C. Turato

SERPINB3 induces epithelial–mesenchymal transition†

Epithelial–mesenchymal transition is believed to facilitate invasion and metastasis formation of epithelial tumour cells. SERPINB3 is a serine protease inhibitor, physiologically found in normal squamous epithelium but over‐expressed in epithelial tumours and known to inhibit apoptosis. We tested the hypothesis that SERPINB3 has a role in invasion by modulating the epithelial–mesenchymal transition programme, using morphological, molecular and cell biology techniques on HepG2 cell clones transfected with the human SERPINB3 gene. The paracrine effect of this serpin was determined by the addition of exogenous recombinant SERPINB3 protein to HepG2 and MDCK cell line. SERPINB3 expression leads to changes in transfected cells morphology, characterized by clusters of loosely connected cells with elongated shape. Ultrastructural analysis confirmed the decrease of desmosomal junctions and widening of intercellular spaces. These alterations were associated with a reduction of E‐cadherin and an increase of β‐catenin, with a parallel increase of cell proliferation. SERPINB3 clones, untransfected HepG2 and MDCK cells treated with exogenous SERPINB3 expressed vimentin, undetectable in controls. SERPINB3 induced significant cell scattering, migration and invasiveness in untransfected cells. These effects were not dependent on the anti‐protease activity of the protein, as documented by the results obtained with an active loop‐deleted recombinant SERPINB3 protein. Scatter activity was inhibited by an anti‐SERPINB3 antibody in a dose‐dependent manner and SERPINB3‐transfected cells formed a significantly higher number of colonies on soft agar than controls. In conclusion, the observed results indicate that SERPINB3 induces deregulation of adhesion processes and increases the invasiveness potential supported by features of epithelial–mesenchymal transition, acting at both the autocrine and the paracrine level. Copyright

SERPINB3 modulates TGF-beta expression in chronic liver disease.

Transforming growth factor-β1 (TGF-β1) is the master cytokine in the pathogenesis of liver fibrosis. TGF-β1 and extent of fibrosis were correlated recently to the serpin SERPINB3 in idiopathic pulmonary fibrosis, a chronic disease recalling liver cirrhosis. The aim of this study was to assess the relation between SERPINB3, TGF-β1 and fibrosis in chronic liver diseases and to determine the effect of this serpin on TGF-β1 expression using in vitro models. SERPINB3 and TGF-β1 were evaluated in liver biopsies of 94 patients with chronic liver disease. The effect of SERPINB3 on TGF-β1 expression was determined in primary human hepatocytes, HepG2 and Huh7 cells transfected with intact SERPINB3 human gene or with reactive site loop deleted mutants. A significant correlation between TGF-β1 and SERPINB3 at the protein level was observed in liver biopsies, confirmed by a positive correlation at mRNA level. Both proteins were correlated to the extent of liver fibrosis. All transfected cells showed increased TGF-β1 mRNA and protein production and the integrity of the reactive site loop of the serpin was crucial to achieve this effect. In conclusion, chronically damaged hepatocytes produce SERPINB3 and TGF-β, and the anti-protease activity of this serpin might be implicated in TGF-β1 induction.

Over-expression of SERPINB3 in hepatoblastoma: A possible insight into the genesis of this tumour?

BACKGROUND The serpin SERPINB3 (SB3) found over-expressed in human hepatocellular carcinoma and in regenerating liver in mice has been shown to induce apoptosis resistance, epithelial-to-mesenchymal transition and increasing cellular invasion. It has also been hypothesised that SB3 may provide a pro-proliferative stimulus for liver cells in vivo. No information is available on SB3 in hepatoblastoma (HB). Aims of the study were to analyse SB3 expression in HB specimens and to investigate its possible correlation with Myc expression and tumour extension at diagnosis as evaluated by the pre-treatment extent of disease evaluation system (PRETEXT). METHODS Frozen tumour specimens from 42 children with HB were analysed for SB3 and Myc expression by real-time PCR. SB3 localisation in tumour specimens was assessed by immunohistochemistry. RESULTS At transcription level SB3 was positive in 79% of the cases. By immunohistochemistry, SB3 expression was found mainly in the embryonic, blastemal, small cell undifferentiated (SCUD) components of HB, while it was not detectable in normal hepatocytes. High SB3 reactivity was also detected in neoplastic cell clusters of portal vein tumour thrombosis. A direct correlation was observed between SB3 gene expression, the up-regulation of Myc (r=0.598, p<0.0001) and tumour extension (PRETEXT III/IV versus I/II, p=0.013). CONCLUSIONS SB3 is over-expressed in HB and its expression is positively correlated with Myc expression and high tumour stage. The role of SB3 in the genesis of HB and in defining the risk profile of children affected by this tumour is hypothesised.

