Common Pediatric Liver Malignancy Research Articles

Metabolic and Epigenetic Mechanisms in Hepatoblastoma: Insights into Tumor Biology and Therapeutic Targets

Background: Hepatoblastoma, the most common pediatric liver malignancy, is characterized by significant molecular heterogeneity and poor prognosis in advanced stages. Recent studies highlight the importance of metabolic reprogramming and epigenetic dysregulation in hepatoblastoma pathogenesis. This review aims to explore the metabolic alterations and epigenetic mechanisms involved in hepatoblastoma and how these processes contribute to tumor progression and survival. Methods: Relevant literature on metabolic reprogramming, including enhanced glycolysis, mitochondrial dysfunction, and shifts in lipid and amino acid metabolism, as well as epigenetic mechanisms like DNA methylation, histone modifications, and non-coding RNAs, was reviewed. The interplay between these pathways and their potential as therapeutic targets were examined. Results: Hepatoblastoma exhibits metabolic shifts that support tumor growth and survival, alongside epigenetic changes that regulate gene expression and promote tumor progression. These pathways are interconnected, with metabolic changes influencing the epigenetic landscape and vice versa. Conclusions: The dynamic interplay between metabolism and epigenetics in hepatoblastoma offers promising avenues for therapeutic intervention. Future research should focus on integrating metabolic and epigenetic therapies to improve patient outcomes, addressing current gaps in knowledge to develop more effective treatments.

Intratumoral erythroblastic islands restrain anti-tumor immunity in hepatoblastoma

Erythroblastic islands (EBIs) are the specialized structures for erythropoiesis, but they have never been found functional in tumors. As the most common pediatric liver malignancy, hepatoblastoma (HB) requires more effective and safer therapies to prevent progression and the lifelong impact of complications on young children. However, developing such therapies is impeded by a lack of comprehensive understanding of the tumor microenvironment. By single-cell RNA sequencing of 13 treatment-naive HB patients, we discover an immune landscape characterized by aberrant accumulation of EBIs, formed by VCAM1+ macrophages and erythroid cells, which is inversely correlated with survival of HB. Erythroid cells inhibit the function of dendritic cells (DCs) via the LGALS9/TIM3 axis, leading to impaired anti-tumor Tcell immune responses. Encouragingly, TIM3 blockades relieve the inhibitory effect of erythroid cells on DCs. Our study provides an immune evasion mechanism mediated by intratumoral EBIs and proposes TIM3 as a promising therapeutic target for HB.

Inhibition of Heat Shock Factor 1 Signaling Decreases Hepatoblastoma Growth via Induction of Apoptosis

Although rare compared with adult liver cancers, hepatoblastoma (HB) is the most common pediatric liver malignancy, and its incidence is increasing. Currently, the treatment includes surgical resection with or without chemotherapy, and in severe cases, liver transplantation in children. The effort to develop more targeted, HB-specific therapies has been stymied by the lack of fundamental knowledge about HB biology. Heat shock factor 1 (HSF1), a transcription factor, is a canonical inducer of heat shock proteins, which act as chaperone proteins to prevent or undo protein misfolding. Recent work has shown a role for HSF1 in cancer beyond the canonical heat shock response. The current study found increased HSF1 signaling in HB versus normal liver. It showed that less differentiated, more embryonic tumors had higher levels of HSF1 than more differentiated, more fetal-appearing tumors. Most strikingly, HSF1 expression levels correlated with mortality. This study used a mouse model of HB to test the effect of inhibiting HSF1 early in tumor development on cancer growth. HSF1 inhibition resulted in fewer and smaller tumors, suggesting HSF1 is needed for aggressive tumor growth. Moreover, HSF1 inhibition also increased apoptosis in tumor foci. These data suggest that HSF1 may be a viable pharmacologic target for HB treatment.

The Cellular and Molecular Landscape of Synchronous Pediatric Sialoblastoma and Hepatoblastoma.

