Forty-eight hours after siRNA transfection, expression levels of STING were detected by immunoblotting. Statistical analyses were performed using unpaired, two-tailed Student t test. P < 0.05 were considered to be statistically significant.

First, we performed a reporter assay using a luciferase reporter plasmid regulated by native IFN-β promoter. Consistent with our previous study,19 overexpression of NS4B, as well as NS3/4A, inhibited the IFN-β promoter activation that was induced by ΔRIG-I and Cardif, respectively (Fig. 1A). We next studied whether NS4B targets STING and inhibits RIG-I pathway–mediated activation of IFN-β production. Expression of NS4B protein significantly suppressed STING-mediated activation of the IFN-β promoter reporter, whereas expression of NS3/4A showed no effect on STING-induced IFN-β promoter activity (Fig. 1A). PS-341 purchase To study whether NS4B blocks the STING-mediated DNA-sensing pathway, we

performed a reporter assay using a luciferase reporter plasmid cotransfection with poly(dA:dT), which is a synthetic analog of B-DNA and has been reported to induce STING-mediated IFN-β production and NS4B. NS4B significantly blocked poly(dA:dT)-induced IFN-β promoter activation, suggesting that NS4B may block STING signaling in the DNA-sensing pathway (Fig. 1A). Activation of RIG-I signaling induces phosphorylation Paclitaxel nmr of IRF-3, which is a hallmark of IRF-3 activation.32 Thus, we examined the effects of NS3/4A and NS4B expression on phosphorylation of IRF-3 by immunoblotting analysis. As shown in Fig. 1B, overexpression of ΔRIG-I, Cardif, or STING in HEK293T cells increased levels of phosphorylated IRF-3 (pIRF-3). Expression Avelestat (AZD9668) of NS4B impaired the IRF-3 phosphorylation that was induced by ΔRIG-I, Cardif, or STING. NS3/4A also blocked production of pIRF-3 induced by ΔRIG-I or Cardif. Intriguingly, NS3/4A did not block STING-induced pIRF-3 production. These results demonstrate that both NS3/4A and NS4B suppress RIG-I–mediated IFN-β production, but they do so by targeting different molecules in the signaling pathway. We next studied the subcellular

localization of NS4B following its overexpression and measured the colocalization of NS4B with Cardif and STING in both HEK293T cells and Huh7 cells by indirect immunofluorescence microscopy. NS4B was localized predominantly in the ER, which is consistent with previous reports33 (Fig. 2A). Cardif was localized in mitochondria but did not colocalize with the ER-resident host protein disulphide-isomerase (PDI). Interestingly, Cardif and NS4B colocalized partly at the boundary of the two proteins, although their original localization was different (Fig. 2A,C). STING was localized predominantly in the ER20, 21 (Fig. 2B,D). STING colocalized partly with Cardif, which is consistent with a previous report by Ishikawa and Barber20 (Fig. 2B,D).

Forty-eight hours after siRNA transfection, expression levels of STING were detected by immunoblotting. Statistical analyses were performed using unpaired, two-tailed Student t test. P < 0.05 were considered to be statistically significant.

First, we performed a reporter assay using a luciferase reporter plasmid regulated by native IFN-β promoter. Consistent with our previous study,19 overexpression of NS4B, as well as NS3/4A, inhibited the IFN-β promoter activation that was induced by ΔRIG-I and Cardif, respectively (Fig. 1A). We next studied whether NS4B targets STING and inhibits RIG-I pathway–mediated activation of IFN-β production. Expression of NS4B protein significantly suppressed STING-mediated activation of the IFN-β promoter reporter, whereas expression of NS3/4A showed no effect on STING-induced IFN-β promoter activity (Fig. 1A). Anti-infection Compound Library ic50 To study whether NS4B blocks the STING-mediated DNA-sensing pathway, we

