High-dose clevudine impairs mitochondrial function and glucose-stimulated insulin secretion in INS-1E cells.
BACKGROUND
Clevudine is a nucleoside analog reverse transcriptase inhibitor that exhibits potent antiviral activity against hepatitis B virus (HBV) without serious side effects. However, mitochondrial myopathy has been observed in patients with chronic HBV infection taking clevudine. Moreover, the development of diabetes was recently reported in patients receiving long-term treatment with clevudine. In this study, we investigated the effects of clevudine on mitochondrial function and insulin release in a rat clonal β-cell line, INS-1E.


METHODS
The mitochondrial DNA (mtDNA) copy number and the mRNA levels were measured by using quantitative PCR. MTT analysis, ATP/lactate measurements, and insulin assay were performed.


RESULTS
Both INS-1E cells and HepG2 cells, which originated from human hepatoma, showed dose-dependent decreases in mtDNA copy number and cytochrome c oxidase-1 (Cox-1) mRNA level following culture with clevudine (10 μM-1 mM) for 4 weeks. INS-1E cells treated with clevudine had reduced total mitochondrial activities, lower cytosolic ATP contents, enhanced lactate production, and more lipid accumulation. Insulin release in response to glucose application was markedly decreased in clevudine-treated INS-1E cells, which might be a consequence of mitochondrial dysfunction.


CONCLUSIONS
Our data suggest that high-dose treatment with clevudine induces mitochondrial defects associated with mtDNA depletion and impairs glucose-stimulated insulin secretion in insulin-releasing cells. These findings partly explain the development of diabetes in patients receiving clevudine who might have a high susceptibility to mitochondrial toxicity.
Department of Internal Medicine, Yonsei University, Wonju College of Medicine, Wonju, 220-701, Korea.
Yoon-Ok
YO
Jang
Xianglan
X
Quan
Ranjan
R
Das
Shanhua
S
Xu
Choon-Hee
CH
Chung
Chan Mug
CM
Ahn
Soon-Koo
SK
Baik
In Deok
ID
Kong
Kyu-Sang
KS
Park
Moon Young
MY
Kim
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000998:Antiviral Agents / Q000009:adverse effects / Q000494:pharmacology*; D001086:Arabinofuranosyluracil / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000494:pharmacology; D002460:Cell Line; D056915:DNA Copy Number Variations / Q000187:drug effects; D004272:DNA, Mitochondrial / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D003576:Electron Transport Complex IV / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology*; D056945:Hep G2 Cells; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007773:Lactates / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects* / Q000502:physiology*; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D051381:Rats
D000998:Antiviral Agents; D004272:DNA, Mitochondrial; D007328:Insulin; D007773:Lactates; D012333:RNA, Messenger; D001086:Arabinofuranosyluracil; D000255:Adenosine Triphosphate; D003576:Electron Transport Complex IV; C034935:clevudine; D005947:Glucose