The antiretroviral agent saquinavir enhances hTERT expression and telomerase activity in human T leukaemia cells in vitro

Riccardo Adamo, Alessandro Comandini, Angelo Aquino, Laura Bonmassar, Loredana Guglielmi, Enzo Bonmassar, Ornella Franzese

Research output: Contribution to journalArticle

Abstract

Background: Saquinavir, a protease inhibitor utilized in HIV infection, shows antitumor activity in various experimental models. In previous studies performed in our laboratory the drug was found to induce a substantial increase of telomerase activity in normal peripheral blood mononuclear cells. Aim of the present investigation was to test whether saquinavir was able to increase telomerase activity and the expression of the catalytic subunit of telomerase, hTERT, in human malignant hematopoietic cells. Methods. Human Jurkat CD4 + T cell leukaemia cell line was used throughout the present study. The antiproliferative effect of saquinavir was tested by the MTT assay. Telomerase activity was determined according to the telomeric repeat amplification protocol. The expression of hTERT mRNA was semi-quantitative evaluated by RT-PCR amplification and quantitative Real Time PCR. The binding of the transcription factor c-Myc to its specific E-Box DNA binding-site of hTERT promoter was analyzed by Electophoretic Mobility Shift Assay (EMSA). The amount of c-Myc in cytoplasm and nucleus of leukemia cells was determined by Western Blot analysis, and c-Myc down-regulation was obtained by siRNA transfection. Results: Saquinavir produced a substantial increase of telomerase activity in Jurkat cells in vitro without increasing but rather reducing target cell proliferation rate. Telomerase up-regulation appeared to be the result of enhanced expression of hTERT. Saquinavir-mediated up-regulation of hTERT gene was the result of the increased binding of proteins to the E-Box sequence of the promoter. Moreover, saquinavir amplified the expression of c-Myc especially in the nuclear cell fraction. The direct influence of saquinavir on this transcription factor was also demonstrated by the antagonistic effect of the drug on siRNA induced c-Myc suppression. Since c-Myc is the main responsible for hTERT transcription, these findings suggest that the main mechanism underlying saquinavir-induced telomerase activation is mediated by c-Myc up-regulation. Conclusions: Saquinavir augments hTERT expression while inhibiting leukemic cell growth. Experimental evidences show that this effect is mediated by saquinavir-influenced increase of c-Myc levels. This could have relevance in terms of enhanced hTERT-dependent tumor cell immunogenicity and suggests new paharmacological approaches interfering with c-Myc dependent pathways.

Original languageEnglish
Article number38
JournalJournal of Experimental and Clinical Cancer Research
Volume32
Issue number1
DOIs
Publication statusPublished - 2013

Fingerprint

Saquinavir
Anti-Retroviral Agents
T-Cell Leukemia
Telomerase
Human Activities
Up-Regulation
Small Interfering RNA
Transcription Factors
E-Box Elements
In Vitro Techniques
Jurkat Cells
Electrophoretic Mobility Shift Assay
Protease Inhibitors
Cell Nucleus
Pharmaceutical Preparations
HIV Infections
Transfection
Real-Time Polymerase Chain Reaction
Blood Cells
Carrier Proteins

Keywords

  • c-Myc
  • hTERT
  • Leukaemia
  • Saquinavir
  • Telomerase

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

Cite this

The antiretroviral agent saquinavir enhances hTERT expression and telomerase activity in human T leukaemia cells in vitro. / Adamo, Riccardo; Comandini, Alessandro; Aquino, Angelo; Bonmassar, Laura; Guglielmi, Loredana; Bonmassar, Enzo; Franzese, Ornella.

In: Journal of Experimental and Clinical Cancer Research, Vol. 32, No. 1, 38, 2013.

Research output: Contribution to journalArticle

Adamo, Riccardo ; Comandini, Alessandro ; Aquino, Angelo ; Bonmassar, Laura ; Guglielmi, Loredana ; Bonmassar, Enzo ; Franzese, Ornella. / The antiretroviral agent saquinavir enhances hTERT expression and telomerase activity in human T leukaemia cells in vitro. In: Journal of Experimental and Clinical Cancer Research. 2013 ; Vol. 32, No. 1.
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AU - Adamo, Riccardo

