This p53 polymorphism modulates risk to smoking-induced lung cancer independently of other genetic risk factors such as germ line polymorphism of CYP1A1 or GST1 genes.
When we analyzed the HLA subtype of lung cancer cell lines with known p53 missense mutations, we found that all of the mutant oncopeptides predicted to be presentable by HLA A*0201 came from tumors that either did not carry the A*0201 allele or had lost that allele in the process of tumorigenesis.
Furthermore, an observed association between abnormal p53 expression and the patients' smoking history suggests that the p53 gene could be a common target of tobacco-associated carcinogenesis in lung cancer.
We sequenced the conserved regions of the p53 tumour suppressor gene in lung cancers from 17 non-smokers from Hiroshima, Japan; 9 were atomic-bomb survivors.
Because of evidence that the nature and site of p53 mutations reflect not only the mutagens involved in tumorigenesis but also the capacity for malignant transformation, the characterization of mutations of the p53 gene may provide a basis for assessing further risk factors, as well as for estimating prognosis in patients with lung cancer.
To demonstrate the program, the mutational spectra of single base substitutions in the p53 gene are compared in (i) bladder cancers from smokers and non-smokers, (ii) small-cell lung cancers, non-small-cell lung cancers and colon cancers and (iii) hepatocellular carcinomas from high- and low-aflatoxin exposure groups. p53 mutations differ in several important aspects from a typical mutational spectra experiment, where a homogeneous population of cells is treated with a specific mutagen and mutations at a specific locus are recovered by phenotypic selection.
Because the p53 recessive oncogene is mutated and anti-p53 antibodies frequently occur in cancer patients, we wondered if the development of anti-HuD antibodies signaled the presence of HuD mutations in lung cancer.
The p53 mutational frequency in the MG-exposed cases is similar to the non-exposed controls and the usual smoking-related lung cancers reported previously.
In contrast to the previous report of biallelic expression of p53 in a case with a germline missense mutation, preferential expression of the wild-type allele was observed in the heterozygous state in both normal lung and peripheral blood lymphocytes of our case, whereas expression of mutant mRNA was readily detectable in her lung cancer in the absence of the remaining wild-type allele.
The typical p53 mutations in lung cancer, G to T transversions and G to A and C to T transitions, associated with smoking, accounted for 46% of the mutations detected.
To investigate possible correlation between p53 gene alteration and the unique characteristics of lung cancer here, p53 gene status of 36 patients with primary, resected non-small-cell lung cancer (NSCLC) was studied by directly sequencing the cDNA of the p53 gene, then acquiring clinical and pathologic data to correlate p53 gene status with clinical parameters and pathologic staging.
The wild-type form of p53 is dominant over the mutant; thus, restoration of wild-type p53 function in lung cancer cells may suppress their growth as tumors.
These results indicate that the p53-positive immunophenotype uncovers the occurrence of p53 point mutations in lung cancer and that p53 and c-myc gene alterations are important but represent independent occurrences in the development of lung tumors.
The ability of this adenovirus construct (Ad-CMV-p53) to express p53 protein was examined by Western blot analysis in the H358 lung cancer cell line, which has a homozygous deletion of the p53 gene.
Thus, mutant p53 genes have been found in urine from patients with bladder cancer, mutant ras genes in stools from patients with colorectal and pancreatic cancers, and both mutant p53 and ras genes in sputum from patients with lung cancer.