Overexpression of miR-4669 Enhances Tumor Aggressiveness and Generates an Immunosuppressive Tumor Microenvironment in Hepatocellular Carcinoma: Its Clinical Value as a Predictive Biomarker

Accumulating evidence suggests the involvement of tumor-derived exosomes in the development and recurrence of hepatocellular carcinoma (HCC). We previously identified miR-4669 as a highly expressed microRNA in circulating exosomes obtained from patients with post-transplant HCC recurrence. This study aimed to explore how overexpression of miR-4669 affects HCC development and recurrence. The impact of miR-4669 overexpression in Hep3B cells on tumor cell behavior and the tumor microenvironment was evaluated in vitro. In addition, the clinical value of exosomal miR-4669 for the prediction of treatment response to HCC downstaging therapies and following post-transplant HCC recurrence was explored. Overexpression of miR-4669 enhanced migration ability and led to acquired sorafenib resistance with an elevation of sirtuin 1 and long noncoding RNA associated with microvascular invasion. Active release of tumor-derived exosomes and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) contributed to generating an immunosuppressive tumor microenvironment through the induction of M2 macrophage polarization. The retrospective analysis demonstrated the clinical value of exosomal miR-4669 for predicting treatment response to HCC downstaging therapies and for risk assessment of post-transplant HCC recurrence. In summary, the present data demonstrate the impact of exosomal miR-4669 on HCC recurrence through the enhancement of tumor aggressiveness and generation of an immunosuppressive tumor microenvironment.

Circulating exosomal miR-92b: Its role for cancer immunoediting and clinical value for prediction of posttransplant hepatocellular carcinoma recurrence

A recurrence of hepatocellular carcinoma (HCC) after living donor liver transplantation (LDLT) is one of the major concerns reflecting the higher mortality of HCC. This study aimed to explore the impact of circulating exosomes on HCC development and recurrence. One-shot transfusion of hepatoma serum to naïve rats induced liver cancer development with gradual elevation of alpha-fetoprotein (AFP), but exosome-free hepatoma serum failed to induce AFP elevation. The microarray analysis revealed miR-92b as one of the highly expressing microribonucleic acids in hepatoma serum exosomes. Overexpression of miR-92b enhanced the migration ability of liver cancer cell lines with active release of exosomal miR-92b. The hepatoma-derived exosomal miR-92b transferred to natural killer (NK) cells, resulting in the downregulation of CD69 and NK cell-mediated cytotoxicity. Furthermore, higher expression of miR-92b in serum exosomes was confirmed in HCC patients before LDLT, and its value at 1 month after LDLT was maintained at a higher level in the patients with posttransplant HCC recurrence. In summary, we demonstrated the impact of circulating exosomes on liver cancer development, partly through the suppression of CD69 on NK cells by hepatoma-derived exosomal miR-92b. The value of circulating exosomal miR-92b may predict the risk of posttransplant HCC recurrence.

A novel moonlight function of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) for immunomodulation

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is an energy metabolism-related enzyme, which generates NADH in glycolysis. Our previous study revealed a novel role of exogenous GAPDH in the amelioration of lipopolysaccharide (LPS)-induced sepsis-related, severe acute lung injury (ALI) in mice. Here, we show the effect of extracellular GAPDH on the physiological functions of macrophages, which play an important role in the onset of sepsis and ALI. GAPDH has no effect on cell viability, while it strongly suppressed cell adhesion, spreading, and phagocytic function of LPS-stimulated macrophages. GAPDH treatment significantly reduced tumor necrosis factor (TNF)-α, while it induced interleukin (IL)-10 production from LPS-stimulated macrophages in a dose-dependent manner. It is noteworthy that heat inactivation of GAPDH lost its immunomodulatory activity. Correspondingly, NADH significantly inhibited TNF-α and enhanced IL-10 production with elevation of both M1/M2 macrophage markers. These data suggest that extracellular GAPDH induces intermediate M1/M2 macrophages for termination of inflammation, partly through its enzyme activity for generation of NADH. © 2018 BioFactors, 44(6):597-608, 2018.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) prevents lipopolysaccharide (LPS)-induced, sepsis-related severe acute lung injury in mice

