The hepatocyte epidermal growth factor receptor (EGFR) pathway regulates the cellular interactome within the liver fibrotic niche.

Liver fibrosis is the consequence of chronic liver injury in the presence of an inflammatory component. Although the main executors of this activation are known, the mechanisms that lead to the inflammatory process that mediates the production of pro-fibrotic factors are not well characterized. Epidermal growth factor receptor (EGFR) signaling in hepatocytes is essential for the regenerative processes of the liver; however, its potential role in regulating the fibrotic niche is not yet clear. Our group generated a mouse model that expresses an inactive truncated form of the EGFR specifically in hepatocytes (ΔEGFR mice). Here, we have analyzed the response of WT and ΔEGFR mice to chronic treatment with carbon tetrachloride (CCl4), which induces a pro-inflammatory and fibrotic process in the liver. The results indicated that the hallmarks of liver fibrosis were attenuated in CCl4-treated ΔEGFR mice when compared with CCl4-treated WT mice, coinciding with a faster resolution of the fibrotic process and ameliorated damage. The absence of EGFR activity in hepatocytes induced changes in the pattern of immune cells in the liver, with a notable increase in the population of M2 macrophages, more related to fibrosis resolution, as well as in the population of lymphocytes related to eradication of the damage. Transcriptome analysis of hepatocytes, and secretome studies of extracellular media from in vitro experiments, allowed us to elucidate the specific molecular mechanisms regulated by EGFR that mediate hepatocyte production of both pro-fibrotic and pro-inflammatory mediators; these have consequences for the deposition of extracellular matrix proteins, as well as for the immune microenvironment. Overall, our study uncovered novel mechanistic insights regarding EGFR kinase-dependent actions in hepatocytes that reveal its key role in chronic liver damage. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

The NADPH oxidase NOX4 regulates redox and metabolic homeostasis preventing HCC progression.

BACKGROUND AND AIMS: The NADPH oxidase NOX4 plays a tumor-suppressor function in HCC. Silencing NOX4 confers higher proliferative and migratory capacity to HCC cells and increases their in vivo tumorigenic potential in xenografts in mice. NOX4 gene deletions are frequent in HCC, correlating with higher tumor grade and worse recurrence-free and overall survival rates. However, despite the accumulating evidence of a protective regulatory role in HCC, the cellular processes governed by NOX4 are not yet understood. Accordingly, the aim of this work was to better understand the molecular mechanisms regulated by NOX4 in HCC in order to explain its tumor-suppressor action. APPROACH AND RESULTS: Experimental models: cell-based loss or gain of NOX4 function experiments, in vivo hepatocarcinogenesis induced by diethylnitrosamine in Nox4 -deficient mice, and analyses in human HCC samples. Methods include cellular and molecular biology analyses, proteomics, transcriptomics, and metabolomics, as well as histological and immunohistochemical analyses in tissues. Results identified MYC as being negatively regulated by NOX4. MYC mediated mitochondrial dynamics and a transcriptional program leading to increased oxidative metabolism, enhanced use of both glucose and fatty acids, and an overall higher energetic capacity and ATP level. NOX4 deletion induced a redox imbalance that augmented nuclear factor erythroid 2-related factor 2 (Nrf2) activity and was responsible for MYC up-regulation. CONCLUSIONS: Loss of NOX4 in HCC tumor cells induces metabolic reprogramming in a Nrf2/MYC-dependent manner to promote HCC progression.

Mitochondrial bioenergetics boost macrophage activation, promoting liver regeneration in metabolically compromised animals.

