Frequency of the TP53 R337H variant in sporadic breast cancer and its impact on genomic instability
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ABSTRACT:
SUBMITTER: Mathias C
PROVIDER: S-EPMC7539008 | biostudies-literature | 2020 Jan
REPOSITORIES: biostudies-literature
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Project description:The germline TP53-R337H mutation is strongly associated with pediatric adrenocortical tumors (ACT) in southern Brazil; it has low penetrance and limited tissue specificity in most families and therefore is not associated with Li-Fraumeni syndrome. However, other tumor types, mainly breast cancer, have been observed in carriers of several unrelated kindreds, raising the possibility that the R337H mutation may also contribute to breast tumorigenesis in a genetic background-specific context.We conducted a case-control study to determine the prevalence of the R337H mutation by sequencing TP53 exon 10 in 123 women with breast cancer and 223 age- and sex-matched control subjects from southern Brazil. Fisher's test was used to compare the prevalence of the R337H.The R337H mutation was found in three patients but in none of the controls (p = 0.0442). Among the carriers, two had familial history of cancer meeting the Li-Fraumeni-like criteria. Remarkably, tumors in each of these three cases underwent loss of heterozygosity by eliminating the mutant TP53 allele rather than the wild-type allele. Polymorphisms were identified within the TP53 (R72P and Ins16) and MDM2 (SNP309) genes that may further diminish TP53 tumor suppressor activity.These results demonstrate that the R337H mutation can significantly increase the risk of breast cancer in carriers, which likely depends on additional cooperating genetic factors. These findings are also important for understanding how low-penetrant mutant TP53 alleles can differentially influence tumor susceptibility.
| S-EPMC2631588 | biostudies-literature
Project description:Sarcomas represent less than 1% of all solid neoplasms in adults and over 20% in children. Their etiology is unclear, but genetic susceptibility plays an important role in this scenario. Sarcoma is central in Li-Fraumeni Syndrome (LFS), a familial predisposition cancer syndrome. In Brazil, the high prevalence of p.Arg337His mutations in the TP53 gene brings about a unique condition: a cluster of LFS. In the present work, we studied 502 sarcoma patients not selected by age or family history in an attempt to assess the impact of the so-called "Brazilian germline TP53 mutation" (p.Arg337His) on this tumor type. We found that 8% of patients are carriers, with leiomyosarcoma being the main histologic type of sarcoma, corresponding to 52.5% of the patients with the mutated TP53 gene. These findings emphasize the importance of genetic counseling and can better guide the management of sarcoma patients.
| S-EPMC6980636 | biostudies-literature
Project description:Mutations in genes encoding chromatin-remodeling proteins are often identified in a variety of cancers. For example, the histone demethylase JARID1C is frequently inactivated in patients with clear cell renal cell carcinoma (ccRCC); however, it is largely unknown how JARID1C dysfunction promotes cancer. Here, we determined that JARID1C binds broadly to chromatin domains characterized by the trimethylation of lysine 9 (H3K9me3), which is a histone mark enriched in heterochromatin. Moreover, we found that JARID1C localizes on heterochromatin, is required for heterochromatin replication, and forms a complex with established players of heterochromatin assembly, including SUV39H1 and HP1?, as well as with proteins not previously associated with heterochromatin assembly, such as the cullin 4 (CUL4) complex adaptor protein DDB1. Transcription on heterochromatin is tightly suppressed to safeguard the genome, and in ccRCC cells, JARID1C inactivation led to the unrestrained expression of heterochromatic noncoding RNAs (ncRNAs) that in turn triggered genomic instability. Moreover, ccRCC patients harboring JARID1C mutations exhibited aberrant ncRNA expression and increased genomic rearrangements compared with ccRCC patients with tumors endowed with other genetic lesions. Together, these data suggest that inactivation of JARID1C in renal cancer leads to heterochromatin disruption, genomic rearrangement, and aggressive ccRCCs. Moreover, our results shed light on a mechanism that underlies genomic instability in sporadic cancers.
