Effects of apricitabine and other nucleoside reverse transcriptase inhibitors on replication of mitochondrial DNA in HepG2 cells

Baar, Michel P. de; Rooij, Esther R de; Smolders, Karlijn; Schijndel, Harm B. van; Timmermans, Eveline C.; Bethell, Richard C.

doi:10.1016/j.antiviral.2007.05.004

Cited by 24 publications

(19 citation statements)

References 26 publications

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“…Furthermore, TFV is a weak inhibitor of DNA polymerase γ [Lewis et al, 2003], the enzyme responsible for mtDNA replication, and does not affect mtDNA content in HepG2 cells [de Baar et al, 2007]. Our study was consistent with this finding, as mtDNA levels were not depleted following 120 h exposure to TFV (Table I).…”

Section: Discussionsupporting

confidence: 81%

“…The liver being the metabolic hub of humans is abundant in mitochondria. The HepG2 cell line has been widely used in previous studies evaluating the effect of antiretroviral drugs on mitochondrial toxicity [Birkus et al, 2002;Walker et al, 2002;Velsor et al, 2004;de Baar et al, 2007;Setzer et al, 2008]. HepG2 cells possess cytochrome P 450 activity and has hence been identified as an early model for xenobiotic metabolism [Roe et al, 1993].…”

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confidence: 99%

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Mitochondrial and Oxidative Stress Response in HepG2 Cells Following Acute and Prolonged Exposure to Antiretroviral Drugs

Nagiah

Phulukdaree

Chuturgoon

2015

J of Cellular Biochemistry

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Chronic HIV treatment with antiretroviral drugs has been associated with adverse health outcomes. Mitochondrial toxicity exhibited by nucleoside reverse transcriptase inhibitors (NRTIs) is pinpointed as a molecular mechanism of toxicity. This study evaluated the effect of NRTIs: Zidovudine (AZT, 7.1 μM), Stavudine (d4T, 4 μM) and Tenofovir (TFV, 1.2 μM), on mitochondrial (mt) stress response, mtDNA integrity and oxidative stress response in human hepatoma cells at 24 and 120 h. Markers for mt function, mt biogenesis, oxidative stress parameters, and antioxidant response were evaluated by spectrophotometry, luminometry, flow cytometry, qPCR and western blots. We found that AZT and d4T reduced mtDNA integrity (120 h, AZT: 76.1%; d4T:36.1%, P < 0.05) and remained unchanged with TFV. All three NRTIs, however, reduced ATP levels (AZT: 38%; d4T: 56.4%; TFV: 27.4%, P = 0.01) and mt membrane potential at 120 h (P < 0.005). Oxidative damage and reactive oxygen species (ROS) were increased by TFV and AZT at 24 h, and by d4T at 120 h (P < 0.05). Antioxidant response molecules and mt biogenesis markers were elevated by all NRTIs, with TFV causing the most significant increase (P < 0.05). Data from this study suggest that AZT, d4T and TFV alter mt function. TFV, however, achieves this independently of mtDNA depletion. Furthermore, AZT exerts toxicity soon after exposure as noted from changes at 24 h and d4T exerts greater toxicity over prolonged exposure (120 h).

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Section: Discussionsupporting

confidence: 81%

mentioning

confidence: 99%

Mitochondrial and Oxidative Stress Response in HepG2 Cells Following Acute and Prolonged Exposure to Antiretroviral Drugs

Nagiah

Phulukdaree

Chuturgoon

2015

J of Cellular Biochemistry

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“…Similar findings are also observed in other in vitro models, including human hepatoblastoma (HepG2) cells (5) and HSMCs (2). The mechanisms of increase in mtDNA by AZT are still unknown; however, these results strongly suggest that AZT upregulates genes encoding mtDNA.…”

Section: Discussionsupporting

confidence: 75%

Impact of Nucleoside Reverse Transcriptase Inhibitors on Mitochondrial DNA and RNA in Human Skeletal Muscle Cells

