Chromate Affects Gene Expression and DNA Methylation in Long-Term In Vitro Experiments in A549 Cells

Area of Science:

• Environmental Toxicology
• Epigenetics
• Cell Biology

Background:

• Chromate exposure can disrupt epigenetic regulation, including DNA methylation, impacting gene expression and genomic stability.
• Existing in vitro studies often use short incubation periods, which may not accurately reflect chronic environmental or occupational exposures.

Purpose of the Study:

• To investigate the differential effects of short-term versus long-term chromate exposure on human adenocarcinoma A549 cells.
• To compare cellular responses, chromium accumulation, cell cycle progression, DNA methylation, and gene expression under varying chromate exposure durations.

Main Methods:

• A549 cells were treated with chromate at different concentrations for short-term (24 h) and long-term (1–5 weeks) periods.
• Analyzed intracellular chromium accumulation, cell cycle arrest (G2), global DNA methylation levels, and gene expression using high-throughput RT-qPCR.

Main Results:

• Chromium accumulation showed time- and concentration-dependency in short-term exposure, reaching a plateau in long-term exposure.
• Short-term exposure induced G2 cell cycle arrest, which was absent in long-term low-dose exposure.
• Long-term exposure resulted in significant, dose-dependent global DNA hypomethylation, contrasting with no effect in short-term exposure.
• Gene expression analysis revealed time-dependent changes, particularly in inflammatory and DNA damage response genes.

Conclusions:

• Short-term and long-term chromate exposures elicit distinct toxicity profiles in A549 cells.
• Chronic exposure is associated with significant epigenetic alterations like DNA hypomethylation and altered gene expression patterns, highlighting its greater relevance for risk assessment.