Aspartyl-(asparaginyl)-beta-hydroxylase regulates hepatocellular carcinoma invasiveness

Chondrosarcoma: Multi-Targeting Therapeutic Effects of Doxorubicin, BEZ235, and the Small Molecule Aspartyl-Asparaginyl-β-hydroxylase Inhibitor SMI1182

BACKGROUND/OBJECTIVES

Chondrosarcoma (CS), the most common malignant bone tumor in adults, exhibits a poor prognosis due to high rates of post-surgical recurrence and metastasis, and resistance to chemotherapy. CS's abundant expression of aspartyl-asparaginyl-β-hydroxylase (ASPH), which drives invasive tumor growth via Notch and PI3K/mTOR activation, opens opportunities for treatment in combination with standard Doxorubicin (DOX) chemotherapy. We hypothesized that the small molecule inhibitor SMI1182, which targets the catalytic domain of ASPH, and BEZ235, which targets PI3K/mTOR, could enhance the chemotherapeutic effects of DOX. Human CS1 (Grade 3) and CDS11 (Grade 2) conventional CS cell lines were treated with broad dose ranges of DOX, BEZ235, or SMI1182 as mono- or combination therapy to assess their anti-tumor effects on cell viability, toxicity, and motility.

METHODS

Mechanistic studies included the analysis of ASPH expression, Notch signaling, and insulin/IGF/IRS pathway activation through mTOR. DOX, BEZ235, or SMI1182 treatments caused dose-dependent cell loss and cytotoxicity.

RESULTS

SMI1182 and BEZ235, with or without DOX, significantly reduced directional motility. Combined treatments had additive cytotoxic effects linked to the reduced expression of ASPH, Notch transcription factors, and insulin receptor substrate type I, which positively regulates both ASPH and Notch.

CONCLUSIONS

Triple-drug treatment with DOX, SMI1182, and BEZ235 could potentially improve disease-free survival with CS by the simultaneous targeting of multiple upstream mediators of aggressive malignant tumor cell behavior.

Integrated gene-metabolite association network analysis reveals key metabolic pathways in gastric adenocarcinoma

Gastric adenocarcinoma is one of the most death cause cancers worldwide. Metabolomics is an effective approach for investigating the occurrence and progression of cancer and detecting prognostic biomarkers by studying the profiles of small bioactive molecules. To fully decipher the functional roles of the disrupted metabolites that modulate the cellular mechanism of gastric cancer, integrated gene-metabolite association network methods are critical to map the associations between metabolites and genes. In this study, we constructed a knowledge-based gene-metabolite association network of gastric cancer using the dysregulated metabolites and genes between gastric cancer patients and control group. The topological pathway analysis and gene-protein-metabolite-disease association analysis revealed four key gene-metabolite pathways which include eleven metabolites associated with modulated genes. The integrated gene-metabolite association network enables mechanistic investigation and provides a comprehensive overview regarding the investigation of molecular mechanisms of gastric cancer, which facilitates the in-depth understanding of metabolic biomarker roles in gastric cancer.

Effects of Scutellaria strigillosa Hemsl. extract on HepG2 cell proliferation and apoptosis through binding to aspartate β-hydroxylase

This study aims to examine the impacts of Scutellaria strigillosa Hemsl. (SSH) on the proliferation, apoptosis of human hepatoma cell HepG2 and screen the bioactive components. We found that SSH extract inhibited HepG2 proliferation, arrested cell division prior to S phase. Additionally, SSH extract exposure induced apoptosis, and increased the proportions of late apoptotic cells. Specifically, we focus on the inhibitory effect of SSH extract on aspartate β-hydroxylase, a key therapeutic target of hepatocellular carcinoma closely related with the proliferation and apoptosis of HepG2. We found SSH extract with notable inhibitory activity against aspartate β-hydroxylase, elucidated the main bioactive constituents by HPLC-Q-TOF/MS and Molecular docking analysis. In conclusion, these results provided the antiproliferative and proapoptotic effects of SSH on HepG2 cell, elucidated the main bioactive constituents based on aspartate β-hydroxylase inhibition. These data revealed the potential value of SSH and its bioactive components for the prevention and treatment of liver cancer for the first time.

Modification of Regulatory T Cell Epitopes Promotes Effector T Cell Responses to Aspartyl/Asparaginyl β-Hydroxylase

Cancer is a leading cause of death worldwide. The search for innovative therapeutic approaches is a principal focus of medical research. Vaccine strategies targeting a number of tumor-associated antigens are currently being evaluated. To date, none have garnered significant success. Purportedly, an immunosuppressive tumor microenvironment and the accumulation of regulatory T cells contribute to a lack of tumor vaccine efficacy. Aspartyl/asparaginyl β-hydroxylase (ASPH), a promising therapeutic target, is overexpressed in a variety of malignant tumors but is expressed negligibly in normal tissues. Computer analysis predicted that ASPH expresses four peptide sequences (epitopes) capable of stimulating regulatory T cell activity. The abolition of these putative regulatory T cell epitopes increased the CD4+ and CD8+ effector T cell responses to monocyte-derived dendritic cells pulsed with a modified, epitope-depleted version of ASPH in an ex vivo human lymphoid tissue-equivalent coculture system while simultaneously decreasing the overall number of FoxP3+ regulatory T cells. These findings suggest that the efficacy of all new vaccine candidates would profit from screening and eliminating potential tolerogenic regulatory T cell epitopes.

Adaptive antitumor immune response stimulated by bio-nanoparticle based vaccine and checkpoint blockade

BACKGROUND

Interactions between tumor and microenvironment determine individual response to immunotherapy. Triple negative breast cancer (TNBC) and hepatocellular carcinoma (HCC) have exhibited suboptimal responses to immune checkpoint inhibitors (ICIs). Aspartate β-hydroxylase (ASPH), an oncofetal protein and tumor associated antigen (TAA), is a potential target for immunotherapy.

METHODS

Subcutaneous HCC and orthotopic TNBC murine models were established in immunocompetent BALB/c mice with injection of BNL-T3 and 4 T1 cells, respectively. Immunohistochemistry, immunofluorescence, H&E, flow cytometry, ELISA and in vitro cytotoxicity assays were performed.

RESULTS

The ASPH-MYC signaling cascade upregulates PD-L1 expression on breast and liver tumor cells. A bio-nanoparticle based λ phage vaccine targeting ASPH was administrated to mice harboring syngeneic HCC or TNBC tumors, either alone or in combination with PD-1 blockade. In control, autocrine chemokine ligand 13 (CXCL13)-C-X-C chemokine receptor type 5 (CXCR5) axis promoted tumor development and progression in HCC and TNBC. Interactions between PD-L1+ cancer cells and PD-1+ T cells resulted in T cell exhaustion and apoptosis, causing immune evasion of cancer cells. In contrast, combination therapy (Vaccine+PD-1 inhibitor) significantly suppressed primary hepatic or mammary tumor growth (with distant pulmonary metastases in TNBC). Adaptive immune responses were attributed to expansion of activated CD4+ T helper type 1 (Th1)/CD8+ cytotoxic T cells (CTLs) that displayed enhanced effector functions, and maturation of plasma cells that secreted high titers of ASPH-specific antibody. Combination therapy significantly reduced tumor infiltration of immunosuppressive CD4+/CD25+/FOXP3+ Tregs. When the PD-1/PD-L1 signal was inhibited, CXCL13 produced by ASPH+ cancer cells recruited CXCR5+/CD8+ T lymphocytes to tertiary lymphoid structures (TLSs), comprising effector and memory CTLs, T follicular helper cells, B cell germinal center, and follicular dendritic cells. TLSs facilitate activation and maturation of DCs and actively recruit immune subsets to tumor microenvironment. These CTLs secreted CXCL13 to recruit more CXCR5+ immune cells and to lyse CXCR5+ cancer cells. Upon combination treatment, formation of TLSs predicts sensitivity to ICI blockade. Combination therapy substantially prolonged overall survival of mice with HCC or TNBC.

CONCLUSIONS

Synergistic antitumor efficacy attributable to a λ phage vaccine specifically targeting ASPH, an ideal TAA, combined with ICIs, inhibits tumor growth and progression of TNBC and HCC.

Aspartate β-Hydroxylase (ASPH) Expression in Acute Myeloid Leukemia: A Potential Novel Therapeutic Target

Background

Aspartate β-hydroxylase (ASPH) is an embryonic transmembrane protein aberrantly upregulated in cancer cells, associated with malignant transformation and, in some reports, with poor clinical prognosis.

Objective

To report the expression patterns of ASPH in acute myeloid leukemia (AML).

Methods

Cell surface expression of ASPH was measured via 8-color multiparameter flow cytometry in 41 AML patient samples (31 bone marrow, 10 blood) using fluorescein isothiocyanate (FITC)-conjugated anti-ASPH antibody, SNS-622. A mean fluorescent intensity (MFI) of 10 was used as a cutoff for ASPH surface expression positivity. Data regarding patient and disease characteristics were collected.

Results

ASPH surface expression was found on AML blasts in 16 samples (39%). Higher ASPH expression was seen in myeloblasts of African American patients (p=0.02), but no correlation was found between ASPH expression and other patient or disease characteristics. No association was found between ASPH status and CR rate (p=0.53), EFS (p=0.87), or OS (p=0.17).

Conclusions

ASPH is expressed on blasts in approximately 40% of AML cases, and may serve as a new therapeutically targetable leukemia-associated antigen.