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is an energy metabolism-related enzyme in the glycolytic pathway. Recently, it has been reported that GAPDH has other physiological functions, such as apoptosis, DNA repair and autophagy. Some in vitro studies have indicated immunological aspects of GAPDH function, although there is no definite study discussing the advantage of GAPDH as a therapeutic target. Here, we show that GAPDH has an anti-inflammatory function by using a lipopolysaccharide (LPS)-induced, sepsis-related severe acute lung injury (ALI) mouse model, which is referred to as acute respiratory distress syndrome (ARDS) in humans. GAPDH pre-injected mice were protected from septic death, and their serum levels of proinflammatory cytokines were significantly suppressed. In lung tissue, LPS-induced acute injury and neutrophil accumulation were strongly inhibited by GAPDH pre-injection. Pulmonary, proinflammatory cytokine gene expression and serum chemokine expression in GAPDH pre-injected mice were also reduced. These data suggest the therapeutic potential of GAPDH for sepsis-related ALI/ARDS.

Biological interactions of CYP2C19 genotypes with CYP3A4*18, CYP3A5*3, and MDR1-3435 in living donor liver transplantation recipients

Background

Polymorphisms in CYP2C19 are related to the metabolic oxidation of drugs to varying degrees. The CYP3A4*18, CYP3A5*3, and MDR1-3435 variant alleles are very important, particularly in tacrolimus metabolism in organ transplant rejection.

Aim

The aim of this study is o explore possible interactions among different CYP2C19 genotypes, namely, between homozygous extensive metabolizers (HomEM), heterozygous extensive metabolizers (HetEM), and poor metabolizers (PM), and the CYP3A4*18, CYP3A5*3, and MDR1-3435 variants in living donors and patients who received a living donor liver transplant (LDLT).

Methods

This prospective study enrolled 133 living donors and 133 corresponding recipients. On the basis of the HomEM, HetEM, and PM CYP2C19 genotypes, the distributions of CYP3A4*18 (exon 10; T878C), CYP3A5*3 (intron 3; A6986G), and MDR1-3435 (exon 26; C3435T) genotypes were analyzed for single nucleotide polymorphisms among donors and recipients.

Results

Among 102 HomEM genotypes, including 56 donors and 46 recipients, 91.2% of individuals harbored the T/T genotype of CYP3A4*18; 53.9% possessed G/G, and 34.3% had A/G genotypes of CYP3A5*3; and 38.2% had C/C and 50.0% had C/T genotypes at MDR1-3435. Among 130 HetEM genotypes, including 58 donors and 72 recipients, 97.7% of individuals possessed T/T genotype at CYP3A4*18; 50.0% harbored G/G and 41.5% had A/G genotypes at CYP3A5*3; and 40.0% had C/C and 49.2% had C/T genotypes at MDR1-3435. In 34 PMs, including 19 donors and 15 recipients, 88.2% had T/T genotypes at CYP3A4*18; 41.2% had G/G and 58.8% had A/G genotypes at CYP3A5*3; and 47.1% possessed C/C and 47.1% had C/T genotypes at MDR1-3435. On the basis of the CYP2C19 genotypes, no statistically significant distribution of genotypes were observed between donors and recipients for all genotypes of CYP3A4*18, CYP3A5*3, and MDR1-3435 (P >0.05).

Conclusions

In conclusion, the CYP2C19 genotypes do not affect the expression of CYP3A4*18, CYP3A5*3, or MDR1-3435 variants, which are independently distributed among donors and recipients during LDLT.

Western blotting analysis for quantitative detection of CYP2C19 expression in liver tissues in the setting of living donor liver transplantation

BACKGROUND

The cytochrome P450 (CYP) drug-metabolizing enzymes play an important role in cellular metabolism. Therapeutic failure or drug toxicity in the period after liver transplantation (LT) is influenced by the drug metabolizing capacity of the graft. The expression levels of CYP2C19 enzyme are often used as an indicator of the functioning of the CYP system. The aim of the present study was to assess the CYP2C19 protein expression in the setting of living donor liver transplantation (LDLT) by using western blotting analysis.