performed a reporter assay using a luciferase reporter plasmid cotransfection with poly(dA:dT), which is a synthetic analog of B-DNA and has been reported to induce STING-mediated IFN-β production and NS4B. NS4B significantly blocked poly(dA:dT)-induced IFN-β promoter activation, suggesting that NS4B may block STING signaling in the DNA-sensing pathway (Fig. 1A). Activation of RIG-I signaling induces phosphorylation GPCR & G Protein inhibitor of IRF-3, which is a hallmark of IRF-3 activation.32 Thus, we examined the effects of NS3/4A and NS4B expression on phosphorylation of IRF-3 by immunoblotting analysis. As shown in Fig. 1B, overexpression of ΔRIG-I, Cardif, or STING in HEK293T cells increased levels of phosphorylated IRF-3 (pIRF-3). Expression Lck of NS4B impaired the IRF-3 phosphorylation that was induced by ΔRIG-I, Cardif, or STING. NS3/4A also blocked production of pIRF-3 induced by ΔRIG-I or Cardif. Intriguingly, NS3/4A did not block STING-induced pIRF-3 production. These results demonstrate that both NS3/4A and NS4B suppress RIG-I–mediated IFN-β production, but they do so by targeting different molecules in the signaling pathway. We next studied the subcellular

localization of NS4B following its overexpression and measured the colocalization of NS4B with Cardif and STING in both HEK293T cells and Huh7 cells by indirect immunofluorescence microscopy. NS4B was localized predominantly in the ER, which is consistent with previous reports33 (Fig. 2A). Cardif was localized in mitochondria but did not colocalize with the ER-resident host protein disulphide-isomerase (PDI). Interestingly, Cardif and NS4B colocalized partly at the boundary of the two proteins, although their original localization was different (Fig. 2A,C). STING was localized predominantly in the ER20, 21 (Fig. 2B,D). STING colocalized partly with Cardif, which is consistent with a previous report by Ishikawa and Barber20 (Fig. 2B,D).

Forty-eight hours after siRNA transfection, expression levels of STING were detected by immunoblotting. Statistical analyses were performed using unpaired, two-tailed Student t test. P < 0.05 were considered to be statistically significant.

First, we performed a reporter assay using a luciferase reporter plasmid regulated by native IFN-β promoter. Consistent with our previous study,19 overexpression of NS4B, as well as NS3/4A, inhibited the IFN-β promoter activation that was induced by ΔRIG-I and Cardif, respectively (Fig. 1A). We next studied whether NS4B targets STING and inhibits RIG-I pathway–mediated activation of IFN-β production. Expression of NS4B protein significantly suppressed STING-mediated activation of the IFN-β promoter reporter, whereas expression of NS3/4A showed no effect on STING-induced IFN-β promoter activity (Fig. 1A). Nutlin3 To study whether NS4B blocks the STING-mediated DNA-sensing pathway, we

performed a reporter assay using a luciferase reporter plasmid cotransfection with poly(dA:dT), which is a synthetic analog of B-DNA and has been reported to induce STING-mediated IFN-β production and NS4B. NS4B significantly blocked poly(dA:dT)-induced IFN-β promoter activation, suggesting that NS4B may block STING signaling in the DNA-sensing pathway (Fig. 1A). Activation of RIG-I signaling induces phosphorylation Quizartinib molecular weight of IRF-3, which is a hallmark of IRF-3 activation.32 Thus, we examined the effects of NS3/4A and NS4B expression on phosphorylation of IRF-3 by immunoblotting analysis. As shown in Fig. 1B, overexpression of ΔRIG-I, Cardif, or STING in HEK293T cells increased levels of phosphorylated IRF-3 (pIRF-3). Expression MTMR9 of NS4B impaired the IRF-3 phosphorylation that was induced by ΔRIG-I, Cardif, or STING. NS3/4A also blocked production of pIRF-3 induced by ΔRIG-I or Cardif. Intriguingly, NS3/4A did not block STING-induced pIRF-3 production. These results demonstrate that both NS3/4A and NS4B suppress RIG-I–mediated IFN-β production, but they do so by targeting different molecules in the signaling pathway. We next studied the subcellular

localization of NS4B following its overexpression and measured the colocalization of NS4B with Cardif and STING in both HEK293T cells and Huh7 cells by indirect immunofluorescence microscopy. NS4B was localized predominantly in the ER, which is consistent with previous reports33 (Fig. 2A). Cardif was localized in mitochondria but did not colocalize with the ER-resident host protein disulphide-isomerase (PDI). Interestingly, Cardif and NS4B colocalized partly at the boundary of the two proteins, although their original localization was different (Fig. 2A,C). STING was localized predominantly in the ER20, 21 (Fig. 2B,D). STING colocalized partly with Cardif, which is consistent with a previous report by Ishikawa and Barber20 (Fig. 2B,D).

