George Michalopoulos

University of Pittsburgh | Pitt · Department of Pathology

[This corrects the article DOI: 10.1371/journal.pone.0059836.].

Prostate cancer remains one of the most lethal malignancies for men in the United States. Predicting the course of prostate cancer is challenging since only a fraction of prostate cancer patients experienced cancer recurrence after radical prostatectomy or radiation therapy. In this report, the expressions of 14 fusion genes in 607 prostate cancer...

In previous studies, we have demonstrated the critical roles of EGFR and HGFR (c‐Met) for liver regeneration and for conversion of hepatocytes to cholangiocytes by a “clean” partial hepatectomy model, in which hepatocytes and cholangiocytes grow rapidly and synchronously. In contrast, the vast majority of liver diseases involve a prolonged patholog...

Background and objective: The extracellular matrix (ECM) is important for survival, differentiation, and normal functioning of cells within the liver; integrins are key signaling receptors in this process. Previous data from our lab has shown that with hepatocyte specific knockout of integrin linked kinase (hILK KO), there is hepatocyte proliferat...

Activation of CAR transcription factor by xenobiotics promotes hepatocellular proliferation, hypertrophy without liver injury, and induces drug metabolism genes. Our previous work demonstrated lymphocyte specific protein-1 (LSP1), an F-actin binding protein and gene involved in human HCC, suppresses hepatocellular proliferation after partial hepate...

Inactivation of Pten gene through deletions and mutations leading to excessive pro-growth signaling pathway activations frequently occurs in cancers. Here, we report a Pten derived pro-cancer growth gene fusion Pten-NOLC1 originated from a chr10 genome rearrangement and identified through a transcriptome sequencing analysis of human cancers. Pten-N...

Integrin Linked Kinase is a vital signaling protein ubiquitously expressed throughout the body. It binds to intracellular integrins to help promote signaling related to cell adhesion, apoptosis, proliferation, migration, and a plethora of other common cellular functions. In this review, ILK’s role in the liver is detailed. Studies have shown ILK to...

Background and aims: Constitutive androstane receptor (CAR) agonists, such as 1,4-bis [2-(3,5-dichloropyridyloxy)] benzene (TCPOBOP), are known to cause robust hepatocyte proliferation and hepatomegaly in mice along with induction of drug metabolism genes without any associated liver injury. Yes-associated protein (Yap) is a key transcription regu...

Elevated levels of estrogen are a risk factor for breast cancer. In addition to inducing DNA damage, estrogens can enhance cell proliferation as well as modulate fatty acid metabolism that collectively contributes to mammary tumorigenesis. Sulforaphane (SFN) is an isothiocyanate derived from broccoli that is currently under evaluation in multiple c...

Hepatocyte nuclear factor 4 alpha (HNF4α) is a transcription factor that plays a critical role in hepatocyte function, and HNF4α‐based reprogramming corrects terminal liver failure in rats with chronic liver disease. In the livers of patients with advanced cirrhosis, HNF4α RNA expression levels decrease as hepatic function deteriorates, and protein...

Previous studies have shown that activation of CD81, (the portal of entry of Hepatitis C virus) by agonistic antibody results in phosphorylation of Ezrin via Syk kinase. We have previously that his is associated with inactivation of the Hippo pathway and increase in YAP. The opposite occurs when Glypican-3 (GPC3) or E2 protein of HCV bind to CD81....

Lymphocyte specific protein‐1 (LSP‐1), an f‐actin binding protein expressed in hematopoietic cells as well as hepatocytes, is the gene with the most copy number variations detected in human HCC. Our previous work has demonstrated that LSP‐1 suppresses hepatocellular proliferation following partial hepatectomy as well as in primary hepatocyte cultur...

Introduction The extracellular matrix (ECM) is important for survival, differentiation, and normal functioning of cells within the liver; integrins are key signaling receptors in this process. Previous data from our lab has shown that with hepatocyte specific knockout of integrin linked kinase (ILK KO), there is hepatocyte proliferation, increased...

MET is a receptor for hepatocyte growth factor (HGF) and is considered critical for liver regeneration after partial hepatectomy (Phx). Combined disruption of MET along with epidermal growth factor receptor (EGFR) signaling results in compete elimination of regenerative response after Phx, highlighting importance of these growth factor receptors in...

It has been shown that up ligation of CD81 (the portal of entry of Hepatitis C virus) by agonistic antibody results in phosphorylation of Ezrin. We have previously shown that in liver, Ezrin phosphorylation occurs via Syk kinase, causing suppression of Hippo pathway, therefore increasing Yap activity. The opposite occurs when Glypican‐3 (GPC3) or E...

Liver failure is the common ending of most irreversible liver diseases. We have identified that shutdown of both MET and EGFR signaling simultaneously in the murine resting or regenerating liver contributes to this process. In this study, we explore the role of MET and EGFR signaling pathways in biliary injury repair after common bile duct ligation...

