BACKGROUND:The inherited, low-penetrance arginine-to-histidine substitution at codon 337 (R337H) of the tumor protein 53 gene (TP53) is clustered in southeast Brazil (estimated frequency, 0.3%). Although its tumorigenic effect initially appeared to be tissue-specific, recent evidence suggests its association with a broader range of tumors. Therefore, the authors of this report investigated the spectrum of pediatric malignancies associated with the TP53 R337H mutation at a single referral institution in southeast Brazil. METHODS: Genomic DNA samples from 493 children with malignancies were screened for the R337H mutation. Available tumor samples from carriers were investigated for loss of heterozygosity (LOH) and nuclear p53 accumulation. Clinical data were obtained from medical records. RESULTS: Sixty-five of 70 patients (93%) with adrenocortical tumors (ACTs), 9 of 13 patients (69%) with choroid plexus carcinoma (CPC), and 3 of 41 patients (7.3%) with osteosarcoma carried the mutation. The proportion of CPC to choroid plexus papilloma (CPP) was much higher than that reported elsewhere. Osteosarcoma in carriers had a significantly poorer outcome (P ¼ .02). The mutation was not identified in patients who had acute lymphoblastic leukemia (ALL) (n ¼ 187), recurrent ALL (n ¼ 49), acute myeloid leukemia (n ¼ 44), lymphoma (n ¼ 30), non-CPC central nervous system tumors (n ¼ 26), Ewing sarcoma (n ¼ 25), or rhabdomyosarcoma (n ¼ 8). Among the tumors that were available for analysis, LOH with retention of the mutant allele was confirmed in 21 of 21 ACTs, in 2 of 2 CPCs, and in 2 of 3 osteosarcomas that were positive for R337H. CPCs and osteosarcomas that were positive for R337H had marked nuclear accumulation of p53. CONCLUSIONS: The current findings demonstrated compellingly that the TP53 R337H mutation is associated not only with ACT but also with CPC and, to a lesser extent, with osteosarcoma, both of which are core-component tumors of the Li-Fraumeni syndrome.

CTNNB1 mutations are not common in childhood ACT but appear to associate with poor prognosis. Nevertheless, most ACT exhibit increased expression of β-catenin and WISP2 and reduced expression of Wnt inhibitor genes (DKK3, SFRP1, and AXIN1). Thus, in addition to CTNNB1 mutations, other genetic events affecting the Wnt/β-catenin pathway may be involved in childhood adrenocortical tumorigenesis.

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.

Background: Impaired apoptosis has been implicated in the development of childhood adrenocortical tumors (ACT), although the expression of apoptosis-related gene expression in such tumors has not been reported. Methods: The mRNA expression levels of the genes CASP3, CASP8, CASP9, FAS, TNF, NFKB, and BCL2 were analyzed by quantitative real-time PCR in consecutive tumor samples obtained at diagnosis from 60 children with a diagnosis of ACT and in 11 non-neoplastic adrenal samples. BCL2 and TNF protein expression was analyzed by immunohistochemistry. Results: A significant association was observed between tumor size R100 g and lower expression levels of the BCL2 (PZ0.03) and TNF (PZ0.05) genes; between stage IV and lower expression levels of CASP3 (PZ0.008), CASP9 (PZ0.02), BCL2 (PZ0.002), TNF (PZ0.05), and NFKB (PZ0.03); Weiss score R3 and lower expression of TNF (PZ0.01); unfavorable event and higher expression values of CASP9 (PZ0.01) and lower values of TNF (PZ0.02); and death and lower expression of BCL2 (PZ0.04). Underexpression of TNF was associated with lower event-free survival in uni-and multivariate analyses (P!0.01). Similar results were observed when patients with Weiss score !3 were excluded. Conclusion: This study supports the participation of apoptosis-related genes in the biology and prognosis of childhood ACT and suggests the complex role of these genes in the pathogenesis of this tumor.