Increased myoendothelial gap junctions mediate the enhanced response to epoxyeicosatrienoic acid and acetylcholine in mesenteric arterial vessels of cirrhotic rats

Background: Cirrhotic portal hypertension is characterized by mesenteric arterial vasodilation and hyporeactivity to vasoconstrictors.

IgM-Linked SerpinB3 and SerpinB4 in Sera of Patients with Chronic Liver Disease

Background Epidemiological studies indicate that a growing number of cirrhotic patients will develop hepatocellular carcinoma (HCC) in the next decade. Recent findings have demonstrated that Squamous cell carcinoma antigen 1 (SCCA1) and 2 (SCCA2) isoforms, now classified as serpinB3 and serpinB4, are over-expressed in HCC, but not in normal liver. As reported, high levels of circulating SCCA-IgM immunocomplexes in patients with cirrhosis are significantly associated with HCC development. Aim To ascertain whether IgM-linked SCCA isoforms circulate in patients with chronic liver disease, compared to total SCCA-IgM levels. Methodology and Findings 79 patients with chronic liver disease were studied, including 17 patients with chronic hepatitis, 36 patients with cirrhosis and 26 with HCC. 28 blood donors were used as control. Monoclonal antibodies against serpinB3 and serpinB4 were used as catcher antibodies to set up specific ELISA assays, while total SCCA-IgM immunocomplexes were detected by commercially available ELISA assay. Overall, the results revealed a better diagnostic sensitivity of total SCCA-IgM assay, compared to both serpinB3 and serpinB4 IgM-linked assays. SerpinB4-IgM median values obtained with SCC103 antibody were moderately higher in patients with cirrhosis than in those with HCC, median values: 0.168 (IQR 0.140–0.427) vs. 0.140 (IQR 0.140–0.278), (p = 0.177). A trend toward decreasing serpinB4-IgM/serpinB3-IgM median ratio was observed in patients with advanced liver disease, being 1.08 in patients with HCC, 1.10 in patients with cirrhosis and 1.40 in patients with chronic hepatitis (p = 0.079). Conclusions IgM-linked SCCA isoforms in serum of patients with chronic liver diseases were quantified for the first time. Although the number of patients was limited, this preliminary study reveals that the relative balance of the two serpin isoforms is altered in HCC and it is characterized by a lower serpinB4-IgM/serpinB3-IgM ratio, determined by lower serpinB4 levels.

MicroRNAs and SerpinB3 in hepatocellular carcinoma.

miRNAs are small non-coding RNAs which target complementary mRNA sequences, usually resulting in gene silencing. They can exhibit oncogenic or tumor suppressor properties, modulating cell homeostasis. Several data have documented that miRNAs are typically deregulated in different types of cancers, including hepatocellular carcinoma (HCC). Some of the miRNAs such as miR-122, miR-221, miR-1 and miR-21 have been found to repress post-transcriptionally the expression of genes involved in cell cycle regulation, cell proliferation, apoptosis, cell migration and invasion. In HCC serum levels of miR-122, miR-221 and miR-16 have been described deregulated, suggesting that they may be used as molecular targets for early detection, prognosis and treatment. The ov-serpin SerpinB3 was found previously increased in liver tumor cancers and associated with apoptosis resistance, increased cell proliferation and invasiveness. Recent data indicate that this serpin may enhance its oncogenic potential through inhibition of several tumor suppressive miRNAs, typically described in HCC.

SERPINB3 expression on B-cell surface in autoimmune diseases and hepatitis C virus-related chronic liver infection:

SERPINB3 is a serine protease inhibitor with pleiotropic functions. It is involved in several physiological and pathological processes, where it appears to exert antiapoptotic effects. Little is known about its expression on immune system cells, the major players in mechanisms of viral defense and autoimmune disorders. The aim of this study was to characterize the expression of SERPINB3 on the surface of peripheral blood mononuclear cell subsets in both normal subjects and in patients with chronic viral infections and autoimmune diseases. Sixty-two patients were analyzed by flow cytometric analysis, including 45 with hepatitis C virus (HCV)-related chronic liver disease and 17 with systemic lupus erythematosus (SLE). SERPINB3 was expressed on B lymphocytes in 79% of the controls, in 32% of the HCV-infected patients and in none of the SLE patients. Surface localization of SERPINB3 was confirmed by confocal microscopy. SERPINB3 positivity was associated with CD27 reactivity (r = 0.98), but not to other activation molecules (CD69, CD71, CD86 and CXCR3). SERPINB3 is physiologically expressed on the surface of CD27+ B lymphocytes, but its expression is reduced in HCV viral infection and not detectable in SLE patients. These results may suggest a role for SERPINB3 in B-cell defects typically found in viral infections and autoimmune disorders.