BACKGROUND AND AIMS: Hepatic ischemia-reperfusion injury (IRI) is the leading cause of early posttransplantation organ failure as mitochondrial respiration and ATP production are affected. A shortage of donors has extended liver donor criteria, including aged or steatotic livers, which are more susceptible to IRI. Given the lack of an effective treatment and the extensive transplantation waitlist, we aimed at characterizing the effects of an accelerated mitochondrial activity by silencing methylation-controlled J protein (MCJ) in three preclinical models of IRI and liver regeneration, focusing on metabolically compromised animal models. APPROACH AND RESULTS: Wild-type (WT), MCJ knockout (KO), and Mcj silenced WT mice were subjected to 70% partial hepatectomy (Phx), prolonged IRI, and 70% Phx with IRI. Old and young mice with metabolic syndrome were also subjected to these procedures. Expression of MCJ, an endogenous negative regulator of mitochondrial respiration, increases in preclinical models of Phx with or without vascular occlusion and in donor livers. Mice lacking MCJ initiate liver regeneration 12 h faster than WT and show reduced ischemic injury and increased survival. MCJ knockdown enables a mitochondrial adaptation that restores the bioenergetic supply for enhanced regeneration and prevents cell death after IRI. Mechanistically, increased ATP secretion facilitates the early activation of Kupffer cells and production of TNF, IL-6, and heparin-binding EGF, accelerating the priming phase and the progression through G1 /S transition during liver regeneration. Therapeutic silencing of MCJ in 15-month-old mice and in mice fed a high-fat/high-fructose diet for 12 weeks improves mitochondrial respiration, reduces steatosis, and overcomes regenerative limitations. CONCLUSIONS: Boosting mitochondrial activity by silencing MCJ could pave the way for a protective approach after major liver resection or IRI, especially in metabolically compromised, IRI-susceptible organs.

Lack of EGFR catalytic activity in hepatocytes improves liver regeneration following DDC-induced cholestatic injury by promoting a pro-restorative inflammatory response.

Despite the well-known hepatoprotective role of the epidermal growth factor receptor (EGFR) pathway upon acute damage, its specific actions during chronic liver disease, particularly cholestatic injury, remain ambiguous and unresolved. Here, we analyzed the consequences of inactivating EGFR signaling in the liver on the regenerative response following cholestatic injury. For that, transgenic mice overexpressing a dominant negative mutant human EGFR lacking tyrosine kinase activity (ΔEGFR) in albumin-positive cells were submitted to liver damage induced by 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC), an experimental model resembling human primary sclerosing cholangitis. Our results show an early activation of EGFR after 1-2 days of a DDC-supplemented diet, followed by a signaling switch-off. Furthermore, ΔEGFR mice showed less liver damage and a more efficient regeneration following DDC injury. Analysis of the mechanisms driving this effect revealed an enhanced activation of mitogenic/survival signals, AKT and ERK1/2-MAPKs, and changes in cell turnover consistent with a quicker resolution of damage in response to DDC. These changes were concomitant with profound differences in the profile of intrahepatic immune cells, consisting of a shift in the M1/M2 balance towards M2 polarity, and the Cd4/Cd8 ratio in favor of Cd4 lymphocytes, overall supporting an immune cell switch into a pro-restorative phenotype. Interestingly, ΔEGFR livers also displayed an amplified ductular reaction, with increased expression of EPCAM and an increased number of CK19-positive ductular structures in portal areas, demonstrating an overexpansion of ductular progenitor cells. In summary, our work supports the notion that hepatocyte-specific EGFR activity acts as a key player in the crosstalk between parenchymal and non-parenchymal hepatic cells, promoting the pro-inflammatory response activated during cholestatic injury and therefore contributing to the pathogenesis of cholestatic liver disease. © 2022 The Pathological Society of Great Britain and Ireland.

Anti-TGFß (Transforming Growth Factor ß) Therapy With Betaglycan-Derived P144 Peptide Gene Delivery Prevents the Formation of Aortic Aneurysm in a Mouse Model of Marfan Syndrome.

Objective: We investigated the effect of a potent TGFß (transforming growth factor ß) inhibitor peptide (P144) from the betaglycan/TGFß receptor III on aortic aneurysm development in a Marfan syndrome mouse model. Approach and Results: We used a chimeric gene encoding the P144 peptide linked to apolipoprotein A-I via a flexible linker expressed by a hepatotropic adeno-associated vector. Two experimental approaches were performed: (1) a preventive treatment where the vector was injected before the onset of the aortic aneurysm (aged 4 weeks) and followed-up for 4 and 20 weeks and (2) a palliative treatment where the vector was injected once the aneurysm was formed (8 weeks old) and followed-up for 16 weeks. We evaluated the aortic root diameter by echocardiography, the aortic wall architecture and TGFß signaling downstream effector expression of pSMAD2 and pERK1/2 by immunohistomorphometry, and Tgfß1 and Tgfß2 mRNA expression levels by real-time polymerase chain reaction. Marfan syndrome mice subjected to the preventive approach showed no aortic dilation in contrast to untreated Marfan syndrome mice, which at the same end point age already presented the aneurysm. In contrast, the palliative treatment with P144 did not halt aneurysm progression. In all cases, P144 improved elastic fiber morphology and normalized pERK1/2-mediated TGFß signaling. Unlike the palliative treatment, the preventive treatment reduced Tgfß1 and Tgfß2 mRNA levels. Conclusions: P144 prevents the onset of aortic aneurysm but not its progression. Results indicate the importance of reducing the excess of active TGFß signaling during the early stages of aortic disease progression.

