The regulatory role of heparin on c-Met signaling in hepatocellular carcinoma cells

Fibulin7 aggravates calcium oxalate-induced acute kidney injury by binding to calcium oxalate crystals

Fibulin7 (Fbln7) is a matricellular protein that is structurally similar to short fibulins but does not possess elastogenic abilities. Fbln7 is localized on the cell surface of the renal tubular epithelium in the adult kidney. We previously reported that Fbln7 binds artificial calcium phosphate particles in vitro, and that heparin counteracts this binding by releasing Fbln7 from the cell surface. Fbln7 gene (Fbln7) deletion in vivo decreased interstitial fibrosis and improved renal function in a high phosphate diet-induced chronic kidney disease mouse model. However, the contribution of Fbln7 during acute injury response remains largely unknown. We hypothesized that Fbln7 serves as an exacerbating factor in acute kidney injury (AKI). We employed three AKI models in vivo and in vitro, including unilateral ureteral obstruction (UUO), cisplatin-induced AKI, and calcium oxalate (CaOx)-induced AKI. Here, we report that Fbln7KO mice were protected from kidney damage in a CaOx-induced AKI model. Using HEK293T cells, we found that Fbln7 overexpression enhanced the CaOx-induced upregulation of EGR1 and LAMB3, and that heparin treatment canceled this effect. Interestingly, the protective function observed in Fbln7KO kidneys was limited to the CaOx-induced AKI model, while Fbln7KO mice were not protected against UUO-induced renal fibrosis or cisplatin-induced renal tubular damage. Taken together, our study indicates that Fbln7 mediates the local deposition of CaOx and damages the renal tubular epithelium. Releasing Fbln7 from the cell surface via heparin/heparin derivatives or Fbln7 inhibitory antibodies may provide a general strategy to mitigate calcium crystal-induced kidney injuries.

Selective Inhibitor of the c-Met Receptor Tyrosine Kinase in Advanced Hepatocellular Carcinoma: No Beneficial Effect With the Use of Tivantinib?

Advanced hepatocellular carcinoma (HCC) remains a formidable health challenge worldwide, with a 5-year survival rate of 2.4% in patients with distant metastases. The hepatocyte growth factor/cellular-mesenchymal-epithelial transition (HGF/c-Met) signaling pathway represents an encouraging therapeutic target for progressive HCC. Tivantinib, a non-adenosine triphosphate-competitive c-Met inhibitor, showed an attractive therapeutic effect on advanced HCC patients with high MET-expression in phase 2 study but failed to meet its primary endpoint of prolonging the overall survival (OS) in two phase 3 HCC clinical trials. Seven clinical trials have been registered in the "ClinicalTrials.gov" for investigating the safety and efficacy of tivantinib in treating advanced or unresectable HCC. Eight relevant studies have been published with results. The sample size ranged from 20 to 340 patients. The methods of tivantinib administration and dosage were orally 120/240/360 mg twice daily. MET overexpression was recorded at 34.6% to 100%. Two large sample phase 3 studies (the METIV-HCC study of Australia and European population and the JET-HCC study of the Japanese population) revealed that tivantinib failed to show survival benefits in advanced HCC. Common adverse events with tivantinib treatment include neutropenia, ascites, rash, and anemia, etc. Several factors may contribute to the inconsistency between the phase 2 and phase 3 studies of tivantinib, including the sample size, drug dosing, study design, and the rate of MET-High. In the future, high selective MET inhibitors combined with a biomarker-driven patient selection may provide a potentially viable therapeutic strategy for patients with advanced HCC.

High glucose induced c-Met activation promotes aggressive phenotype and regulates expression of glucose metabolism genes in HCC cells

Hepatocellular carcinoma (HCC) is strongly associated with metabolic dysregulations/deregulations and hyperglycemia is a common metabolic disturbance in metabolic diseases. Hyperglycemia is defined to promote epithelial to mesenchymal transition (EMT) of cancer cells in various cancers but its molecular contribution to HCC progression and aggressiveness is relatively unclear. In this study, we analyzed the molecular mechanisms behind the hyperglycemia-induced EMT in HCC cell lines. Here, we report that high glucose promotes EMT through activating c-Met receptor tyrosine kinase via promoting its ligand-independent homodimerization. c-Met activation is critical for high glucose induced acquisition of mesenchymal phenotype, survival under high glucose stress and reprogramming of cellular metabolism by modulating glucose metabolism gene expression to promote aggressiveness in HCC cells. The crucial role of c-Met in high glucose induced EMT and aggressiveness may be the potential link between metabolic syndrome-related hepatocarcinogenesis and/or HCC progression. Considering c-Met inhibition in hyperglycemic patients would be an important complementary strategy for therapy that favors sensitization of HCC cells to therapeutics.