The molecular signature of impaired diabetic wound healing identifies serpinB3 as a healing biomarker.

Aims/hypothesisChronic foot ulceration is a severe complication of diabetes, driving morbidity and mortality. The mechanisms underlying delaying wound healing in diabetes are incompletely understood and tools to identify such pathways are eagerly awaited.MethodsWound biopsies were obtained from 75 patients with diabetic foot ulcers. Matched subgroups of rapidly healing (RH, n = 17) and non-healing (NH, n = 11) patients were selected. Proteomic analysis was performed by labelling with isobaric tag for relative and absolute quantification and mass spectrometry. Differentially expressed proteins were analysed in NH vs RH for identification of pathogenic pathways. Individual sample gene/protein validation and in vivo validation of candidate pathways in mouse models were carried out.ResultsPathway analyses were conducted on 92/286 proteins that were differentially expressed in NH vs RH. The following pathways were enriched in NH vs RH patients: apoptosis, protease inhibitors, epithelial differentiation, serine endopeptidase activity, coagulation and regulation of defence response. SerpinB3 was strongly upregulated in RH vs NH wounds, validated as protein and mRNA in individual samples. To test the relevance of serpinB3 in vivo, we used a transgenic mouse model with α1-antitrypsin promoter-driven overexpression of human SERPINB3. In this model, wound healing was unaffected by SERPINB3 overexpression in non-diabetic or diabetic mice with or without hindlimb ischaemia. In an independent validation cohort of 47 patients, high serpinB3 protein content was confirmed as a biomarker of healing improvement.Conclusions/interpretationWe provide a benchmark for the unbiased discovery of novel molecular targets and biomarkers of impaired diabetic wound healing. High serpinB3 protein content was found to be a biomarker of successful healing in diabetic patients.

SERPINB3 is associated with longer survival in transgenic mice

The physiological roles of the protease inhibitor SERPINB3 (SB3) are still largely unknown. The study was addressed to assess the biological effects of this serpin in vivo using a SB3 transgenic mouse model. Two colonies of mice (123 transgenic for SB3 and 148 C57BL/6J controls) have been studied. Transgenic (TG) mice showed longer survival than controls and the difference was more remarkable in males than in females (18.5% vs 12.7% life span increase). In TG mice decreased IL-6 in serum and lower p66shc in the liver were observed. In addition, TG males showed higher expression of mTOR in the liver. Liver histology showed age-dependent increase of steatosis and decrease of glycogen storage in both groups and none of the animals developed neoplastic lesions. In conclusion, the gain in life span observed in SB3-transgenic mice could be determined by multiple mechanisms, including the decrease of circulating IL-6 and the modulation of ageing genes in the liver.

SerpinB3 and Yap Interplay Increases Myc Oncogenic Activity.

SerpinB3 has been recently described as an early marker of liver carcinogenesis, but the potential mechanistic role of this serpin in tumor development is still poorly understood. Overexpression of Myc often correlates with more aggressive tumour forms, supporting its involvement in carcinogenesis. Yes-associated protein (Yap), the main effector of the Hippo pathway, is a central regulator of proliferation and it has been found up-regulated in hepatocellular carcinomas. The study has been designed to investigate and characterize the interplay and functional modulation of Myc by SerpinB3 in liver cancer. Results from this study indicate that Myc was up-regulated by SerpinB3 through calpain and Hippo-dependent molecular mechanisms in transgenic mice and hepatoma cells overexpressing human SerpinB3, and also in human hepatocellular carcinomas. Human recombinant SerpinB3 was capable to inhibit the activity of Calpain in vitro, likely reducing its ability to cleave Myc in its non oncogenic Myc-nick cytoplasmic form. SerpinB3 indirectly increased the transcription of Myc through the induction of Yap pathway. These findings provide for the first time evidence that SerpinB3 can improve the production of Myc through direct and indirect mechanisms that include the inhibition of generation of its cytoplasmic form and the activation of Yap pathway.