Active site characterization and activity of the human aspartyl (asparaginyl) β-hydroxylase

Human aspartyl/asparaginyl beta-hydroxylase (HAAH) is a member of the superfamily of nonheme Fe2+/α-ketoglutarate (αKG) dependent oxygenase enzymes with a noncanonical active site. HAAH hydroxylates epidermal growth factor (EGF) like domains to form the β-hydroxylated product from substrate asparagine or aspartic acid and has been suggested to have a negative impact in a variety of cancers. In addition to iron, HAAH also binds divalent calcium, although the role of the latter is not understood. Herein, the metal binding chemistry and influence on enzyme stability and activity have been evaluated by a combined biochemical and biophysical approach. Metal binding parameters for the HAAH active site were determined by use of isothermal titration calorimetry, demonstrating a high-affinity regulatory binding site for Ca2+ in the catalytic domain in addition to the catalytic Fe2+ cofactor. We have analyzed various active site derivatives, utilizing LC-MS and a new HPLC technique to determine the role of metal binding and the second coordination sphere in enzyme activity, discovering a previously unreported residue as vital for HAAH turnover. This analysis of the in vitro biochemical function of HAAH furthers the understanding of its importance to cellular biochemistry and metabolic pathways.

The Placenta as a Target for Alcohol During Pregnancy: The Close Relation with IGFs Signaling Pathway

Alcohol is one of the most consumed drugs in the world, even during pregnancy. Its use is a risk factor for developing adverse outcomes, e.g. fetal death, miscarriage, fetal growth restriction, and premature birth, also resulting in fetal alcohol spectrum disorders. Ethanol metabolism induces an oxidative environment that promotes the oxidation of lipids and proteins, triggers DNA damage, and advocates mitochondrial dysfunction, all of them leading to apoptosis and cellular injury. Several organs are altered due to this harmful behavior, the brain being one of the most affected. Throughout pregnancy, the human placenta is one of the most important organs for women's health and fetal development, as it secretes numerous hormones necessary for a suitable intrauterine environment. However, our understanding of the human placenta is very limited and even more restricted is the knowledge of the impact of toxic substances in its development and fetal growth. So, could ethanol consumption during this period have wounding effects in the placenta, compromising proper fetal organ development? Several studies have demonstrated that alcohol impairs various signaling cascades within G protein-coupled receptors and tyrosine kinase receptors, mainly through its action on insulin and insulin-like growth factor 1 (IGF-1) signaling pathway. This last cascade is involved in cell proliferation, migration, and differentiation and in placentation. This review tries to examine the current knowledge and gaps in our existing understanding of the ethanol effects in insulin/IGFs signaling pathway, which can explain the mechanism to elucidate the adverse actions of ethanol in the maternal-fetal interface of mammals.

An Eight-CircRNA Assessment Model for Predicting Biochemical Recurrence in Prostate Cancer

Prostate cancer (PCa) is a high morbidity malignancy in males, and biochemical recurrence (BCR) may appear after the surgery. Our study is designed to build up a risk score model using circular RNA sequencing data for PCa. The dataset is from the GEO database, using a cohort of 144 patients in Canada. We removed the low abundance circRNAs (FPKM < 1) and obtained 546 circRNAs for the next step. BCR-related circRNAs were selected by Logistic regression using the “survival” and “survminer” R package. Least absolute shrinkage and selector operation (LASSO) regression with 10-fold cross-validation and penalty was used to construct a risk score model by “glmnet” R software package. In total, eight circRNAs (including circ_30029, circ_117300, circ_176436, circ_112897, circ_112897, circ_178252, circ_115617, circ_14736, and circ_17720) were involved in our risk score model. Further, we employed differentially expressed mRNAs between high and low risk score groups. The following Gene Ontology (GO) analysis were visualized by Omicshare Online tools. As per the GO analysis results, tumor immune microenvironment related pathways are significantly enriched. “CIBERSORT” and “ESTIMATE” R package were used to detect tumor-infiltrating immune cells and compare the level of microenvironment scores between high and low risk score groups. What’s more, we verified two of eight circRNA’s (circ_14736 and circ_17720) circular characteristics and tested their biological function with qPCR and CCK8 in vitro. circ_14736 and circ_17720 were detected in exosomes of PCa patients’ plasma. This is the first bioinformatics study to establish a prognosis model for prostate cancer using circRNA. These circRNAs were associated with CD8⁺ T cell activities and may serve as a circRNA-based liquid biopsy panel for disease prognosis.

An innovative cell selection approach in developing human cells overexpressing aspartyl/asparaginyl β-hydroxylase

Background and purpose:

Aspartyl/asparaginyl β-hydroxylase (ASPH) is abundantly expressed in malignant neoplastic cells. The establishment of a human cell line overexpressing ASPH could provide the native-like recombinant protein needed for developing theranostic probes. In the process of transfection, the obtained cells normally contain a range of cells expressing the different levels of the target of interest. In this paper, we report on our simple innovative approach in the selection of best-transfected cells with the highest expression of ASPH using subclone selection, quantitative real-time polymerase chain reaction, and gradual increment of hygromycin concentration.

Experimental approach:

To achieve this goal, human embryonic kidney (HEK 293T) cells were transfected with an ASPH-bearing pcDNA3.1/Hygro(+) vector. During antibiotic selection, single accumulations of the resistant cells were separately cultured and the ASPH mRNA levels of each flask were evaluated. The best subclones were treated with a gradually increasing amount of hygromycin. The ASPH protein expression of the obtained cells was finally evaluated using flow cytometry and immunocytochemistry.

Findings / Results:

The results showed that different selected subclones expressed different levels of ASPH. Furthermore, the gradual increment of hygromycin (up to 400mg/mL) improved the expression of ASPH. The best relative fold change in mRNA levels was 57.59 ± 4.11. Approximately 90.2% of HEK^ASPH cells overexpressed ASPH on their surface.

Conclusion and implications:

The experiments indicated that we have successfully constructed and evaluated a recombinant human cell line overexpressing ASPH on the surface. Moreover, our innovative selection approach provided an effective procedure for enriching highly expressing recombinant cells.

Diverse molecular functions of aspartate β‑hydroxylase in cancer (Review)

Aspartate/asparagine β-hydroxylase (AspH) is a type II transmembrane protein that catalyzes the post-translational hydroxylation of definite aspartyl and asparaginyl residues in epidermal growth factor-like domains of substrates. In the last few decades, accumulating evidence has indicated that AspH expression is upregulated in numerous types of human malignant cancer and is associated with poor survival and prognosis. The AspH protein aggregates on the surface of tumor cells, which contributes to inducing tumor cell migration, infiltration and metastasis. However, small-molecule inhibitors targeting hydroxylase activity can markedly block these processes, both in vitro and in vivo. Immunization of tumor-bearing mice with a phage vaccine fused with the AspH protein can substantially delay tumor growth and progression. Additionally, AspH antigen-specific CD4⁺ and CD8⁺ T cells were identified in the spleen of tumor-bearing mice. Therefore, these agents may be used as novel strategies for cancer treatment. The present review summarizes the current progress on the underlying mechanisms of AspH expression in cancer development.

Aspartate β-hydroxylase targeting in castration-resistant prostate cancer modulates the NOTCH/HIF1α/GSK3β crosstalk

Castration-resistant prostate cancer (CRPC) is an incurable stage of the disease. A multivariate principal component analysis on CRPC in vitro models identified aspartyl (asparaginyl) β hydrolase (ASPH) as the most relevant molecule associated with the CRPC phenotype. ASPH is overexpressed in various malignant neoplasms and catalyzes the hydroxylation of aspartyl and asparaginyl residues in the epidermal growth factor (EGF)-like domains of proteins like NOTCH receptors and ligands, enhancing cell motility, invasion and metastatic spread. Bioinformatics analyses of ASPH in prostate cancer (PCa) and CRPC datasets indicate that ASPH gene alterations have prognostic value both in PCa and CRPC patients. In CRPC cells, inhibition of ASPH expression obtained through specific small interfering RNA or culturing cells in hypoxic conditions, reduced cell proliferation, invasion and cyclin D1 expression through modulation of the NOTCH signaling. ASPH and HIF1α crosstalk, within a hydroxylation-regulated signaling pathway, might be transiently driven by the oxidative stress evidenced inside CRPC cells. In addition, increased phosphorylation of GSK3β by ASPH silencing demonstrates that ASPH regulates GSK3β activity inhibiting its interactions with upstream kinases. These findings demonstrate the critical involvement of ASPH in CRPC development and may represent an attractive molecular target for therapy.

Aspartate β-hydroxylase as a target for cancer therapy

As metastasis is a major cause of death in cancer patients, new anti-metastatic strategies are needed to improve cancer therapy outcomes. Numerous pathways have been shown to contribute to migration and invasion of malignant tumors. Aspartate β-hydroxylase (ASPH) is a key player in the malignant transformation of solid tumors by enhancing cell proliferation, migration, and invasion. ASPH also promotes tumor growth by stimulation of angiogenesis and immunosuppression. These effects are mainly achieved via the activation of Notch and SRC signaling pathways. ASPH expression is upregulated by growth factors and hypoxia in different human tumors and its inactivation may have broad clinical impact. Therefore, small molecule inhibitors of ASPH enzymatic activity have been developed and their anti-metastatic effect confirmed in preclinical mouse models. ASPH can also be targeted by monoclonal antibodies and has also been used as a tumor-associated antigen to induce both cluster of differentiation (CD) 8+ and CD4+ T cells in mice. The PAN-301-1 vaccine against ASPH has already been tested in a phase 1 clinical trial in patients with prostate cancer. In summary, ASPH is a promising target for anti-tumor and anti-metastatic therapy based on inactivation of catalytic activity and/or immunotherapy.

