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Detection of gene amplification by genomic hybridization to cDNA microarrays
M A Heiskanen1, M L Bittner, Y Chen
1Cancer Genetics Branch, National Human Genome Research Institute, NIH, Bethesa, Maryland 20892, USA.
Abstract:
Gene amplification is one of the major mechanisms of oncogene activation in tumorigenesis. To facilitate the identification of genes mapping to amplified regions, we have used a technique based on the hybridization of total genomic DNA to cDNA microarrays. To aid detection of the weak signals generated in this complex hybridization, we have used a tyramide-based technique that allows amplification of a fluorescent signal up to 1000-fold. Dilution experiment suggests that amplifications of 5-fold and higher can be detected by this approach. The technique was validated using cancer cell lines with several known gene amplifications, such as those affecting MYC, MYCN, ERBB2, and CDK4. In addition to the detection of the known amplifications, we identified a novel amplified gene, ZNF133, in the neuroblastoma cell line NGP. Hybridization of NGP cDNA on an identical array also revealed over expression of ZNF133. Parallel analysis of genomic DNA for copy number and cDNA for expression now provides rapid approach to the identification of amplified genes and chromosomal regions in tumor cells.
Insights
This study introduces a novel tyramide-based technique for detecting gene amplification in tumors. This method enhances fluorescent signals, enabling the identification of amplified genes and chromosomal regions in cancer cells.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Gene amplification is a key driver of oncogene activation in cancer development.
- Identifying amplified genes is crucial for understanding tumorigenesis and developing targeted therapies.
- Existing methods for detecting gene amplification can be complex and lack sensitivity.
Purpose of the Study:
- To develop and validate a sensitive technique for identifying gene amplifications in tumor cells.
- To facilitate the rapid detection of amplified genes and chromosomal regions.
- To discover novel amplified genes in specific cancer types.
Main Methods:
- Utilized a tyramide-based signal amplification technique combined with cDNA microarrays.
- Hybridized total genomic DNA to cDNA microarrays to detect gene copy number variations.
- Validated the technique using cancer cell lines with known gene amplifications (MYC, MYCN, ERBB2, CDK4).
Main Results:
- The tyramide-based method achieved up to 1000-fold fluorescent signal amplification.
- The technique successfully detected amplifications of 5-fold and higher.
- Confirmed known gene amplifications and identified a novel amplified gene, ZNF133, in neuroblastoma cells (NGP).
- Observed overexpression of ZNF133 in NGP cells.
Conclusions:
- The developed technique provides a rapid and sensitive approach for identifying amplified genes and chromosomal regions in tumor cells.
- Parallel analysis of genomic DNA copy number and cDNA expression aids in pinpointing amplified oncogenes.
- This method has potential for broader application in cancer research and diagnostics.