The Tumor Microenvironment Drives Intrahepatic Cholangiocarcinoma Progression.

Intrahepatic cholangiocarcinoma (iCCA) is a highly aggressive cancer with limited therapeutic options and short overall survival. iCCA is characterized by a strong desmoplastic reaction in the surrounding ecosystem that likely affects tumoral progression. Overexpression of the Notch pathway is implicated in iCCA development and progression. Our aim was to investigate the effectiveness of Crenigacestat, a selective inhibitor of NOTCH1 signaling, against the cross-talk between cancer cells and the surrounding ecosystem in an in vivo HuCCT1-xenograft model. In the present study, a transcriptomic analysis approach, validated by Western blotting and qRT-PCR on iCCA tumor masses treated with Crenigacestat, was used to study the molecular pathways responsive to drug treatment. Our results indicate that Crenigacestat significantly inhibited NOTCH1 and HES1, whereas tumor progression was not affected. In addition, the drug triggered a strong immune response and blocked neovascularization in the tumor ecosystem of the HuCCT1-xenograft model without affecting the occurrence of fibrotic reactions. Therefore, although these data need further investigation, our observations confirm that Crenigacestat selectively targets NOTCH1 and that the desmoplastic response in iCCA likely plays a key role in both drug effectiveness and tumor progression.

Direct and Indirect Effect of TGFß on Treg Transendothelial Recruitment in HCC Tissue Microenvironment.

The balance between anti-tumor and tumor-promoting immune cells, such as CD4+ Th1 and regulatory T cells (Tregs), respectively, is assumed to dictate the progression of hepatocellular carcinoma (HCC). The transforming growth factor beta (TGFß) markedly shapes the HCC microenvironment, regulating the activation state of multiple leukocyte subsets and driving the differentiation of cancer associated fibroblasts (CAFs). The fibrotic (desmoplastic) reaction in HCC tissue strongly depends on CAFs activity. In this study, we attempted to assess the role of TGFß on transendothelial migration of Th1-oriented and Treg-oriented CD4+ T cells via a direct or indirect, CAF-mediated mechanisms, respectively. We found that the blockage of TGFß receptor I-dependent signaling in Tregs resulted in impaired transendothelial migration (TEM) of these cells. Interestingly, the secretome of TGFß-treated CAFs inhibited the TEM of Tregs but not Th1 cells, in comparison to the secretome of untreated CAFs. In addition, we found a significant inverse correlation between alpha-SMA and FoxP3 (marker of Tregs) mRNA expression in a microarray analysis involving 78 HCCs, thus suggesting that TGFß-activated stromal cells may counteract the trafficking of Tregs into the tumor. The apparent dual behavior of TGFß as both pro- and anti-tumorigenic cytokines may add a further level of complexity to the mechanisms that regulate the interactions among cancerous, stromal, and immune cells within HCC, as well as other solid tumors, and contribute to better manipulation of the TGFß signaling as a therapeutic target in HCC patients.

Epithelial-Mesenchymal Transition (EMT) Induced by TGF-ß in Hepatocellular Carcinoma Cells Reprograms Lipid Metabolism.

(1) Background: The transforming growth factor (TGF)-ß plays a dual role in liver carcinogenesis. At early stages, it inhibits cell growth and induces apoptosis. However, TGF-ß expression is high in advanced stages of hepatocellular carcinoma (HCC) and cells become resistant to TGF-ß induced suppressor effects, responding to this cytokine undergoing epithelial-mesenchymal transition (EMT), which contributes to cell migration and invasion. Metabolic reprogramming has been established as a key hallmark of cancer. However, to consider metabolism as a therapeutic target in HCC, it is necessary to obtain a better understanding of how reprogramming occurs, which are the factors that regulate it, and how to identify the situation in a patient. Accordingly, in this work we aimed to analyze whether a process of full EMT induced by TGF-ß in HCC cells induces metabolic reprogramming. (2) Methods: In vitro analysis in HCC cell lines, metabolomics and transcriptomics. (3) Results: Our findings indicate a differential metabolic switch in response to TGF-ß when the HCC cells undergo a full EMT, which would favor lipolysis, increased transport and utilization of free fatty acids (FFA), decreased aerobic glycolysis and an increase in mitochondrial oxidative metabolism. (4) Conclusions: EMT induced by TGF-ß in HCC cells reprograms lipid metabolism to facilitate the utilization of FFA and the entry of acetyl-CoA into the TCA cycle, to sustain the elevated requirements of energy linked to this process.

