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K-ras point mutations in routinely processed tissues: non-radioactive screening by single strand conformational
S H Korn1, P T Moerkerk, A F de Goeij
1Department of Pathology, University of Limburg Academic Hospital, Maastricht, The Netherlands.
Journal of Clinical Pathology
|July 1, 1993
Summary
This study introduces a non-radioactive single-strand conformational polymorphism (SSCP) method for detecting K-ras gene mutations in colon cancer specimens. The technique successfully identified common K-ras mutations in archival paraffin-embedded tissues, offering a rapid screening approach.
Area of Science:
- Molecular Biology
- Oncology
- Genetics
Background:
- Point mutations in the K-ras gene are significant in colorectal cancer development.
- Traditional methods for mutation detection can be time-consuming or involve radioactivity.
- Archival paraffin-embedded tissues are a valuable resource for molecular studies.
Purpose of the Study:
- To establish a non-radioactive screening method for point mutations in fixed, paraffin-embedded specimens.
- To evaluate the efficacy of single-strand conformational polymorphism (SSCP) analysis for detecting K-ras point mutations.
- To assess the utility of SSCP for identifying K-ras mutations in archival colon cancer samples.
Main Methods:
- DNA extraction from archival colon cancer tissues and cell lines.
- Polymerase chain reaction (PCR) amplification of K-ras exon 1 (codons 12 and 13).
- Single-strand conformational polymorphism (SSCP) analysis using polyacrylamide gel electrophoresis under non-denaturing conditions, followed by Southern blotting and digoxigenin-labeled probe detection.
Main Results:
- Electrophoretic mobility shifts were observed, indicating the presence of wild-type and mutated K-ras alleles.
- Common K-ras mutations at codon 12 were readily detected in DNA from paraffin-embedded colon cancer tissues.
- Wild-type K-ras alleles were detected in all tumor samples, likely originating from non-neoplastic cells within the specimen.
Conclusions:
- The SSCP method provides a rapid, non-radioactive approach for screening K-ras gene point mutations in colorectal adenomas and carcinomas.
- While SSCP effectively detects potential mutations via electrophoretic mobility shifts, definitive identification requires confirmation by sequencing or oligonucleotide hybridization.