| S-EPMC4665784 | biostudies-literature
Project description:Although next-generation sequencing has allowed for the detection of somatic mutations in myelodysplastic syndromes (MDS), the clinical relevance of variant allele frequency (VAF) for the majority of mutations is unknown. We profiled TP53 and 20 additional genes in our training set of 219 patients with MDS or secondary acute myeloid leukemia with findings confirmed in a validation cohort. When parsed by VAF, TP53 VAF predicted for complex cytogenetics in both the training (P=0.001) and validation set (P<0.0001). MDS patients with a TP53 VAF > 40% had a median overall survival (OS) of 124 days versus an OS that was not reached in patients with VAF <20% (hazard ratio (HR), 3.52; P=0.01) with validation in an independent cohort (HR, 4.94, P=0.01). TP53 VAF further stratified distinct prognostic groups independent of clinical prognostic scoring systems (P=0.0005). In multivariate analysis, only a TP53 VAF >40% was an independent covariate (HR, 1.61; P<0.0001). In addition, SRSF2 VAF predicted for monocytosis (P=0.003), RUNX1 VAF with thrombocytopenia (P=0.01) and SF3B1 with ringed sideroblasts (P=0.001). Together, our study indicates that VAF should be incorporated in patient management and risk stratification in MDS.
| S-EPMC7864381 | biostudies-literature
Project description:BackgroundThe prognostic impact of an indication of chromosomal instability (CIN) is evaluated in a consecutive series of 952 colorectal cancer patients treated at Aker University Hospital, Norway, during 1993-2003. Microsatellite instability (MSI) in this case series has recently been reported and made it possible to find the co-occurrence and compare the prognostic significance of CIN and MSI.MethodsData sets for overall survival (OS; n=855) and time to recurrence (TTR; n=579) were studied. To reveal CIN we used automated image cytometry (ICM). Non-diploid histograms were taken as indicative of the presence of CIN. PCR-based measures of MSI in this material have already been described.ResultsAs with MSI, CIN was found to be an independent predictor of early relapse and death among stage II patients (TTR: n=278: HR 2.19 (95% CI: 1.35-3.55), P=0.002). Of the MSI tumours (16%), 71% were found to be DNA diploid, 21% were DNA tetraploid and 8% were DNA aneuploid. Among microsatellite stable tumours, 24% were DNA diploid, 15% were DNA tetraploid and 61% were DNA aneuploid.ConclusionFor patients presenting with stage II disease, genomic instability as detected by DNA image cytometry has the potential to provide a useful biomarker for relapse and cancer-related death following surgery with curative intent.
| S-EPMC3992498 | biostudies-literature
Project description:Breast cancer is a heterogeneous disease, appreciable by molecular markers, gene-expression profiles, and most recently, patterns of genomic alteration. In particular, genomic profiling has revealed three distinct patterns of DNA copy-number alteration: a "simple" type with few gains or losses of whole chromosome arms, an "amplifier" type with focal high-level DNA amplifications, and a "complex" type marked by numerous low-amplitude changes and copy-number transitions. The three patterns are associated with distinct gene-expression subtypes, and preferentially target different loci in the genome (implicating distinct cancer genes). Moreover, the different patterns of alteration imply distinct underlying mechanisms of genomic instability. The amplifier pattern may arise from transient telomere dysfunction, although new data suggest ongoing "amplifier" instability. The complex pattern shows similarity to breast cancers with germline BRCA1 mutation, which also exhibit "basal-like" expression profiles and complex-pattern genomes, implicating a possible defect in BRCA1-associated repair of DNA double-strand breaks. As such, targeting presumptive DNA repair defects represents a promising area of clinical investigation. Future studies should clarify the pathogenesis of breast cancers with amplifier and complex-pattern genomes, and will likely identify new therapeutic opportunities.
| S-EPMC2904860 | biostudies-other
Project description:PurposeThe incidence of pediatric adrenocortical tumors (ACTs) is remarkably high in southern Brazil, where more than 90% of patients carry the germline TP53 mutation R337H. We assessed the impact of early detection of this mutation and of surveillance of carriers.Patients and methodsFree newborn screening was offered at all hospitals in the state of Paraná. Parents of positive newborns were tested, and relatives in the carrier line were offered screening. Positive newborns and their relatives age < 15 years were offered surveillance (periodic clinical, laboratory, and ultrasound evaluations). ACTs detected by imaging were surgically resected.ResultsOf 180,000 newborns offered screening, 171,649 were screened, and 461 (0.27%) were carriers. As of April 2012, ACTs had been diagnosed in 11 of these carriers but in only two neonatally screened noncarriers (P < .001); six patient cases were identified among 228 carrier relatives age < 15 years (total, 19 ACTs). Surveillance participants included 347 (49.6%) of 699 carriers. Tumors were smaller in surveillance participants (P < .001) and more advanced in nonparticipants (four with stage III disease; two deaths). Neonatally screened carriers also had neuroblastoma (n = 1), glioblastoma multiforme (n = 1), choroid plexus carcinoma (n = 2), and Burkitt lymphoma (n = 1). Cancer histories and pedigrees were obtained for 353 families that included 1,704 identified carriers. ACTs were the most frequent cancer among carrier children (n = 48).ConclusionThese findings establish the prevalence of the TP53 R337H mutation in Paraná state and the penetrance of ACTs among carriers. Importantly, screening and surveillance of heterozygous carriers are effective in detecting ACTs when readily curable.