lncRNA HOTAIR overexpression induced downregulation of c-Met signaling promotes hybrid epithelial/mesenchymal phenotype in hepatocellular carcinoma cells

Background

Epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET) are both reversible processes, and regulation of phenotypical transition is very important for progression of several cancers including hepatocellular carcinoma (HCC). Recently, it is defined that cancer cells can attain a hybrid epithelial/mesenchymal (hybrid E/M) phenotype. Cells with hybrid E/M phenotype comprise mixed epithelial and mesenchymal properties, they can be more resistant to therapeutics and also more capable of initiating metastatic lesions. However, the mechanisms regulating hybrid E/M in HCC are not well described yet. In this study, we investigated the role of the potential crosstalk between lncRNA HOTAIR and c-Met receptor tyrosine kinase, which are two essential regulators of EMT and MET, in acquiring of hybrid E/M phenotype in HCC.

Methods

Expression of c-Met and lncRNA HOTAIR were defined in HCC cell lines and patient tissues through HCC progression. lncRNA HOTAIR was overexpressed in SNU-449 cells and its effects on c-Met signaling were analyzed. c-Met was overexpressed in SNU-398 cells and its effect on HOTAIR expression was analyzed. Biological significance of HOTAIR/c-Met interplay was defined in means of adhesion, proliferation, motility behavior, invasion, spheroid formation and metastatic ability. Effect of ectopic lncRNA HOTAIR expression on phenotype was defined with investigation of molecular epithelial and mesenchymal traits.

Results

In vitro and in vivo experiments verified the pivotal role of lncRNA HOTAIR in acquisition of hybrid E/M phenotype through modulating expression and activation of c-Met and its membrane co-localizing partner Caveolin-1, and membrane organization to cope with the rate limiting steps of metastasis such as survival in adhesion independent microenvironment, escaping from anoikis and resisting to fluidic shear stress (FSS) in HCC.

Conclusions

Our work provides the first evidence suggesting a role for lncRNA HOTAIR in the modulation of c-Met to promote hybrid E/M phenotype. The balance between lncRNA HOTAIR and c-Met might be critical for cell fate decision and metastatic potential of HCC cells.

Structural and Functional Insight Into the Glycosylation Impact Upon the HGF/c-Met Signaling Pathway

Upon interactions with its specific ligand hepatocyte growth factor (HGF), the c-Met signal is relayed to series of downstream pathways, exerting essential biological roles. Dysregulation of the HGF-c-Met signaling pathway has been implicated in the onset, progression and metastasis of various cancers, making the HGF-c-Met axis a promising therapeutic target. Both c-Met and HGF undergo glycosylation, which appears to be biologically relevant to their function and structural integrity. Different types of glycoconjugates in the local cellular environment can also regulate HGF/c-Met signaling by distinct mechanisms. However, detailed knowledge pertaining to the glycosylation machinery of the HGF-c-Met axis as well as its potential applications in oncology research is yet to be established. This mini review highlights the significance of the HGF-c-Met signaling pathway in physiological and pathological context, and discusses the molecular mechanisms by which affect the glycosylation of the HGF-c-Met axis. Owing to the crucial role played by glycosylation in the regulation of HGF/c-Met activity, better understanding of this less exploited field may contribute to the development of novel therapeutics targeting glycoepitopes.

Increased expression of hematological and neurological expressed 1 (HN1) is associated with a poor prognosis of hepatocellular carcinoma and its knockdown inhibits cell growth and migration partly by down-regulation of c-Met

