Activated NOTCH2 is overexpressed in hepatoblastomas: an immunohistochemical study

Study of WNT and NOTCH Signaling Pathways in Hepatoblastoma: Role in Diagnosis and Prognosis

Background. Hepatoblastoma has an aggressive course in a subset of children. Studying various markers related to the signaling pathways can aid in understanding its pathogenesis at the molecular level and may pave the way for targeted therapy. We conducted this study to evaluate the immunohistochemical expression of markers related to WNT and NOTCH signaling pathways in hepatoblastoma and to compare them among its histological subtypes. Methods. The specimens of hepatoblastoma diagnosed over a period of 8 years were retrieved. Clinicoradiological data was obtained. Slides were reviewed and detailed histopathological parameters, diagnosis, and subtypes were reevaluated. Immunohistochemistry for β-catenin, CCND1, glutamine synthetase, MYC, AXIN2, NOTCH2, DLK1, and HES1 was performed. Statistical analysis was done. Results. A total of 51 samples of hepatoblastoma were included in the study. Mixed epithelial-mesenchymal hepatoblastoma was the most common histologic subtype. PRETEXT IV, high-risk group, high mitotic index, and less differentiated histologic subtype were associated with worse outcomes. β-catenin, AXIN2, CCND1, expression was more in less differentiated subtypes. MYC, HES1, and glutamine synthetase expression was more common in the fetal component. NOTCH2 and DLK1 expression was seen across all types. A statistically significant association was observed among AXIN2 expression with β-catenin, CCND1, and MYC nuclear expression. Mean overall survival was 66.6 months and mean event-free survival was 54.7 months. Conclusions. The NOTCH pathway converges with the WNT pathway. Differential expression of the immunohistochemical markers of these pathways helps in the semiquantitation of various epithelial components, guides adjuvant treatment, and patient prognostication.

Hepatoblastoma: From Molecular Mechanisms to Therapeutic Strategies

Hepatoblastoma (HB) is the most common malignant liver tumor in children under five years of age. Although globally rare, it accounts for a large proportion of liver cancer in children and has poor survival rates in high-risk and metastatic cases. This review discusses the molecular mechanisms, diagnostic methods, and therapeutic strategies of HB. Mutations in the CTNNB1 gene and the activation of the Wnt/β-catenin pathway are essential genetic factors. Furthermore, genetic syndromes like Beckwith-Wiedemann syndrome (BWS) and Familial Adenomatous Polyposis (FAP) considerably heighten the risk of associated conditions. Additionally, epigenetic mechanisms, such as DNA methylation and the influence of non-coding RNAs (ncRNAs), are pivotal drivers of tumor development. Diagnostics include serum biomarkers, immunohistochemistry (IHC), and imaging techniques. Standard treatments are chemotherapy, surgical resection, and liver transplantation (LT). Emerging therapies like immunotherapy and targeted treatments offer hope against chemotherapy resistance. Future research will prioritize personalized medicine, novel biomarkers, and molecular-targeted therapies to improve survival outcomes.

Specific knockout of Notch2 in Treg cells significantly inhibits the growth and proliferation of head and neck squamous cell carcinoma in mice

OBJECTIVE

To investigate the effect of Notch2 gene knockout in Treg cells on head and neck squamous cell carcinoma (HNSCC) in mice.

METHODS

A mouse model of HNSCC was constructed. Flow cytometry and immunofluorescence were used to examine the numbers of related immune cells and programmed cell death in tumor cells in the spleen and tumor microenvironment of mice. Western blotting was used to measure the expression of related proteins in tumor tissues.

RESULTS

The tumor volume of regulatory T (Treg) cell-specific Notch2-knockout mice (experimental group) was significantly smaller than that of control mice (control group) (P < 0.05). Compared with those in the control group, the number of Treg cells and the expression of Ki67 in Treg cells in the spleen and tumor tissue were significantly decreased in the experimental group, while the numbers of CD45+ hematopoietic cells, CD4+ T cells, CD8+ T cells, T helper 1 (Th1) cells, CD11b+ cells (macrophages), and CD11b+CD11c+ cells (dendritic cells) and the expression of Ki67 in CD4+ T cells and CD8+ T cells were significantly increased (P < 0.05). There was no significant difference in the number of Th2 cells between the two groups (P > 0.05). Immunofluorescence analysis showed that the numbers of CD4+ T cells and CD8+ T cells in the tumor tissue in the experimental group were significantly higher than those in the control group (P < 0.05). Compared with that in the control group, programmed cell death in the experimental group was significantly increased (P < 0.05). Moreover, the expression levels of NLRP3, Caspase-1 and GSDMD in the tumor tissues of the experimental group were higher than those in the control group (P < 0.01), while the expression levels of BCL2, Bax, ATG5, LC3 and p62 were not significantly different (P > 0.05).