Clathrin switches transforming growth factor-ß role to pro-tumorigenic in liver cancer.

BACKGROUND & AIMS: Upon ligand binding, tyrosine kinase receptors, such as epidermal growth factor receptor (EGFR), are recruited into clathrin-coated pits for internalization by endocytosis, which is relevant for signalling and/or receptor degradation. In liver cells, transforming growth factor-ß (TGF-ß) induces both pro- and anti-apoptotic signals; the latter are mediated by the EGFR pathway. Since EGFR mainly traffics via clathrin-coated vesicles, we aimed to analyse the potential role of clathrin in TGF-ß-induced signalling in liver cells and its relevance in liver cancer. METHODS: Real-Time PCR and immunohistochemistry were used to analyse clathrin heavy-chain expression in human (CLTC) and mice (Cltc) liver tumours. Transient knockdown (siRNA) or overexpression of CLTC were used to analyse its role on TGF-ß and EGFR signalling in vitro. Bioinformatic analysis was used to determine the effect of CLTC and TGFB1 expression on prognosis and overall survival in patients with hepatocellular carcinoma (HCC). RESULTS: Clathrin expression increased during liver tumorigenesis in humans and mice. CLTC knockdown cells responded to TGF-ß phosphorylating SMADs (canonical signalling) but showed impairment in the anti-apoptotic signals (EGFR transactivation). Experiments of loss or gain of function in HCC cells reveal an essential role for clathrin in inhibiting TGF-ß-induced apoptosis and upregulation of its pro-apoptotic target NOX4. Autocrine TGF-ß signalling in invasive HCC cells upregulates CLTC expression, switching its role to pro-tumorigenic. A positive correlation between TGFB1 and CLTC was found in HCC cells and patients. Patients expressing high levels of TGFB1 and CLTC had a worse prognosis and lower overall survival. CONCLUSIONS: This work describes a novel role for clathrin in liver tumorigenesis, favouring non-canonical pro-tumorigenic TGF-ß pathways. CLTC expression in human HCC samples could help select patients that would benefit from TGF-ß-targeted therapy. LAY SUMMARY: Clathrin heavy-chain expression increases during liver tumorigenesis in humans (CLTC) and mice (Cltc), altering the cellular response to TGF-ß in favour of anti-apoptotic/pro-tumorigenic signals. A positive correlation between TGFB1 and CLTC was found in HCC cells and patients. Patients expressing high levels of TGFB1 and CLTC had a worse prognosis and lower overall survival. CLTC expression in HCC human samples could help select patients that would benefit from therapies targeting TGF-ß.

c-Met Signaling Is Essential for Mouse Adult Liver Progenitor Cells Expansion After Transforming Growth Factor-ß-Induced Epithelial-Mesenchymal Transition and Regulates Cell Phenotypic Switch.

Adult hepatic progenitor cells (HPCs)/oval cells are bipotential progenitors that participate in liver repair responses upon chronic injury. Recent findings highlight HPCs plasticity and importance of the HPCs niche signals to determine their fate during the regenerative process, favoring either fibrogenesis or damage resolution. Transforming growth factor-ß (TGF-ß) and hepatocyte growth factor (HGF) are among the key signals involved in liver regeneration and as component of HPCs niche regulates HPCs biology. Here, we characterize the TGF-ß-triggered epithelial-mesenchymal transition (EMT) response in oval cells, its effects on cell fate in vivo, and the regulatory effect of the HGF/c-Met signaling. Our data show that chronic treatment with TGF-ß triggers a partial EMT in oval cells based on coexpression of epithelial and mesenchymal markers. The phenotypic and functional profiling indicates that TGF-ß-induced EMT is not associated with stemness but rather represents a step forward along hepatic lineage. This phenotypic transition confers advantageous traits to HPCs including survival, migratory/invasive and metabolic benefit, overall enhancing the regenerative potential of oval cells upon transplantation into a carbon tetrachloride-damaged liver. We further uncover a key contribution of the HGF/c-Met pathway to modulate the TGF-ß-mediated EMT response. It allows oval cells expansion after EMT by controlling oxidative stress and apoptosis, likely via Twist regulation, and it counterbalances EMT by maintaining epithelial properties. Our work provides evidence that a coordinated and balanced action of TGF-ß and HGF are critical for achievement of the optimal regenerative potential of HPCs, opening new therapeutic perspectives. Stem Cells 2019;37:1108-1118.