Short-term administration of sorafenib triggered activation of hepatic NK cells in wildtype and tumor-bearing mice. In vitro, sorafenib sensitized Mϕ to lipopolysaccharide,

reverted alternative Mϕ polarization and enhanced IL12 secretion selleck chemical (P = 0.0133). NK cells activated by sorafenib-treated Mϕ showed increased degranulation (15.3 ± 0.2% versus 32.0 ± 0.9%, P < 0.0001) and interferon-gamma (IFN-γ) secretion (2.1 ± 0.2% versus 8.0 ± 0.2%, P < 0.0001) upon target cell contact. Sorafenib-triggered NK cell activation was verified by coculture experiments using TAM. Sorafenib-treated Mϕ increased cytolytic NK cell function against K562, Raji, and HepG2 target cells in a dose-dependent manner. Neutralization of interleukin (IL)12 or IL18 as well as inhibition of the nuclear factor kappa B (NF-κB) pathway reversed NK cell activation in Mϕ/NK cocultures. Conclusion: Sorafenib triggers proinflammatory activity of TAM and subsequently induces antitumor NK cell responses in a cytokine- and NF-κB-dependent fashion. This observation is relevant for HCC therapy, as sorafenib is a compound in clinical use that reverts alternative polarization of TAM in HCC. (HEPATOLOGY 2013;57:2358–2368) Tumor-associated macrophages (TAM) located in the hepatocellular carcinoma (HCC) environment increase HCC recurrence after resection and reduce patient survival.1,

2 TAM thereby fosters tumor cell proliferation and tumor spread.3 Natural killer (NK) cell numbers and activity, on the other hand, are associated with lower HCC stages and improved Atezolizumab patient survival.4, 5 An outstanding feature of TAM is their cytokine-dependent inhibition of lymphocyte and NK cell functions.6 TAM also promote T-cell exhaustion7 and are associated with the intratumoral accumulation of regulatory cells contributing to immune tolerance.2 TAM themselves represent alternatively polarized macrophages (Mϕ), which are opposed by proinflammatory Mϕ populations.3 Mϕ plasticity therefore

balances tumor protection and immunogenic tumor rejection. Hence, interference with Mϕ polarization leading to an anticancer immune response represents a potential approach for therapy. Tyrosine kinase inhibitors are promising candidates for TAM-directed therapy, as Mϕ polarization is regulated by tyrosine kinases.3, 6 Sorafenib, a multi-tyrosine kinase inhibitor, find more has become a standard palliative treatment for HCC.8 Sorafenib blocks different tyrosine kinases, such as rat sarcoma (RAS), rat fibrosarcoma (RAF), and extracellular-regulated protein kinase (ERK), thereby inhibiting proliferation and survival of tumor cells. In combination with antiangiogenic effects, this eventually results in HCC regression.9 Previous reports also indicate that sorafenib subverts immune responses by mitigating mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling.10, 11 In addition, inhibition of MAPKp38 by sorafenib may affect Mϕ polarization and innate immune surveillance.

Short-term administration of sorafenib triggered activation of hepatic NK cells in wildtype and tumor-bearing mice. In vitro, sorafenib sensitized Mϕ to lipopolysaccharide,

reverted alternative Mϕ polarization and enhanced IL12 secretion PARP inhibitor (P = 0.0133). NK cells activated by sorafenib-treated Mϕ showed increased degranulation (15.3 ± 0.2% versus 32.0 ± 0.9%, P < 0.0001) and interferon-gamma (IFN-γ) secretion (2.1 ± 0.2% versus 8.0 ± 0.2%, P < 0.0001) upon target cell contact. Sorafenib-triggered NK cell activation was verified by coculture experiments using TAM. Sorafenib-treated Mϕ increased cytolytic NK cell function against K562, Raji, and HepG2 target cells in a dose-dependent manner. Neutralization of interleukin (IL)12 or IL18 as well as inhibition of the nuclear factor kappa B (NF-κB) pathway reversed NK cell activation in Mϕ/NK cocultures. Conclusion: Sorafenib triggers proinflammatory activity of TAM and subsequently induces antitumor NK cell responses in a cytokine- and NF-κB-dependent fashion. This observation is relevant for HCC therapy, as sorafenib is a compound in clinical use that reverts alternative polarization of TAM in HCC. (HEPATOLOGY 2013;57:2358–2368) Tumor-associated macrophages (TAM) located in the hepatocellular carcinoma (HCC) environment increase HCC recurrence after resection and reduce patient survival.1,