Sialoblastoma (SBL) is an infrequent embryonal malignant tumor originating from the salivary gland, resembling primitive salivary gland anlage, whereas hepatoblastoma (HB) is the most common pediatric liver malignancy. The simultaneous occurrence of both tumors is extremely rare. Here we reported a case of a 6-month-old infant diagnosed with synchronous SBL and HB. The patient received neoadjuvant chemotherapy followed by surgical resection. Fresh tissues of both tumors were collected before and after chemotherapy, which were further profiled by whole exome sequencing (WES) and single-cell RNA sequencing (scRNA-seq). WES analysis revealed potential somatic driver mutation PIK3CA p.Glu454Lys for SBL and canonical mutation CTNNB1 p.Ser45Pro for HB. No shared somatic variants or common copy number alterations were found between SBL and HB primary tumor samples. Though scRNA-seq, single-cell atlases were constructed for both tumors. SBL may recapitulate a pre-acinar stage in the development of salivary gland, including basaloid, duct-like, myoepithelial-like, and cycling phenotypes. In the meantime, HB was composed of tumor cells resembling different stages of the liver, including hepatocyte-like, hepatic progenitor-like, and hepatoblast-like cells. After chemotherapy, both tumors were induced into a more mature phenotype. In terms of transcriptional signatures, SBL and HB showed enhanced expression of epithelial markers KRT8, KRT18, and essential embryo development genes SDC1, MDK, indicating the disruption of normal embryo epithelium development. Finally, heterozygous deleterious germline mutation BLM and FANCI were identified which could predispose the patient to higher cancer risk. It partially explained the reason for the co-occurrence of SBL and HB. Taken together, we provided valuable resources for deciphering cellular heterogeneity and adaptive change of tumor cells after chemotherapy for synchronous SBL and HB, providing insights into the mechanisms leading to synchronous pediatric tumors.

HSF1 Signaling Inhibits Apoptosis in Hepatoblastoma

IntroductionHepatoblastoma (HB) is the most common pediatric liver malignancy. While relatively rare, its incidence is increasing. Currently surgical resection with or without chemotherapy is the main treatment for the tumor though in severe cases children require liver transplantation. Development of precision therapy for the tumor has been hampered by gaps in fundamental knowledge about how the tumor develops and grows. Heat shock factor 1 (HSF1) is the master regulator of the heat shock response, which classically mediates cellular stress from heat but it likely has a cancer specific. Recent work has shown that HSF1 controls a suite of genes in cancer related to apoptosis, cell cycle signaling, DNA repair, energy metabolism and extracellular matrix formation. Previously, we conducted a meta‐analysis of six human HB transcriptomic data sets, which found expression levels of HSF1 was higher in tumors versus normal liver. Intriguingly, we found higher levels of HSF1 expression in tumors correlated with mortality. We wanted to investigate how inhibiting HSF1 impacted tumor growth in our lab’s mouse model of hepatoblastoma based on transfection with constitutively active forms of β‐catenin and yes‐associated protein 1 (Yap1). This model induces tumors that genetically and histologically resemble human hepatoblastoma. The objective of this study was to investigate the specific role of HSF1 signaling in the development of hepatoblastoma. Our hypothesis is inhibiting HSF1 in our mouse model of hepatoblastoma leads to increased apoptosis in tumor cells and thus decreased tumor size and number.MethodsWe inhibited HSF1 signaling in mice by co‐transfecting a dominant negative HSF1 (dnHSF1) plasmid along with β‐catenin and Yap1 plasmids. The dnHSF1 forms a truncated form of the protein that cannot initiate transcription of target genes. Mice injected with just β‐catenin and Yap1 plasmids served as controls. Eight weeks after transfection, the mice were harvested and the livers were preserved for analysis. Liver and body weights of each mouse was measured to calculate liver‐to‐body weight ratio, an index of tumor burden. At least three mice per condition was assessed.ResultsWe found transfection with the dnHSF1 lead to decreased liver‐to‐body weight ratio compared to control mice transfected with just the β‐catenin and Yap1 plasmids (p‐value<0.05)(Figure 1). What few tumor foci remained featured larger, more differentiated cells. Indeed, these foci showed positive staining via immunohistochemistry (IHC) for both activated mTORC1 and glutamine synthetase, markers seen early in tumor development. Next, we assessed apoptosis by conducting IHC for cleaved caspase 3 and by performing a TUNEL assay on liver sections from both dnHSF1/β‐catenin/Yap1 mice and from control β‐catenin/Yap1 animals. Staining for both markers was increased nearly three times in dnHSF1 treated animals versus control(p‐value<0.05)(Figure 2).ConclusionsWe conclude inhibiting HSF1 signaling in burgeoning hepatoblastoma cells leads to smaller, more differentiated tumors via increased apoptosis. More work is needed to determine if HSF1 is a viable pharmacologic target for hepatoblastoma.