Hematologic and neurological expression 1 (HN1) has been reported to involved in certain cancers, but its role in hepatocellular carcinoma (HCC) is largely unknown. The contribution of HN1 to HCC progression was investigated in the present study. We found that HN1 was significantly up-regulated in HCC tissues, compared with normal tissues, by analyzing the Oncomine and Human Protein Atlas database; and found that high expression of HN1 was markedly associated with worse overall survival, relapse-free survival, progression- free survival and disease-specific survival in HCC patients via exploring the Kaplan-Meier plotter database. Functional assays revealed that HN1 knockdown by siRNA induced G1 cell cycle arrest, and inhibited the growth and migration of HCC cells; accordingly, HN1 over-expression promoted HCC cells proliferation and migration. Further studies indicated that HN1 knockdown reduced the expression of cyclin D1 and CDK4, while upregulated the cell cycle inhibitor p21WAF1/Cip1. Moreover, HN1 knockdown decreased c-Met (receptor tyrosine kinase of hepatocyte growth factor) expression, and suppressed ERK activation, which is a common downstream signaling pathway triggered by c-Met; consistently, HN1 over-expression reversed these effects. Meanwhile, down-regulation of c-Met partly eliminated the effect of HN1 over-expression in HCC cells. Thus, the present findings suggested that HN1 promotes the progression of HCC to some extent by up-regulating the expression of c-Met, and may act as a potential biomarker and therapeutic target for the treatment of HCC.

Extracellular Matrix Influencing HGF/c-MET Signaling Pathway: Impact on Cancer Progression

The extracellular matrix (ECM) is a crucial component of the tumor microenvironment involved in numerous cellular processes that contribute to cancer progression. It is acknowledged that tumor–stromal cell communication is driven by a complex and dynamic network of cytokines, growth factors and proteases. Thus, the ECM works as a reservoir for bioactive molecules that modulate tumor cell behavior. The hepatocyte growth factor (HGF) produced by tumor and stromal cells acts as a multifunctional cytokine and activates the c-MET receptor, which is expressed in different tumor cell types. The HGF/c-MET signaling pathway is associated with several cellular processes, such as proliferation, survival, motility, angiogenesis, invasion and metastasis. Moreover, c-MET activation can be promoted by several ECM components, including proteoglycans and glycoproteins that act as bridging molecules and/or signal co-receptors. In contrast, c-MET activation can be inhibited by proteoglycans, matricellular proteins and/or proteases that bind and sequester HGF away from the cell surface. Therefore, understanding the effects of ECM components on HGF and c-MET may provide opportunities for novel therapeutic strategies. Here, we give a short overview of how certain ECM components regulate the distribution and activation of HGF and c-MET.

A Comparison of the Effectiveness of Silibinin and Resveratrol in Preventing Alpha-Amanitin-Induced Hepatotoxicity

Amanita phalloides species mushrooms containing alpha-amanitin (α-AMA) are responsible for the majority of fatal mushroom intoxications and can lead to severe poisonings resulting in hepatotoxicity and acute hepatic failure. Existing antidotes, such as silibinin, are not sufficiently effective in the prevention and/or resolution of α-AMA-induced hepatotoxicity. We investigated the effects of resveratrol on α-AMA-induced hepatotoxicity and compared with silibinin, a known antidote using in vivo and in vitro toxicity models. In the in vivo protocol, resveratrol (30 mg/kg) was given simultaneously with α-AMA (α-AMA + SR) or 12 (α-AMA + 12R) or 24 (α-AMA + 24R) hr after α-AMA administration. Silibinin (5 mg/kg) (α-AMA + Sil) and normal saline (α-AMA + NS) were given simultaneously with α-AMA. We found that liver transaminase levels in α-AMA + SR and α-AMA + 12R groups and histomorphologic injury score in the α-AMA + SR, α-AMA + 12R, α-AMA + 24R and α-AMA + Sil groups were significantly lower than that of the α-AMA + NS group. Resveratrol decreased mononuclear cell infiltration, necrosis and active caspase-3 immunopositivity in the liver. In the in vitro protocol, the effects of resveratrol and silibinin were evaluated in a reduction in cell viability induced by α-AMA in THLE-2 and THLE-3 hepatocytes. Neither resveratrol nor silibinin was found to be effective in increasing cell viability decreased by α-AMA + NS. As a conclusion, resveratrol was found to be effective in α-AMA-induced hepatotoxicity with its anti-inflammatory properties in in vivo conditions. It is a promising compound with the potential for use in the treatment of hepatotoxicity associated with Amanita phalloides type mushroom poisonings.

Norcantharidin alone or in combination with crizotinib induces autophagic cell death in hepatocellular carcinoma by repressing c-Met-mTOR signaling

There is an urgent need for effective molecular therapies for hepatocellular carcinoma (HCC), the third-leading cause of cancer-related deaths worldwide. Norcantharidin (NCTD), a demethylated derivative of cantharidin, reportedly exhibits anticancer activity against various types of tumors, including HCC, though the mechanisms involved remain largely unknown. Here, we report that NCTD reduces viability of human MHCC-97H (97H) and HepG2 HCC cells, and induces cell death by triggering high levels of autophagy. Moreover, a significant attenuation of tumor growth was observed after NCTD treatment of HepG2 tumors in vivo, and this effect was enhanced by co-treatment with the c-Met inhibitor crizotinib. Interestingly, western blot analyses showed that the cytotoxic autophagy induced by NCTD correlates with a reduction in the phosphorylation status of both c-Met and m-TOR. These results suggest that cytotoxic autophagy resulting from inhibition of c-Met/mTOR signaling may be achieved in HCC by combined NCTD and crizotinib administration. Further studies to validate the therapeutic potential of this approach are warranted.