Altered TGF-ß endocytic trafficking contributes to the increased signaling in Marfan syndrome.

The main cardiovascular alteration in Marfan syndrome (MFS) is the formation of aortic aneurysms in which augmented TGF-ß signaling is reported. However, the primary role of TGF-ß signaling as a molecular link between the genetic mutation of fibrillin-1 and disease onset is controversial. The compartmentalization of TGF-ß endocytic trafficking has been shown to determine a signaling response in which clathrin-dependent internalization leads to TGF-ß signal propagation, and caveolin-1 (CAV-1) associated internalization leads to signal abrogation. We here studied the contribution of endocytic trafficking compartmentalization to increased TGF-ß signaling in vascular smooth muscle cells (VSMC) from MFS patients. We examined molecular components involved in clathrin- (SARA, SMAD2) and caveolin-1- (SMAD7, SMURF2) dependent endocytosis. Marfan VSMC showed higher recruitment of SARA and SMAD2 to membranes and their increased interaction with TGF-ß receptor II, as well as higher colocalization of SARA with the early endosome marker EEA1. We assessed TGF-ß internalization using a biotinylated ligand (b-TGF-ß), which colocalized equally with either EEA1 or CAV-1 in VSMC from Marfan patients and controls. However, in Marfan cells, colocalization of b-TGF-ß with SARA and EEA1 was increased and accompanied by decreased colocalization with CAV-1 at EEA1-positive endosomes. Moreover, Marfan VSMC showed higher transcriptional levels and membrane enrichment of RAB5. Our results indicate that increased RAB5-associated SARA localization to early endosomes facilitates its TGF-ß receptor binding and phosphorylation of signaling mediator SMAD2 in Marfan VSMC. This is accompanied by a reduction of TGF-ß sorting into multifunctional vesicles containing cargo from both internalization pathways.

Bone morphogenetic protein 9 as a key regulator of liver progenitor cells in DDC-induced cholestatic liver injury.

BACKGROUND & AIMS: Bone morphogenetic protein 9 (BMP9) interferes with liver regeneration upon acute injury, while promoting fibrosis upon carbon tetrachloride-induced chronic injury. We have now addressed the role of BMP9 in 3,5 diethoxicarbonyl-1,4 dihydrocollidine (DDC)-induced cholestatic liver injury, a model of liver regeneration mediated by hepatic progenitor cell (known as oval cell), exemplified as ductular reaction and oval cell expansion. METHODS: WT and BMP9KO mice were submitted to DDC diet. Livers were examined for liver injury, fibrosis, inflammation and oval cell expansion by serum biochemistry, histology, RT-qPCR and western blot. BMP9 signalling and effects in oval cells were studied in vitro using western blot and transcriptional assays, plus functional assays of DNA synthesis, cell viability and apoptosis. Crosslinking assays and short hairpin RNA approaches were used to identify the receptors mediating BMP9 effects. RESULTS: Deletion of BMP9 reduces liver damage and fibrosis, but enhances inflammation upon DDC feeding. Molecularly, absence of BMP9 results in overactivation of PI3K/AKT, ERK-MAPKs and c-Met signalling pathways, which together with an enhanced ductular reaction and oval cell expansion evidence an improved regenerative response and decreased damage in response to DDC feeding. Importantly, BMP9 directly targets oval cells, it activates SMAD1,5,8, decreases cell growth and promotes apoptosis, effects that are mediated by Activin Receptor-Like Kinase 2 (ALK2) type I receptor. CONCLUSIONS: We identify BMP9 as a negative regulator of oval cell expansion in cholestatic injury, its deletion enhancing liver regeneration. Likewise, our work further supports BMP9 as an attractive therapeutic target for chronic liver diseases.

