the treatment of gastric cancer.
Feng
Run-Hua
RH
Shanghai Institute of Digestive Surgery, Ruijin Hospital, Shanghai Second Medical University, Shanghai 200025, China.
Zhu
Zheng-Gang
ZG
Li
Jian-Fang
JF
Liu
Bin-Ya
BY
Yan
Min
M
Yin
Hao-Ran
HR
Lin
Yan-Zhen
YZ
D017209:Apoptosis / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D015870:Gene Expression; D005822:Genetic Vectors; D006801:Humans; D016372:RNA, Antisense / Q000235:genetics / Q000494:pharmacology*; D013274:Stomach Neoplasms / Q000201:enzymology / Q000473:pathology / Q000628:therapy; D019098:Telomerase / Q000037:antagonists & inhibitors* / Q000235:genetics; D014407:Tumor Cells, Cultured
D016372:RNA, Antisense; D019098:Telomerase