Drastic Effect of GermlineTP53Missense Mutations in Li-Fraumeni Patients

Abstract

In contrast to other tumor suppressor genes, the majority of TP53 alterations are missense mutations. We have previously reported that in the Li-Fraumeni syndrome (LFS), germline TP53 missense mutations are associated with an earlier age of tumor onset. In a larger series, we observed that mean age of tumor onset in patients harboring dominant negative missense mutations and clearly null mutations was 22.6 and 37.5 years, respectively. To assess the impact of heterozygous germline TP53 mutations in the genetic context of the patients, we developed a new functional assay of the p53 pathway on the basis of induction of DNA damage in Epstein-Barr-virus-immortalized lymphocytes, followed by comparative gene-expression profiling. In wild-type lymphocytes, we identified a core of 173 genes whose expression was induced more than twofold, of which 46 were known p53 target genes. In LFS lymphocytes with canonical missense mutations, the number of induced genes and the level of known p53 target genes induction were strongly reduced as compared with controls and LFS lymphocytes with null mutations. These results show that certain germline missense TP53 mutations, such as those with dominant negative effect, dramatically alter the response to DNA damage. This probably explains why TP53 alterations are predominantly missense mutations.

A case study of an integrative genomic and experimental therapeutic approach for rare tumors: identification of vulnerabilities in a pediatric poorly differentiated carcinoma

“…The identified TP53 (p.R248Q) mutation is a previously described gain-of-function mutation which is associated with early-onset development of many tumor types [30–32]. The somatic APC (p.R790*) mutation has also been previously reported in the Catalogue Of Somatic Mutations In Cancer (COSMIC) database [33, 34].…”

Second malignancy risk among pediatric, adolescent, and young adult survivors of fusion‐positive and fusion‐negative sarcomas: Results from the SEER database, 1992 through 2012

“…Although a recent study evaluating the prevalence of germline mutations in children with cancer identified TP53 mutations in 4 of 46 patients with Ewing sarcoma, 26 there traditionally has been consensus that these mutations are not associated with Ewing sarcoma (F 1 sarcoma) susceptibility. 28 Two additional cases of Ewing sarcoma included in the International Agency for Research on Cancer database could not be confirmed by review of the reference publication. 28 Two additional cases of Ewing sarcoma included in the International Agency for Research on Cancer database could not be confirmed by review of the reference publication.…”

A new genotoxicity assay based on p53 target gene induction

“…After superposition of the RT-QMPSF profiles generated from exposed and unexposed cells, by adjusting the CG peak heights, the expression fold-change is determined for each TG and the average of fold-changes yields an arbitrary genotoxicity score. One of the key aspects of the p53 genotoxicity assay is that the specificity of induction can easily be demonstrated by performing the same experiment in control lymphocytes derived from LFS patients, harboring heterozygous dominant-negative TP53 mutations that compromise the response to DNA damage [9].…”

“…Comparative gene expression profiling of wild-type and mutant (p.R248W; NP 000537.3) TP53 EBV-immortalized lymphocytes treated or not with doxorubicin, ethidium bromide, 5-FU, cisplatin or mitotic spindle poison (paclitaxel or vindesine) for 16 h was performed using Whole Human Genome Oligo 4 × 44 K Microarray (G4845A, Agilent), according to the Agilent Two-Color Gene Expression workflow as previously described [9]. Briefly, starting from 100 ng of total RNA, cRNA was synthesized and labelled using the low input Quick Amp Labeling Kit (Agilent), with Cy3 (for unexposed cells) and Cy5 (for exposed cells).…”

“…Therefore, transcriptional induction of p53 target genes can be considered as a global and early indicator of genotoxic stress. Q4 We recently developed from patient lymphocytes a new p53 functional assay to determine the biological impact of the different germline TP53 mutations detected in Li-Fraumeni syndrome (LFS; MIM # 151623), a remarkable inherited form of cancer characterized by early-onset cancers and a wide tumor spectrum [9]. In this previous work, we demonstrated that germline TP53 mutations with dominant-negative activity over the wild-type protein dramatically alter the p53-mediated transcriptional response to the DNA damaging agent Doxorubicin.…”