2 TAM thereby fosters tumor cell proliferation and tumor spread.3 Natural killer (NK) cell numbers and activity, on the other hand, are associated with lower HCC stages and improved Cell Cycle inhibitor patient survival.4, 5 An outstanding feature of TAM is their cytokine-dependent inhibition of lymphocyte and NK cell functions.6 TAM also promote T-cell exhaustion7 and are associated with the intratumoral accumulation of regulatory cells contributing to immune tolerance.2 TAM themselves represent alternatively polarized macrophages (Mϕ), which are opposed by proinflammatory Mϕ populations.3 Mϕ plasticity therefore

balances tumor protection and immunogenic tumor rejection. Hence, interference with Mϕ polarization leading to an anticancer immune response represents a potential approach for therapy. Tyrosine kinase inhibitors are promising candidates for TAM-directed therapy, as Mϕ polarization is regulated by tyrosine kinases.3, 6 Sorafenib, a multi-tyrosine kinase inhibitor, Histidine ammonia-lyase has become a standard palliative treatment for HCC.8 Sorafenib blocks different tyrosine kinases, such as rat sarcoma (RAS), rat fibrosarcoma (RAF), and extracellular-regulated protein kinase (ERK), thereby inhibiting proliferation and survival of tumor cells. In combination with antiangiogenic effects, this eventually results in HCC regression.9 Previous reports also indicate that sorafenib subverts immune responses by mitigating mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling.10, 11 In addition, inhibition of MAPKp38 by sorafenib may affect Mϕ polarization and innate immune surveillance.

However, in all models that we generated using this technique, transfected cells were fully differentiated hepatocytes located in zone 3 and, thus, preneoplastic lesions developed always in zone 3 vein proximity.[7] The morphological demonstration, showing that affected single cells in AKT/Notch1 mice

were never located in zone 1 but always in zone 3 (Fig. 1D-I) is a proof of the physiologic principle of the method,[6] in line with all our models,[7] and in absolute contradiction to the progenitor-cell hypothesis. Furthermore, electron microscopy showed the presence of tight junctions between transfected and normal hepatocytes (supporting Fig. 10),[2] thus indicating their hepatocellular nature. Matthias Evert, M.D.1Frank Dombrowski, M.D.1Biao

Fan, M.D., Ph.D.2Silvia Ribback, M.D.1Xin Chen, Ph.D.2Diego F. Calvisi, M.D.1 “
“T cells play a crucial role for viral clearance or persistence; however, the precise mechanisms www.selleckchem.com/products/azd-1208.html that control their responses during viral infection remain incompletely understood. microRNAs (miR) have been implicated as key regulators controlling diverse biological processes through posttranscriptional repression. Here, we demonstrate that hepatitis C virus (HCV)-mediated decline of miR-181a expression impairs CD4+ T cell responses via over-expression of dual specific phosphatase 6 (DUSP6). Specifically, a significant decline of miR-181a expression along with over-expression of DUSP6 were observed in CD4+ T cells from chronically HCV-infected individuals compared Lapatinib datasheet to healthy subjects, and the levels of miR-181a loss were found to be negatively associated with the levels of DUSP6 over-expression Adenosine in these cells. Importantly, reconstitution of miR-181a or blockade of DUSP6 expression

in CD4+ T cells led to improved T cell responses including enhanced CD25 and CD69 expressions, increased IL-2 expression, and improved proliferation of CD4+ T cells derived from chronically HCV-infected individuals. Since a decline of miR-181a concomitant with DUSP6 over-expression are the signature markers for age-associated T cell senescence, these findings provide novel mechanistic insights into HCV-mediated premature T cell aging via miR-181a-regulated DUSP6 signaling, and reveal new targets for therapeutic rejuvenation of impaired T cell responses during chronic viral infection. This article is protected by copyright. All rights reserved. “
“In a recent issue of Hepatology, Herrera et al.[1] reported that human bone-marrow derived mesenchymal stem cells (hMSCs) provided protection from death from fulminant liver failure (FLF) induced by intraperitoneal injection of D-galactosamine/lipopolysaccharide (GalN/LPS) in severe combined immune deficiency (SCID) mice. SCID mice lack functional T and B cells and have been used extensively in xenotransplantation. However, the mice still possess normal natural killer (NK) cells.