CONCLUSIONS

Specific knockout of the Notch2 gene in Treg cells significantly decreases the function of Treg cells, inhibits the growth of HNSCC and improves the immune microenvironment in mice, thus effectively treating HNSCC.

Pituitary Tumor-Transforming Gene 1/Delta like Non-Canonical Notch Ligand 1 Signaling in Chronic Liver Diseases

The management of chronic liver diseases (CLDs) remains a challenge, and identifying effective treatments is a major unmet medical need. In the current review we focus on the pituitary tumor transforming gene (PTTG1)/delta like non-canonical notch ligand 1 (DLK1) axis as a potential therapeutic target to attenuate the progression of these pathological conditions. PTTG1 is a proto-oncogene involved in proliferation and metabolism. PTTG1 expression has been related to inflammation, angiogenesis, and fibrogenesis in cancer and experimental fibrosis. On the other hand, DLK1 has been identified as one of the most abundantly expressed PTTG1 targets in adipose tissue and has shown to contribute to hepatic fibrosis by promoting the activation of hepatic stellate cells. Here, we extensively analyze the increasing amount of information pointing to the PTTG1/DLK1 signaling pathway as an important player in the regulation of these disturbances. These data prompted us to hypothesize that activation of the PTTG1/DLK1 axis is a key factor upregulating the tissue remodeling mechanisms characteristic of CLDs. Therefore, disruption of this signaling pathway could be useful in the therapeutic management of CLDs.

Notch Signaling and Liver Cancer

Interactions between liver cells are closely regulated by Notch signaling. Notch signaling has been reported clinically related to bile duct hypogenesis in Alagille syndrome, which is caused by mutations in the Jagged1 gene. Notch activation and hepatocarcinogenesis are closely associated since cancer signaling is affected by the development of liver cells and cancer stem cells. Gene expression and genomic analysis using a microarray revealed that abnormalities in Notch-related genes were associated with the aggressiveness of liver cancer. This pattern was also accompanied with α-fetoprotein- and EpCAM-expressing phenotypes in vitro, in vivo, and in clinical tissues. Hepatitis B or C virus chronic infection or alcohol- or steatosis-related liver fibrosis induces liver cancer. Previous reports demonstrated that HBx, a hepatitis B virus protein, was associated with Jagged1 expression. We found that the Jagged1 and Notch1 signaling pathways were closely associated with the transcription of covalently closed circular hepatitis B virus DNA, which regulated cAMP response element-binding protein, thereby affecting Notch1 regulation by the E3 ubiquitin ligase ITCH. This viral pathogenesis in hepatocytes induces liver cancer. In conclusion, Notch signaling exerts various actions and is a clinical signature associated with hepatocarcinogenesis and liver context-related developmental function.

TUG1 Promoted Tumor Progression by Sponging miR-335-5p and Regulating CXCR4-Mediated Infiltration of Pro-Tumor Immunocytes in CTNNB1-Mutated Hepatoblastoma

Introduction

HB presents with the highest frequency of CTNNB1 mutations, resulting in activation of Wnt signaling pathway. A number of studies have demonstrated CTNNB1 mutation contributed to the development of HB. However, limited research explored the function of lncRNAs in HB with CTNNB1 mutation.

Methods

We screened lncRNA expression profiles in CTNNB1-mutated HB samples and identified lncRNAs associated with malignant phenotype in HB. The association between lncRNA and immune microenvironment was investigated. The biological function of lncRNA was further explored using in vitro experiments.

Results

TUG1 was identified as onco-lncRNA in CTNNB1-mutated HB. TUG1 was shown to be associated with the infiltration of pro-tumor immunocytes via regulating the expression of CXCR4, a chemokine receptor playing a critical role in regulation of immune microenvironment. Inhibiting TUG1 could increase endogenous levels of miR-335-5p and consequently downregulating CXCR4, a direct target of miR-335-5p.

Conclusion

Our findings provide evidence for TUG1 mediating infiltration of pro-tumor immunocytes in HB patients carrying CTNNB1 mutation. TUG1-miR-335-5p-CXCR4 axis might be a promising immunological target for the treatment of HB patients.