TGF-ß and the Tissue Microenvironment: Relevance in Fibrosis and Cancer.

Transforming growth factor-β (TGF-β) is a cytokine essential for the induction of the fibrotic response and for the activation of the cancer stroma. Strong evidence suggests that a strong cross-talk exists among TGF-β and the tissue extracellular matrix components. TGF-β is stored in the matrix as part of a large latent complex bound to the latent TGF-β binding protein (LTBP) and matrix binding of latent TGF-β complexes, which is required for an adequate TGF-β function. Once TGF-β is activated, it regulates extracellular matrix remodelling and promotes a fibroblast to myofibroblast transition, which is essential in fibrotic processes. This cytokine also acts on other cell types present in the fibrotic and tumour microenvironment, such as epithelial, endothelial cells or macrophages and it contributes to the cancer-associated fibroblast (CAF) phenotype. Furthermore, TGF-β exerts anti-tumour activity by inhibiting the host tumour immunosurveillance. Aim of this review is to update how TGF-β and the tissue microenvironment cooperate to promote the pleiotropic actions that regulate cell responses of different cell types, essential for the development of fibrosis and tumour progression. We discuss recent evidences suggesting the use of TGF-β chemical inhibitors as a new line of defence against fibrotic disorders or cancer.

Dissecting the role of epidermal growth factor receptor catalytic activity during liver regeneration and hepatocarcinogenesis.

UNLABELLED: Different data support a role for the epidermal growth factor receptor (EGFR) pathway during liver regeneration and hepatocarcinogenesis. However, important issues, such as the precise mechanisms mediating its actions and the unique versus redundant functions, have not been fully defined. Here, we present a novel transgenic mouse model expressing a hepatocyte-specific truncated form of human EGFR, which acts as negative dominant mutant (ΔEGFR) and allows definition of its tyrosine kinase-dependent functions. Results indicate a critical role for EGFR catalytic activity during the early stages of liver regeneration. Thus, after two-thirds partial hepatectomy, ΔEGFR livers displayed lower and delayed proliferation and lower activation of proliferative signals, which correlated with overactivation of the transforming growth factor-ß pathway. Altered regenerative response was associated with amplification of cytostatic effects of transforming growth factor-ß through induction of cell cycle negative regulators. Interestingly, lipid synthesis was severely inhibited in ΔEGFR livers after partial hepatectomy, revealing a new function for EGFR kinase activity as a lipid metabolism regulator in regenerating hepatocytes. In spite of these profound alterations, ΔEGFR livers were able to recover liver mass by overactivating compensatory signals, such as c-Met. Our results also indicate that EGFR catalytic activity is critical in the early preneoplastic stages of the liver because ΔEGFR mice showed a delay in the appearance of diethyl-nitrosamine-induced tumors, which correlated with decreased proliferation and delay in the diethyl-nitrosamine-induced inflammatory process. CONCLUSION: These studies demonstrate that EGFR catalytic activity is critical during the initial phases of both liver regeneration and carcinogenesis and provide key mechanistic insights into how this kinase acts to regulate liver pathophysiology. (Hepatology 2016;63:604-619).

Hybrid polymeric-protein nano-carriers (HPPNC) for targeted delivery of TGFß inhibitors to hepatocellular carcinoma cells.

TGFß1 pathway antagonists have been considered promising therapies to attenuate TGFß downstream signals in cancer cells. Inhibiting peptides, as P-17 in this study, are bound to either TGFß1 or its receptors, blocking signal transduction. However, for efficient use of these TGFß1antagonist as target therapeutic tools, improvement in their delivery is required. Here, a plasmid carrying specific shDNA (SHT-DNA), small interfering RNA (siRNA), and the peptide (P-17) were loaded separately into folic acid (FA)-functionalized nano-carriers made of Bovine Serum Albumin (BSA). The two building blocks of the carrier, (BSA and FA) were used because of the high affinity of albumin for liver and for the overexpression of folate receptors on the membrane of hepatocellular carcinoma cells. The empty and the encapsulated carriers were thoroughly investigated to characterize their structure, to evaluate the colloidal stability and the surface functionalization. The entrapment of SHT-DNA, siRNA and P-17, respectively, was demonstrated by morphological and quantitative analysis. Finally, cellular studies were performed to assess the targeting efficiency of the hybrid carriers. These vectors were used because of the high affinity of albumin for liver and for the overexpression of folate receptors on the membrane hepatocellular carcinoma cells. The empty and the encapsulated carriers were thoroughly investigated to characterize their structure, to evaluate the colloidal stability and the surface functionalization. The entrapment of SHT-DNA, siRNA and P-17, respectively, was demonstrated by morphological and quantitative analysis. A novel fabrication of Hybrid Polymeric-Protein Nano-Carriers (HPPNC) for delivering TGF ß1 inhibitors to HCC cells has been developed. SHT-DNA, siRNA and P-17 have been successfully encapsulated. TGF ß1 inhibitors-loaded HPPNC were efficiently uptaken by HLF cells.