METHODOLOGY

We performed CYP2C19 genotyping of liver biopsy samples obtained from 24 donors and 8 recipients each in the pre- and post-LT periods, after which we analyzed the CYP enzyme activity by using western blotting analysis.

RESULTS

The CYP2C19/β-actin ratio, which was an indicator of CYP expression, was 61.75% (23-100%) in donors, 59.13% (15-100%) in pre-LT recipients and 46.71% (12-67%) in post-LT recipients (p>0.05). The CYP2C19 expression levels associated with different genotypes were as follows: homozygous extensive metabolizers (HomEMs; n=24), 56.63±24.74%; heterozygous extensive metabolizers (HetEMs; n=15), 63.0±25.14% and poor metabolizers (PMs; n=1), 82.0% (p>0.05).

CONCLUSIONS

Western blotting analysis showed low CYP2C19 protein expression not only in samples from the pre- and post-LT recipients but also from the donors.

Homogenous phenomenon of graft liver CYP2C19 genotypes after living donor liver transplantation

BACKGROUND

The donor liver grafts with different allelic patterns do not affect CYP2C19 genotypes in the peripheral blood of living donor liver transplantation (LDLT) recipients.

AIM

This study investigated the influence of graft liver CYP2C19 genotypes on recipients who received the same or different CYP2C19 genotypes from donors after LDLT.

METHODS

There were 30 donors and 30 recipients with the same CYP2C19 genotypes and 47 donors and 47 recipients with different CYP2C19 genotypes. Genomic DNA was isolated from the liver tissue of recipients. The CYP2C19 haplotypes were determined by polymerase chain reaction.

RESULTS

A homogenous phenomenon in the sequences of graft liver CYP2C19 genotypes was indicated because the recipients showed mixed patterns that were similar to that of the original donor after LDLT. A significant decrease in homozygous extensive metabolizer (HomEM) and an increase in poor metabolizer (PM) distribution were observed in recipients with different CYP2C19 genotypes from their donors compared with recipients with the same CYP2C19 genotype as their donors (P < 0·05).

CONCLUSIONS

Homogenous phenomenon of sequence changes in graft liver CYP2C19 from the different genotypes between the donors and the recipients may play a role in graft stability by causing decreased HomEM and increased PM after LDLT.

Donor graft does not affect the P450 2C19 genotype expressed in peripheral blood in recipients of living donor liver transplantation

The function of cytochrome P450 2C19 (CYP2C19) is altered in patients with end-stage liver disease (ESLD) that require liver transplantation (LT). The status of CYP2C19 is of considerable interest because the transplanted healthy donor livers are perfused with the blood of the recipient with ESLD. This study aims to clarify the changes in CYP2C19 in the peripheral blood before and after LT. Thirty pairs of living donors and recipients were enrolled in this study. The CYP2C19 genotype in peripheral blood mononuclear cells (PBMCs) was studied immediately before operation in donors, on the day preceding the operation in the unstable recipients, and one month after LT in stable recipients. Limited data suggest that the post-LT genotype in liver biopsy is the same as donor's original genotype in most cases (80.0%) and that only 2 patients in the study cohort had the same liver tissue genotype as the respective recipient PBMCs. However, expression of the CYP2C19 genotype after living donor LT (LDLT) was identical to pre-transplant expression in 100% (30/30) of recipients, i.e., CYP2C19 genotypes in recipient PBMCs did not change after LDLT, suggesting that the donor liver did not render any mutations to the CYP2C19 genotypes after LT.