Prometastatic secretome trafficking via exosomes initiates pancreatic cancer pulmonary metastasis

To demonstrate multifaceted contribution of aspartate β-hydroxylase (ASPH) to pancreatic ductal adenocarcinoma (PDAC) pathogenesis, in vitro metastasis assay and patient derived xenograft (PDX) murine models were established. ASPH propagates aggressive phenotypes characterized by enhanced epithelial-mesenchymal transition (EMT), 2-D/3-D invasion, extracellular matrix (ECM) degradation/remodeling, angiogenesis, stemness, transendothelial migration and metastatic colonization/outgrowth at distant sites. Mechanistically, ASPH activates Notch cascade through direct physical interactions with Notch1/JAGs and ADAMs. The ASPH-Notch axis enables prometastatic secretome trafficking via exosomes, subsequently initiates MMPs mediated ECM degradation/remodeling as an effector for invasiveness. Consequently, ASPH fosters primary tumor development and pulmonary metastasis in PDX models, which was blocked by a newly developed small molecule inhibitor (SMI) specifically against ASPH's β-hydroxylase activity. Clinically, ASPH is silenced in normal pancreas, progressively upregulated from pre-malignant lesions to invasive/advanced stage PDAC. Relatively high levels of ASPH-Notch network components independently/jointly predict curtailed overall survival (OS) in PDAC patients (log-rank test, Ps < 0.001; Cox proportional hazards regression, P < 0.001). Therefore, ASPH-Notch axis is essential for propagating multiple-steps of metastasis and predicts prognosis of PDAC patients. A specific SMI targeting ASPH offers a novel therapeutic approach to substantially retard PDAC development/progression.

Kinetic parameters of human aspartate/asparagine-β-hydroxylase suggest that it has a possible function in oxygen sensing

Human aspartate/asparagine-β-hydroxylase (AspH) is a 2-oxoglutarate (2OG)-dependent oxygenase that catalyzes the post-translational hydroxylation of Asp and Asn residues in epidermal growth factor-like domains (EGFDs). Despite its biomedical significance, studies on AspH have long been limited by a lack of assays for its isolated form. Recent structural work has revealed that AspH accepts substrates with a noncanonical EGFD disulfide connectivity (i.e. the Cys 1-2, 3-4, 5-6 disulfide pattern). We developed stable cyclic thioether analogues of the noncanonical EGFD AspH substrates to avoid disulfide shuffling. We monitored their hydroxylation by solid-phase extraction coupled to MS. The extent of recombinant AspH-catalyzed cyclic peptide hydroxylation appears to reflect levels of EGFD hydroxylation observed in vivo, which vary considerably. We applied the assay to determine the kinetic parameters of human AspH with respect to 2OG, Fe(II), l-ascorbic acid, and substrate and found that these parameters are in the typical ranges for 2OG oxygenases. Of note, a relatively high Km for O2 suggested that O2 availability may regulate AspH activity in a biologically relevant manner. We anticipate that the assay will enable the development of selective small-molecule inhibitors for AspH and other human 2OG oxygenases.

Aspartate/asparagine-β-hydroxylase: a high-throughput mass spectrometric assay for discovery of small molecule inhibitors

The human 2-oxoglutarate dependent oxygenase aspartate/asparagine-β-hydroxylase (AspH) catalyses the hydroxylation of Asp/Asn-residues in epidermal growth factor-like domains (EGFDs). AspH is upregulated on the surface of malign cancer cells; increased AspH levels correlate with tumour invasiveness. Due to a lack of efficient assays to monitor the activity of isolated AspH, there are few reports of studies aimed at identifying small-molecule AspH inhibitors. Recently, it was reported that AspH substrates have a non-canonical EGFD disulfide pattern. Here we report that a stable synthetic thioether mimic of AspH substrates can be employed in solid phase extraction mass spectrometry based high-throughput AspH inhibition assays which are of excellent robustness, as indicated by high Z'-factors and good signal-to-noise/background ratios. The AspH inhibition assay was applied to screen approximately 1500 bioactive small-molecules, including natural products and active pharmaceutical ingredients of approved human therapeutics. Potent AspH inhibitors were identified from both compound classes. Our AspH inhibition assay should enable the development of potent and selective small-molecule AspH inhibitors and contribute towards the development of safer inhibitors for other 2OG oxygenases, e.g. screens of the hypoxia-inducible factor prolyl-hydroxylase inhibitors revealed that vadadustat inhibits AspH with moderate potency.

Aspartate β-hydroxylase promotes pancreatic ductal adenocarcinoma metastasis through activation of SRC signaling pathway

BACKGROUND

Signaling pathways critical for embryonic development re-emerge in adult pancreas during tumorigenesis. Aspartate β-hydroxylase (ASPH) drives embryonic cell motility/invasion in pancreatic development/differentiation. We explored if dysregulated ASPH is critically involved in pancreatic cancer pathogenesis.

METHODS

To demonstrate if/how ASPH mediates malignant phenotypes, proliferation, migration, 2-D/3-D invasion, pancreatosphere formation, immunofluorescence, Western blot, co-immunoprecipitation, invadopodia formation/maturation/function, qRT-PCR, immunohistochemistry (IHC), and self-developed in vitro metastasis assays were performed. Patient-derived xenograft (PDX) models of human pancreatic ductal adenocarcinoma (PDAC) were established to illustrate in vivo antitumor effects of the third-generation small molecule inhibitor specifically against ASPH's β-hydroxylase activity. Prognostic values of ASPH network components were evaluated with Kaplan-Meier plots, log-rank tests, and Cox proportional hazards regression models.

RESULTS

ASPH renders pancreatic cancer cells more aggressive phenotypes characterized by epithelial-mesenchymal transition (EMT), 2-D/3-D invasion, invadopodia formation/function as demonstrated by extracellular matrix (ECM) degradation, stemness (cancer stem cell marker upregulation and pancreatosphere formation), transendothelial migration (mimicking intravasation/extravasation), and sphere formation (mimicking metastatic colonization/outgrowth at distant sites). Mechanistically, ASPH activates SRC cascade through direct physical interaction with ADAM12/ADAM15 independent of FAK. The ASPH-SRC axis enables invadopodia construction and initiates MMP-mediated ECM degradation/remodeling as executors for invasiveness. Pharmacologic inhibition of invadopodia attenuates in vitro metastasis. ASPH fosters primary tumor development and pulmonary metastasis in PDX models of PDAC, which is blocked by a leading compound specifically against ASPH enzymatic activity. ASPH is silenced in normal pancreas, progressively upregulated from pre-malignant lesions to invasive/advanced stages of PDAC. Expression profiling of ASPH-SRC network components independently/jointly predicts clinical outcome of PDAC patients. Compared to a negative-low level, a moderate-very high level of ASPH, ADAM12, activated SRC, and MMPs correlated with curtailed overall survival (OS) of pancreatic cancer patients (log-rank test, ps < 0.001). The more unfavorable molecules patients carry, the more deleterious prognosis is destinated. Patients with 0-2 (n = 4), 3-5 (n = 8), 6-8 (n = 24), and 9-12 (n = 73) unfavorable expression scores of the 5 molecules had median survival time of 55.4, 15.9, 9.7, and 5.0 months, respectively (p < 0.001).

CONCLUSION

Targeting the ASPH-SRC axis, which is essential for propagating multi-step PDAC metastasis, may specifically/substantially retard development/progression and thus improve prognosis of PDAC.

ASPH-notch Axis guided Exosomal delivery of Prometastatic Secretome renders breast Cancer multi-organ metastasis

BACKGROUND

Aspartate β-hydroxylase (ASPH) is silent in normal adult tissues only to re-emerge during oncogenesis where its function is required for generation and maintenance of malignant phenotypes. Exosomes enable prooncogenic secretome delivering and trafficking for long-distance cell-to-cell communication. This study aims to explore molecular mechanisms underlying how ASPH network regulates designated exosomes to program development and progression of breast cancer.

METHODS

Stable cell lines overexpressing or knocking-out of ASPH were established using lentivirus transfection or CRISPR-CAS9 systems. Western blot, MTT, immunofluorescence, luciferase reporter, co-immunoprecipitation, 2D/3-D invasion, tube formation, mammosphere formation, immunohistochemistry and newly developed in vitro metastasis were applied.

RESULTS

Through physical interactions with Notch receptors, ligands (JAGs) and regulators (ADAM10/17), ASPH activates Notch cascade to provide raw materials (especially MMPs/ADAMs) for synthesis/release of pro-metastatic exosomes. Exosomes orchestrate EMT, 2-D/3-D invasion, stemness, angiogenesis, and premetastatic niche formation. Small molecule inhibitors (SMIs) of ASPH's β-hydroxylase specifically/efficiently abrogated in vitro metastasis, which mimics basement membrane invasion at primary site, intravasation/extravasation (transendothelial migration), and colonization/outgrowth at distant sites. Multiple organ-metastases in orthotopic and tail vein injection murine models were substantially blocked by a specific SMI. ASPH is silenced in normal adult breast, upregulated from in situ malignancies to highly expressed in invasive/advanced ductal carcinoma. Moderate-high expression of ASPH confers more aggressive molecular subtypes (TNBC or Her2 amplified), early recurrence/progression and devastating outcome (reduced overall/disease-free survival) of breast cancer. Expression profiling of Notch signaling components positively correlates with ASPH expression in breast cancer patients, confirming that ASPH-Notch axis acts functionally in breast tumorigenesis.

CONCLUSIONS

ASPH-Notch axis guides particularly selective exosomes to potentiate multifaceted metastasis. ASPH's pro-oncogenic/pro-metastatic properties are essential for breast cancer development/progression, revealing a potential target for therapy.

Recent advances in research on aspartate β-hydroxylase (ASPH) in pancreatic cancer: A brief update

Pancreatic cancer (PC) is a highly aggressive tumor, often difficult to diagnose and treat. Aspartate β-hydroxylase (ASPH) is a type II transmembrane protein and the member of α-ketoglutarate-dependent dioxygenase family, found to be overexpressed in different cancer types, including PC. ASPH appears to be involved in the regulation of proliferation, invasion and metastasis of PC cells through multiple signaling pathways, suggesting its role as a tumor biomarker and therapeutic target. In this review, we briefly summarize the possible mechanisms of action of ASPH in PC and recent progress in the therapeutic approaches targeting ASPH.