Attenuation of MET-mediated migration and invasion in hepatocellular carcinoma cells by SOCS1

AIM

To investigate the role of suppressor of cytokine signaling 1 (SOCS1) in regulating MET-mediated invasive potential of hepatocellular carcinoma (HCC) cells.

METHODS

Stable derivatives of mouse (Hepa1-6) and human (hep3B, HepG2) HCC cell lines expressing SOCS1 or control vector were evaluated for their ability to migrate towards hepatocyte growth factor (HGF) in the transwell migration assay, invade extracellular matrix in response to HGF stimulation in a 3-D invasion assay by confocal microscopy, and to undergo anchorage-independent proliferation in semisolid agar. Following intravenous and intrasplenic inoculation into NOD.scid.gamma mice, the ability of Hepa cells to form othotopic tumors was evaluated. Following HGF stimulation of Hepa and Hep3B cells, expression of proteins implicated in epithelial-to-mesenchymal transition was evaluated by western blot and qRT-PCR.

RESULTS

SOCS1 expression in mouse and human HCC cells inhibited HGF-induced migration through matrigel. In the 3-D invasion assay, HGF stimulation induced invasion of HCC cells across type-I collagen matrix, and SOCS1 expression significantly reduced the depth of invasion. SOCS1 expression also reduced the number and size of colonies formed by anchorage-independent growth in semisolid agar. Following intravenous inoculation, control Hepa cell formed large tumor nodules that obliterated the liver whereas the SOCS1-expressing Hepa cells formed significantly smaller nodules. Tumors formed by SOCS1-expressing cells showed reduced phosphorylation of STAT3 and ERK that was accompanied by reduced levels of MET protein expression. HGF stimulated Hepa cells expressing SOCS1 showed increased expression of E-cadherin and decreased expression of EGR1, SNAI1 and ZEB1. Comparable results were obtained with Hep3B cells. SOCS1 expressing HCC cells also showed reduced levels of EGR1 and SNAI1 transcripts.

CONCLUSION

Our findings indicate that loss of SOCS1-dependent control over epithelial-to-mesenchymal transition may contribute to MET-mediated migration, invasion and metastatic growth of HCC.

Heparin/Collagen 3D Scaffold Accelerates Hepatocyte Differentiation of Wharton's Jelly-Derived Mesenchymal Stem Cells

Both mature and stem cell-derived hepatocytes lost their phenotype and functionality under conventional culture conditions. However, the 3D scaffolds containing the main extracellular matrix constitutions, such as heparin, may provide appropriate microenvironment for hepatocytes to be functional. The current study aimed to investigate the efficacy of the differentiation capability of hepatocytes derived from human Wharton's jelly mesenchymal stem cells (WJ-MSCs) in 3D heparinized scaffold. In this case, the human WJ-MSCs were cultured on the heparinized and non-heparinized 2D collagen gels or within 3D scaffolds in the presence of hepatogenic medium. Immunostaining was performed for anti-alpha fetoprotein, cytokeratin-18 and -19 antibodies. RT-PCR was performed for detection of hepatic nuclear factor-4 (HNF-4), albumin, cytokeratin-18 and -19, glucose-6-phosphatase (G6P), c-met and Cyp2B. The results indicated that hepatogenic media induced the cells to express early liver-specific markers including HNF4, albumin, cytokeratin-18 and 19 in all conditions. The cells cultured on both heparinized culture conditions expressed late liver-specific markers such as G6P and Cyp2B as well. Besides, the hepatocytes differentiated in 3D heparinized scaffolds stored more glycogen that indicated they were more functional. Non-heparinized 2D gel was the superior condition for cholangiocyte differentiation as indicated by higher levels of cytokeratin 19 expression. In conclusion, the heparinized 3D scaffolds provided a microenvironment to mimic Disse space. Therefore, 3D heparinized collagen scaffold can be suggested as a good vehicle for hepatocyte differentiation.