Environmental Contaminants Modulate Breast Cancer Development and Outcome in TP53 p.R337H Carriers and Noncarriers.

Two major concerns associated with cancer development in Paraná state, South Brazil, are environmental pollution and the germline TP53 p.R337H variant found in 0.27−0.30% of the population. We assessed breast cancer (BC) risk in rural (C1 and C2) and industrialized (C3) subregions, previously classified by geochemistry, agricultural productivity, and population density. C2 presents lower organochloride levels in rivers and lower agricultural outputs than C1, and lower levels of chlorine anions in rivers and lower industrial activities than C3. TP53 p.R337H status was assessed in 4658 women aged >30 years from C1, C2, and C3, subsequent to a genetic screening (Group 1, longitudinal study). BC risk in this group was 4.58 times higher among TP53 p.R337H carriers. BC prevalence and risk were significantly lower in C2 compared to that in C3. Mortality rate and risk associated with BC in women aged >30 years (n = 8181 deceased women; Group 2) were also lower in C2 than those in C3 and C1. These results suggest that environmental factors modulate BC risk and outcome in carriers and noncarriers.

The Common Germline TP53-R337H Mutation Is Hypomorphic and Confers Incomplete Penetrance and Late Tumor Onset in a Mouse Model.

The TP53-R337H founder mutation exists at a high frequency throughout southern Brazil and represents one of the most common germline TP53 mutations reported to date. It was identified in pediatric adrenocortical tumors in families with a low incidence of cancer. The R337H mutation has since been found in association with early-onset breast cancers and Li-Fraumeni syndrome (LFS). To study this variability in tumor susceptibility, we generated a knockin mutant p53 mouse model (R334H). Endogenous murine p53-R334H protein was naturally expressed at high levels in multiple tissues and was functionally compromised in a tissue- and stress-specific manner. Mutant p53-R334H mice developed tumors with long latency and incomplete penetrance, consistent with many human carriers being at a low but elevated risk for cancer. These findings suggest the involvement of additional cooperating genetic alterations when TP53-R337H occurs in the context of LFS, which has important implications for genetic counseling and long-term clinical follow-up. SIGNIFICANCE: A p53-R334H knockin mouse serves as an important model for studying the most common inherited germline TP53 mutation (R337H) that is associated with variable tumor susceptibility.

Spatial trends in congenital malformations and stream water chemistry in Southern Brazil.

The incidence of variable congenital malformation (CM) among 399 municipalities in the state of Paraná, southern Brazil, suggests the etiological role of environmental factors. This study examined a) environmental concentrations of chlorine anions (Cl-) associated with organochlorines (OCs) and b) associations between these chemicals and agricultural output with CMs using a geographical information system. In one of the three years during the sampling period (2008, 2009 or 2010) Cl-, dichlorodiphenyltrichloroethane (p,p'-DDT), dichlorodiphenyldichloroethylene (p,p'-DDE), dichlorodiphenyldichloroethane (p,p'-DDD), and endosulfan levels were measured in 465 (465/736, 63%) catchment basins. Agricultural outputs for crops during 2006-2010 were also evaluated (t/km2). Further, CM kernel density for the 399 municipalities in Paraná during 2007-2014 was investigated. Cl- levels increased significantly in one of the three years (2008, 2009 or 2010) in western catchment basins, compared to 1996 (p < 0.0001). The municipalities were divided according to the obtained Cl- levels, where sub-region C2 (central-southern) < 1.8 mg/L ≤ sub-regions C1 (northern-western) and C3 (eastern-southern). We identified 8756 cases of CMs among 1,221,287 newborns (NB) in all sub-regions. C1 had higher DDT-DDE-DDD (p,p'-DDT + p,p'-DDE + p,p'-DDD) concentrations, agricultural output, and CM kernel density. C2 and C3 had minor agricultural outputs (per square kilometer) and CM densities. A 2.96 mg/L increase in Cl- between sub-regions C1 and C2 was co-localized with a 45% increase in CM density (spatial relative risk = 1.45, CI 95%: 1.36-1.55). C1 had the highest log likelihood ratios (p = 0.001) identified via SaTScan clustering analyses. Organochlorines and other toxic chlorinated chemicals may contribute to CMs in humans, and these chemicals are ultimately transformed and release Cl- in rivers. Higher Cl- levels were correlated significantly with higher agricultural productivity, DDT-DDE-DDD levels, and CMs in some parts of the northern and western sub-regions (C1).