AU - Comandini, Alessandro

AU - Aquino, Angelo

AU - Bonmassar, Laura

AU - Guglielmi, Loredana

AU - Bonmassar, Enzo

AU - Franzese, Ornella

PY - 2013

Y1 - 2013

N2 - Background: Saquinavir, a protease inhibitor utilized in HIV infection, shows antitumor activity in various experimental models. In previous studies performed in our laboratory the drug was found to induce a substantial increase of telomerase activity in normal peripheral blood mononuclear cells. Aim of the present investigation was to test whether saquinavir was able to increase telomerase activity and the expression of the catalytic subunit of telomerase, hTERT, in human malignant hematopoietic cells. Methods. Human Jurkat CD4 + T cell leukaemia cell line was used throughout the present study. The antiproliferative effect of saquinavir was tested by the MTT assay. Telomerase activity was determined according to the telomeric repeat amplification protocol. The expression of hTERT mRNA was semi-quantitative evaluated by RT-PCR amplification and quantitative Real Time PCR. The binding of the transcription factor c-Myc to its specific E-Box DNA binding-site of hTERT promoter was analyzed by Electophoretic Mobility Shift Assay (EMSA). The amount of c-Myc in cytoplasm and nucleus of leukemia cells was determined by Western Blot analysis, and c-Myc down-regulation was obtained by siRNA transfection. Results: Saquinavir produced a substantial increase of telomerase activity in Jurkat cells in vitro without increasing but rather reducing target cell proliferation rate. Telomerase up-regulation appeared to be the result of enhanced expression of hTERT. Saquinavir-mediated up-regulation of hTERT gene was the result of the increased binding of proteins to the E-Box sequence of the promoter. Moreover, saquinavir amplified the expression of c-Myc especially in the nuclear cell fraction. The direct influence of saquinavir on this transcription factor was also demonstrated by the antagonistic effect of the drug on siRNA induced c-Myc suppression. Since c-Myc is the main responsible for hTERT transcription, these findings suggest that the main mechanism underlying saquinavir-induced telomerase activation is mediated by c-Myc up-regulation. Conclusions: Saquinavir augments hTERT expression while inhibiting leukemic cell growth. Experimental evidences show that this effect is mediated by saquinavir-influenced increase of c-Myc levels. This could have relevance in terms of enhanced hTERT-dependent tumor cell immunogenicity and suggests new paharmacological approaches interfering with c-Myc dependent pathways.

AB - Background: Saquinavir, a protease inhibitor utilized in HIV infection, shows antitumor activity in various experimental models. In previous studies performed in our laboratory the drug was found to induce a substantial increase of telomerase activity in normal peripheral blood mononuclear cells. Aim of the present investigation was to test whether saquinavir was able to increase telomerase activity and the expression of the catalytic subunit of telomerase, hTERT, in human malignant hematopoietic cells. Methods. Human Jurkat CD4 + T cell leukaemia cell line was used throughout the present study. The antiproliferative effect of saquinavir was tested by the MTT assay. Telomerase activity was determined according to the telomeric repeat amplification protocol. The expression of hTERT mRNA was semi-quantitative evaluated by RT-PCR amplification and quantitative Real Time PCR. The binding of the transcription factor c-Myc to its specific E-Box DNA binding-site of hTERT promoter was analyzed by Electophoretic Mobility Shift Assay (EMSA). The amount of c-Myc in cytoplasm and nucleus of leukemia cells was determined by Western Blot analysis, and c-Myc down-regulation was obtained by siRNA transfection. Results: Saquinavir produced a substantial increase of telomerase activity in Jurkat cells in vitro without increasing but rather reducing target cell proliferation rate. Telomerase up-regulation appeared to be the result of enhanced expression of hTERT. Saquinavir-mediated up-regulation of hTERT gene was the result of the increased binding of proteins to the E-Box sequence of the promoter. Moreover, saquinavir amplified the expression of c-Myc especially in the nuclear cell fraction. The direct influence of saquinavir on this transcription factor was also demonstrated by the antagonistic effect of the drug on siRNA induced c-Myc suppression. Since c-Myc is the main responsible for hTERT transcription, these findings suggest that the main mechanism underlying saquinavir-induced telomerase activation is mediated by c-Myc up-regulation. Conclusions: Saquinavir augments hTERT expression while inhibiting leukemic cell growth. Experimental evidences show that this effect is mediated by saquinavir-influenced increase of c-Myc levels. This could have relevance in terms of enhanced hTERT-dependent tumor cell immunogenicity and suggests new paharmacological approaches interfering with c-Myc dependent pathways.

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