Signals related to liver regeneration (LR) have been identified by triggering proliferation in hepatocyte cultures, delay of regeneration associated with signal ablation in genomically modified mice, or response of intact liver in vivo by injecting specific signaling substances. This chapter discusses these signals with emphasis on their effects on...

[This corrects the article DOI: 10.1371/journal.pone.0096053.].

EGFR is a critical regulator of hepatocyte proliferation and liver regeneration. Our recent work indicated EGFR can also regulate lipid metabolism during liver regeneration after partial‐hepatectomy. Based on these findings, we investigated role of EGFR in a mouse model of NAFLD utilizing a pharmacological inhibition strategy. C57BL6/J mice were fe...

Obesity is a major risk factor for type 2 diabetes because of chronic hepatic inflammation and resultant insulin resistance. Hepatocyte growth factor (HGF) is responsible for resetting hepatic homeostasis after injury following activation by urokinase-type plasminogen activator (u-PA; encoded by the PLAU gene). Plasminogen activator inhibitor type-...

Lymphocyte specific protein‐1 is the gene with the most copy number variations in a cohort of human hepatocellular carcinoma cases. Previous studies have demonstrated that LSP‐1 acts as a suppressor of hepatocellular proliferation in both cancer cell lines and during liver regeneration after partial hepatectomy as well as an inhibitor of migration....

Introduction Biliary diseases accounted for over 100,000 deaths in the United States in 2016. When biliary cells (cholangiocytes) experience chronic injury during these diseases, hepatocytes can transdifferentiate into cholangiocytes to supplant the lost biliary cells. While the phenomena of transdifferentiation in the liver has been observed by ma...

TCPOBOP (1,4‐Bis [2‐(3,5‐Dichloropyridyloxy)] benzene) is a direct ligand of constitutive androstane receptor (CAR), which induces robust hepatocyte proliferation and hepatomegaly in mice without any liver injury or tissue loss. Organ size including that of liver is known to be tightly controlled by transcriptional regulator, yes‐associated protein...

Our recent study (Paranjpe S. et al, Hepatology 2016 Nov;64(5):1711–1724) showed that in mice, combined systemic elimination of EGFR and MET signaling abolishes liver regeneration after partial hepatectomy, leading to liver decompensation and death at 15–18 days post‐surgery. In the current study, we investigated the role of EGFR and MET in resting...

Background Alpha‐1 antitrypsin (α1‐AT) deficiency is the most common genetic cause of pediatric liver disease, which can progress to cirrhosis and hepatocellular carcinoma. Hepatocellular injury is caused by accumulation of the insoluble mutant alpha‐1‐antitrypsin Z (α1‐ATZ) molecule in intracellular globules. Hepatocytes containing these globules...

The experiments that integrate different pathways in normal and abnormal circumstances will help us to develop better targeted therapies because of multiple pathways involve in the solid tumor carcinogenesis. GPC3 is over‐expressed in HCC. Previous studies have shown that GPC3 is associated with inhibition of hepatocyte growth and GPC3 transgenic m...

Growth factor receptors MET and EGFR are known to play a critical role in liver regeneration after partial hepatectomy. TCPOBOP (1,4‐Bis [2‐(3,5‐Dichloropyridyloxy)] benzene), a CAR agonist, induces robust hepatocyte proliferation and hepatomegaly without any injury or tissue loss. The underlying mechanisms are considered to be different compared t...

Leukocyte specific protein‐1 (LSP1), an f‐actin binding protein expressed in hematopoietic cells and hepatocytes, is the gene with the highest copy number variation in human hepatocellular carcinoma. Our previous work has demonstrated that loss of LSP1 expression leads to increased proliferation and migration of rat hepatocellular carcinoma cells....

The gene leukocyte-specific protein-1 (LSP1), encodes an F-actin binding protein that directly interacts with the mitogen-activated protein kinase pathway. LSP1 has copy number variations in 52% of human hepatocellular carcinoma (HCC). LSP1 suppresses proliferation and migration in hepatocytes. LSP1 binds to the rapidly accelerated fibrosarcoma (RA...

MET and epidermal growth factor receptor (EGFR) tyrosine kinases are crucial for liver regeneration and normal hepatocyte function. Recently we demonstrated that in mice, combined inhibition of these two signaling pathways abolished liver regeneration following hepatectomy, with subsequent hepatic failure and death at 15 to 18 days post-resection....

Conclusion: Taken together, combined disruption of EGFR and MET signaling lead to dramatic impairment of TCPOBOP-induced proliferative response without altering CAR activation. This article is protected by copyright. All rights reserved.