Hydroxylase Activity of ASPH Promotes Hepatocellular Carcinoma Metastasis Through Epithelial-to-Mesenchymal Transition Pathway

Over-expression of aspartyl (asparagynal)-β-hydroxylase (ASPH) contributes to hepatocellular carcinoma (HCC) invasiveness, but the role of ASPH hydroxylase activity in this process remains to be defined. As such, the current study investigated the role of ASPH hydroxylase activity in downstream signalling of HCC tumorgenesis and, specifically, metastasis development. Over-expression of wild-type ASPH, but not a hydroxylase mutant, promoted HCC cell migration in vitro, as well as intrahepatic and distant metastases in vivo. The enhanced migration and epithelial to mesenchymal transition (EMT) activation was notably absent in response to hydroxylase activity blockade. Vimentin, a regulator of EMT, interacted with ASPH and likely mediated the effect of ASPH hydroxylase activity with cell migration. The enhanced hydroxylase activity in tumor tissues predicted worse prognoses of HCC patients. Collectively, the hydroxylase activity of ASPH affected HCC metastasis through interacting with vimentin and regulating EMT. As such, ASPH might be a promising therapeutic target of HCC.

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Over-expression of ASPH promoted HCC intrahepatic and distant metastases in vivo.

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ASPH interacts with vimentin to promote HCC cell migration.

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Enhanced hydroxylase activity in tumor predicted worse prognoses of HCC patients.

Hepatocellular carcinoma has aggressive invasiveness and high metastatic rate. The reason for metastasis is largely unknown and the effective treatment is still lacking. Although over-expression of ASPH has been demonstrated to enhance hepatocellular carcinoma invasiveness, whether its hydroxylase activity is necessary remains uncharacterized. Here, we found the hydroxylase activity was critical to promote hepatocellular carcinoma invasiveness in vitro and metastasis in vivo, and associated with post-surgery survival. ASPH hydroxylase activity play an important role in epithelial-to-mesenchymal transition through interacting with vimentin. Our findings imply that ASPH antagonists might be promising in developing novel therapy.

Construction and Characterization of Adenovirus Vectors Encoding Aspartate-β-Hydroxylase to Preliminary Application in Immunotherapy of Hepatocellular Carcinoma

Dendritic cells (DCs) harboring tumor-associated antigen are supposed to be a potential immunotherapy for hepatocellular carcinoma (HCC). Aspartate-β-hydroxylase (AAH), an overexpressed tumor-associated cell surface protein, is considered as a promising biomarker and therapeutic target for HCC. In this study, we constructed adenovirus vector encoding AAH gene by gateway recombinant cloning technology and preliminarily explored the antitumor effects of DC vaccines harboring AAH. Firstly, the total AAH mRNA was extracted from human HCC tissues; the cDNA was amplified by RT-PCR, verified, and sequenced after TA cloning. Gateway technology was used and the obtained 18T-AAH was used as a substrate, to yield the final expression vector Ad-AAH-IRES2-EGFP. Secondly, bone marrow-derived DCs were infected by Ad-AAH-IRES2-EGFP to yield AAH-DC vaccines. Matured DCs were demonstrated by increased expression of CD11c, CD80, and MHC-II costimulatory molecules. A dramatically cell-killing effect of T lymphocytes coculturing with AAH-DCs on HepG2 HCC cell line was demonstrated by CCK-8 and FCM assays in vitro. More importantly, in an animal experiment, the lysis effect of cytotoxic T lymphocytes (CTLs) on HepG2 cells in the AAH-DC group was stronger than that in the control groups. In conclusion, the gateway recombinant cloning technology is a powerful method of constructing adenovirus vector, and the product Ad-AAH-IRES2-EGFP may present as a potential candidate for DC-based immunotherapy of HCC.

Endocrine sensitivity of estrogen receptor-positive breast cancer is negatively correlated with aspartate-β-hydroxylase expression

Although prognostic markers for early estrogen receptor (ER)‐positive breast cancer have been extensively developed, predictive markers for adjuvant endocrine therapy are still lacking. Focusing on the mechanisms underlying endocrine resistance, we investigated whether the endocrine sensitivity of ER‐positive breast cancer cells was correlated with the expression of aspartate‐β‐hydroxylase (ASPH), which is involved in the development of hepatocellular carcinoma. ASPH expression in ER‐positive and tamoxifen‐resistant breast cancer cells was upregulated by the MAPK and phosphoinositide‐3 kinase (PI3K) pathways, which both play pivotal roles in endocrine resistance. In the clinical setting, ASPH expression was negatively correlated with recurrence‐free survival of luminal B breast cancer patients that received adjuvant endocrine therapy, but not in patients that did not receive adjuvant endocrine therapy. Luminal B breast cancer is one of the intrinsic molecular subtypes identified by the Prediction Analysis of Microarray 50 (PAM50) multiple gene classifier, and because of its poor response to endocrine therapy, chemotherapy in addition to endocrine therapy is generally required after surgical resection. Our results suggest that the endocrine sensitivity of luminal B breast cancer can be assessed by examining ASPH expression, which promotes the consideration of a prospective study on the association between ASPH expression at the mRNA and protein levels in luminal B breast cancer and subsequent response to endocrine therapy.

Aspartate β-hydroxylase disrupts mitochondrial DNA stability and function in hepatocellular carcinoma

The mechanism of aberrant mitochondrial genome and function in hepatocellular carcinoma (HCC) remains largely unknown. Our previous study demonstrated an increased expression of aspartate β-hydroxylase (ASPH) in HCC tissues, which was associated with tumor invasiveness and a worse prognosis. Currently, we unexpectedly observed the presence of ASPH in purified mitochondrial protein fraction. In addition, immunostaining of both exogenously and endogenously expressed ASPH showed a colocalization with mitochondrial biomarkers. This study aimed to investigate whether the mitochondrial ASPH is involved in mitochondrial malfunction in HCC. Our results showed that ASPH overexpression in HCC tissues was correlated with decreased copy numbers of displacement loop (D-loop) and NADH dehydrogenase subunit 1 (ND-1) and enhanced D-loop mutation, suggesting the disrupted mitochondrial DNA (mtDNA) stability. The reduced mtDNA copy numbers were associated with aggressive clinicopathological features of HCC. The loss of mtDNA integrity induced by enforced expression of ASPH was accompanied with mitochondrial dysfunction, which was characterized by the aberrant mitochondrial membrane potential, decreased ATP generation and enhanced reactive oxygen species. In contrast, knocking down ASPH by siRNA in HCC cell lines showed the opposite impact on mtDNA integrity and function. Mass spectrometry and co-immunoprecipitation further identified that ASPH interacted with histone H2A member X (H2AX). ASPH overexpression diminished the interaction between H2AX and mitochondrial transcription factor A (mtTFA), an important DNA-binding protein for mtDNA replication, which then reduced the binding of mtTFA to D-loop region. Collectively, our results demonstrate that ASPH overexpression disrupts the mtDNA integrity through H2AX-mtTFA signal, thereby affecting mitochondrial functions in HCC.

Phosphorylation Modulates Aspartyl-(Asparaginyl)-β Hydroxylase Protein Expression, Catalytic Activity and Migration in Human Immature Neuronal Cerebellar Cells

Background

Abundant aspartyl-asparaginyl-β-hydroxylase (ASPH) expression supports robust neuronal migration during development, and reduced ASPH expression and function, as occur in fetal alcohol spectrum disorder, impair cerebellar neuron migration. ASPH mediates its effects on cell migration via hydroxylation-dependent activation of Notch signaling networks. Insulin and Insulin-like growth factor (IGF-1) stimulate ASPH mRNA transcription and enhance ASPH protein expression by inhibiting Glycogen Synthase Kinase-3β (GSK-3β). This study examines the role of direct GSK-3β phosphorylation as a modulator of ASPH protein expression and function in human cerebellar-derived PNET2 cells.

Methods

Predicted phosphorylation sites encoded by human ASPH were ablated by S/T→A site-directed mutagenesis of an N-Myc-tagged wildtype (WT) cDNA regulated by a CMV promoter. Phenotypic and functional features were assessed in transiently transfected PNET2 cells.

Results

Cells transfected with WT ASPH had increased ASPH protein expression, directional motility, Notch-1 and Jagged-1 expression, and catalytic activity relative to control. Although most single- and multi-point ASPH mutants also had increased ASPH protein expression, their effects on Notch and Jagged expression, directional motility and adhesion, and catalytic activity varied such that only a few of the cDNA constructs conferred functional advantages over WT. Immunofluorescence studies showed that ASPH phosphorylation site deletions can alter the subcellular distribution of ASPH and therefore its potential interactions with Notch/Jagged at the cell surface.

Conclusions

Inhibition of ASPH phosphorylation enhances ASPH protein expression, but attendant alterations in intra-cellular trafficking may govern the functional consequences in relation to neuronal migration, adhesion and Notch activated signaling.

Aspartate-β-hydroxylase (ASPH): A potential therapeutic target in human malignant gliomas

BACKGROUND

Despite therapeutic advances, survival with glioblastoma multiforme (GBM) remains below 15 months from diagnosis due to GBM's highly infiltrative nature which precludes complete surgical resection. Patient outcomes could potentially be improved by targeting genes and pathways that drive neoplastic cell motility and invasiveness, including hypoxia-inducible factor-1 (HIF-1α), NOTCH, and aspartate-β-hydroxylase (ASPH).

METHODS

Human astrocytoma biopsy specimens (n = 37), WHO Grades II-IV, were analyzed for levels and distributions of ASPH and HIF-1α immunoreactivity by immunohistochemical staining, and ASPH, Notch, JAG, HES1, HEY1 and HIF1α mRNA expression by quantigene multiplex analysis. The effects of small molecule inhibitors on ASPH's catalytic activity, cell viability and directional motility were examined in vitro in established GBM cell lines and primary tumor cells from an invasive mouse model of GBM.