Recent updates on the classification of hepatoblastoma according to the International Pediatric Liver Tumors Consensus.

Hepatoblastoma is the most common pediatric liver malignancy and usually occurs within the first 3 years of life. In recent years, the overall incidence of hepatoblastoma has exhibited the greatest increase among all pediatric malignancies worldwide. The diagnosis of hepatoblastoma may be challenging due to the lack of a current consensus classification system. The International Pediatric Liver Tumors Consensus introduced guidelines and a consensus classification for the diagnosis of hepatoblastoma as either epithelial or mixed epithelial and mesenchymal and in the updated 5th edition of the World Health Organization Classification of Digestive System Tumors.

Genetic and epigenetic basis of hepatoblastoma diversity

Hepatoblastoma (HB) is the most common pediatric liver malignancy; however, hereditary predisposition and acquired molecular aberrations related to HB clinicopathological diversity are not well understood. Here, we perform an integrative genomic profiling of 163 pediatric liver tumors (154 HBs and nine hepatocellular carcinomas) based on the data acquired from a cohort study (JPLT-2). The total number of somatic mutations is precious low (0.52/Mb on exonic regions) but correlated with age at diagnosis. Telomerase reverse transcriptase (TERT) promoter mutations are prevalent in the tween HBs, selective in the transitional liver cell tumor (TLCT, > 8 years old). DNA methylation profiling reveals that classical HBs are characterized by the specific hypomethylated enhancers, which are enriched with binding sites for ASCL2, a regulatory transcription factor for definitive endoderm in Wnt-pathway. Prolonged upregulation of ASCL2, as well as fetal-liver-like methylation patterns of IGF2 promoters, suggests their “cell of origin” derived from the premature hepatoblast, similar to intestinal epithelial cells, which are highly proliferative. Systematic molecular profiling of HB is a promising approach for understanding the epigenetic drivers of hepatoblast carcinogenesis and deriving clues for risk stratification.

Neuropilin-2 Is Associated With Increased Hepatoblastoma Cell Viability and Motility.

The neuropilins NRP1 and NRP2 are multifunctional glycoproteins that have been implicated in several cancer-related processes including cell survival, migration, and invasion in various tumor types. Here, we examine the role of neuropilins in hepatoblastoma (HB), the most common pediatric liver malignancy. Using a combination of immunohistochemistry, RNA analysis and western blotting, we observed high level expression of NRP1 and NRP2 in 19 of 20 HB specimens and in a majority of human HB cell lines (HUH6 and five cell lines established from patient-derived xenografts) studied but not in normal hepatocytes. Silencing of NRP2 expression in HUH6 and HB-282 HB cells resulted in decreased cell viability, impaired cytoskeleton remodeling, and reduced cell motility, suggesting that NRP2 contributes to the malignant phenotype. We propose that neuropilins warrant further investigation as biomarkers of HB and potential therapeutic targets.

MDM4 inhibition: a novel therapeutic strategy to reactivate p53 in hepatoblastoma

Hepatoblastoma (HB) is the most common pediatric liver malignancy. High-risk patients have poor survival, and current chemotherapies are associated with significant toxicities. Targeted therapies are needed to improve outcomes and patient quality of life. Most HB cases are TP53 wild-type; therefore, we hypothesized that targeting the p53 regulator Murine double minute 4 (MDM4) to reactivate p53 signaling may show efficacy. MDM4 expression was elevated in HB patient samples, and increased expression was strongly correlated with decreased expression of p53 target genes. Treatment with NSC207895 (XI-006), which inhibits MDM4 expression, or ATSP-7041, a stapled peptide dual inhibitor of MDM2 and MDM4, showed significant cytotoxic and antiproliferative effects in HB cells. Similar phenotypes were seen with short hairpin RNA (shRNA)-mediated inhibition of MDM4. Both NSC207895 and ATSP-7041 caused significant upregulation of p53 targets in HB cells. Knocking-down TP53 with shRNA or overexpressing MDM4 led to resistance to NSC207895-mediated cytotoxicity, suggesting that this phenotype is dependent on the MDM4-p53 axis. MDM4 inhibition also showed efficacy in a murine model of HB with significantly decreased tumor weight and increased apoptosis observed in the treatment group. This study demonstrates that inhibition of MDM4 is efficacious in HB by upregulating p53 tumor suppressor signaling.