Glypican 3 (GPC3) is over-expressed in hepatocellular carcinomas (HCC). GPC3 binds to CD81. Forced expression of CD81 in a GPC3 expressing HCC cell line caused activation of Hippo, decrease in Ezrin phosphorylation, and decrease in Yap. CD81 is also associated with HCV entry into hepatocytes. Activation of CD81 by agonistic antibody causes activati...

Background: Hepatocyte to biliary transdifferentiation has been documented in various models of bile duct injury. In this process, mature hepatocytes transform into mature biliary epithelial cells by acquiring biliary phenotypic markers. Several signaling pathways including PI3 kinase, Notch, Hes1, Sox9, and Hippo are shown to be involved in the p...

AIMS: In regenerating liver, hepatic progenitor cells (HPCs) are recruited in response to injury; however, few highly specific human HPC markers exist for the hepatocyte lineage. LGR5, a Wnt-associated stem cell marker, has been extensively studied in intestinal stem cells, but little is known about its expression in human liver. We hypothesized th...

Aims In regenerating liver, hepatic progenitor cells (HPCs) are recruited in response to injury; however, few highly specific human HPC markers exist for the hepatocyte lineage. Leucine-rich repeat-containing G-protein coupled receptor 5 (LGR5), a Wnt-associated stem cell marker, has been extensively studied in intestinal stem cells, but little is...

Bid is a Bcl-2 family protein. In addition to its pro-apoptosis function, Bid can also promote cell proliferation, maintain S phase checkpoint, and facilitate inflammasome activation. Bid plays important roles in tissue injury and regeneration, hematopoietic homeostasis, and tumorigenesis. Bid participates in hepatic carcinogenesis but the mechanis...

Up-regulated genes in livers of wild type mice treated with DEN for 4–6 months. (PDF)

Up-regulated genes in livers of Bid-deficient mice treated with DEN for 4–6 months. (PDF)

Up-regulated genes in livers of bid-deficient mice treated with DEN for 10–12 months. (PDF)

Genes that are involved in amino acid metabolism, and that are down-regulated in WT mice treated with DEN for 10–12 Months. (PDF)

Pathway analysis of the gene expression profile in wild type mice treated with DEN for 10–12 months. (PDF)

List of qRT-PCR primers. (PDF)

Down-regulated genes in livers of wild type mice treated with DEN for 10–12 months. (PDF)

Down-regulated genes in livers of Bid-deficient mice treated with DEN for 4–6 months. (PDF)

Genes that are involved in immune response and/or inflammation, and that are upregulated in WT mice treated with DEN for 10–12 Months. (PDF)

Pathway analysis of the gene expression profile in bid-deficient mice treated with DEN for 4–6 months. (PDF)

Pathway analysis of the gene expression profile in bid-deficient mice treated with DEN for 10–12 months. (PDF)

Down-regulated genes in livers of wild type mice treated with DEN for 4–6 months. (PDF)

Up-regulated genes in livers of wild type mice treated with DEN for 10–12 months. (PDF)

Down-regulated genes in livers of Bid-deficient pe mice treated with DEN for 10–12 months. (PDF)

DAVID pathway analysis of differentially expressed genes in DEN-treated mouse livers. (PDF)

Pathway analysis of the gene expression profile in wild type mice treated with DEN for 4–6 months. (PDF)

Liver failure is a common outcome of end‐stage liver diseases. Modern stem cell and tissue engineering techniques can't achieve functional unique liver with multi cell types. Transplantation can only save limited amount of patients, the realistic approach for the majority of patients is to use residual functional liver tissue to restore impaired li...

Trans differentiation of liver epithelial cells (hepatocytes and biliary cells) into each other provides a rescue mechanism in liver disease under situations where either cell compartment fails to regenerate by itself. The mechanisms underlying such trans differentiation of terminally differentiated epithelial cells are not fully elucidated. Recent...

The Liver has an amazing ability to regenerate following loss of mass. Regeneration is a complex process that involves integration of multiple growth signaling pathways. Liver regeneration has been experimentally studied by surgical removal of 2/3 rd of liver in rodents. Following a partial hepatectomy (PHx), more than 100 genes exhibit differentia...

It is known that a large number of circulating extracellular signals including growth factors, cytokines, and other ligands mobilizing specific signaling pathways are involved in the stimulation of liver regeneration. Studies have shown that these extracellular signals vary to a great degree and details in their capacity to stimulate hepatocyte gro...

Unlabelled: Hepatocellular carcinoma (HCC) is the most commonly diagnosed form of liver cancer with high morbidity and mortality. Copy number variation (CNV) analysis of human HCC revealed that leukocyte-specific protein 1 (LSP1) had the highest number of cases with CNV. LSP1, a F-actin-binding protein, is expressed in hematopoietic cells and inte...

