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Mutation analysis of the coding sequences of MEK-1 and MEK-2 genes in human lung cancer cell lines
A Bansal1, R D Ramirez, J D Minna
1Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, Dallas 75235, USA.
Abstract:
Recently, constitutively active mutants of MEK (MAP/ERK kinase) were shown to be capable of transforming cells to tumorigenicity suggesting that MEK can function as a dominant oncogene and potentially play a role in human carcinogenesis. Human lung cancer cells exhibit mutations in other components of the MAP kinase signaling pathway such as the Her-2/neu and ras oncogenes. Thus, the coding sequences of both MEK-1 and MEK-2 cDNAs from human lung cancer cell lines were screened by single strand conformation polymorphism analysis and DNA sequencing for alterations in these two genes. In 37 lung cancer cell lines we found: an allelic variant in MEK-1 cDNA, nt 783 G-->A, (no amino acid change); a MEK-2 cDNA change (nt 977 C-->T mutation leading to 298 Pro-->Leu change); a MEK-2 cDNA change nt 537 C-->T (no amino acid change); and a frequent MEK-2 cDNA germline polymorphism nt 744, A-->C (no amino acid change) with an allele frequency of 0.5 for each form. These results suggest that mutations in the MEK-1 and MEK-2 gene occur at a very low frequency in human lung cancer.
Insights
Mutations in MEK-1 and MEK-2 genes are rare in human lung cancer, despite MEK (MAP/ERK kinase) potentially acting as a dominant oncogene. This study screened lung cancer cell lines for alterations in these key signaling pathway genes.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Genetics
Background:
- Mitogen-activated protein kinase (MAPK) pathway components, including Her-2/neu and ras oncogenes, are frequently mutated in human lung cancer.
- Constitutively active mutants of MEK (MAP/ERK kinase) can transform cells, suggesting MEK's role as a dominant oncogene in carcinogenesis.
Purpose of the Study:
- To investigate the frequency of mutations in MEK-1 and MEK-2 genes within human lung cancer cell lines.
- To determine if alterations in MEK-1 and MEK-2 contribute to human lung carcinogenesis.
Main Methods:
- Screening of MEK-1 and MEK-2 cDNA coding sequences from 37 human lung cancer cell lines.
- Utilized single-strand conformation polymorphism (SSCP) analysis and DNA sequencing to detect genetic alterations.
Main Results:
- Identified an allelic variant in MEK-1 cDNA (nt 783 G-->A) with no amino acid change.
- Detected MEK-2 cDNA alterations: a proline to leucine substitution (nt 977 C-->T) and a silent mutation (nt 537 C-->T).
- Found a common MEK-2 germline polymorphism (nt 744 A-->C) with equal allele frequencies (0.5).
Conclusions:
- Mutations in MEK-1 and MEK-2 genes appear to occur at a very low frequency in human lung cancer.
- The identified alterations and polymorphism do not strongly implicate MEK-1 and MEK-2 as frequent drivers in lung cancer development.