Mechanisms regulating cell membrane localization of the chemokine receptor CXCR4 in human hepatocarcinoma cells.

Hepatocellular carcinoma (HCC) cells with a mesenchymal phenotype show an asymmetric subcellular distribution of the chemokine receptor CXCR4, which is required for cell migration and invasion. In this work we examine the mechanisms that regulate the intracellular trafficking of CXCR4 in HCC cells. Results indicate that HCC cells present CXCR4 at the cell surface, but most of this protein is in endomembranes colocalizing with markers of the Golgi apparatus and recycling endosomes. The presence of high protein levels of CXCR4 present at the cell surface correlates with a mesenchymal-like phenotype and a high autocrine activation of the Transforming Growth Factor-beta (TGF-ß) pathway. CXCR4 traffics along the Golgi/exocyst/plasma membrane pathway and requires EXOC4 (Sec8) component of the exocyst complex. HCC cells use distinct mechanisms for the CXCR4 internalization such as dynamin-dependent endocytosis and macropinocytosis. Regardless of the endocytic mechanisms, colocalization of CXCR4 and Rab11 is observed, which could be involved not only in receptor recycling but also in its post-Golgi transport. In summary, this work highlights membrane trafficking pathways whose pharmacological targeting could subsequently result in the inactivation of one of the main guiding mechanisms used by metastatic cells to colonize secondary organs and tissues.

Silencing of CD47 and SIRPα by Polypurine reverse Hoogsteen hairpins to promote MCF-7 breast cancer cells death by PMA-differentiated THP-1 cells.

BACKGROUND: In the context of tumor immunology, tumor cells have been shown to overexpress CD47, an anti-phagocytic signal directed to macrophages to escape from phagocytosis by interacting with Signal Regulatory Protein α SIRPα. In the present work, we designed Polypurine reverse Hoogsteen hairpins, PPRHs, to silence the expression of CD47 in tumor cells and SIRPα in macrophages with the aim to eliminate tumor cells by macrophages in co-culture experiments. METHODS: THP-1 cells were differentiated to macrophages with PMA. The mRNA levels of differentiation markers CD14 and Mcl-1 mRNA and pro-inflammatory cytokines (IL-1ß, IL-18, IL-6, IL-8 and TNF-α) were measured by qRT-PCR. The ability of PPRHs to silence CD47 and SIRPα was evaluated at the mRNA level by qRT-PCR and at the protein level by Western Blot. Macrophages were co-cultured with tumor cells in the presence of PPRHs to silence CD47 and/or SIRPα. Cell viability was assessed by MTT assays. RESULTS: THP-1 cells differentiated to macrophages with PMA showed an increase in macrophage surface markers (CD14, Mcl-1) and pro-inflammatory cytokines (IL-1ß, IL-18, IL-6, IL-8 and TNF-α). PPRHs were able to decrease both CD47 expression in MCF-7 cell line and SIRPα expression in macrophages at the mRNA and protein levels. In the presence of PPRHs, MCF-7 cells were eliminated by macrophages in co-culture experiments, whereas they survived in the absence of PPRHs. CONCLUSIONS: Our data support the usage of PPRHs to diminish CD47/SIRPα interaction by decreasing the expression of both molecules thus resulting in an enhanced killing of MCF-7 cells by macrophages, which might translate into beneficial effects in cancer therapy. These results indicate that PPRHs could represent a new approach with immunotherapeutic applications.

The rationale for targeting TGF-ß in chronic liver diseases.

