Mutagenesis Advance Access originally published online on March 22, 2005
Mutagenesis 2005 20(2):139-146; doi:10.1093/mutage/gei019
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Published by Oxford University Press on behalf of the UK Environmental Mutagen Society 2005
Zidovudine induces S-phase arrest and cell cycle gene expression changes in human cells
Carcinogen–DNA Interactions Section, Laboratory of Cellular Carcinogenesis and Tumor Promotion, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA and 1Laboratory of Molecular Oncology, Quilmes National University, Bernal, Argentina
Antiretroviral therapy for the human immunodeficiency virus-1 (HIV-1) typically includes two nucleoside reverse transcriptase inhibitors (NRTIs). 3'-Azido-3'-deoxythymidine (AZT, Zidovudine) plus 2'-deoxy-3'-thiacytidine (3TC, Lamivudine) is a combination that is used frequently. The NRTIs are mutagenic nucleoside analogs that become incorporated into DNA and terminate replication. We therefore hypothesized that exposure to this class of drug may alter cell cycle parameters. We used flow cytometry to examine the cell cycle in human epithelioid carcinoma (HeLa) cells exposed to AZT and 3TC alone, as well as a series of AZT/3TC dose combinations: (A) 125.0 µM AZT/12.5 µM 3TC; (B) 250.0 µM AZT/25.0 µM 3TC; and (C) 500 µM AZT/50 µM 3TC. At 24 h, at all doses, there was a good cell viability (
68%), and incorporation of AZT into nuclear DNA. Using flow cytometry, a dose-related increase in the percentage of cells in S phase, from 9.5% with no drug, to 36.0% with dose C, was observed in cells exposed for 24 h (P = 0.001, ANOVA). A concomitant decrease in the percentage of cells in G1 phase, from 82.6% with no drug to 58.5% with dose C, was observed in cells exposed for 24 h (P = 0.017, ANOVA). A similar S phase arrest was seen in cells exposed to 125, 250 and 500 µM AZT alone, but there was no S phase alteration with 50 µM 3TC alone, suggesting that AZT is responsible for the accumulation of cells in S phase. To elucidate the accumulation of cells in S phase and explore the cell cycle gene expression changes induced by AZT and 3TC, we used c-DNA microarray, Cell Cycle Super Array and real-time PCR. There was a strong upregulation of the DNA damage-inducible transcript 3 (DDIT3 or GADD153) in NRTI-exposed cells. In addition, AZT induced an upregulation of cyclin D1 accompanied by a downregulation of the cyclin D1-associated inhibitors P18 and P57, and the G1-S check point gene P21, the net effect of which would be to foster a cell progression into S phase. Cyclin A2 was down-regulated in cells exposed to AZT, suggesting a block in S–G2–M progression that would also be consistent with the accumulation of cells in S phase. Overall, the study demonstrates that AZT, but not 3TC, causes an arrest of cells in S phase with a consistent alteration in the expression of several cell cycle genes.
* To whom correspondence should be addressed at: Building 37, Room 4032B, NIH, 37 Convent Drive, MSC-4255, Bethesda, MD 20892-4255, USA. Tel: +1 301 435 7843; Fax: +1 301 402 8230; Email: oliveroo{at}exchange.nih.gov
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  J.-L. Fang and F. A. Beland Long-Term Exposure to Zidovudine Delays Cell Cycle Progression, Induces Apoptosis, and Decreases Telomerase Activity in Human Hepatocytes Toxicol. Sci., September 1, 2009; 111(1): 120 - 130. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J.-L. Fang, L. J. McGarrity, and F. A. Beland Interference of cell cycle progression by zidovudine and lamivudine in NIH 3T3 cells Mutagenesis, March 1, 2009; 24(2): 133 - 141. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Powles, D. Robinson, J. Stebbing, J. Shamash, M. Nelson, B. Gazzard, S. Mandelia, H. Moller, and M. Bower Highly Active Antiretroviral Therapy and the Incidence of Non-AIDS-Defining Cancers in People With HIV Infection J. Clin. Oncol., February 20, 2009; 27(6): 884 - 890. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Behl, P. Krothapalli, T. Desta, A. DiPiazza, S. Roy, and D. T. Graves Diabetes-Enhanced Tumor Necrosis Factor-{alpha} Production Promotes Apoptosis and the Loss of Retinal Microvascular Cells in Type 1 and Type 2 Models of Diabetic Retinopathy Am. J. Pathol., May 1, 2008; 172(5): 1411 - 1418. [Abstract] [Full Text] [PDF]
|
|