Saitoh

Haas²,

Naviaux

et al. 2008

Antimicrob Agents Chemother

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We previously reported that 2,3-dideoxyinosine (didanosine, or ddI) significantly altered mitochondrial DNA (mtDNA) in peripheral blood mononuclear cells in human immunodeficiency virus type 1 (HIV-1)-infected children who had undetectable plasma HIV-1 RNA for more than 2 years while receiving highly active antiretroviral therapy. This research examines the in vitro effects of nucleoside reverse transcriptase inhibitors (NRTIs) on mitochondria of human skeletal muscle cells (HSMCs), including myoblasts and differentiated myotubes. mtDNA, mitochondrial RNA (mtRNA), and mRNA levels for nuclear mitochondrial regulatory factors were quantified in vitro using HSMCs, including myoblasts and differentiated myotubes, treated with NRTIs singly and in combination. After 5 days of treatment, mtDNA was significantly decreased in myoblasts and myotubes treated with ddI (P < 0.001 and P ‫؍‬ 0.01, respectively) and ddI-containing regimens (P < 0.001 and P < 0.001, respectively) compared to levels in untreated cells. mtRNA (MTCYB) was also significantly decreased in the myoblasts and myotubes treated with ddI (P ‫؍‬ 0.004) and ddI-containing regimens (P < 0.001). Regardless of the NRTI regimens examined, NRTI combinations significantly decreased mtRNA (MTCO3) in myoblasts and myotubes (P ‫؍‬ 0.02 and P ‫؍‬ 0.01, respectively). No significant differences were observed for nuclear mitochondrial regulatory factor mRNA in myoblasts or myotubes when treated with NRTIs (P > 0.07). ddI and ddI-containing regimens significantly decrease mtDNA and mtRNA in HSMCs, most notably in myoblasts. These findings may be of particular importance in developing countries, where ddI is widely used for first-line treatment of HIV-infected children.

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“…This apparent increase in cell size coincides with the measured twofold increase in mtDNA per cell, suggesting higher numbers of mitochondria per cell. Previous studies that did not show LVD mitochondrial toxicity in culture did not expose cells to concentrations of LVD as high as those tested in the present study (34, 39); the 833 M concentration at (12). Adverse events associated with LVD therapy that were consistent with mitochondrial toxicity have been reported on rare occasions (11,33).…”

Section: Discussionsupporting

confidence: 52%

“…In addition, combinations of ETV with the other anti-HBV NRTIs were also tested in culture. HepG2 cells were chosen for the present study because of their extensive use in the HBV field, including those that established inhibition of HBV replication and intracellular phosphorylation of the agents tested, as well as several key studies on the effects of NRTIs on mitochondrial metabolism (1,2,12,34,39). Finally, the ability of ETV-TP to be recognized by Pol ␥ was assessed in vitro.…”

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confidence: 99%

Entecavir for Treatment of Hepatitis B Virus Displays No In Vitro Mitochondrial Toxicity or DNA Polymerase Gamma Inhibition

Mazzucco

Hamatake

Colonno

et al. 2008

Antimicrob Agents Chemother

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Therapy with nucleoside reverse transcriptase inhibitors (NRTIs) can be associated with mitochondrial toxicity. In vitro studies have been used to predict the predisposition for and characterize the mechanisms causing mitochondrial toxicity. Entecavir (ETV) is an approved deoxyguanosine nucleoside for the treatment of chronic hepatitis B virus (HBV) infection that exhibits potent activity against viral reverse transcriptase. We assessed the potential for mitochondrial toxicity of ETV in long-term cultures of HepG2 hepatoma cells by measuring mitochondrial function (through lactate secretion), levels of mitochondrial DNA (mtDNA), and levels of mitochondrial proteins COX II and COX IV. Furthermore, we tested the activity of ETV-triphosphate (ETV-TP) against mitochondrial DNA polymerase ␥ (Pol ␥) in vitro. ETV concentrations as high as 100 times the maximal clinical exposure (C max ) did not affect cell proliferation, levels of lactate, mitochondrial DNA, or mitochondrial proteins throughout the 15-day culture. The lack of mitochondrial toxicity was consistent with the finding that ETV-TP was not recognized by mitochondrial DNA Pol ␥ and failed to be incorporated into DNA or inhibit the polymerase assay at the highest levels tested, 300 M. Combinations of ETV with each of the other HBV NRTI antivirals, adefovir, tenofovir, and lamivudine at 10 times their respective C max levels also failed to result in cellular or mitochondrial toxicity. In summary, cell culture and enzymatic studies yielded no evidence that would predict mitochondrial toxicity of ETV at exposure levels in excess of those expected to be achieved clinically.

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Effects of apricitabine and other nucleoside reverse transcriptase inhibitors on replication of mitochondrial DNA in HepG2 cells

Cited by 24 publications

References 26 publications

Mitochondrial and Oxidative Stress Response in HepG2 Cells Following Acute and Prolonged Exposure to Antiretroviral Drugs

Mitochondrial and Oxidative Stress Response in HepG2 Cells Following Acute and Prolonged Exposure to Antiretroviral Drugs

Impact of Nucleoside Reverse Transcriptase Inhibitors on Mitochondrial DNA and RNA in Human Skeletal Muscle Cells

Entecavir for Treatment of Hepatitis B Virus Displays No In Vitro Mitochondrial Toxicity or DNA Polymerase Gamma Inhibition

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