Cecília Maria Lima da Costa

Recurrent somatic mutation in DROSHA induces microRNA profile changes in Wilms tumour

Wilms tumour (WT) is an embryonal kidney neoplasia for which very few driver genes have been identified. Here we identify DROSHA mutations in 12% of WT samples (26/222) using whole-exome sequencing and targeted sequencing of 10 microRNA (miRNA)-processing genes. A recurrent mutation (E1147K) affecting a metal-binding residue of the RNase IIIb domain is detected in 81% of the DROSHA-mutated tumours. In addition, we identify non-recurrent mutations in other genes of this pathway (DGCR8, DICER1, XPO5 and TARBP2). By assessing the miRNA expression pattern of the DROSHA-E1147K-mutated tumours and cell lines expressing this mutation, we determine that this variant leads to a predominant downregulation of a subset of miRNAs. We confirm that the downregulation occurs exclusively in mature miRNAs and not in primary miRNA transcripts, suggesting that the DROSHA E1147K mutation affects processing of primary miRNAs. Our data underscore the pivotal role of the miRNA biogenesis pathway in WT tumorigenesis, particularly the major miRNA-processing gene DROSHA.

Molecular profiling of isolated histological components of Wilms tumor implicates a common role for the Wnt signaling pathway in kidney and tumor development

Wilms tumor (WT), a tumor composed of three histological components – blastema (BL), epithelia and stroma – is considered an appropriate model system to study the biological relationship between differentiation and tumorigenesis. To investigate molecular associations between nephrogenesis and WT, the gene expression pattern of individual cellular components was analyzed, using a customized platform containing 4,608 genes. WT gene expression patterns were compared to genes regulated during kidney differentiation. BL had a closer gene expression pattern to the earliest stage of normal renal development. The BL gene expression pattern was compared to that of fetal kidney (FK) and also between FK and mature kidney, identifying 25 common deregulated genes supposedly involved in the earliest events of WT onset. Quantitative RT-PCR was performed, confirming the difference in expression levels for 13 of 16 genes (81.2%) in the initial set and 8 of 13 (61.5%) in an independent set of samples. An overrepresentation of genes belonging to the Wnt signaling pathway was identified, namely PLCG2, ROCK2 and adenomatous polyposis coli (APC). Activation of the Wnt pathway was confirmed in WT, using APC at protein level and PLCG2 at mRNA and protein level. APC showed positive nuclear immunostaining for an independent set of WT samples, similarly to the FK in week 11. Lack of PLCG2 expression was confirmed in WT and in FK until week 18. Taken together, these results provided molecular evidence of the recapitulation of the embryonic kidney by WT as well as involvement of the Wnt pathway in the earliest events of WT onset.

Gene expression analysis of blastemal component reveals genes associated with relapse mechanism in Wilms tumour.

Wilms tumour (WT) is a paediatric kidney tumour, composed of blastemal, epithelial and stromal cells, with a relapse rate of approximately 15%. Long-term survival for patients with relapse remains approximately 50%. Current clinical and molecular research is directed towards identifying prognostic factors to define the minimal and intensive therapy for successful treatment of children with low and high risk of relapse, respectively. Blastemal component presents a high level of aggressiveness and responsiveness to chemotherapy. To identify molecular prognostic markers that are predictive of chemotherapy sensitivity in tumour relapse, blastemal-enriched samples from stage III and IV WT, from patients with relapse or without relapse, were analysed for 4608 human genes immobilised on a customised cDNA platform. These analyses revealed 69 differentially expressed genes, and the top nine genes were further evaluated by qRT-PCR in the initial WT samples. TSPAN3, NCOA6, CDO1, MPP2 and MCM2 were confirmed to be down-regulated in relapse WT, and TSPAN3 and NCOA6 were also validated in an independent sample group. Protein expression of MCM2 and NCOA6 were observed in 38% (13 out of 34) and 28% (9 out of 32), respectively, of independent stage III and IV WT blastema samples, without association with relapse. However, a significant association between MCM2 positive staining and chemotherapy as first treatment suggests the involvement of MCM2 with drug metabolism in WT blastemal cells.

Abdominal recurrence of osteogenic sarcoma: A case report

Purpose Nonpulmonary metastases from osteogenic sarcoma are rare. A patient had a localized osteogenic sarcoma of the left femur which recurred in the abdomen, a previously unreported metastatic site. Patient and Methods An 18-year-old boy was treated for osteosarcoma. He had abdominal pain, vomiting, weight loss, and symptoms of intestinal obstruction at the time of relapse. Results The patient had diffuse widespread intraabdominal osteogenic sarcoma as the only site of initial recurrence. Abdominal computerized tomography revealed ascites and calcified masses on the hepatic and peritoneal surfaces. Laparoscopic visualization of the abdomen showed hemorrhagic ascites and multiple calcified tumor on the peritoneum, diaphragm, and liver. A biopsy of a representative lesion confirmed the diagnosis of osteogenic sarcoma. The patient died from progressive disease. Conclusion As the initial treatment for patients with osteogenic sarcoma is intensified, the pattern of metastases may change. Unusual sites of recurrence such as in this patient may become more prevalent. A clinical presentation of an acute abdomen in a patient previously treated for osteogenic sarcoma should prompt suspicion of intraabdominal recurrence.