RESULTS

The highest grade astrocytoma, i.e. GBM was associated with the highest levels of ASPH and HIF1α, and both proteins were more abundantly distributed in hypoxic compared with normoxic regions of tumor. Furthermore, mining of the TCGA database revealed higher levels of ASPH expression in the mesenchymal subtype of GBM, which is associated with more aggressive and invasive behavior. In contrast, lower grade astrocytomas had low expression levels of ASPH and HIF1α. In vitro experiments demonstrated that small molecule inhibitors targeting ASPH's catalytic activity significantly reduced GBM viability and directional motility. Similar effects occurred in GBM cells that were transduced with a lentiviral sh-ASPH construct.

CONCLUSION

This study demonstrates that increased ASPH expression could serve as a prognostic biomarker of gliomas and may assist in assigning tumor grade when biopsy specimens are scant. In addition, the findings suggest that GBM treatment strategies could be made more effective by including small molecule inhibitors of ASPH.

Aspartate β-hydroxylase modulates cellular senescence through glycogen synthase kinase 3β in hepatocellular carcinoma

Aspartate β-hydroxylase (ASPH) is an enzyme overexpressed in human hepatocellular carcinoma (HCC) tumors that participates in the malignant transformation process. We determined if ASPH was a therapeutic target by exerting effects on cellular senescence to retard HCC progression. ASPH knockdown or knockout was achieved by short hairpin RNAs or the CRISPR/Cas9 system, respectively, whereas enzymatic inhibition was rendered by a potent second-generation small molecule inhibitor of ASPH. Alterations of cell proliferation, colony formation, and cellular senescence were evaluated in human HCC cell lines. The potential mechanisms for activating cellular senescence were explored using murine subcutaneous and orthotopic xenograft models. Inhibition of ASPH expression and enzymatic activity significantly reduced cell proliferation and colony formation but induced tumor cell senescence. Following inhibition of ASPH activity, phosphorylation of glycogen synthase kinase 3β and p16 expression were increased to promote senescence, whereas cyclin D1 and proliferating cell nuclear antigen were decreased to reduce cell proliferation. The mechanisms involved demonstrate that ASPH binds to glycogen synthase kinase 3β and inhibits its subsequent interactions with protein kinase B and p38 upstream kinases as shown by coimmunoprecipitation. In vivo experiments demonstrated that small molecule inhibitor treatment of HCC bearing mice resulted in significant dose-dependent reduced tumor growth, induced phosphorylation of glycogen synthase kinase 3β, enhanced p16 expression in tumor cells, and promoted cellular senescence.

CONCLUSIONS

We have identified a new mechanism that promotes HCC growth and progression by modulating senescence of tumor cells; these findings suggest that ASPH enzymatic activity is a novel therapeutic target for HCC.

Potential Co-Factor Role of Tobacco Specific Nitrosamine Exposures in the Pathogenesis of Fetal Alcohol Spectrum Disorder

BACKGROUND

Cerebellar developmental abnormalities in Fetal Alcohol Spectrum Disorder (FASD) are linked to impairments in insulin signaling. However, co-morbid alcohol and tobacco abuses during pregnancy are common. Since smoking leads to tobacco specific Nitrosamine (NNK) exposures which have been shown to cause brain insulin resistance, we hypothesized that neurodevelopmental abnormalities in FASD could be mediated by ethanol and/or NNK.

METHODS

Long Evans rat pups were intraperitoneal (IP) administered ethanol (2 g/kg) on postnatal days (P) 2, 4, 6 and/or NNK (2 mg/kg) on P3, P5, and P7 to simulate third trimester human exposures. The Cerebellar function, histology, insulin and Insulin-like Growth Factor (IGF) signaling, and neuroglial protein expression were assessed.

RESULTS

Ethanol, NNK and ethanol+NNK groups had significant impairments in motor function (rotarod tests), abnormalities in cerebellar structure (Purkinje cell loss, simplification and irregularity of folia, and altered white matter), signaling through the insulin and IGF-1 receptors, IRS-1, Akt and GSK-3β, and reduced expression of several important neuroglial proteins. Despite similar functional effects, the mechanisms and severity of NNK and ethanol+NNK induced alterations in cerebellar protein expression differed from those of ethanol.

CONCLUSIONS

Ethanol and NNK exert independent but overlapping adverse effects on cerebellar development, function, insulin signaling through cell survival, plasticity, metabolic pathways, and neuroglial protein expression. The results support the hypothesis that tobacco smoke exposure can serve as a co-factor mediating long-term effects on brain structure and function in FASD.

Modulation of sensitivity and resistance to multikinase inhibitors by microenvironmental platelet factors in HCC

INTRODUCTION

Response of a tumor to chemotherapy or multikinase inhibitor therapy has been traditionally thought to be a reflection of the sum of the characteristics of both the drug and of the tumor cell resistance mechanisms. More recently, there has been a growing awareness of the role of non-tumor factors-both cellular and humoral-in the tumor microenvironment that can increase or decrease the tumor cellular responses to the therapy. This article focuses on platelet factors in clinical HCC and experimental evidence that they provide growth stimulants that can antagonize the growth inhibitory effects of therapy.

AREAS COVERED

Review of the mechanisms of multikinase cancer growth inhibitors and of the role of platelets in providing growth factors that can antagonize their effects.

EXPERT OPINION

These new ideas and data show that the response of a tumor to multikinase inhibitors or chemotherapy may be strongly influenced by microenvironmental factors. Conversely, antagonists to these environmental factors, such as EGFR inhibitors and IGF1-R inhibitors, might be expected to augment the anti-tumor effect of both chemotherapy and multikinase inhibitors.

Potential Role of Phosphorylation as a Regulator of Aspartyl-(asparaginyl)-β-hydroxylase: Relevance to Infiltrative Spread of Human Hepatocellular Carcinoma

Abundant expression of aspartyl-(asparaginyl)-β-hydroxylase (AAH) correlates with infiltrative growth of hepatocellular carcinoma (HCC). Herein, we examine the role of phosphorylation in relation to AAH's protein expression, hydroxylase activity, promotion of cell motility, and activation of Notch signaling in human Huh7 hepatoma cells. Predicted glycogen synthase kinase-3β (GSK-3β), protein kinase A (PKA), protein kinase C (PKC), and casein kinase 2 (CK2) phosphorylation sites encoded by human AAH cDNA were ablated by S/T→A site-directed mutagenesis using N-Myc-tagged constructs in which gene expression was controlled by a cytomegalovirus promoter. Functional consequences were assessed in transiently transfected Huh7 cells. Cells transfected with wildtype AAH had significantly increased AAH expression, catalytic activity, HES-1 expression, and directional motility relative to controls. Single phosphorylation site mutations in the C-terminus largely abrogated these effects and further inhibited catalytic activity relative to that in cells transfected with empty vector, whereas the effects of single point mutations within the N-terminus were more varied. In contrast, AAH cDNAs carrying multiple phosphorylation site mutations exhibited wildtype levels of AAH catalytic activity suggesting that the effects of AAH phosphorylation are complex and non-uniform. AAH expression and function can be modulated by direct phosphorylation of the protein. These findings suggest additional strategies for inhibiting infiltrative growth of HCC.

Dose effect of gestational ethanol exposure on placentation and fetal growth

INTRODUCTION

Prenatal ethanol exposure compromises fetal growth by impairing placentation. Invasive trophoblastic cells, which mediate placentation, express the insulin-IGF regulated gene, aspartyl-asparaginyl β-hydroxylase (ASPH), which has a critical role in cell motility and invasion. The aims of this study were to characterize effects of ethanol on trophoblastic cell motility, and assess ethanol dose-dependent impairments in placentation and fetal development.

METHODS

Pregnant Long Evans dams were fed with isocaloric liquid diets containing 0%, 8%, 18% or 37% ethanol (caloric content) from gestation day (GD) 6 to GD18. Fetal development, placental morphology, density of invasive trophoblasts at the mesometrial triangle, as well as placental and mesometrial ASPH and Notch-1 protein expression were evaluated. Directional motility of control and ethanol-exposed HTR-8/SVneo cells was assessed by ATP Luminescence-Based assay.

RESULTS

Severity of fetal growth impairment correlated with increasing doses of ethanol. Ethanol exposure produced dose-dependent alterations in branching morphogenesis at the labyrinthine zone, and inhibited physiological transformation of maternal arteries. ASPH and Notch-1 protein expression levels were reduced, corresponding with impairments in placentation.

DISCUSSION

Prenatal ethanol exposure compromises fetal growth and placentation in a dose-responsive manner. Ethanol's adverse effects on placental development are mediated by: (1) altered branching morphogenesis in labyrinthine zone; (2) suppression of invasive trophoblastic precursor cells; and (3) inhibition of trophoblastic cell adhesion and motility, corresponding with reduced ASPH and Notch-1 protein expression.

Aspartate-β-hydroxylase induces epitope-specific T cell responses in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has a poor prognosis due to high recurrence rate. Aspartate-β-hydroxylase (ASPH) is a highly conserved transmembrane protein, which is over expressed in HCC and promotes a malignant phenotype. The capability of ASPH protein-derived HLA class I and II peptides to generate antigen specific CD4(+) and CD8(+) immune responses is unknown. Therefore, these studies aim to define the epitope specific components required for a peptide based candidate vaccine. Monocyte-derived dendritic cells (DCs) generated from the peripheral blood mononuclear cells (PBMCs) of HCC patients were loaded with ASPH protein. Helper CD4(+) T cells and CD8(+) cytotoxic T lymphocytes (CTLs) were co-incubated with the DCs; T cell activation was evaluated by flow cytometric analysis. Immunoinformatics tools were used to predict HLA class I- and class II-restricted ASPH sequences, and the corresponding peptides were synthesized. The immunogenicity of each peptide in cultures of human PBMCs was determined by IFN-γ ELISpot assay. ASPH protein-loaded DCs activated both CD4(+) and CD8(+) T cells contained within the PBMC population derived from HCC patients. Furthermore, the predicted HLA class I- and class II-restricted ASPH peptides were significantly immunogenic. Both HLA class I- and class II-restricted peptides derived from ASPH induce T cell activation in HCC. We observed that ASPH protein and related peptides were highly immunogenic in patients with HCC and produce the type of cellular immune responses required for generation of anti-tumor activity.

