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[Effect of NMBzA on the oncogene and multiple tumor suppressor genes in monkey esophageal epithelium]
Abstract:
Mutations of ras oncogene and multiple tumor suppressor genes p53, Rb and APC in esophageal epithelium of rhesus monkey fed with one dose of N-methyl-N-benzylnitrosamine (NMBzA 30mg/kg), which was found in high incidence areas of esophageal cancer in China, were analysed by PCR and direct sequencing. Mutation at codon 12 of Ha-ras gene was not found in esophageal epithelium of monkey fed with NMBzA. Some mutations of p53 gene were found in esophageal epithelium of monkey after being fed with NMBzA for 24-48 hours. Some mutation of Rb and APC were found in esophageal epithelium of monkey after being fed with NMBzA for 48 hours. The mutation fingerprints of these genes disappeared in esophageal epithelium of monkey after being fed with NMBzA for 5 days. The results demonstrated that chemical carcinogen NMBzA can induce mutations of multiple tumor suppressor genes in monkey (in vivo) and indicated that the alteration of tumor suppressor genes in the initial stage of carcinogenesis needs many hits by chemical carcinogen. These alterations of p53, Rb, APC genes were similar to the changes of these genes in some reported previously primary esophageal cancer.
Insights
N-methyl-N-benzylnitrosamine (NMBzA) induced mutations in tumor suppressor genes p53, Rb, and APC in rhesus monkeys. These initial genetic alterations in esophageal epithelium resemble those in human esophageal cancer.
Area of Science:
- Oncology
- Molecular Biology
- Carcinogenesis
Context:
- Esophageal cancer is prevalent in China, often linked to chemical carcinogens.
- Rhesus monkeys serve as a model for studying human diseases due to physiological similarities.
Purpose:
- To investigate the in vivo mutagenic effects of N-methyl-N-benzylnitrosamine (NMBzA) on key oncogenes and tumor suppressor genes in rhesus monkey esophageal epithelium.
- To analyze mutations in Ha-ras, p53, Rb, and APC genes following NMBzA exposure.
Summary:
- Exposure to NMBzA in rhesus monkeys induced mutations in p53, Rb, and APC genes within 24-48 hours.
- No Ha-ras mutations were detected at codon 12. Gene mutation patterns reverted by day 5.
- These findings suggest multiple genetic "hits" are required for early carcinogenesis, mirroring changes seen in human esophageal cancer.
Impact:
- Demonstrates NMBzA's capacity to induce multiple tumor suppressor gene mutations in vivo.
- Highlights the role of accumulating genetic alterations in the initial stages of chemical carcinogenesis.
- Provides insights into molecular mechanisms relevant to esophageal cancer development and prevention strategies.