Abstract 5408: Chloroquine inhibits PARP expression in hepatoblastoma

Abstract Hepatoblastoma is the most common pediatric liver malignancy accounting 1 % of all pediatric malignancies. Despite advances in medical treatment and surgical techniques, the prognosis for advanced metastatic hepatoblastoma remains poor, underscoring the need for new therapeutic modalities. Chloroquine (CQ), a drug used to treat malaria and rheumatologic diseases, has been shown to inhibit the growth and survival of various cancer types. In this study we examined the antineoplastic activity of CQ on HB cells. Established human HB cell line (HUH6) cells were cultured in presence of clinically acceptable concentrations of CQ. Morphology, viability, and apoptosis were assessed after 48 h and 96 h of CQ treatment showing decreased cell survival and increased caspase 3/7 activity representing induction of apoptosis. Metabolomic profiling of CQ treated HUH6 cells demonstrated significant decrease in NAD+ and aspartate concentration. Furthermore, RT-qPCR based Death Pathway Finder array was conducted to elucidate the molecular mechanisms underlying the CQ effect showing downregulated expression of PARP1 and PARP2. Quantitative western blotting was performed to validate differentially expressed genes at the protein level. Taken together, CQ treatment inhibits cell survival in HB cells in vitro, presumably by disturbing NAD+/NADH balance, impairing aspartate biosynthesis, and reducing PARP expression. CQ thus holds potential as a new treatment modality in HB management. Citation Format: Marjut Pihlajoki, Katja Eloranta, Antti Kyrönlahti, Markku Heikinheimo. Chloroquine inhibits PARP expression in hepatoblastoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5408.

Chloroquine Triggers Cell Death and Inhibits PARPs in Cell Models of Aggressive Hepatoblastoma.

Background: Hepatoblastoma (HB) is the most common pediatric liver malignancy. Despite advances in chemotherapeutic regimens and surgical techniques, the survival of patients with advanced HB remains poor, underscoring the need for new therapeutic approaches. Chloroquine (CQ), a drug used to treat malaria and rheumatologic diseases, has been shown to inhibit the growth and survival of various cancer types. We examined the antineoplastic activity of CQ in cell models of aggressive HB.Methods: Seven human HB cell models, all derived from chemoresistant tumors, were cultured as spheroids in the presence of relevant concentrations of CQ. Morphology, viability, and induction of apoptosis were assessed after 48 and 96 h of CQ treatment. Metabolomic analysis and RT-qPCR based Death Pathway Finder array were used to elucidate the molecular mechanisms underlying the CQ effect in a 2-dimensional cell culture format. Quantitative western blotting was performed to validate findings at the protein level.Results: CQ had a significant dose and time dependent effect on HB cell viability both in spheroids and in 2-dimensional cell cultures. Following CQ treatment HB spheroids exhibited increased caspase 3/7 activity indicating the induction of apoptotic cell death. Metabolomic profiling demonstrated significant decreases in the concentrations of NAD+ and aspartate in CQ treated cells. In further investigations, oxidation of NAD+ decreased as consequence of CQ treatment and NAD+/NADH balance shifted toward NADH. Aspartate supplementation rescued cells from CQ induced cell death. Additionally, downregulated expression of PARP1 and PARP2 was observed.Conclusions: CQ treatment inhibits cell survival in cell models of aggressive HB, presumably by perturbing NAD+ levels, impairing aspartate bioavailability, and inhibiting PARP expression. CQ thus holds potential as a new agent in the management of HB.