Ceramide inhibitor myriocin restores insulin/insulin growth factor signaling for liver remodeling in experimental alcohol-related steatohepatitis

BACKGROUND AND AIM

Alcohol-related liver disease (ALD) is mediated in part by insulin resistance. Attendant dysregulation of lipid metabolism increases accumulation of hepatic ceramides that worsen insulin resistance and compromise the structural and functional integrity of the liver. Insulin and insulin growth factor (IGF) stimulate aspartyl-asparaginyl-β-hydroxylase (AAH), which promotes cell motility needed for structural maintenance and remodeling of the liver. AAH mediates its effects by activating Notch, and in ALD, insulin/IGF signaling, AAH, and Notch are inhibited.

METHOD

To test the hypothesis that in ALD, hepatic ceramide load contributes to impairments in insulin, AAH, and Notch signaling, control and chronic ethanol-fed adult Long-Evans rats were treated with myriocin, an inhibitor of serine palmitoyl transferase. Livers were used to assess steatohepatitis, insulin/IGF pathway activation, and expression of AAH-Notch signaling molecules.

RESULTS

Chronic ethanol-fed rats had steatohepatitis with increased ceramide levels; impairments in signaling through the insulin receptor, insulin receptor substrate, and Akt; and decreased expression of AAH, Notch, Jagged, Hairy-Enhancer of Split-1, hypoxia-inducible factor 1α, and proliferating cell nuclear antigen. Myriocin abrogated many of these adverse effects of ethanol, particularly hepatic ceramide accumulation, steatohepatitis, and impairments of insulin signaling through Akt, AAH, and Notch.

CONCLUSIONS

In ALD, the histopathology and impairments in insulin/IGF responsiveness can be substantially resolved by ceramide inhibitor treatments, even in the context of continued chronic ethanol exposure.

Upregulation of T-cell factor-4 isoform-responsive target genes in hepatocellular carcinoma

BACKGROUND

The Wnt/β-catenin signalling pathway regulates genes involved in cell proliferation, survival, migration and invasion through regulation by T-cell factor (TCF)-4 transcription factor proteins. However, the role of TCF-4 isoforms generated by alternative splicing events in hepatocellular carcinoma (HCC) is unknown.

AIM

Here, we investigated TCF-4 isoforms (TCF-4J and K)-responsive target genes that are important in hepatic oncogenesis and tumour development.

METHODS

Gene expression microarray was performed on HCC cells overexpressing TCF-4J and K isoforms. Expression level of selected target genes was evaluated and correlations were made between their expression level and that of TCF-4 isoform in 47 pairs of human HCC tumours.

RESULTS

Comparison by gene expression microarray revealed that 447 genes were upregulated and 343 downregulated more than 2.0-fold in TCF-4J compared with TCF-4K expressing cells. We validated expression of 18 selected target genes involved in Wnt/β-catenin, insulin/IGF-1/IRS1 and Notch signalling pathways in 47 pairs of human HCCs and adjacent uninvolved liver tissues. It was observed that 13 genes (CLDN2, STK17B, SPP1, AXIN2, WISP2, MMP7, IRS1, ANXA1, CAMK2N1, ASPH, GPR56, CD24 and JAG1) activated by TCF-4J isoform in HCC cells, were also upregulated in HCC tumours compared with adjacent peritumour tissue; more importantly, 10 genes exhibited a significant correlation with the TCF-4J expression level in tumour.

CONCLUSION

TCF-4 isoforms (TCF-4J and K) activated different downstream target genes in HCC. The biological consequence of TCF-4J isoform expression was upregulation of genes associated with tripartite Wnt/β-catenin, insulin/IGF-1/IRS1 and Notch signal transduction pathway activation, which contribute to the pathogenesis of HCC.

Tumor progression-related transmembrane protein aspartate-β-hydroxylase is a target for immunotherapy of hepatocellular carcinoma

BACKGROUND & AIMS

Hepatocellular carcinoma (HCC) has a poor survival rate due to recurrent intrahepatic metastases and lack of effective adjuvant therapy. Aspartate-β-hydroxylase (ASPH) is an attractive cellular target since it is a highly conserved transmembrane protein overexpressed in both murine and human HCC tumors, and promotes a malignant phenotype as characterized by enhanced tumor cell migration and invasion.

METHODS

Dendritic cells (DCs), expanded and isolated from the spleen, were incubated with a cytokine cocktail to optimize IL-12 secretion and co-stimulatory molecule expression, then subsequently loaded with ASPH protein for immunization. Mice were injected with syngeneic BNL HCC tumor cells followed by subcutaneous inoculation with 5-10×10(5) ASPH loaded DCs using a prophylactic and therapeutic experimental approach. Tumor infiltrating lymphocytes (TILs) were characterized, and their role in producing anti-tumor effects determined. The immunogenicity of ASPH protein with respect to activating antigen specific CD4+ T cells derived from human peripheral blood mononuclear cells (PBMCs) was also explored.

RESULTS

We found that immunotherapy with ASPH-loaded DCs suppressed and delayed established HCC and tumor growth when administered prophylactically. Ex-vivo re-stimulation experiments and in vivo depletion studies demonstrated that both CD4+ and CD8+ cells contributed to anti-tumor effects. Using PBMCs derived from healthy volunteers and HCC patients, we showed that ASPH stimulation led to significant development of antigen-specific CD4+ T-cells.

CONCLUSIONS

Immunization with ASPH-loaded DCs has substantial anti-tumor effects which could reduce the risk of HCC recurrence.

Glial vascular degeneration in CADASIL

CADASIL is a genetic vascular dementia caused by mutations in the Notch 3 gene on Chromosome 19. However, little is known about the mechanisms of vascular degeneration. We characterized upstream components of Notch signaling pathways that may be disrupted in CADASIL, by measuring expression of insulin, IGF-1, and IGF-2 receptors, Notch 1, Notch 3, and aspartyl-(asparaginyl)-β-hydroxylase (AAH) in cortex and white matter from 3 CADASIL and 6 control brains. We assessed CADASIL-associated cell loss by measuring mRNA corresponding to neurons, oligodendroglia, and astrocytes, and indices of vascular degeneration by measuring smooth muscle actin (SMA) and endothelin-1 expression in isolated vessels. Immunohistochemical staining was used to assess SMA degeneration. Significant abnormalities, including reduced cerebral white matter mRNA levels of Notch 1, Notch 3, AAH, SMA, IGF receptors, myelin-associated glycoproteins, and glial fibrillary acidic protein, and reduced vascular expression of SMA, IGF receptors, Notch 1, and Notch 3 were detected in CADASIL-lesioned brains. In addition, we found CADASIL-associated reductions in SMA, and increases in ubiquitin immunoreactivity in the media of white matter and meningeal vessels. No abnormalities in gene expression or immunoreactivity were observed in CADASIL cerebral cortex. In conclusion, molecular abnormalities in CADASIL are largely restricted to white matter and white matter vessels, corresponding to the distribution of neuropathological lesions. These preliminary findings suggest that CADASIL is mediated by both glial and vascular degeneration with reduced expression of IGF receptors and AAH, which regulate Notch expression and function.

Gene-environment interactions of novel variants associated with head and neck cancer

BACKGROUND

A genome-wide association study for upper aerodigestive tract cancers identified 19 candidate single-nucleotide polymorphisms (SNPs). We used these SNPs to investigate the potential gene-gene and gene-environment interactions in head and neck squamous cell carcinoma (HNSCC) risk.

METHODS

The 19 variants were genotyped using Taqman assays among 575 cases and 676 controls in our population-based case-control study.

RESULTS

A restricted cubic spline model suggested both ADH1B and HEL308 modified the association between smoking pack-years and HNSCC. Classification and regression tree analysis demonstrated a higher-order interaction between smoking status, ADH1B, FLJ13089, and FLJ35784 in HNSCC risk. Compared with ever smokers carrying ADH1B T/C+T/T genotypes, smokers carrying ADH1B C/C genotype and FLJ13089 A/G+A/A genotypes had the highest risk of HNSCC (odds ratio = 1.84).

CONCLUSIONS

Our results suggest that the risk associated with these variants may be specifically important among specific exposure groups.

siRNA inhibition of aspartyl-asparaginyl β-hydroxylase expression impairs cell motility, Notch signaling, and fetal growth

Aspartyl-asparaginyl-β-hydroxylase (AAH) regulates cell motility and invasiveness by enhancing Notch signaling. Invasive trophoblastic cells, which mediate placentation, normally express high levels of AAH. Previously, we showed that ethanol-impaired placentation is associated with reduced AAH expression. The present study determines the degree to which inhibition of AAH expression is sufficient to impair functions required for placentation. Immortalized, first trimester-derived, human trophoblastic cells (HTR-8/SVneo) were transfected with siRNA targeting AAH (siRNA-AAH) or no specific sequences (siRNA-Scr) using the Amaxa electroporation system. Directional motility was measured using an ATP luminescence-based assay. For in vivo studies, we microinjected siRNA-AAH or siRNA-Scr directly into the implantation sites (mesometrial triangle) of gestation-day-17, Long Evans pregnant rats, and harvested placentas 24 h later for histologic and molecular studies. siRNA-AAH transfection reduced AAH expression and directional motility in HTR-8/SVneo cells. In vivo delivery of siRNA-AAH reduced AAH expression and mean number of invasive trophoblastic cells at the implantation site. These adverse effects of siRNA-AAH were associated with impaired fetal growth and significantly reduced expression of Notch-signaling network genes. AAH is an important, positive regulator of trophoblastic cell motility, and inhibition of AAH in vivo leads to impaired implantation and fetal growth, and alters Notch-signaling mechanisms, similar to the effects of chronic ethanol exposure.

