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Gene expression changes associated with cytotoxicity identified using cDNA arrays
M A Gore1, M M Morshedi, J F Reidhaar-Olson
1Affymax Research Institute, 3410 Central Expressway, Santa Clara, CA 95051, USA.
Abstract:
In order to investigate gene expression changes associated with cytotoxicity, we used cDNA arrays to monitor the expression of over 5,000 genes in response to toxic stress in the HepG2 liver cell line. Cells were treated with cytotoxic doses of acetaminophen, caffeine or thioacetamide for nine time points ranging from 1 to 24 h. Samples of mRNA from each time point were used to prepare radiolabeled cDNA, which was hybridized to nylon-membrane-based cDNA arrays. High-stringency washes were applied to reduce cross-hybridization. Analysis of spot intensities revealed that each compound led to approximately 150-250 gene expression changes that were sustained over at least three adjacent time points. The affected genes could be classified into clusters based on their temporal patterns of differential expression. A common set of 44 genes showed similar expression changes in response to all three compounds. Of these changes, 90% could be confirmed by quantitative RT-PCR analysis. The results indicate that detailed array-based time-course studies, coupled with a sensitive and highly specific confirmation assay, provide a powerful means of identifying cytotoxicity-associated gene expression changes.
Insights
This study monitored over 5,000 genes in HepG2 liver cells exposed to toxic stress. Researchers identified common gene expression changes linked to cytotoxicity, confirming a powerful method for toxicological studies.
Area of Science:
- Toxicology
- Molecular Biology
- Genomics
Background:
- Cytotoxicity can induce significant changes in cellular gene expression.
- Understanding these changes is crucial for assessing toxicological effects and identifying potential biomarkers.
- HepG2 liver cells are a widely used model for studying drug metabolism and toxicity.
Purpose of the Study:
- To investigate gene expression alterations in response to cytotoxic agents.
- To identify common gene expression patterns induced by different toxins.
- To evaluate the utility of cDNA arrays for time-course toxicological studies.
Main Methods:
- Utilized cDNA arrays to monitor over 5,000 genes in HepG2 cells.
- Treated cells with acetaminophen, caffeine, and thioacetamide across nine time points (1-24 hours).
- Employed high-stringency washes to minimize cross-hybridization and quantitative RT-PCR for confirmation.
Main Results:
- Each compound induced 150-250 sustained gene expression changes.
- Affected genes were clustered based on temporal expression patterns.
- A common set of 44 genes exhibited similar expression changes across all three compounds, with 90% confirmed by RT-PCR.
Conclusions:
- Array-based time-course studies are effective for identifying cytotoxicity-associated gene expression changes.
- Quantitative RT-PCR provides reliable confirmation of array-based findings.
- This approach offers a powerful tool for toxicological research and biomarker discovery.