Cell cycle pathway dysregulation in human keratinocytes during chronic exposure to low arsenite

• Arsenite induces differential expression of 644 mRNAs at early stages of exposure.
• Arsenite exposure induced differential mRNA expression indicates cell cycle dysregulation.
• Arsenite delays cells in G2/M compartment.

BackgroundArsenic is naturally prevalent in the earth's crust and widely distributed in air and water. Chronic low arsenic exposure is associated with several cancers in vivo, including skin cancer, and with transformation in vitro of cell lines including immortalized human keratinocytes (HaCaT). Arsenic also is associated with cell cycle dysregulation at different exposure levels in multiple cell lines. In this work, we analyzed gene expression in HaCaT cells to gain an understanding of gene expression changes contributing to transformation at an early time point.MethodsHaCaT cells were exposed to 0 or 100 nM NaAsO2 for 7 weeks. Total RNA was purified and analyzed by microarray hybridization. Differential expression with fold change ≥ | 1.5 | and p-value ≤ 0.05 was determined using Partek Genomic Suite™ and pathway and network analyses using MetaCore™ software (FDR ≤ 0.05). Cell cycle analysis was performed using flow cytometry.Results644 mRNAs were differentially expressed. Cell cycle/cell cycle regulation pathways predominated in the list of dysregulated pathways. Genes involved in replication origin licensing were enriched in the network. Cell cycle assay analysis showed an increase in G2/M compartment in arsenite-exposed cells.ConclusionsArsenite exposure induced differential gene expression indicating dysregulation of cell cycle control, which was confirmed by cell cycle analysis. The results suggest that cell cycle dysregulation is an early event in transformation manifested in cells unable to transit G2/M efficiently. Further study at later time points will reveal additional changes in gene expression related to transformation processes.