The Hippo Effector Transcriptional Coactivator with PDZ-Binding Motif Cooperates with Oncogenic β-Catenin to Induce Hepatoblastoma Development in Mice and Humans

Hepatoblastoma (HB) is the most common pediatric liver tumor. Though Wnt/β-catenin and Hippo cascades are implicated in HB development, studies on crosstalk between β-catenin and Hippo downstream effector transcriptional coactivator with PDZ-binding motif (TAZ) in HB are lacking. Expression levels of TAZ and β-catenin in human HB specimens were assessed by immunohistochemistry. Functional interplay between TAZ and β-catenin was determined by overexpression of an activated form of TAZ (TAZS89A), either alone or combined with an oncogenic form of β-catenin (ΔN90-β-catenin), in mouse liver via hydrodynamic transfection. Activation of TAZ often co-occurred with that of β-catenin in clinical specimens. Although the overexpression of TAZS89A alone did not induce hepatocarcinogenesis, concomitant overexpression of TAZS89A and ΔN90-β-catenin triggered the development of HB lesions exhibiting both epithelial and mesenchymal features. Mechanistically, TAZ/β-catenin-driven HB development required TAZ interaction with transcriptional enhanced associate domain factors. Blockade of the Notch cascade did not inhibit TAZ/β-catenin-dependent HB formation in mice but suppressed the mesenchymal phenotype. Neither Yes-associated protein nor heat shock factor 1 depletion affected HB development in TAZ/β-catenin mice. In human HB cell lines, silencing of TAZ resulted in decreased cell growth, which was further reduced when TAZ knockdown was associated with suppression of either β-catenin or Yes-associated protein. Overall, our study identified TAZ as a crucial oncogene in HB development and progression.

Long Noncoding RNA (lncRNA) MIR22HG Suppresses Gastric Cancer Progression through Attenuating NOTCH2 Signaling

BACKGROUND Long noncoding RNAs (lncRNAs) are important regulators in human disease, including cancers. LncRNA MIR22HG has been shown to inhibit the progression of endometrial carcinoma, lung cancer, and hepatocellular carcinoma. Its role in gastric cancer is unclear. This study investigated MIR22HG effects on gastric cancer. MATERIAL AND METHODS Gastric cancer tissues (n=43) and adjacent normal tissues (n=21) were collected. Patients' 5-year overall survival rate was analyzed. Human normal gastric mucosal cell line (GES-1) and gastric cancer cell lines (MKN-45, AGS, SGC-7901) were cultured. AGS and MKN-45 cells were transfected by pcDNA3 empty vector, pcDNA3-MIR22HG overexpression vector, MIR22HG siRNA and its negative control, NOTCH2 siRNA and its negative control, respectively. Proliferation was explored by CCK-8 assay. Migration and invasion were explored by Transwell. qRT-PCR and western blot were used to investigate mRNA and proteins expression, respectively. RESULTS MIR22HG expression was decreased in gastric cancer tissues and cells (P<0.05). Low MIR22HG expression indicated lower 5-year overall survival rate (P<0.05). Upregulation of MIR22HG inhibited AGS and MKN-45 cell proliferation, migration and invasion (all P<0.05). Downregulation of MIR22HG elevated AGS and MKN-45 cell proliferation, migration, and invasion (all P<0.05). MIR22HG negatively regulated NOTCH2 signaling. Silencing MIR22HG elevated HEY1 and nucleus NOTCH2 expression. Silencing of NOTCH2 suppressed AGS and MKN-45 cells proliferation, migration and invasion (all P<0.05). CONCLUSIONS LncRNA MIR22HG suppressed gastric cancer progression through attenuating NOTCH2 signaling.

miR-146a-5p mediates epithelial-mesenchymal transition of oesophageal squamous cell carcinoma via targeting Notch2

Background:

Our previous study found that dysregulated microRNA-146a-5p (miR-146a-5p) is involved in oesophageal squamous cell cancer (ESCC) proliferation. This article aimed to evaluate its detailed mechanisms in ESCC epithelial–mesenchymal transition (EMT) progression.

Methods:

Invasion assay, qRT-PCR and western blotting were used to validate the roles of miR-146a-5p and Notch2 in EMT progression. miRNA target gene prediction databases and dual-luciferase reporter assay were used to validate the target gene.

Results:

miR-146a-5p inhibitor led to increase of invaded ESCC cells, while miR-146a-5p mimics inhibited invasion ability of ESCC cells. Protein level of E-cadherin decreased, whereas those of Snail and Vimentin increased in the anti-miR-146a-5p group, which demonstrated that miR-146a-5p inhibits EMT progression of ESCC cells. miRNA target gene prediction databases indicated the potential of Notch2 as a direct target gene of miR-146a-5p and dual-luciferase reporter assay validated it. Importantly, shRNA-Notch2 restrained EMT and partially abrogated the inhibiting effects of miR-146a-5p on EMT progression of ESCC cells.