Abstract B76: Characterizing vascular invasion in hepatoblastoma

Abstract Hepatoblastoma (HB) is the most common pediatric liver malignancy, and patients with high-risk, metastatic disease have a five-year overall survival (OS) of only about 40%. Of note, HB patients with vascular invasion (VI) have a much worse OS. Our hypothesis is that HB tumors with VI possess unique clones that invade the vasculature, resulting in dissemination of disease. We injected the aggressive HepT1 cell line with confirmed CTNNB1 and NFE2L2 mutations in the livers of immunocompromised NSG mice to generate intrahepatic tumors. After 4 weeks, we had 100% take of tumors in animals. Serum human α-fetoprotein (AFP) increased with the growth of tumors. At time of death, we saw clear presence of intrahepatic VI, vena caval tumor thrombus, extrahepatic disease including within periportal lymph nodes, and lung metastasis in animals with tumors. We grew adherent and nonadherent cell lines from tumor samples, including one cell line from intrahepatic VI and one from vena caval tumor thrombus. Cells derived from VI areas had obvious differences in phenotype from cells from the primary tumor (PT). To further pursue these provocative changes between PT and VI areas, we generated two unique patient-derived xenograft (PDX) models of HB with intrahepatic implantation of PT and VI tumor samples from a nonmetastatic pretreatment extent of disease (PRETEXT) stage 4 patient. Mice harboring the VI PDX showed serum elevation of human AFP and obvious tumor with MRI. PT and VI PDX tissues expressed established HB markers nuclear Beta-catenin, Glypican-3, and AFP, resembling the primary patient sample. We also developed a novel cell line with growth of cells from a VI tumor in vitro. With both the HepT1 and PDX models, gene set enrichment transcriptomic analyses of RNA sequencing data showed clear changes in expression in aggressive tissues that invaded vessels, including significant (p<0.05) changes in pathways associated with liver damage, inflammation, and metabolism. Further exploration of these pathways and agents that target these pathways could improve outcomes for HB patients with invasive disease. Citation Format: Sarah E. Woodfield, Roma H. Patel, Aryana M. Ibarra, Barry Zorman, Andrew Badachhape, Ketan B. Ghaghada, Dolores Lopez-Terrada, Pavel Sumazin, Sanjeev A. Vasudevan. Characterizing vascular invasion in hepatoblastoma [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr B76.

CDK9 is dispensable for YAP-driven hepatoblastoma development.

Hepatoblastoma (HB) is the most common pediatric liver malignancy, occurring mainly during the first 4 years of life. Recent studies unraveled the frequent, coordinated activation of Wnt/β-catenin and YAP/Hippo (where YAP is yes-associated protein) pathways in human HB samples. Furthermore, it was found that concomitant overexpression of activated forms of β-catenin and YAP in the mouse liver triggers HB formation in YAP/β-catenin mice. Cyclin-dependent kinases 9 (CDK9) is an elongating kinase, which has been shown to mediate YAP-driven tumorigenesis. The role of CDK9 in HB molecular pathogenesis has not been investigated to date. CDK9 expression was determined in human HB lesions, HB cell lines, and YAP/β-catenin mouse livers. CDK9 was silenced in human HB cell lines and the effects on growth rate and YAP targets were analyzed. Hydrodynamic transfection of YAPS127A and ∆N90-β-catenin together with either shCdk9 or control shLuc (where Luc is luciferase) plasmids was employed to assess the requirement of Cdk9 for HB development in vivo. Nuclear immunoreactivity for CDK9 protein was more pronounced in human HB samples and YAP/β-catenin mouse HB tumor tissues than in corresponding surrounding nontumorous liver tissues. CDK9 protein was also expressed in human HB cell lines. Silencing of CDK9 in human HB cell lines did not lead to consistent effects on HB cell growth or YAP target gene expression. Surprisingly, silencing of Cdk9 led to accelerated liver tumorigenesis in YAP/β-catenin mice. CDK9 is not a major downstream mediator of YAP oncogenic function in HB development and progression.

Animal Modeling of Pediatric Liver Cancer.

Hepatoblastoma (HB) is the most common pediatric liver malignancy. Management of HB requires multidisciplinary efforts. The 5-year overall survival of this disease is about 80% in developed countries. Despite advances in the care of these patients, survival in recurrent or treatment-refractory disease is lower than 50%. This is due to more complex tumor biology, including hepatocellular carcinoma (HCC)-like mutations and expression of aggressive gene signatures leading to chemoresistance, vascular invasion, and metastatic spread. The current treatment protocols for pediatric liver cancer do not incorporate targeted therapies, and the ability to test these therapies is limited due to the inaccessibility of cell lines and mouse models. In this review, we discuss the current status of preclinical animal modeling in pediatric liver cancer, primarily HB. Although HB is a rare cancer, the research community has worked together to develop a range of interesting and relevant mouse models for diverse preclinical studies.

MTOR inhibition affects Yap1-β-catenin-induced hepatoblastoma growth and development.