| S-EPMC3808236 | biostudies-literature
Project description:Brain metastasis from breast cancer is usually associated with a poor prognosis and early death. Alteration of p53 may contribute to malignant progression by abrogation of apoptosis induced by oncogene activation and by acquisition of gain-of-function properties, which promote tumour aggression. Mutation in TP53 occurs at high frequency in carcinomas of the lung and gastro-intestinal tract, but is much less frequent, at 25%, in primary breast cancer. The frequency of TP53 alteration in the central nervous system (CNS) metastatic breast cancer is not known.In all, 23 cases of histologically confirmed CNS metastatic breast cancer were identified and the coding sequence of TP53 determined. TP53 was also sequenced in two control series of primary breast carcinomas from independent clinical centres.We demonstrate a strikingly high frequency of TP53 mutation in the CNS metastatic lesions with an over-representation of complex mutations (non-sense/deletions/insertions). Complex mutations occur in metastatic lesions in both triple-negative breast cancer and hormone receptor/HER2-positive cases. Analysis of paired primary carcinomas and brain metastatic lesions revealed evidence for both clonal selection and generation of new mutations (missense and complex) in progression from a primary breast carcinoma to brain metastasis.Mutation in TP53 is the most common genetic alteration reported during metastasis to the brain in breast cancer.
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Project description:Chromosomal breakage followed by faulty DNA repair leads to gene amplifications and deletions in cancers. However, the mere assessment of the extent of genomic changes, amplifications and deletions may reduce the complexity of genomic data observed by array comparative genomic hybridization (array CGH). We present here a novel approach to array CGH data analysis, which focuses on putative breakpoints responsible for rearrangements within the genome.We performed array comparative genomic hybridization in 29 primary tumors from high risk patients with breast cancer. The specimens were flow sorted according to ploidy to increase tumor cell purity prior to array CGH. We describe the number of chromosomal breaks as well as the patterns of breaks on individual chromosomes in each tumor. There were differences in chromosomal breakage patterns between the 3 clinical subtypes of breast cancers, although the highest density of breaks occurred at chromosome 17 in all subtypes, suggesting a particular proclivity of this chromosome for breaks. We also observed chromothripsis affecting various chromosomes in 41% of high risk breast cancers.Our results provide a new insight into the genomic complexity of breast cancer. Genomic instability dependent on chromosomal breakage events is not stochastic, targeting some chromosomes clearly more than others. We report a much higher percentage of chromothripsis than described previously in other cancers and this suggests that massive genomic rearrangements occurring in a single catastrophic event may shape many breast cancer genomes.
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Project description:Most studies of tumor instability are PCR-based. PCR-based methods may underestimate mutation frequencies of heterogeneous tumor genomes. Using a novel PCR-free random cloning/sequencing method, we analyzed 100 kb of total genomic DNA from blood lymphocytes, normal prostate and tumor prostate taken from six individuals. Variations were identified by comparison of the sequence of the cloned fragments with the nr-database in Genbank. After excluding known polymorphisms (by comparison to the NCBI dbSNP), we report a significant over-representation of variants in the tumors: 0.66 variations per kilobase of sequence, compared with the corresponding normal prostates (0.14 variations/kb) or blood (0.09 variations/kb). Extrapolating the observed difference between tumor and normal prostate DNA, we estimate 1.8 million somatic (de novo) alterations per tumor cell genome, a much higher frequency than previous measurements obtained by mostly PCR-based methods in other tumor types. Moreover, unlike the normal prostate and blood, most of the tumor variations occur in a specific motif (P = 0.046), suggesting common etiology. We further report high tumor cell-to-cell heterogeneity. These data have important implications for selecting appropriate technologies for cancer genome projects as well as for understanding prostate cancer progression.
| S-EPMC2794161 | biostudies-literature