Conclusions:

miR-146a-5p functions as a tumour-suppressive miRNA targeting Notch2 and inhibits the EMT progression of ESCC.

Hepatoblastoma modeling in mice places Nrf2 within a cancer field established by mutant -catenin

Aberrant wnt/β-catenin signaling and amplification/overexpression of Myc are associated with hepatoblastoma (HB), the most prevalent type of childhood liver cancer. To address their roles in the pathogenesis of HB, we generated mice in which Myc and mutant β-catenin were targeted to immature cells of the developing mouse liver. Perinatal coexpression of both genes promoted the preferential development of HBs over other tumor types in neonatal mice, all of which bore striking resemblance to their human counterparts. Integrated analysis indicated that tumors emerged as a consequence of Myc-driven alterations in hepatoblast fate in a background of pan-hepatic injury, inflammation, and nuclear factor (erythroid-derived 2)-like 2/Nrf2-dependent antioxidant signaling, which was specifically associated with expression of mutant β-catenin but not Myc. Immunoprofiling of human HBs confirmed that approximately 50% of tumors demonstrated aberrant activation of either Myc or Nfe2l2/Nrf2, while knockdown of Nrf2 in a cell line-derived from a human HB with NFE2L2 gene amplification reduced tumor cell growth and viability. Taken together, these data indicate that β-catenin creates a protumorigenic hepatic environment in part by indirectly activating Nrf2 and implicate oxidative stress as a possible driving force for a subset of β-catenin-driven liver tumors in children.

Notch2 is a crucial regulator of self-renewal and tumorigenicity in human hepatocellular carcinoma cells

The Notch pathway plays an important role in both stem cell biology and cancer. Notch2 was reported to be upregulated in human hepatocellular carcinoma (HCC) tissues. However, the biological function of Notch2 in human HCC cells has not yet been documented. The aim of this study was to investigate its possible function on the progression of human HCC cells. The expression of Notch2 was detected in four human HCC cell lines by western blotting. Next, Notch2 was knocked down by small interference RNA (siRNA) in human HCC cells. The role of Notch2 in human HCC cells was investigated by cell proliferation assay, colony formation assay, chemoresistance and xenograft formation assay. In the present study, western blotting revealed that the expression of Notch2 was upregulated in human HCC cell lines. Genetic depletion of Notch2 in HCC cells not only resulted in significantly inhibited proliferation, cell cycle progression and colony formation ability but also increased its sensitivity to 5-fluorouracil (5-FU) compared with controls. In addition, upregulation of Notch2 was discovered in CD90 positive HCC cells, CD90 is a marker of hepatic stem cells. Most importantly, knockdown of Notch2 in HCC cells impaired the tumor formation in vivo. Taken together, our findings indicate that Notch2 may confer stemness properties in HCC; downregulation of Notch2 inhibited the proliferation and tumor formation of HCC cells and increase their sensitivity to 5-FU, suggesting Notch2 as a potential therapeutic target for HCC.

Notch2 as a promising prognostic biomarker for oesophageal squamous cell carcinoma

We aimed to examine Notch2 expression in oesophageal squamous cell carcinoma (ESCC) patients and to evaluate its prognostic potential. Immunohistochemical (IHC) staining, quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analysis were utilized to investigate the Notch2 expression status and prognostic value. Furtherly, CCK8 and clonogenic assays were conducted to determine if Notch2 inhibition by shRNA could lead to a decrease in the proliferation and survival of ESCC cells. A notably higher Notch2 expression level was found in ESCC tissues at the mRNA (P < 0.0001) and protein levels (IHC: P = 0.004; western blot: P = 0.021). Log-rank analysis demonstrated that Notch2 overexpression was significantly associated with worse overall survival (OS) (29.1% vs. 49.1%; P = 0.013) and progression-free survival (PFS) (15.3% vs. 34.4%; P = 0.006) rates in ESCC patients. The multivariate analysis revealed Notch2 as an independent prognostic factor for OS and PFS (P = 0.002 and 0.006, resp.). Besides, in vitro assays showed that OD450 values and colony formations were significantly reduced in Notch2-shRNA group (all P < 0.0001). In conclusion, these results show that Notch2 is up-regulated in ESCC tissues and could serve as a promising biomarker for identifying individuals with poor prognostic potential.

