Cancer risk is highly variable in carriers of the common TP53-R337H founder allele, possibly due to the influence of modifier genes. Whole-genome sequencing identified a variant in the tumor suppressor XAF1 (E134*/Glu134Ter/rs146752602) in a subset of R337H carriers. Haplotype-defining variants were verified in 203 patients with cancer, 582 relatives, and 42,438 newborns. The compound mutant haplotype was enriched in patients with cancer, conferring risk for sarcoma (P = 0.003) and subsequent malignancies (P = 0.006). Functional analyses demonstrated that wild-type XAF1 enhances transactivation of wild-type and hypomorphic TP53 variants, whereas XAF1-E134* is markedly attenuated in this activity. We propose that cosegregation of XAF1-E134* and TP53-R337H mutations leads to a more aggressive cancer phenotype than TP53-R337H alone, with implications for genetic counseling and clinical management of hypomorphic TP53 mutant carriers.
Purpose
SIX2 and CITED1 are transcriptional regulators that specify self-renewing nephronic progenitor cells of the embryonic kidney. We hypothesized that SIX2, which promotes and maintains this stem cell population, and CITED1 remain active in Wilms Tumor (WT).
Methods
To evaluate expression domains and the pathogenic significance of SIX2 and CITED1 across WT, the Children’s Oncology Group provided 40 WT specimens of stages I–IV (n=10/stage), which were enriched for unfavorable histology (n=20) and treatment failure (relapse or death; n=20). SIX2 and CITED1 protein expression was evaluated qualitatively (immunohistochemistry) and quantitatively (Western blot; WB). Gene transcription was estimated using qRT-PCR.
Results
SIX2 was visualized by immunohistochemistry in 36/38 specimens (94.7%). Protein and mRNA expression of SIX2 were quantitatively similar across all stages of disease (p=0.48 WB; p=0.38 qPCR), in favorable or unfavorable histology (p=0.51 WB; p=0.58 qPCR), and in treatment failure or success (p=0.86 WB; p=0.49 qPCR). Although CITED1 expression paralleled SIX2 qualitatively, no quantitative correlation between SIX2 and CITED1 expression was observed (Spearman’s correlation coefficient 0.28, p=0.08). As in the fetal kidney, overlapping, but also distinct, WT cellular expression domains were observed between SIX2 and CITED1.
Conclusion
SIX2 and CITED1 remain active across all disease characteristics of WT. Activity of these genes in WT potentially identifies a population of self-renewing cancer cells that exhibit an embryonic, stem-like phenotype. Taken together, these transcriptional regulators may be fundamental to WT cellular self-renewal and may represent targets for novel therapies that promote terminal differentiation.
Pleuropulmonary blastomas (PPB) are pediatric, embryonal cancers of the lung parenchyma and pleural surfaces and are among the most common DICER1—related disorders. These tumors undergo evolution through several forms, allowing division into types I, Ir, II, and III, with correlates to the age of diagnosis and prognosis. We sought to provide a comprehensive review of the relevant literature describing the characteristics of these tumors and their multidisciplinary treatment, with an emphasis on surgical management. We describe the complementary roles of chemotherapy and surgery in the successful management of this disease. We discuss the timing of surgery and options for surgical approaches. We address the differentiation of PPB from congenital pulmonary airway malformation and the role of DICER1 testing for children with pulmonary cysts.
The original version of this article included a misprint of the Gene Expression Omnibus (GEO) number for the microarray data reported in the paper. The actual accession number is GEO: GSE63761. In addition, the Supplemental Information was published with the Supplemental Experimental Procedures missing. Both of these errors have since been corrected online. The journal apologizes for any inconvenience.
Despite multimodal treatment, DSRCT is associated with dismal outcomes. Facilities familiar with treating this uncommon disease may experience superior outcomes.
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