Sepse grave e choque séptico em crianças com câncer: fatores preditores de óbito

BACKGROUND This report describes the clinical characteristics of children and adolescents bearers of oncological disease who were admitted to PICU with severe sepsis and septic shock. The predicting factors for mortality and for need of pulmonary mechanical ventilation were also determined. METHODS Thirty-three children diagnosed with severe sepsis and septic shock were evaluated prospectively at the PICU of Hospital do Câncer between June and December of 2001. RESULTS Thirty-three admissions were analyzed during this period; ages ranged from 1 to 23 years; 16 (48%) were boys and 17 (52%) were girls. Twenty patients had leukemia/lymphoma and 13 patients had solid tumors. Twenty-eight patients had a diagnosis of infectious diseases. In 73% of the patients, infection germs were isolated and gram negative organisms were responsible for 67% of the samples. Respiratory support was necessary for 18 patients (54%), inotropic support for 22 (67%) and dialysis for four patients. The mortality rate was of 41% for patients who needed inotropic support, of 69% for those requiring respiratory support and of 100% for those with an indication for dialysis. The overall mortality rate was of 27%. CONCLUSIONS This research suggests that early intensive treatment for children with cancer exhibiting severe sepsis and/or septic shock could be an important factor to influence the mortality rate of these patients. Moreover, that noninvasive ventilation could be an option to reduce endotracheal intubation and invasive ventilation.

Upregulated genes at 2q24 gains as candidate oncogenes in hepatoblastomas

AIM Cytogenetic data of hepatoblastomas, a rare embryonal tumor of the liver, mostly consist of descriptions of whole-chromosome aneuploidies and large chromosome alterations. High-resolution cytogenetics may provide clues to hepatoblastoma tumorigenesis and indicate markers with clinical significance. PATIENTS & METHODS We used array-CGH (180K) to screen for genomic imbalances in nine hepatoblastomas. Additionally, we investigated the expression pattern of selected genes exhibiting copy number changes. RESULTS Analysis showed mainly whole-chromosome or chromosome-arm aneuploidies, but some focal aberrations were also mapped. Expression analysis of 48 genes mapped at one 10 Mb amplification at 2q24 revealed upregulation of DAPL1, ERMN, GALNT5, SCN1A and SCN3A in the set of tumors compared with differentiated livers. CONCLUSION These genes appear as candidates for hepatoblastoma tumorigenesis.

Large germline copy number variations as predisposing factor in childhood neoplasms

AIMS Constitutive genetic factors are believed to predispose to cancer in children. This study investigated the role of rare germline copy number variations (CNVs) in pediatric cancer predisposition. PATIENTS & METHODS A total of 54 patients who developed cancer in infancy were screened by array-CGH for germline CNVs. RESULTS In total, 12 rare CNVs were detected, including a Xq27.2 triplication, and two >1.8 Mb deletions: one of them at 13q31, containing only RNA genes, and another at 3q26.33-q27.1, in a patient with congenital malformations. Detected rare CNVs are significantly larger than those identified in controls, and encompass genes never implicated in cancer predisposition. CONCLUSION Our results suggest that constitutive CNVs contribute to the etiology of pediatric neoplasms, revealing new candidate genes for tumorigenesis.

The genetic and epigenetic landscapes of hepatoblastomas

Primary liver cancers are rare in children, and the most common type is hepatoblastoma (HB), an embryonal tumor with histological features that resemble different stages of liver cell differentiation. However, mainly because of its rarity, molecular data on HB tumorigenesis remain scarce. This article reviews the current knowledge regarding genetic and epigenetic alterations reported in HB cases, with emphasis on the recent findings of next-generation sequencing studies.