Hepatoblastoma (HB) is the most common pediatric liver malignancy. Around 80% of HB demonstrate simultaneous activation of β-catenin and Yes-associated protein 1 (Yap1). The mechanism by which these signaling pathways contribute to HB pathogenesis remain obscure. Recently, mTORC1 activation was reported in human HB cells and in a murine HB model driven by β-catenin and Yap1. Here, we directly investigate the therapeutic impact of mTOR inhibition following HB development in the Yap1-β-catenin model. HB were established by hydrodynamic tail vein injection of Sleeping Beauty transposase and plasmids coding for ΔN90-β-catenin and S127A-Yap1. Five weeks after injection, when HB were evident, mice were randomized into Rapamycin diet-fed or basal-diet-fed groups for 5-weeks. Tumor growth was monitored via ultrasound imaging and mice in both groups were euthanized after 5-weeks for molecular analysis. Transcriptomic analysis showed a strong correlation in gene expression between HB in the Yap1-β-catenin model and HB patient cohorts. Rapamycin treatment decreased HB burden, almost normalizing liver weight to body weight ratio. Ultrasound imaging showed reduction in tumor growth over the duration of Rapamycin treatment as compared to controls. Majority of HB in the controls exhibited crowded fetal or embryonal histology, while remnant tumors in the experimental group showed well-differentiated fetal morphology. Immunohistochemistry confirmed inhibition of mTORC1 in the Rapamycin group. Thus, Rapamycin reduces HB in a clinically relevant model driven by β-catenin and Yap1, supporting use of mTORC1 inhibitors in their therapy. We also show the utility of standard and 3D ultrasound imaging for monitoring liver tumors in mice.

Abstract B35: Reactivation of p53 signaling in hepatoblastoma with a stapled peptide dual inhibitor of MDM2 and MDM4

Abstract Introduction: Hepatoblastoma is the most common pediatric liver malignancy. Despite aggressive therapeutic regimens, long-term survival of patients with high-risk, metastatic disease is less than 50%. Most cases of hepatoblastoma do not carry mutations in the TP53 tumor suppressor gene; therefore, we hypothesized that targeting the two major regulators of p53, MDM2 and MDM4, with the stapled peptide dual inhibitor, ATSP-7041, to reactivate p53 signaling would be an effective therapeutic strategy for hepatoblastoma. Methods: Levels of MDM2 and MDM4 gene expression were examined in HB cell lines and in a cohort of 18 primary HB patient samples from stage III (n=12) and IV (n=6) patients in comparison to expression in four adjacent uninvolved liver samples with qPCR experiments. The effects of the dual MDM2/MDM4 inhibitor ATSP-7041 (Aileron Therapeutics) on the same cell lines were analyzed with MTT assays for cytotoxicity and qPCR experiments to look at changes in mRNA expression of p53 targets Bax, Puma, CDKN1A, and MDM2. Results: In 16 of 18 samples, MDM4 expression was higher than average in the uninvolved liver samples; in five samples expression was at least 5-fold higher and in four samples expression was at least 10-fold higher. Of note, all four samples with at least 10-fold higher expression were from stage IV patients. In comparison, MDM2 expression was only elevated in one of the 18 patient samples. All three hepatoblastoma cell lines showed expression of both MDM2 and MDM4. Treatment with ATSP-7041 showed cytotoxic (5.7-8.6 μM) effects in all cell lines tested. All cell lines also showed upregulation of p53 targets Bax (1.4- to 2.4-fold), Puma (2.4- to 3.2-fold), CDKN1A (2.4- to 7.2-fold), and MDM2 (6.1- to 8.3-fold) with treatment. Conclusions: Dual inhibition of MDM2 and MDM4 shows efficacy in preclinical models of hepatoblastoma by upregulating p53 tumor-suppressor signaling in TP53 wild-type cells and is a promising therapeutic strategy for high-risk patients with wild-type TP53. Citation Format: Sarah E. Woodfield, Roma H. Patel, Aryana M. Ibarra, Zhenghu Chen, Sanjeev A. Vasudevan. Reactivation of p53 signaling in hepatoblastoma with a stapled peptide dual inhibitor of MDM2 and MDM4 [abstract]. In: Proceedings of the AACR Special Conference: Pediatric Cancer Research: From Basic Science to the Clinic; 2017 Dec 3-6; Atlanta, Georgia. Philadelphia (PA): AACR; Cancer Res 2018;78(19 Suppl):Abstract nr B35.

