If this proves a more general pattern of expression of mutant p53 in individuals with germline mutations, these findings may explain the paucity of tumors in individuals affected with the Li-Fraumeni syndrome.
Using p53 heterozygous mutant epithelial cells from patients with Li-Fraumeni syndrome, we show that monoallelic mutation of p53 was associated with elevated levels of CYP1A1 and CYP1B1 under both basal conditions and following treatment with benzo[a]pyrene.
We have determined "functional fingerprints" of sporadic breast cancer-related p53 mutants, many of which are also associated with familial cancer proneness such as the Li-Fraumeni syndrome and germline BRCA1/2 mutant-associated cancers.
Our observations support the functional significance of CHK2 mutations in rare cases of LFS and suggest that such mutations may substitute for inactivation of TP53.
They find an increased frequency of p53 signatures, with associated evidence of DNA damage and loss of heterozygosity at the wild-type TP53 allele, but postulate, as Li-Fraumeni syndrome is not associated with an increased risk of pelvic serous carcinoma, that these events are not sufficient for the development of carcinoma.
TP53 germline mutations are present in up to 80 % of families with classic Li-Fraumeni syndrome, and in 20-60 % of families with Li-Fraumeni like phenotypes.
Epidermal growth factor receptor (EGFR) mutation-driven lung cancer is a rare occurrence in patients with Li-Fraumeni syndrome (LFS) characterized by germline mutations in the tumor protein 53 (TP53) gene.
Cells from individuals belonging to an LFS family show reduced HCR in all cases where the cells were derived from persons carrying one mutated p53 allele, whereas cells derived from members with two wild-type alleles show normal HCR.
Patients with Li-Fraumeni syndrome (LFS) have a germ-line mutation of p53 (TP53) and are predisposed to develop a variety of malignancies at an early age.
Notably, no individuals with confirmed germline or likely germline TP53 PVs met classic Li-Fraumeni syndrome (LFS) criteria, only 41% met Chompret LFS criteria, and 59% met neither criteria, based upon provider-reported personal and family cancer history.
Mutation of p53 is also the predominant molecular basis of the Li-Fraumeni familial cancer susceptibility syndrome. p53 is a transcription factor that functions to regulate the integrity of the genome in response to DNA damage by inducing genes that promote cell cycle arrest, cell death, or repair of damaged DNA.
We therefore endeavored to study further the LFS-associated p53 mutation at the molecular level by creating an equivalent lesion in a p53 expression construct and functionally characterizing it.
Li-Fraumeni syndrome and the LF-like syndrome, rare heritable conditions that predispose to the development of malignancy, are associated with germline mutations of the tumor suppressor gene p53.
Genetic analysis of the proband revealed a TP53 germline mutation in exon 5 determining a nucleotide alteration at codon 175 (R175H), a hot spot mutation site related to LFS and a reported pathogenic mutation.
Prevalence of germline TP53 mutations and history of Li-Fraumeni syndrome in families with childhood adrenocortical tumors, choroid plexus tumors, and rhabdomyosarcoma: a population-based survey.
This response was indistinguishable from that seen in cells derived from normal individuals, and occurred in cases with missense mutations in the TP53 gene at codons 175, 180, 220 and 248 and also in two LFS-like individuals with no TP53 mutation.
Mutations and deletions of the p53 gene have been described in many tumor types and in the germline of some individuals with the Li-Fraumeni syndrome, but reports on the status of the p53 and mdm2 (a gene coding for a p53-associated protein reportedly amplified in human sarcomas) genes in medulloblastomas are few and an indication of their roles, if any, in the etiology of this important childhood tumor has yet to emerge.
These findings identify an important subgroup of young patients with cancer who carry germline mutations in the p53 tumor-suppressor gene but whose family histories are not indicative of the Li-Fraumeni syndrome.
Indeed, in this issue, a paper by Senzer et al. documents, for the first time, successful use of adenoviral p53 therapy to treat a tumor in a patient with Li Fraumeni Syndrome, a hereditary cancer syndrome caused by the mutation of the p53 tumor suppressor gene.
This study aimed to characterize the TP53 mutational spectrum in patients suspected to have LFS in Portugal and to evaluate the influence of the MDM2-SNP309 and TP53-72Arg variants and of telomere length on age of tumor onset.
With the increasing use of multigene next-generation sequencing panels in hereditary cancer risk assessment, clinicians will be faced with the challenge of interpreting the biologic and clinical significance of germline TP53 mutations in families whose phenotypes are atypical for Li-Fraumeni syndrome.