The Inherited p53 Mutation in the Brazilian Population.

A common criticism of studying rare diseases is the often-limited relevance of the findings to human health. Here, we review ∼15 years of research into an unusual germline TP53 mutation (p.R337H) that began with its detection in children with adrenocortical carcinoma (ACC), a remarkably rare childhood cancer that is associated with poor prognosis. We have come to learn that the p.R337H mutation exists at a very high frequency in Southern and Southeastern Brazil, occurring in one of 375 individuals within a total population of ∼100 million. Moreover, it has been determined that carriers of this founder mutation display variable tumor susceptibility, ranging from isolated cases of pediatric ACC to Li-Fraumeni or Li-Fraumeni-like (LFL) syndromes, thus representing a significant medical issue for this country. Studying the biochemical and molecular consequences of this mutation on p53 tumor-suppressor activity, as well as the putative additional genetic alterations that cooperate with this mutation, is advancing our understanding of how p53 functions in tumor suppression in general. These studies, which originated with a rare childhood tumor, are providing important information for guiding genetic counselors and physicians in treating their patients and are already providing clinical benefit.

Impact of neonatal screening and surveillance for the TP53 R337H mutation on early detection of childhood adrenocortical tumors.

PURPOSE: The 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 METHODS: Free 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. RESULTS: Of 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). CONCLUSION: These 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.

Placental alkaline phosphatase in pediatric adrenocortical cancer.

The germline R337H mutation in the TP53 gene is considered to be responsible for the increased incidence of adrenocortical tumors (ACTs) in children from Brazil. High level production of hormones in ACTs (>95%) cause virilization alone (60%), Cushing syndrome (<5%), the mixed type (30%), or other rarer manifestations. ACT probably develops owing to events occurring during the final stages of intrauterine life based on the very common early onset of signs and symptoms shortly after birth. In this study, we determined by immunohistochemistry and enzyme assays whether placental alkaline phosphatase (PLAP) is expressed in pediatric ACTs. Immunohistochemical analysis revealed positive p53 expression in 88% of the tested ACTs (29 of 33). PLAP was detected at a slightly lower frequency based on immunohistochemical (17 of 33, 51%) and enzyme activity analyses (9 of 16, 56%). In conclusion, probably at a certain time point during adrenocortical development (end of gestation to early postnatal period), some fetal zone cells survive owing to defective apoptosis and develop into childhood ACT, maintaining some characteristics of the embryonal period, such as PLAP expression. Further studies of PLAP should investigate the functional role, if any, of PLAP in such tumors.

Association of the germline TP53 R337H mutation with breast cancer in southern Brazil.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

High frequency of loss of heterozygosity at 11p15 and IGF2 overexpression are not related to clinical outcome in childhood adrenocortical tumors positive for the R337H TP53 mutation.

A germline TP53 R337H mutation is present in childhood adrenocortical tumors (ACT) from southern Brazil. Other genetic alterations are also frequently found in these tumors. This study was designed to assess whether alterations of the 11p15 region exist in childhood ACT, accounting for IGF2 overexpression in these tumors, and how they are related to clinical outcome. Tumor DNA of 12 children with ACT (4 adenomas and 8 carcinomas) and from the blood of their parents was analyzed. All patients showed 11p15 loss of heterozygosity (LOH) in the tumor. In contrast to the single case of paternal LOH, IGF2 was overexpressed in tumors with maternal allele loss. Our data show that 11p15 LOH is a widespread finding in childhood ACT not related with malignancy, contrary to adult ACT. Alterations in the expression of other genes in the same region (e.g., CDKN1C) may contribute to ACT tumorigenesis.