BACKGROUND: Transforming growth factor (TGF)-ß is a pluripotent cytokine that displays several tissue-specific biological activities. In the liver, TGF-ß is considered a fundamental molecule, controlling organ size and growth by limiting hepatocyte proliferation. It is involved in fibrogenesis and, therefore, in worsening liver damage, as well as in triggering the development of hepatocellular carcinoma (HCC). TGF-ß is known to act as an oncosuppressor and also as a tumour promoter in HCC, but its role is still unclear. DESIGN: In this review, we discuss the potential role of TGF-ß in regulating the tumoural progression of HCC, and therefore the rationale for targeting this molecule in patients with HCC. RESULTS: A considerable amount of experimental preclinical evidence suggests that TGF-ß is a promising druggable target in patients with HCC. To support this hypothesis, a phase II clinical trial is currently ongoing using a TGF-ß pathway inhibitor, and results will soon be available. CONCLUSIONS: The identification of new TGF-ß related biomarkers will help to select those patients most likely to benefit from therapy aimed at inhibiting the TGF-ß pathway. New formulations that may provide a more controlled and sustained delivery of the drug will improve the therapeutic success of such treatments.

Vascular smooth muscle cell phenotypic changes in patients with Marfan syndrome.

OBJECTIVE: Marfan's syndrome is characterized by the formation of ascending aortic aneurysms resulting from altered assembly of extracellular matrix microfibrils and chronic tissue growth factor (TGF)-ß signaling. TGF-ß is a potent regulator of the vascular smooth muscle cell (VSMC) phenotype. We hypothesized that as a result of the chronic TGF-ß signaling, VSMC would alter their basal differentiation phenotype, which could facilitate the formation of aneurysms. This study explores whether Marfan's syndrome entails phenotypic alterations of VSMC and possible mechanisms at the subcellular level. APPROACH AND RESULTS: Immunohistochemical and Western blotting analyses of dilated aortas from Marfan patients showed overexpression of contractile protein markers (α-smooth muscle actin, smoothelin, smooth muscle protein 22 alpha, and calponin-1) and collagen I in comparison with healthy aortas. VSMC explanted from Marfan aortic aneurysms showed increased in vitro expression of these phenotypic markers and also of myocardin, a transcription factor essential for VSMC-specific differentiation. These alterations were generally reduced after pharmacological inhibition of the TGF-ß pathway. Marfan VSMC in culture showed more robust actin stress fibers and enhanced RhoA-GTP levels, which was accompanied by increased focal adhesion components and higher nuclear localization of myosin-related transcription factor A. Marfan VSMC and extracellular matrix measured by atomic force microscopy were both stiffer than their respective controls. CONCLUSIONS: In Marfan VSMC, both in tissue and in culture, there are variable TGF-ß-dependent phenotypic changes affecting contractile proteins and collagen I, leading to greater cellular and extracellular matrix stiffness. Altogether, these alterations may contribute to the known aortic rigidity that precedes or accompanies Marfan's syndrome aneurysm formation.

A mesenchymal-like phenotype and expression of CD44 predict lack of apoptotic response to sorafenib in liver tumor cells.

The multikinase inhibitor sorafenib is the only effective drug in advanced cases of hepatocellular carcinoma (HCC). However, response differs among patients and effectiveness only implies a delay. We have recently described that sorafenib sensitizes HCC cells to apoptosis. In this work, we have explored the response to this drug of six different liver tumor cell lines to define a phenotypic signature that may predict lack of response in HCC patients. Results have indicated that liver tumor cells that show a mesenchymal-like phenotype, resistance to the suppressor effects of transforming growth factor beta (TGF-ß) and high expression of the stem cell marker CD44 were refractory to sorafenib-induced cell death in in vitro studies, which correlated with lack of response to sorafenib in nude mice xenograft models of human HCC. In contrast, epithelial-like cells expressing the stem-related proteins EpCAM or CD133 were sensitive to sorafenib-induced apoptosis both in vitro and in vivo. A cross-talk between the TGF-ß pathway and the acquisition of a mesenchymal-like phenotype with up-regulation of CD44 expression was found in the HCC cell lines. Targeted CD44 knock-down in the mesenchymal-like cells indicated that CD44 plays an active role in protecting HCC cells from sorafenib-induced apoptosis. However, CD44 effect requires a TGF-ß-induced mesenchymal background, since the only overexpression of CD44 in epithelial-like HCC cells is not sufficient to impair sorafenib-induced cell death. In conclusion, a mesenchymal profile and expression of CD44, linked to activation of the TGF-ß pathway, may predict lack of response to sorafenib in HCC patients.