Single-chain variable fragment antibody against human aspartyl/asparaginyl beta-hydroxylase expressed in recombinant Escherichia coli

The human aspartyl beta-hydroxylase (HAAH) is a highly conserved enzyme that hydroxylates epidermal growth factor-like domains in transformation-associated proteins. Previous studies showed that the gene of HAAH was overexpressed in many human malignancies. In the present study, the HAAH-specific single-chain variable fragment (ScFv) antibody was produced in recombinant Escherichia coli. The variable regions of the genes of the heavy chain (VH) and light chain (VL) cloned from the hybridoma cells G3/F11 were connected with a flexible linker using an overlap extension polymerase chain reaction. Nucleotide sequence analysis revealed that the anti-HAAH VH was a member of the VH V gene family and the VL gene belonged to the Vκ gene family VI subgroup. Extensive efforts to express the functional ScFv antibody in E. coli have been made by using two different prokaryotic expression vectors-pHEN1 and pET-16b-to compare the expression level and solubility of the antibody. The recombinant pHEN1/E1-anti-HAAH vector could express soluble ScFv, although the yield was only 7.8% of the total cellular protein. However, the pET-16b/E2-anti-HAAH vector produced the ScFv as inclusion bodies inside the host cytoplasm, although the expression level of the antibody was quite high (28.5% of the total cellular protein). Soluble ScFv antibody produced by pHEN1/E1-anti-HAAH was characterized for its antigen-binding characteristics. Its antigen affinity as antibody was measured by indirect enzyme linked immunosorbent assay analysis and proved to have high binding activity to the antigen HAAH.

Peroxisome proliferator-activated receptor agonist treatment of alcohol-induced hepatic insulin resistance

AIM

  Chronic ethanol exposure impairs insulin signaling in the liver. Peroxisome-proliferator activated receptor (PPAR) agonists function as insulin sensitizers and are used to treat type 2 diabetes mellitus. We examined the therapeutic effectiveness of PPAR agonists in reducing alcoholic hepatitis and hepatic insulin resistance in a model of chronic ethanol feeding.

METHODS

  Adult male Long Evans rats were pair fed with isocaloric liquid diets containing 0% (control) or 37% ethanol (caloric content; 9.2% v/v) for 8 weeks. After 3 weeks on the diets, the rats were treated with vehicle, or a PPAR-α, PPAR-δ or PPAR-γ agonist twice weekly by i.p. injection. Livers were harvested for histopathological, gene expression (reverse transcription polymerase chain reaction), protein (western and ELISA) and receptor binding studies.

RESULTS

  Ethanol-fed rats developed steatohepatitis with disordered hepatic chord architecture, increased hepatocellular apoptosis, reduced binding to the insulin, insulin-like growth factor (IGF)-1 and IGF-2 receptors, and decreased expression of glyceraldehyde-3-phosphate dehydrogenase and aspartyl-(asparaginyl)-β-hydroxylase (mediating remodeling), which are regulated by insulin/IGF signaling. PPAR-α, PPAR-δ or PPAR-γ agonist treatments reduced the severity of ethanol-mediated liver injury, including hepatic architectural disarray and steatosis. In addition, PPAR-δ and PPAR-γ agonists reduced insulin/IGF resistance and increased insulin/IGF-responsive gene expression.

CONCLUSION

  PPAR agonists may help reduce the severity of chronic ethanol-induced liver injury and insulin/IGF resistance, even in the context of continued high-level ethanol consumption.

si-RNA inhibition of brain insulin or insulin-like growth factor receptors causes developmental cerebellar abnormalities: relevance to fetal alcohol spectrum disorder

BACKGROUND

In experimental models of fetal alcohol spectrum disorder (FASD), cerebellar hypoplasia and hypofoliation are associated with insulin and insulin-like growth factor (IGF) resistance with impaired signaling through pathways that mediate growth, survival, plasticity, metabolism, and neurotransmitter function. To more directly assess the roles of impaired insulin and IGF signaling during brain development, we administered intracerebroventricular (ICV) injections of si-RNA targeting the insulin receptor, (InR), IGF-1 receptor (IGF-1R), or IGF-2R into postnatal day 2 (P2) Long Evans rat pups and examined the sustained effects on cerebellar function, structure, and neurotransmitter-related gene expression (P20).

RESULTS

Rotarod tests on P20 demonstrated significant impairments in motor function, and histological studies revealed pronounced cerebellar hypotrophy, hypoplasia, and hypofoliation in si-InR, si-IGF-1R, and si-IGF-2R treated rats. Quantitative RT-PCR analysis showed that si-InR, and to a lesser extent si-IGF-2R, broadly inhibited expression of insulin and IGF-2 polypeptides, and insulin, IGF-1, and IGF-2 receptors in the brain. ELISA studies showed that si-InR increased cerebellar levels of tau, phospho-tau and β-actin, and inhibited GAPDH. In addition, si-InR, si-IGF-1R, and si-IGF-2R inhibited expression of choline acetyltransferase, which mediates motor function. Although the ICV si-RNA treatments generally spared the neurotrophin and neurotrophin receptor expression, si-InR and si-IGF-1R inhibited NT3, while si-IGF-1R suppressed BDNF.

CONCLUSIONS

early postnatal inhibition of brain InR expression, and to lesser extents, IGF-R, causes structural and functional abnormalities that resemble effects of FASD. The findings suggest that major abnormalities in brains with FASD are mediated by impairments in insulin/IGF signaling. Potential therapeutic strategies to reduce the long-term impact of prenatal alcohol exposure may include treatment with agents that restore brain insulin and IGF responsiveness.

Role of aspartyl-(asparaginyl)-β-hydroxylase mediated notch signaling in cerebellar development and function

BACKGROUND

Aspartyl-(Asparaginyl)-β-Hydroxylase (AAH) is a hydroxylating enzyme that promotes cell motility by enhancing Notch-Jagged-HES-1 signaling. Ethanol impaired cerebellar neuron migration during development is associated with reduced expression of AAH.

METHODS

To further characterize the role of AAH in relation to cerebellar development, structure, and function, we utilized an in vivo model of early postnatal (P2) intracerebro-ventricular gene delivery to silence AAH with small interfering RNA (siAAH), or over-express it with recombinant plasmid DNA (pAAH). On P20, we assessed cerebellar motor function by rotarod testing. Cerebella harvested on P21 were used to measure AAH, genes/proteins that mediate AAH's downstream signaling, i.e. Notch-1, Jagged-1, and HES-1, and immunoreactivity corresponding to neuronal and glial elements.

RESULTS

The findings demonstrated that: 1) siAAH transfection impaired motor performance and blunted cerebellar foliation, and decreased expression of neuronal and glial specific genes; 2) pAAH transfection enhanced motor performance and increased expression of neuronal and glial cytoskeletal proteins; and 3) alterations in AAH expression produced similar shifts in Notch-1, Jagged-1, and HES-1 protein or gene expression.

CONCLUSIONS

The results support our hypothesis that AAH is an important mediator of cerebellar development and function, and link AAH expression to Notch signaling pathways in the developing brain.

Aspartyl-(asparaginyl) beta-hydroxylase, hypoxia-inducible factor-alpha and Notch cross-talk in regulating neuronal motility

Aspartyl-(Asparaginyl)-β-Hydroxylase (AAH ) promotes cell motility by hydroxylating Notch. Insulin and insulin-like growth factor, type 1 (IGF-I) stimulate AAH through Erk MAP K and phosphoinositol-3-kinase-Akt (PI3K-Akt). However, hypoxia/oxidative stress may also regulate AAH . Hypoxia-inducible factor-1alpha (HIF-1α) regulates cell migration, signals through Notch, and is regulated by hypoxia/oxidative stress, insulin/IGF signaling and factor inhibiting HIF-1α (FIH) hydroxylation. To examine cross-talk between HIF-1α and AAH , we measured AAH , Notch-1, Jagged-1, FIH, HIF-1α, HIF-1β and the hairy and enhancer of split 1 (HE S-1) transcription factor expression and directional motility in primitive neuroectodermal tumor 2 (PNET2) human neuronal cells that were exposed to H₂O₂ or transfected with short interfering RNA duplexes (siRNA) targeting AAH , Notch-1 or HIF-1α. We found that: (1) AAH , HIF-1α and neuronal migration were stimulated by H2O2; (2) si-HIF-1α reduced AAH expression and cell motility; (3) si-AAH inhibited Notch and cell migration, but not HIF-1α and (4) si-Notch-1 increased FIH and inhibited HIF-1α. These findings suggest that AAH and HIF-1α crosstalk within a hydroxylation-regulated signaling pathway that may be transiently driven by oxidative stress and chronically regulated by insulin/IGF signaling.

Overexpression of aspartyl-(asparaginyl)-beta-hydroxylase in hepatocellular carcinoma is associated with worse surgical outcome

The association between the overexpression of aspartyl-(asparaginyl)-beta-hydroxylase (AAH) and the invasiveness of hepatocellular carcinoma (HCC) in vitro has been reported. However, the prognostic value of AAH expression in HCC remains unclear. The purpose of this study was to investigate the relationship between AAH expression, tumor recurrence, and patient survival. We identified AAH as the most overexpressed gene in HCC by way of complementary DNA microarray hybridization. A prospective study of 233 patients undergoing curative resection indicated that AAH expression was an independent factor affecting recurrence (hazard ratio [HR] 3.161, 95% confidence interval [CI] 2.115-4.724, P < 0.001) and survival (HR 2.712, 95% CI 1.734-4.241, P < 0.001). Patients with AAH overexpression had a poorer prognosis than those with AAH underexpression (P < 0.001 for both recurrence and survival). In Barcelona Clinic Liver Cancer stage A patients with AAH overexpression or underexpression, the tumor recurrence and survival rates were also statistically different (45% and 85% versus16% and 33% in 1- and 3-year cumulative recurrence rates, respectively; 73% and 37% versus 90% and 80% in 1- and 3-year survival rates, respectively; P < 0.001 for both). Furthermore, in stage A patients with tumors measuring < or =5 cm in diameter, the time to recurrence was 26.7 +/- 1.6 versus 51.9 +/- 2.8 months, and the 1- and 3- year survival rates were 97% and 52% versus 100% and 90% in AAH overexpression and underexpression patients, respectively (P < 0.001 for both).