DNA methylation landscape of hepatoblastomas reveals arrest at early stages of liver differentiation and cancer-related alterations

Hepatoblastomas are uncommon embryonal liver tumors accounting for approximately 80% of childhood hepatic cancer. We hypothesized that epigenetic changes, including DNA methylation, could be relevant to hepatoblastoma onset. The methylomes of eight matched hepatoblastomas and non-tumoral liver tissues were characterized, and data were validated in an independent group (11 hepatoblastomas). In comparison to differentiated livers, hepatoblastomas exhibited a widespread and non-stochastic pattern of global low-level hypomethylation. The analysis revealed 1,359 differentially methylated CpG sites (DMSs) between hepatoblastomas and control livers, which are associated with 765 genes. Hypomethylation was detected in hepatoblastomas for ~58% of the DMSs with enrichment at intergenic sites, and most of the hypermethylated CpGs were located in CpG islands. Functional analyses revealed enrichment in signaling pathways involved in metabolism, negative regulation of cell differentiation, liver development, cancer, and Wnt signaling pathway. Strikingly, an important overlap was observed between the 1,359 DMSs and the CpG sites reported to exhibit methylation changes through liver development (p<0.0001), with similar patterns of methylation in both hepatoblastomas and fetal livers compared to adult livers. Overall, our results suggest an arrest at early stages of liver cell differentiation, in line with the hypothesis that hepatoblastoma ontogeny involves the disruption of liver development. This genome-wide methylation dysfunction, taken together with a relatively small number of driver genetic mutations reported for both adult and pediatric liver cancers, shed light on the relevance of epigenetic mechanisms for hepatic tumorigenesis.Hepatoblastomas are uncommon embryonal liver tumors accounting for approximately 80% of childhood hepatic cancer. We hypothesized that epigenetic changes, including DNA methylation, could be relevant to hepatoblastoma onset. The methylomes of eight matched hepatoblastomas and non-tumoral liver tissues were characterized, and data were validated in an independent group (11 hepatoblastomas). In comparison to differentiated livers, hepatoblastomas exhibited a widespread and non-stochastic pattern of global low-level hypomethylation. The analysis revealed 1,359 differentially methylated CpG sites (DMSs) between hepatoblastomas and control livers, which are associated with 765 genes. Hypomethylation was detected in hepatoblastomas for ~58% of the DMSs with enrichment at intergenic sites, and most of the hypermethylated CpGs were located in CpG islands. Functional analyses revealed enrichment in signaling pathways involved in metabolism, negative regulation of cell differentiation, liver development, cancer, and Wnt signaling pathway. Strikingly, an important overlap was observed between the 1,359 DMSs and the CpG sites reported to exhibit methylation changes through liver development (p<0.0001), with similar patterns of methylation in both hepatoblastomas and fetal livers compared to adult livers. Overall, our results suggest an arrest at early stages of liver cell differentiation, in line with the hypothesis that hepatoblastoma ontogeny involves the disruption of liver development. This genome-wide methylation dysfunction, taken together with a relatively small number of driver genetic mutations reported for both adult and pediatric liver cancers, shed light on the relevance of epigenetic mechanisms for hepatic tumorigenesis.

Abstract A32: Urine as a potential liquid biopsy for detecting tumor DNA in Wilms tumor patient: Detection of somatic mutations in urine opens perspectives of monitoring chemotherapy response in WT patients

Detection of tumor DNA in urine has been shown as viable method of diagnosis not only for urinary tract (e.g., kidney and bladder) cancers but also for other types, e.g. prostate. Applications of such method, resemble those which use plasma DNA and include cancer detection, monitoring of tumor growth or recurrence and response to chemotherapy or radiation therapy. As far as we know, there is a lack of studies applying urine DNA detection in Wilms tumor (WT), an embryonary kidney cancer type. Here we show evidences of detection for two somatic variants in the urine DNA of one WT patient. By using NGS exome sequencing of tumor tissue and leukocytes samples of the same patient we were able to find new somatic variants: a frame-shift indel in TNRC18 and a misssense SNV in INTS1 gene. Target sequencing applied to the DNA from the patient9s urine revealed the presence of these two somatic variants. More interestingly, both variants could not be found in the urine DNA of this patient after treatment (chemotherapy and nephrectomy). Additionally, these genes are poorly characterized in WT contributing for the comprehension of the cellular processes that are operating in tumorigenesis of WT. Altogether, our findings contribute with the mutational repertoire of WT and reveals the potential of using urine DNA sequencing as a noninvasive cancer screening approach. Citation Format: Ana C. K. Miguez, Rodrigo F. Ramalho, Elisa N. Ferreira, Bruna D. F. Barros, Claudia A. A. de Paula, Renan Valieris, Louise D. C. Mota, Jorge E. Souza, Isabela W. Cunha, Cecilia L. Costa, Sandro J. de Souza, Dirce M. Carraro. Urine as a potential liquid biopsy for detecting tumor DNA in Wilms tumor patient: Detection of somatic mutations in urine opens perspectives of monitoring chemotherapy response in WT patients. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Pediatric Cancer Research: From Mechanisms and Models to Treatment and Survivorship; 2015 Nov 9-12; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(5 Suppl):Abstract nr A32.