Neuroprotective Role of Coenzyme Q10 against Dysfunction of Mitochondrial Respiratory Chain at Rostral Ventrolateral Medulla during Fatal Mevinphos Intoxication in the Rat

We evaluated the functional changes in the mitochondrial respiratory chain at the rostral ventrolateral medulla (RVLM), the medullary origin of sympathetic vasomotor tone, in an experimental model of fatal organophosphate poisoning using the insecticide mevinphos (Mev). We also investigated the neuroprotective role of coenzyme Q10 (CoQ10) in this process. Intravenous administration of Mev (1 mg/kg) in Sprague-Dawley rats maintained with propofol elicited an initial hypertension followed by hypotension, accompanied by bradycardia, with death ensuing within 10 min. Enzyme assay revealed a significant depression of the activity of nicotinamide adenine dinucleotide cytochrome c reductase, succinate cytochrome c reductase, and cytochrome c oxidase in the RVLM during this fatal Mev intoxication. ATP production also underwent a significant decrease. Pretreatment by microinjection bilaterally of CoQ10 (4 microg) into the RVLM significantly prevented mortality, antagonized the cardiovascular suppression, and reversed the depressed mitochondrial respiratory enzyme activities, or reduced ATP production in the RVLM induced during Mev intoxication. Our results indicated that dysfunction of mitochondrial respiratory chain and energy production at the RVLM takes place during fatal Mev intoxication. We further demonstrated that CoQ10 provides neuroprotection against Mev-induced cardiovascular depression and fatality through maintenance of activity of the key mitochondrial respiratory enzymes in the RVLM.

CYP2K6 from zebrafish (Danio rerio): cloning, mapping, developmental/tissue expression, and aflatoxin B1 activation by baculovirus expressed enzyme

A full-length zebrafish (Danio rerio) cytochrome P450 (CYP) 2K6 cDNA, was obtained (GenBank accession No. AF283813) through polymerase chain reaction cloning using degenerated primers based on a consensus CYP2 sequence and the heme-binding domain. This first CYP2K family member cloned from zebrafish had 1861 bp which contained 27 bp of 5'-untranslated region (5'-UTR), an open reading frame (ORF) of 1518 bp, and a 300 bp 3'-UTR with a poly A tail. The deduced 506 amino acid sequence of CYP2K6 had 63%, 62% and 59% identity with rainbow trout CYP2K1, CYP2K4 and CYP2K3, respectively; and 45%, 42%, and 42% identity with rabbit CYP2C1, human CYP2C19 and mouse CYP2C39, respectively. CYP2K6 mapped to 107.49cR on LG3 using the LN54 radiation hybrid panel. Its mRNA was detected at 5 days post-fertilization and in the adult liver and ovary among nine tissues examined. The ORF, including the 27 bp of the 5'-UTR, was cloned into pFastBac donor vector and then transferred into the baculovirus genome (bacmid DNA) in DH10Bac competent cells. The recombinant bacmid DNA was used to infect Spodoptera frugiperda insect cells to express the CYP2K6 protein (Bv-2K6). As its ortholog, rainbow trout Bv-2K1 [Yang, Y.H., Miranda, C.L., Henderson, M.C., Wang-Buhler, J.-L., Buhler, D.R., 2000. Heterologous expression of CYP2K1 and identification of the expressed protein (Bv-2K1) as lauric acid (omega-1)-hydroxylase and aflatoxin B1 exo-epoxidase. Drug Metab. Disp. 28,1279-83.], Bv-2K6 also catalyzed the conversion of aflatoxin B1 (AFB1) to its exo-8,9-epoxide as assessed by the trapping of a glutathione (GSH) adduct in the presence of a specific mouse alpha class glutathione S-transferase. The identity of the AFB1-GSH adduct was verified by liquid chromatography-mass spectrometry (LC-MS) and mass spectrometry-mass spectrometry (MS-MS) analysis. Although rainbow trout Bv-2K1 was capable of oxidizing lauric acid, zebrafish Bv-2K6 protein showed no activity against this substrate.

