Cytotoxicity patterns of arsenic trioxide exposure on HaCaT keratinocytes

Abstract

Background

Arsenic is a ubiquitous environmental toxicant, and abnormalities of the skin are the most common outcomes of long-term, low-dose, chronic arsenic exposure. If the balance between keratinocyte proliferation, differentiation, and death is perturbed, pathologic changes of the epidermis may result, including psoriasis, atopic dermatitis, and certain forms of ichthyosis. Therefore, research investigations using in vitro human epidermal cells could help elucidate cellular and molecular processes in keratinocytes affected by arsenic. Data from such investigations could also provide the basis for developing cosmetic intervention for skin diseases caused by arsenic.

Methods

The viability of HaCaT keratinocyte cultures with or without prior exposure to low-dose arsenic trioxide was compared for varying concentrations of arsenic trioxide over a time course of 14 days because in untreated control cultures, approximately 2 weeks is required to complete cell differentiation. Long-term cultures were established by culturing HaCaT cells on collagen IV, and cells were subsequently exposed to 0 parts per million (ppm), 1 ppm, 5 ppm, 7.5 ppm, 10 ppm, and 15 ppm of arsenic trioxide. The percentages of viable cells as well as DNA damage after exposure were determined on Day 2, Day 5, Day 8, and Day 14.

Results

Using both statistical and visual analytics approaches for data analysis, we have observed a biphasic response at a 5 ppm dose with cell viability peaking on Day 8 in both chronic and acute exposures. Further, a low dose of 1 ppm arsenic trioxide enhanced HaCaT keratinocyte proliferation, whereas doses above 7.5 ppm inhibited growth.

Conclusion

The time course profiling of arsenic trioxide cytotoxicity using long-term HaCaT keratinocyte cultures presents an approach to modeling the human epidermal cellular responses to varying doses of arsenic trioxide treatment or exposure. A low dose of arsenic trioxide appears to aid cell growth but concomitantly disrupts the DNA transcription process.

Keywords:

• arsenic trioxide
• chronic exposure
• DNA damage
• HaCaT
• keratinocyte
• visual analytics

Acknowledgments

RCMI-Center for Environmental Health, Jackson State University; National Institutes of Health (NIH-NCRR G12RR13459, NIH-NIGMS T36GM095335, NIH-NIMHD 1P20MD002725-01, NIH-NCRR-P20RR016476, NIH-NCRR- P20RR016460), National Science Foundation (EPS-0903787, NSF-DBI-0958179, DBI-1062057), and US Department of Homeland Security Science and Technology Directorate (2007-ST-104-000007, 2009- ST-062-000014, 2009-ST-104-000021). Disclaimer: the views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the funding agencies.

Disclosure

The authors report no conflicts of interest in this work.