CONCLUSION

AAH overexpression in HCC is strongly correlated with worse surgical outcome, and this molecule likely provides a more precise prognostic predictor in early stage HCCs.

Monoclonal antibodies against human aspartyl (asparaginyl) beta-hydroxylase developed by DNA immunization

We newly cloned the gene encoding the human aspartyl (asparaginyl) beta-hydroxylase (HAAH) from the surgical tissue of a patient with hepatocellular carcinoma. This study was designed to generate HAAH-specific monoclonal antibody (MAb) for further exploration of its structure and function. Mice were co-immunized with naked plasmid DNA containing N-terminal domain of encoding HAAH gene and recombinant HAAH polypeptide. Hybridomas were developed by the electrofusion of the splenocytes from mice immunized with plasmid DNA to Sp2/0 myeloma cells in vitro. Three hybridoma cell lines (designated G3, G9, and F11, respectively) stably secreting HAAH-specific MAbs were obtained. The specificity and sensitivity of MAbs were assessed by indirect enzyme-linked immunosorbent assay (ELISA) and Western blot analysis. Results showed that the three MAbs belong to IgG1 kappa isotype, the titer of MAbs reached was 5 x 10(4) - 1 x 10(5), and the affinity constant (k(aff)) of MAbs ranged between 2.5 x 10(8) - 1.1 x 10(9). MAb G3 was preliminarily applied to detection expression of HAAH for seven tumor tissues, including hepatocellular carcinoma, lung cancer, kidney cancer, cholangiocarcinoma, prostate cancer, breast cancer, and glioblastoma by immunohistochemical stain. Our studies demonstrated that co-immunization of naked DNA containing encoding gene of target antigen and recombinant target protein, and combined with in vitro electrofusion, is an effective and simple method to raise MAbs.

Collagen and calcium-binding EGF domains 1 is frequently inactivated in ovarian cancer by aberrant promoter hypermethylation and modulates cell migration and survival

Background:

Collagen and calcium-binding EGF domains 1 (CCBE1) is an uncharacterised gene that has down-regulated expression in breast cancer. As CCBE1 maps to 18q21.32, a region frequently exhibiting loss of heterozygosity in ovarian cancer, the aim of this study was to determine the expression and function of CCBE1 in ovarian cancer.

Methods:

Expression and methylation patterns of CCBE1 were determined in ovarian cancer cell lines and primary tumours. CCBE1 contains collagen repeats and an aspartic acid/asparagine hydroxylation/EGF-like domain, suggesting a function in extracellular matrix remodelling and migration, which was determined using small-interfering RNA (siRNA)-mediated knockdown and over-expression of CCBE1 in cell lines.

Results:

CCBE1 is expressed in normal ovary, but is reduced in ovarian cancer cell lines and primary carcinomas. Pharmacological demethylation/deacetylation in ovarian cancer cell lines re-induced CCBE1 expression, indicating that epigenetic mechanisms contribute to its silencing in cancer. CCBE1 promoter hypermethylation was detected in 6/11 (55%) ovarian cancer cell lines and 38/81 (41%) ovarian carcinomas. siRNA-mediated knockdown of CCBE1 in ovarian cancer cell lines enhanced their migration; conversely, re-expression of CCBE1 reduced migration and survival. Hence, loss of CCBE1 expression may promote ovarian carcinogenesis by enhancing migration and cell survival.

Conclusions:

These data suggest that CCBE1 is a new candidate tumour suppressor in ovarian cancer.

Alternative splicing in the differentiation of human embryonic stem cells into cardiac precursors

The role of alternative splicing in self-renewal, pluripotency and tissue lineage specification of human embryonic stem cells (hESCs) is largely unknown. To better define these regulatory cues, we modified the H9 hESC line to allow selection of pluripotent hESCs by neomycin resistance and cardiac progenitors by puromycin resistance. Exon-level microarray expression data from undifferentiated hESCs and cardiac and neural precursors were used to identify splice isoforms with cardiac-restricted or common cardiac/neural differentiation expression patterns. Splice events for these groups corresponded to the pathways of cytoskeletal remodeling, RNA splicing, muscle specification, and cell cycle checkpoint control as well as genes with serine/threonine kinase and helicase activity. Using a new program named AltAnalyze (http://www.AltAnalyze.org), we identified novel changes in protein domain and microRNA binding site architecture that were predicted to affect protein function and expression. These included an enrichment of splice isoforms that oppose cell-cycle arrest in hESCs and that promote calcium signaling and cardiac development in cardiac precursors. By combining genome-wide predictions of alternative splicing with new functional annotations, our data suggest potential mechanisms that may influence lineage commitment and hESC maintenance at the level of specific splice isoforms and microRNA regulation.

The reprogramming of pluripotent stem cells from adult cells is a crucial step toward producing patient-specific cells for transplant therapy. Critical to this goal is the ability to reproducibly drive the differentiation of these cells to specific fates, such as cardiac and neural cells. While gene expression is important in tissue specific differentiation, the impact of alternative splicing on the biology of differentiating cells has not been fully realized. To identify specific splicing events that may determine cell-type-specific differentiation, we compared splicing profiles of human embryonic stem cells (ESCs) and derived cardiac and neural precursors using Affymetrix exon tiling arrays. Segregation of splicing profiles into cardiac-restricted and common cardiac/neural differentiation pattern groups revealed unique groups of genes with clear implications for the biology of cardiomyocyte function and the maintenance of pluripotent ESCs. Alternative splicing of many of these genes, notably regulators of cell death and proliferation, were often predicted to impact protein domain or microRNA binding site inclusion, suggesting that the function or expression of these proteins is altered during differentiation. These results provide further evidence that alternative splicing is important in shaping the functional repertoire of ESCs and differentiated cells.

Overexpression of insulin receptor substrate-1 and hepatitis Bx genes causes premalignant alterations in the liver

Activation of the insulin (IN)/insulin receptor substrate-1 (IRS-1)/mitogen-associated protein kinase (MAPK) and the Wnt/beta-catenin signaling cascades occurs frequently in hepatocellular carcinoma (HCC) associated with persistent viral infection. The aims of this study were to provide a chronic proliferative stimulus through IRS-1 in the context of hepatitis Bx (HBx) protein expression in transgenic mice and determine if constitutive expression of these genes is sufficient to cause hepatocyte dysplasia and cellular transformation. We generated transgenic mice in which the HBx (ATX), IRS-1, or both (ATX+/IRS-1) genes were expressed under a liver-specific promoter. We also assessed histology and oxidative damage as well as up-regulation of molecules related to these signal transduction cascades in the liver by quantitative reverse-transcriptase polymerase chain reaction. Whereas mice with a single transgene (ATX or IRS-1) did not develop tumors, ATX+/IRS-1+ double transgenic livers had increased frequency of hepatocellular dysplasia and developed HCC. All three transgenic lines had significantly increased insulin growth factor 1 (IGF-1), Wnt 1 and Wnt 3 mRNA levels, and evidence of DNA damage and oxidative stress. The ATX+/IRS+ double transgenic mice were distinguished by having the highest level of activation of Wnt 3 and Frizzled 7 and selectively increased expression of IGF-II, proliferating cell nuclear antigen, and aspartyl-(asparaginyl)-beta-hydroxylase, a gene associated with increased cell migration.

CONCLUSION

These results suggest that continued expression of the ATX or IRS-1 transgenes can contribute to hepatocyte transformation but are not sufficient to trigger neoplastic changes in the liver. However, dual expression that activates both the IN/IRS-1/MAPK and Wnt/beta-catenin cascades is sufficient to cause dysplasia and HCC in a previously normal liver.

Ethanol inhibition of aspartyl-asparaginyl-beta-hydroxylase in fetal alcohol spectrum disorder: potential link to the impairments in central nervous system neuronal migration

Fetal alcohol spectrum disorder (FASD) is caused by prenatal exposure to alcohol and associated with hypoplasia and impaired neuronal migration in the cerebellum. Neuronal survival and motility are stimulated by insulin and insulin-like growth factor (IGF), whose signaling pathways are major targets of ethanol neurotoxicity. To better understand the mechanisms of ethanol-impaired neuronal migration during development, we examined the effects of chronic gestational exposure to ethanol on aspartyl (asparaginyl)-beta-hydroxylase (AAH) expression, because AAH is regulated by insulin/IGF and mediates neuronal motility. Pregnant Long-Evans rats were pair-fed isocaloric liquid diets containing 0, 8, 18, 26, or 37% ethanol by caloric content from gestation day 6 through delivery. Cerebella harvested from postnatal day 1 pups were used to examine AAH expression in tissue, and neuronal motility in Boyden chamber assays. We also used cerebellar neuron cultures to examine the effects of ethanol on insulin/IGF-stimulated AAH expression, and assess the role of GSK-3beta-mediated phosphorylation on AAH protein levels. Chronic gestational exposure to ethanol caused dose-dependent impairments in neuronal migration and corresponding reductions in AAH protein expression in developing cerebella. In addition, prenatal ethanol exposure inhibited insulin and IGF-I-stimulated directional motility in isolated cerebellar granule neurons. Ethanol-treated neuronal cultures (50mMx96h) also had reduced levels of AAH protein. Mechanistically, we showed that AAH protein could be phosphorylated on Ser residues by GSK-3beta, and that chemical inhibition of GSK-3beta and/or global Caspases increases AAH protein in both control- and ethanol-exposed cells. Ethanol-impaired neuronal migration in FASD is associated with reduced AAH expression. Because ethanol increases the activities of both GSK-3beta and Caspases, the inhibitory effect of ethanol on neuronal migration could be mediated by increased GSK-3beta phosphorylation and Caspase degradation of AAH protein.