Comprehensive analysis and experimental verification of LINC01314 as a tumor suppressor in hepatoblastoma

Hepatoblastoma (HB), as a common pediatric liver malignancy, is composed of a variety of subgroups with different clinical outcomes. Long-noncoding RNA (lncRNA) has crucial roles in cancer biology. However, the association between lncRNA and HB has not been fully investigated. In this study, we screened lncRNA expression profiles that were annotated from the GSE75271 dataset. A total of 225 differentially expressed lncRNAs (DELs) were identified based on comparison between three prognostic subgroups, and seven of them (XR_241302, XR_923061, NR_038322, XR_951687, XR_934593, NR_120317 and XR_93406) that exhibited highly predictive accuracies were selected for functional analysis. Weighted gene correlation network analysis (WGCNA) was employed to predict the biological functions of the seven DELs. The Hippo-YAP signaling pathway was predicted to be the most statistically significant predicted pathway associated with the seven DELs. Furthermore, we performed in vitro experiments to validate the biological function of one DEL, NR_120317 (LINC01314). Our results showed decreased proliferation and migration activities of HB cells overexpressing LINC01314. Moreover, mechanistic investigations revealed that LINC01314 overexpression inhibited nuclear translocation of YAP, by inducing MST1 expression and promoting phosphorylation of LATS1 and YAP, consequently downregulating the expression of cell cycle regulatory proteins (MCM7 and cyclin D1). Taken together, our findings provide evidence for LINC01314 as a potential biomarker and anti-cancer therapeutic target in patients with HB.

Novel Advances in Understanding of Molecular Pathogenesis of Hepatoblastoma: A Wnt/β-Catenin Perspective.

Hepatoblastoma is the most common pediatric liver malignancy, typically striking children within the first 3 years of their young lives. While advances in chemotherapy and newer surgical techniques have improved survival in patients with localized disease, unfortunately, for the 25% of patients with metastasis, the overall survival remains poor. These tumors, which are thought to arise from hepatic progenitors or hepatoblasts, hence the name hepatoblastoma, can be categorized by histological subtyping based on their level of cell differentiation. Genomic and histological analysis of human tumor samples has shown exon-3 deletions or missense mutations in gene coding for β-catenin, a downstream effector of the Wnt signaling pathway, in up to 90% of hepatoblastoma cases. The current article will review key aberrations in molecular pathways that are implicated in various subtypes of hepatoblastoma with an emphasis on Wnt signaling. It will also discuss cooperation among components of pathways such as β-catenin and Yes-associated protein in cancer development. Understanding the complex network of molecular signaling in oncogenesis will undoubtedly aid in the discovery of new therapeutics to help combat hepatoblastoma.

The Advances in Molecular Biology of Hepatoblastoma: Implications for Diagnostic Pathology

As the most common pediatric liver malignancy, hepatoblastoma (HB) accounts for more than 90% of primary hepatic malignant tumors in children less than five years of age in the US, and its incidence has been increasing in the past decades. Despite extensive studies, the pathogenesis of HB remains to be elucidated. Multiple signaling pathways may be involved in the oncogenic process of HB. The best characterized pathways include the canonical Wnt/beta-catenin pathway, the hepatocyte growth factor (HGF)/c-Met signaling pathway, the Notch pathway and the Hedgehog pathway. In addition, signaling molecules associated with these signaling pathways have been shown to be potential novel tumor markers for HB. Preoperative chemotherapy is the current standard of care for HB. Highly sensitive and specific tumor markers are not only important for the accurate diagnosis of HB but are also essential for predicting its clinical behaviors and prognosis. This review summarizes the recent advances in the molecular aspects of HB with a focus on the pathogenic signaling pathways and tumor markers. Their implications for diagnostics and prognostics are also discussed from a pathologist’s point of view.

Where do we stand with hepatoblastoma? A review.

Hepatoblastoma (HB) is the most common pediatric liver malignancy, comprising approximately 1% of all pediatric cancers. The disparate clinical staging systems and histologic classifications that were developed during the last decades, nevertheless, reflect the remaining difficulties and uncertainties in characterizing HB. Furthermore, the combination of surgery and (neo)adjuvant chemotherapy has improved patient outcomes dramatically. A poor prognosis is associated with large tumor size, multifocality, extrahepatic disease, and metastatic spread. The exact etiology of HB remains unknown, but the cytogenetic alterations, phenotypic features, and biologic aspects that accompany this neoplasm yield more and more insight into its pathogenesis. New cell-biologic and molecular-biologic insights may lead to the development of new treatment modalities, especially for patients with a bad prognosis. This review summarizes the different aspects of this intriguing tumor and discusses the current status of research and treatment for patients with HB.