DEPRESSION OF MITOCHONDRIAL RESPIRATORY ENZYME ACTIVITY IN ROSTRAL VENTROLATERAL MEDULLA DURING ACUTE MEVINPHOS INTOXICATION IN THE RAT

We investigated possible changes in bioenergetics at the rostral ventrolateral medulla (RVLM), a medullary site where sympathetic vasomotor tone originates and where the organophosphate poison mevinphos (Mev) acts to elicit cardiovascular intoxication. In Sprague-Dawley rats maintained under propofol anesthesia, microinjection bilaterally of Mev (10 nmol) into the RVLM induced progressive hypotension that was accompanied by an early augmentation (80-100 min post-Mev; Phase I), followed by a decrease (>100 min post-Mev; Phase II) in the power density of the vasomotor components (0-0.8 Hz) in systemic arterial pressure (SAP) signals. Enzyme assay revealed that local application of Mev into the RVLM also significantly and progressively depressed the activity of NADH cytochrome c reductase (marker for Complexes I and III) and cytochrome c oxidase (marker for Complex IV) in the mitochondrial respiratory chain of the RVLM, but not the heart. On the other hand, the activity of succinate cytochrome c reductase (marker for Complexes II and III) remained unaltered. Both the cardiovascular consequences and depression of mitochondrial respiratory chain enzymes elicited by Mev were significantly antagonized on comicroinjection of atropine (3.5 or 7 nmol) bilaterally into the RVLM. We conclude that Mev adversely effects cardiovascular control by acting as a cholinesterase inhibitor in the RVLM, whose neuronal activity is intimately related to the death process. The resulting accumulation of acetylcholine and prolonged activation of muscarinic receptors in the RVLM is manifested by a selective dysfunction of respiratory enzyme Complexes I and IV in the mitochondrial respiratory chain that underlies cardiovascular toxicity associated with organophosphate poisons such as Mev.

Identification of two down-regulated genes in rat liver allografts by mRNA differential display

Total RNA differential display (DD) using random primers was performed for rat orthotopic liver transplantation (OLT) models. DA (RT1a) donor livers were transplanted into DA, PVG (RT1c), and LEW (RT1l) recipients: (1) syngeneic OLT (DA-DA): no rejection occurs; (2) allogeneic OLT (DA-PVG): rejection occurs, but is naturally overcome without immunosuppression; (3) allogeneic OLT (DA-LEW): animals die of acute rejection within 14 days. cDNA was isolated from selected bands, re-amplified for sequencing, and confirmed by Northern blots. Two down-regulated genes were observed in day-7 allogeneic OLT livers (DA-PVG, DA-LEW), while they were consistently expressed in day-7 syngeneic OLT (DA-DA) livers. These two genes were identified as alpha-glutathione sulfotransferase (alpha-GST) Ya gene and estrogen sulfotransferase (EST), respectively. Northern blots confirmed that their expression was down-regulated in OLT (DA-PVG) livers on days 7-26 and gradually restored. The mRNA expression of GST and EST may be good markers to predict rejection or induction of tolerance.

Identification of the indoleamine 2,3-dioxygenase nucleotide sequence in a rat liver transplant model

A tryptophan catabolizer, indoleamine 2,3-dioxygenase (IDO) is highly expressed in the placenta and plays an essential role in maternal tolerance. Recent data have shown that the administration of an IDO inhibitor blocked not only maternal tolerance but also liver allograft tolerance. However, little is known about the induction of IDO in liver allografts, although a gene specific for tryptophan 2,3-dioxygenase (TDO) is believed to be expressed in the liver. In the present study, we investigated whether IDO is induced in liver allografts. Synthetic oligonucleotide primers based on the mouse IDO cDNA sequence were used to amplify RNA derived from livers of donor, syngeneic or allogeneic OLT rats. RNA encoding IDO was induced in the rat allogeneic liver after orthotopic liver transplantation (OLT), but not in syngeneic OLT. The rat nucleotide sequence of the RT-PCR products obtained from OLT livers revealed identities of 89% homology to the mouse IDO and of 68% to the human IDO. This study demonstrated the presence of RNA encoding IDO in allogeneic OLT livers, which may be involved in the immune response after liver transplantation.

