Inhibition of telomerase with human telomerase reverse transcriptase antisense increases the sensitivity of tumor necrosis factor-α-induced apoptosis in prostate cancer cells

Aim： To investigate the effect of inhibition of telomerase with human telomerase reverse transcriptase （hTERT） antisense on tumor necrosis factor-α （TNF-α-induced apoptosis in prostate cancer cells （PC3）. Methods： Antisense phosphorothioate oligodeoxynucleotide （AS PS-ODN） was synthesized and purified. Telomerase activity was measured using the telomeric repeat amplification protocol （TRAP） and polymerase chain reaction enzyme-linked immunoassay （PCR-ELISA）. hTERT mRNA was measured by reverse transcription PCR （RT-PCR） assay and gel-image system, hTERT protein was detected by immunochemistry and flow cytometry. Cell viability was detected by 3-（4, 5-dimethylthiazol-2-yl）-2,5-Diphenyltetrazolium （MTT） assay. Cell apoptosis was observed by morphological method and determined by flow cytometry. Results： The telomerase activity decreased with time after hTERT AS PS-ODN treatment. The levels of hTERT mRNA decreased with time after hTERT AS PS-ODN treatment, which appeared before the decline of the telomerase activity. The percentage of positive cells of hTERT protein declined with time after hTERT AS PS-ODN treatment, which appeared after the decline of hTERT mRNA. There was no difference in telomerase activity, hTERT mRNA and protein levels between hTERT sense phosphorothioate oligodeoxynucleotide （S PS-ODN） and the control group. The cell viability decreased with time after hTERT AS PS-ODN combined with TNF-α treatment. The percentage of apoptosis increased with time after hTERT AS PS-ODN combined with TNF-α treatment. There was no difference in cell viability and the percentage of apoptosis between hTERT S PS-ODN and the control group. Conclusion： hTERT AS PS-ODN can significantly inhibit telomerase activity by downregulating the hTERT mRNA and protein expression, and inhibition of telomerase with hTERT antisense can enhance TNF-α- induced apoptosis of PC3 cells.

Inhibition of telomerase with human telomerase reverse transcriptase antisense enhances tumor necrosis factor-a-induced apoptosis in bladder cancer cells

Background Telomerase activity is found in 85%-90% of all human cancers but not in their adjacent normal cells. Human telomerase reverse transcriptase （hTERT） is an essential component in the telomerase complex that plays an important role in telomerase activity. This study investigated the effect of the telomerase inhibition with an hTERT antisense oligodeoxynucleotide （ODN） in bladder cancer cells （T24） on tumor necrosis factor-α （TNF-α）-induced apoptosis. Methods Antisense phosphorothioate oligodeoxynucleotide （AS PS-ODN） was synthesized and purified. Telomerase activity was measured by polymerase chain reaction enzyme-linked immunoassay （PCR-ELISA）. hTERT mRNA expression was measured by reverse transcription polymerase chain reaction （RT-PCR） assay and a gel-image system. hTERT protein was detected by immunochemistry and flow cytometry. Cell viability was measured by the 3-（4, 5-dimethylthiazol-2-yl）-2, 5-Diphenyltetrazolium （MTT） assay. Cell apoptosis was observed by a morphological method and determined by flow cytometry. Results AS PS-ODN significantly inhibited telomerase activity and decreased the levels of hTERT mRNA which preceded the decline in the telomerase activity. AS PS-ODN significantly reduced the percentage of positive cells expressing hTERT protein following the decline of hTERT mRNA levels. There was no difference seen in the telomerase activity, hTERT mRNA expression or the protein levels between the sense phosphorothioate oligodeoxynucleotide （SPS-ODN） and the control group. AS PS-ODN treatment significantly decreased the cell viability and enhanced the apoptotic rate of T24 cells in response to TNF-α while there was no difference in cell viability and apoptotic rate between the S PS-ODN and the control group. Conclusions AS PS-ODN can significantly inhibit telomerase activity by downregulating the hTERT mRNA and protein expression. Treatment with AS PS-ODN may be a potential and most promising strategy for bladder cancer with telomerase activity.