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Prevalence of RAS oncogene mutation in head and neck carcinomas
J A Anderson1, J C Irish, B Y Ngan
1Department of Otolaryngology, University of Toronto, Ontario, Canada.
Abstract:
RAS genes encode for a protein (p21) known to play an important role in the regulation of normal signal transduction and cell growth. Activation of RAS genes have been strongly implicated in the pathogenesis of cancer in cell line studies, animal models and in human tumors. RAS genes have been shown to be mutated in 10 to 15% of human solid tumors but the frequency of mutation varies widely depending on the tumor type. The prevalence of RAS mutation has not been well-established in head and neck squamous cell carcinomas (SCC). The purpose of our study was to screen a relatively large number (50) SCC tumors using a gene amplification technique, the polymerase chain reaction (PCR). H-RAS gene mutation is identified by diagnostic restriction length polymorphism, created by introducing specific mismatched primers in the PCR. The first 20 tumors were also amplified and directly sequenced for K-RAS codon 12 and 13. Four of the 50 screened tumors were positive for H-RAS codon 12 mutation. All tumor DNA screened normal at codon 61 and the first 20 tumors were also normal at K-RAS codon 12 and 13. The prevalence of RAS mutations appears to be low in head and neck squamous cell carcinomas. Tumors positive for point mutation in the H-RAS gene revealed some unusual clinical characteristics.
Insights
RAS gene mutations are uncommon in head and neck squamous cell carcinomas (SCC). This study found a low prevalence of RAS mutations, with some H-RAS mutations correlating with unusual clinical features in SCC patients.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- RAS genes encode p21 protein, crucial for signal transduction and cell growth regulation.
- RAS gene activation is linked to cancer pathogenesis across various models and human tumors.
- RAS mutations occur in 10-15% of human solid tumors, with variable frequencies by cancer type.
Purpose of the Study:
- To determine the prevalence of RAS gene mutations in head and neck squamous cell carcinomas (SCC).
- To investigate the clinical characteristics of SCC tumors with RAS gene mutations.
Main Methods:
- Screened 50 head and neck SCC tumors for RAS gene mutations using polymerase chain reaction (PCR).
- Identified H-RAS gene mutations via diagnostic restriction fragment length polymorphism with mismatched primers.
- Sequenced K-RAS codons 12 and 13 in the initial 20 tumors for comparison.
Main Results:
- Four out of 50 SCC tumors exhibited H-RAS codon 12 mutations.
- No RAS mutations were detected at K-RAS codons 12 and 13, or H-RAS codon 61.
- SCC tumors with H-RAS point mutations displayed distinct clinical characteristics.
Conclusions:
- RAS mutations are infrequent in head and neck squamous cell carcinomas.
- The study identified a low prevalence of RAS mutations in this specific cancer type.
- Further research is warranted to understand the clinical implications of H-RAS mutations in head and neck SCC.