High expression of IGF2-derived intronic miR-483 predicts outcome in hepatoblastoma.

BACKGROUND: The role of microRNAs (miRs) as biomarkers to predict outcome in hepatoblastoma (HB), the most common malignant liver tumor in childhood, has still to be determined. Recently, the so-called four-miR signature has been described to efficiently stratify HB patients according to their prognosis. OBJECTIVE: We examined the recently described four-miR signature for its clinical relevance in an independent validation cohort of HB patients and tried to optimize its predictive value by analyzing four additional miRs involved in HB biology. METHODS: Expression of eight miR was determined in 29 tumor and 10 normal liver samples by TaqMan assays and association studies and Kaplan-Meier estimators determined their clinical relevance. RESULTS: Stratifying HB patients by the four-miR signature showed no difference in patients' outcome, which was also reflected by the lack of association with any clinical risk parameter. Adding miR-23b-5p and miR-23b-3p did also not increase its discriminating power. However, the integration of miR-483-5p and miR-483-3p into the four-miR signature could predict patients with poor outcome that were associated with large tumors and vessel invasive growth with high accuracy. CONCLUSIONS: The expansion of the four-miR signature by miR-483 serves as a useful biomarker to predict outcome of HB patients.

Vessel adherent growth represents a major challenge in the surgical resection of neuroblastoma and Is associated with adverse outcome.

PURPOSE: Neuroblastoma (NB) is the most common extracranial, solid tumor in childhood, with a peak incidence in children under 6 years of age. Due to its variable course of disease, which ranges from spontaneous regression to metastatic spread, NB still represents a significant therapeutic challenge. Strikingly, a certain number of NBs intraoperatively show vessel adhesion and/or infiltrative growth, which is often not visible in pre-operative imaging. We proposed the term unexpected vessel infiltration of NB (UVIN) to denote this phenomenon. UVIN represents a major surgical challenge. METHODS: In this study, we determined frequency and clinical relevance of UVIN in a cohort of 100 NB-patients with subsequent correlation to several unfavorable characteristics of disease. RNA expression levels of MYCN and its co-regulated antisense transcript MYCNOS to identify markers was measured by PCR. RESULTS: We found UVIN to be present in 34% of cases and significantly correlated with incomplete resection, MYCN amplification, complications, neoadjuvant therapy, tumor grade and MYCNOS expression levels. MYCN expression levels showed no significant results with UVIN. CONCLUSION: Collectively, our data show that UVIN represents a frequent surgical problem associated with a poor outcome in NB patients. MYCN and MYCNOS seem to be no appropriate markers for UVIN. TYPE OF STUDY: Prognosis study. LEVEL OF EVIDENCE: Level III.

Targeting excessive MYCN expression using MLN8237 and JQ1 impairs the growth of hepatoblastoma cells.

Hepatoblastoma (HB) is the most common liver tumor in children under the age of 3 years worldwide. While many patients achieve good outcomes with surgical resection and conventional chemotherapy, there is still a high­risk population that exhibits a poor treatment response and unfavorable prognosis, which warrants the search for novel treatment options. In recent years, it has become clear that genetic events alone are not sufficient to explain the aggressive phenotype of this embryonal malignancy. Instead, epigenetic modifications and aberrant gene expression seem to be key drivers of HB. In the present study, expression analyses such as reverse transcription­quantitative polymerase chain reaction revealed that the oncogene, MYCN proto­oncogene basic­helix­loop­helix transcription factor (MYCN) was upregulated in HB and other pediatric liver tumors, due to the transcriptional activity of its antisense transcript MYCN opposite strand (MYCNOS). Pyrosequencing demonstrated the hypomethylated regions in the promoter of MYCN and MYCNOS, suggesting that an epigenetic mechanism may underlie the induction of aberrant expression. Transient MYCN knockdown in HB cells resulted in growth inhibition over time. In addition, treating HB cells with the MYCN inhibitors JQ1 and MLN8237 led to the significant downregulation of MYCN either at the mRNA or protein levels, respectively. The underlying mechanism of action of the two inhibitors was revealed to be associated with the induction of dose­dependent growth arrest, by arresting cells at either the G1/G0 or G2 phase. Furthermore, MLN8237 and JQ1 were able to cause spindle disturbances and/or apoptosis in HB cells. The present results suggest that MYCN may be a promising biomarker for HB and a potential therapeutic target in patients with tumors overexpressing MYCN.

Connectivity map identifies HDAC inhibition as a treatment option of high-risk hepatoblastoma.

Hepatoblastoma (HB) is the most common liver tumor of childhood, usually occurring in children under the age of 3 y. The prognosis of patients presenting with distant metastasis, vascular invasion and advanced tumor stages remains poor and children that do survive often face severe late effects from the aggressive chemotherapy regimen. To identify potential new therapeutics for high risk HB we used a 1,000-gene expression signature as input for a Connectivity Map (CMap) analysis, which predicted histone deacetylase (HDAC) inhibitors as a promising therapy option. Subsequent expression analysis of primary HB and HB cell lines revealed a general overexpression of HDAC1 and HDAC2, which has been suggested to be predictive for the efficacy of HDAC inhibition. Accordingly, treatment of HB cells with the HDAC inhibitors SAHA and MC1568 resulted in a potent reduction of cell viability, induction of apoptosis, reactivation of epigenetically suppressed tumor suppressor genes, and the reversion of the 16-gene HB classifier toward the more favorable expression signature. Most importantly, the combination of HDAC inhibitors and cisplatin - a major chemotherapeutic agent of HB treatment - revealed a strong synergistic effect, even at significantly reduced doses of cisplatin. Our findings suggest that HDAC inhibitors skew HB cells toward a more favorable prognostic phenotype through changes in gene expression, thus indicating a targeted molecular mechanism that seems to enhance the anti-proliferative effects of conventional chemotherapy. Thus, adding HDAC inhibitors to the treatment regimen of high risk HB could potentially improve outcomes and reduce severe late effects.