NOTCH2 signaling confers immature morphology and aggressiveness in human hepatocellular carcinoma cells

The NOTCH family of membranous receptors plays key roles during development and carcinogenesis. Since NOTCH2, yet not NOTCH1 has been shown essential for murine hepatogenesis, NOTCH2 rather than NOTCH1 may be more relevant to human hepatocarcinogenesis; however, no previous studies have supported this hypothesis. We therefore assessed the role of NOTCH2 in human hepatocellular carcinoma (HCC) by immunohistochemistry and cell culture. Immunohistochemically, 19% of primary HCCs showed nuclear staining for NOTCH2, indicating activated NOTCH2 signaling. NOTCH2-positive HCCs were on average in more advanced clinical stages, and exhibited more immature cellular morphology, i.e. higher nuclear-cytoplasmic ratios and nuclear densities. Such features were not evident in NOTCH1‑positive HCCs. In human HCC cell lines, abundant NOTCH2 expression was associated with anaplasia, represented by loss of E-cadherin. When NOTCH2 signaling was stably downregulated in HLF cells, an anaplastic HCC cell line, the cells were attenuated in potential for in vitro invasiveness and migration, as well as in vivo tumorigenicity accompanied by histological maturation. Generally, inverse results were obtained for a differentiated HCC cell line, Huh7, manipulated to overexpress activated NOTCH2. These findings suggested that the NOTCH2 signaling may confer aggressive behavior and immature morphology in human HCC cells.

The 4 Notch receptors play distinct and antagonistic roles in the proliferation and hepatocytic differentiation of liver progenitors

The Notch signaling pathway is involved in liver development and regeneration. Here, we investigate the role of the 4 mammalian Notch paralogs in the regulation of hepatoblast proliferation and hepatocytic differentiation. Our model is based on bipotential mouse embryonic liver (BMEL) progenitors that can differentiate into hepatocytes or cholangiocytes in vitro and in vivo. BMEL cells were subjected to Notch antagonists or agonists. Blocking Notch activation with a γ-secretase inhibitor, at 50 μM for 48 h, reduced cell growth by 50%. S-phase entry was impaired, but no apoptosis was induced. A systematic paralog-specific strategy was set using lentiviral transduction with constitutively active forms of each Notch receptor along with inhibition of endogenous Notch signaling. This assay demonstrates that proliferation of BMEL cells requires Notch2 and Notch4 activity, resulting in significant down-regulation of p27(Kip1) and p57(Kip2) cyclin-dependent kinase inhibitors. Conversely, Notch3-expressing cells proliferate less and express 3-fold higher levels of p57(Kip2). The Notch3 cells present a hepatocyte-like morphology, enhanced multinucleation, and a ploidy shift. Moreover, Notch3 activity is conducive to hepatocytic differentiation in vitro, while its paralogs impede this fate. Our study provides the first evidence of a functional diversity among the mammalian Notch homologues in the proliferation and hepatocytic-lineage commitment of liver progenitors.

Possible roles of DLK1 in the Notch pathway during development and disease

The Delta-Notch pathway is an evolutionarily conserved signaling pathway which controls a broad range of developmental processes including cell fate determination, terminal differentiation and proliferation. In mammals, four Notch receptors (NOTCH1-4) and five activating canonical ligands (JAGGED1, JAGGED2, DLL1, DLL3 and DLL4) have been described. The precise function of noncanonical Notch ligands remains unclear. Delta-like 1 homolog (DLK1), the best studied noncanonical Notch ligand, has been shown to act as an inhibitor of Notch signaling in vitro, but its function in vivo is poorly understood. In this review we summarize Notch signaling during development and highlight recent studies in DLK1expression that reveal new insights into its function.

Hepatoblastoma: recent developments in research and treatment

Hepatoblastoma is the most common liver tumor of early childhood. According to recent studies its incidence seems to be increasing in North America and Europe. Since new histological variants have been described recently the formerly clear-cut distinction of hepatoblastoma and hepatocellular carcinoma may not be valid anymore and a new histological classification will be inaugurated by an international working group. Recent research identified prognostically relevant gene signatures as well as potential molecular targets for therapy of hepatoblastoma. The multicentric study groups in the USA, Europe and Japan recommend cisplatin based chemotherapy for neoadjuvant and adjuvant treatment. However, their risk stratification systems and general treatment strategies differ substantially. Therefore the four groups agreed to pool their patients' data for an analysis of prognostic criteria which can be used for defining common risk groups. While 90% of standard risk and 65% of high risk hepatoblastomas can be cured, the still dismal outcome of multifocal disseminated and metastasising tumors warrants the investigation of new cytotoxic drugs and substances against specific molecular targets.