The mutation frequency (46%) of the p53 gene in tumors carrying mutated ras genes was essentially the same as the overall frequency in lung cancers, suggesting that accumulation of mutations in these two genes in a tumor is a random phenomenon.
None of the mutations were G:C to T:A transversions in the coding strand of the p53 gene, which are the most frequent base substitutions associated with tobacco smoking, and none were found at the hotspot codons described in lung cancer.
These results indicate that mutation of the p53 tumor suppressor gene plays an important role in the development of primary lung cancer, and that nuclear accumulation of p53 protein is a potential prognostic factor in adenocarcinoma of the lung.
We conclude that there are low- and high-expression groups of p53 mutants in lung cancer and that the detection of protein expression in tumor cells by immunocytochemistry and immunoblotting is dependent upon the type of mutation of the p53 tumor-suppressor gene.
Mutation of the p53 gene is the most frequently identified genetic change in human lung cancer; these findings suggest that simple immunohistological methods can provide strong evidence of such mutation.
However, the presence of p53 mutations was not significantly associated with tumor stage, nodal status or sex and was found in all histologic types of lung cancer.
These findings further support the role of inactivation of the p53 gene in the pathogenesis of lung cancer and indicate the role of intronic point mutation in this process.
The high incidence of loss of 17p (14 of 21 specimens) appears to be compatible with reports implicating the TP53 gene (at band 17p13) as a frequent site for genetic alteration in lung cancer.
These findings, coupled with the previous demonstration of 17p allele loss in lung cancer, strongly implicate p53 as an anti-oncogene whose disruption is involved in the pathogenesis of human lung cancer.
We have applied these methods in several applications, including detection of the p53 gene in human tumor samples, localization of insulin-like growth factor-IA mRNA in cell lines with low levels of expression, and distribution of transferrin mRNA in lung cancer cell lines and tumors.
An association between the BstU I 1-1 (Pro-Pro) genotype of the p53 codon 72 polymorphism and lung cancer has previously been reported by Kawajiri et al.