Supplemental Methods

We describe a new preservation modality combining machine perfusion (MP) at subnormothermic conditions (21°C) with a new hemoglobin-based oxygen carrier (HBOC) solution. MP (n = 6) was compared to cold static preservation (CSP; n = 6) in porcine orthotopic liver transplants after 9 h of cold ischemia and 5-day follow-up. Recipients' peripheral bloo...

Miniature chromosome maintenance 7 (MCM7) is an essential component of DNA replication licensing complex. Recent studies indicate that MCM7 is amplified and over-expressed in a variety of human malignancies. In this report, we showed that MCM7 binds SF3B3. The binding motif is located in the N-terminus (aa221-248) of MCM7. Knocked-down of MCM7 or S...

The mechanisms underlying the potential for aggressive behavior of prostate cancer (PCa) remain elusive. In this study, whole genome and/or transcriptome sequencing was performed on 19 specimens of PCa, matched adjacent benign prostate tissues, matched blood specimens, and organ donor prostates. A set of novel fusion transcripts was discovered in P...

Liver regeneration after partial hepatectomy is the only example of a regenerative process in mammals in which the organ/body weight ratio returns to 100% of the original when the process is complete. The adjustment of liver weight to the needs of the body suggests a complicated set of control points, a 'hepatostat'. There has been much progress in...

The recent three decades emphasized research on liver regeneration, which focused on signals leading hepatocytes into proliferation and liver into regeneration. Mitogenic growth factors (ligands of EGFR and HGF) were identified as direct mitogens for both hepatocyte cultures as well as whole animals in vivo. Multiple other signals (including norepi...

Exogenous interleukin 6 (IL-6), synthesized at the initiation of the acute phase response, is considered responsible for signaling hepatocytes to produce acute phase proteins. It is widely posited that IL-6 is either delivered to the liver in an endocrine fashion from immune cells at the site of injury, or alternatively, in a paracrine manner by he...

Chemically defined serum-free media for rat hepatocytes have been useful in identifying EGFR ligands and HGF/MET signaling as direct mitogenic factors for rat hepatocytes. The absence of such media for mouse hepatocytes has prevented screening for discovery of such mitogens for mouse hepatocytes. We present results obtained by designing such a chem...

This Commentary highlights the article by Sekiya and Suzuki, detailing genetic lineage tracing to determine the origin of cells that form primitive ductules in a mouse model of chronic liver injury.

62 Background: Prognostic biomarkers are needed for superficial gastroesophageal adenocarcinoma (EAC) to predict clinical outcomes and select therapy. Although recurrent mutations have been characterized in EAC, little is known about their clinical and prognostic significance. Aneuploidy is predictive of clinical outcome in many malignancies but ha...

Prognostic biomarkers are needed for superficial gastroesophageal adenocarcinoma (EAC) to predict clinical outcomes and select therapy. Although recurrent mutations have been characterized in EAC, little is known about their clinical and prognostic significance. Aneuploidy is predictive of clinical outcome in many malignancies but has not been eval...

DNA methylation is one of the most important epigenetic mechanisms in regulating gene expression. Genome hypermethylation has been proposed as a critical mechanism in human malignancies. However, whole-genome quantification of DNA methylation of human malignancies has rarely been investigated, and the significance of the genome distribution of CpG...

Particularly interesting new cysteine-histidine-rich protein (PINCH) protein is part of the ternary complex known as the IPP (integrin linked kinase (ILK)-PINCH-Parvin-α) complex. PINCH itself binds to ILK and to another protein known as Rsu-1 (Ras suppressor 1). We generated PINCH 1 and PINCH 2 Double knockout mice (referred as PINCH DKO mice). PI...

Previous studies from our laboratory have found glypican 3 (GPC3) as a negative regulator of growth. CD81 was found to be a binding partner for GPC3, and its expression and co-localization with GPC3 increased at the end of hepatocyte proliferation. However, the mechanisms through which these two molecules might regulate liver regeneration are not k...

Altered genome methylation is a hallmark of human malignancies. To investigate the global methylation profile of prostate cancer, high-throughput analysis of concordant methylation and gene expression events was carried out for 124 human prostate specimens, including prostate cancer (T), normal adjacent to tumor (AT), and organ donor (OD). Methylat...

Hepatic stellate cell (HSC) activation and trans‐differentiation into myofibroblast‐like (MFB‐like) cells is a key process in liver injury and fibrogenesis, a known prelude to cirrhosis. This study investigated the role of tissue‐type plasminogen activator (t‐PA) and its receptor, LRP1, in HSC activation. Primary rat HSCs or rat HSC‐T6 cells were t...

The HGF receptor MET and the EGF receptor (EGFR) are mitogenic receptor‐tyrosine kinases for hepatocytes. We report the results on liver regeneration in mouse following concurrent inhibition of kinase activity of MET & EGFR by using Gefitinib and JNJ 38877605 respectively. Mice were administered two doses of Gefitinib (300 mg/kg) and JNJ 38877605 (...