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Morphologic analysis correlates with gene expression changes in cultured F344 rat mesothelial cells
L M Crosby1, K S Hyder, A B DeAngelo
1Curriculum in Toxicology, University of North Carolina at Chapel Hill, USA.
Toxicology and Applied Pharmacology
|January 3, 2001
Summary
Potassium bromate exposure induces oxidative stress, DNA repair gene activation, and cell cycle disruption in rat mesothelial cells, leading to a proposed model of carcinogenesis. This study investigates the molecular mechanisms behind potassium bromate-induced cancer. Keywords: potassium bromate, oxidative stress, gene expression, carcinogenesis, mesothelial cells.
Area of Science:
- Toxicology and Carcinogenesis
- Molecular Biology
- Cell Biology
Background:
- Potassium bromate (KBrO3) is a known carcinogen and oxidative stressor affecting the kidney and thyroid.
- Mesothelial cells, lining body cavities, are susceptible to environmental insults.
- Understanding the molecular response of mesothelial cells to KBrO3 is crucial for assessing carcinogenic risk.
Purpose of the Study:
- To determine the gene expression patterns in rat mesothelial cells following exposure to potassium bromate (KBrO3).
- To investigate the cellular mechanisms, including oxidative stress, cell cycle regulation, and apoptosis, induced by KBrO3.
- To propose a model for KBrO3-induced carcinogenicity in rat mesothelium.
Main Methods:
- Immortalized rat peritoneal mesothelial cells were exposed to KBrO3 for 4 or 12 hours.
- Gene expression changes were analyzed using cDNA arrays and Polymerase Chain Reaction (PCR).
- Morphological endpoints, including mitotic figures and apoptotic cells, were examined, along with HO-1 protein expression.
Main Results:
- KBrO3 exposure led to significant alterations in gene expression, indicating oxidative stress, mitotic arrest, and apoptosis.
- Upregulation of oxidative stress-responsive genes (e.g., HO-1, HSP70), DNA repair genes (e.g., PCNA, msh2), and transcriptional regulators (e.g., c-jun, c-fos).
- Downregulation of anti-apoptotic genes (e.g., bcl-2) and cell cycle control elements, alongside an increase in cell cycle inhibitors (e.g., Cyclin G, p14ink4b).
Conclusions:
- KBrO3 induces a complex molecular response in mesothelial cells, characterized by redox signaling, p53 activation, and dysregulation of growth control.
- Imperfect DNA repair mechanisms following KBrO3 exposure may contribute to the initiation of carcinogenesis.
- A model for KBrO3-induced mesothelial carcinogenicity is proposed, involving oxidative stress, altered gene expression, and impaired DNA repair.