Clusterin may be involved in rat liver allograft tolerance

Little is known about the possible role of complement inhibitors on tolerance induced by liver allografts. Clusterin, which is a plasma glycoprotein, inhibits cytolytic membrane attack complex (MAC) of complement by binding to soluble C5b-7 complex. The role of clusterin in relation to the naturally achieved tolerance in a rat orthotopic liver transplantation (OLT) has not been investigated before. Here we determined the kinetics of clusterin expression at different post-transplantation time points in a tolerogenic model (DA-PVG) where rejection was naturally overcome without any immunosuppressive drugs in comparison with the syngenic OLT model (DA-DA). Peripheral blood and liver tissues were taken from OLT at various post-operative time points. A strong expression of soluble clusterin was observed on post-transplantation day 7, which occurred at the peak of the rejection in this tolerogenic OLT model. The expression of clusterin remained strong even after tolerance was achieved. The intensity of clusterin expression was much stronger when compared with the syngenic OLT (DA-DA) model after OLT. A strong expression of clusterin mRNA was also observed in the tolerogenic model on post-OLT day (POD) 7 and the expression persisted when compared with the syngenic model on post-OLT day 60. Our data have shown that the strongest levels of clusterin during the reaction phase in tolerogenic OLT may be involved in tolerance induction.

Telomerase activity in rat liver allografts

BACKGROUND

Telomerase activity in grafts may be involved in the alteration of cellular senescence after transplantation or its relevant immunological events.

METHODS

At the age of 20 weeks, donor livers harvested from DA (RT1a) were orthotopically transplanted into PVG (RT1c) or LEW (RT1(1)) rats. Rats having undergone orthotopic liver transplantation (OLT; DA-PVG) naturally overcome rejection, whereas all OLT (DA-LEW) rats die from acute rejection within 14 days. Telomerase activity in liver allografts was measured at various intervals post OLT.

RESULTS

At day 7 when the most severe rejection episode was observed in OLT (DA-LEW) and OLT (DA-PVG), the telomerase activity was significantly higher than in syngeneic OLT (DA-DA) rats, in which no rejection occurred. Telomerase activity in tolerogenic OLT (DA-PVG) livers remained elevated for at least 2 months.

CONCLUSION

These results suggest that telomerase activity in allogeneic OLT livers may reflect regenerating hepatocytes or activation of lymphocytes and/or hematopoietic stem cells associated with rejection or tolerance.

Effect of antioxidant in endothelial cells exposed to oxidized low-density lipoproteins

Antioxidants such as probucol and alpha-tocopherol have been shown to attenuate the oxidation of low-density lipoproteins (LDL) and atherosclerotic lesions in animal models of atherosclerosis. The purpose of this study is to determine the protection effect of antioxidants on endothelial cells when exposed to oxidized and native LDL. In a cell-free system, we found that probucol, alpha-tocopherol, and ascorbic acid inhibited copper-induced LDL oxidation by a dose-dependent fashion (from 1 microM to 10 mM). In porcine aortic endothelial cells, antioxidants alone did not change basal endothelin-1 (ET-1) secretion. When porcine aortic endothelial cells were exposed to LDL and oxidized-LDL, both of them stimulated ET-1 secretion dose-dependently, whereas oxidized-LDL elicited higher ET-1 secretion. However, probucol, alpha-tocopherol, and ascorbic acid did not prevent LDL or oxidized-LDL induced ET-1 secretion. Furthermore, nimodipine inhibited both of native and oxidized LDL induced ET-1 secretion. Since Ca2+ channel blocker reduced the elevation of induced ET-1 secretion, the [Ca2+]i is possibly involved for the regulation of ET-1 secretion. Our results suggest that antioxidants can only prevent the oxidation of LDL rather than oxidized and native LDL-induced ET-1 secretion in vascular endothelial cells. The increase in the [Ca2+]i of endothelial cells through the opening of voltage-dependent Ca2+ channels may be involved in the LDL-induced ET-1 release.