We used the commercially available Human Whole GenomeOligo DNA Microarray Kit (Agilent Technologies, Santa Clara, CA, USA). Labeled cDNA was fragmented and hybridized to an oligonucleotide microarray (Whole Human Genome 4 × 44 K Agilent G4112F). Fluorescence intensities were determined with an Agilent DNA Microarray Scanner and analyzed using G2567AA Feature Extraction Software Version A.7.5.1 (Agilent Technologies), which find more used the LOWESS (locally weighted linear regression curve fit) normalization method. This microarray study followed MIAMI (Minimum Information About a Microarray Experiment) guidelines issued by the Microarray Gene Expression Datagroup.

Further analyses were performed using GeneSpring version 7.3 (Silicon Genetics, San Carlos, CA, USA). Array-CGH was performed using the Agilent Human Genome Microarray Kit 244 K (Agilent Technologies). The array-CGH platform is a high-resolution 60-mer oligonucleotide-based microarray containing approximately 244 400 probes spanning coding and non-coding genomic sequences with median spacing of 7.4 kb and 16.5 kb, respectively. Labeling and hybridization were performed according to the protocol provided by Agilent (Protocol v4.0, June 2006). Arrays were analyzed using the Agilent DNA microarray scanner.

Samples were classified into two groups based on the differences in two clinicopathological features: diabetes mellitus and hyperlipidemia. For each group, the expression levels were summarized as the means ± standard deviation. The statistical significance of www.selleckchem.com/products/INCB18424.html the difference Morin Hydrate in expression levels between the two groups was examined by Welch’s t-test using R (http://www.r-project.org/). The expression data were also used for a Jonckheere–Terpstra trend test to examine the correlation between the expression pattern of genes and the allele pattern of rs6983267. The trend analysis was performed using the “SAGx” package of

the Bioconductor project (http://www.bioconductor.org/). The study group was subdivided according to SNP genotype. There were 18 risk allele cases (GG) and 89 non-risk allele cases (GT or TT). From the array-CGH data, we selected 38 genes related to diabetes or fat metabolism. Table 2 shows the coefficient of correlation between the genome copy number of the region of the SNP at 8q24 and that of each gene. In the risk allele cases, no gene had a significant association with 8q24 at the genomic level. However, in the non-risk allele cases, there were 10 genes indicating a coefficient correlation with the genomic copy number of 8q24. We next extracted the 10 genes from the c-DNA array data. Table 3 shows the correlation between the genome copy number of the region where SNP at 8q24 was located and the average expression level of each gene. Three genes had a positive correlation in both risk allele cases and non-risk allele cases (IGF-2 receptor [IGF2R]: P = 0.016 in risk allele cases and P < 0.

We used the commercially available Human Whole GenomeOligo DNA Microarray Kit (Agilent Technologies, Santa Clara, CA, USA). Labeled cDNA was fragmented and hybridized to an oligonucleotide microarray (Whole Human Genome 4 × 44 K Agilent G4112F). Fluorescence intensities were determined with an Agilent DNA Microarray Scanner and analyzed using G2567AA Feature Extraction Software Version A.7.5.1 (Agilent Technologies), which find more used the LOWESS (locally weighted linear regression curve fit) normalization method. This microarray study followed MIAMI (Minimum Information About a Microarray Experiment) guidelines issued by the Microarray Gene Expression Datagroup.

Further analyses were performed using GeneSpring version 7.3 (Silicon Genetics, San Carlos, CA, USA). Array-CGH was performed using the Agilent Human Genome Microarray Kit 244 K (Agilent Technologies). The array-CGH platform is a high-resolution 60-mer oligonucleotide-based microarray containing approximately 244 400 probes spanning coding and non-coding genomic sequences with median spacing of 7.4 kb and 16.5 kb, respectively. Labeling and hybridization were performed according to the protocol provided by Agilent (Protocol v4.0, June 2006). Arrays were analyzed using the Agilent DNA microarray scanner.

Samples were classified into two groups based on the differences in two clinicopathological features: diabetes mellitus and hyperlipidemia. For each group, the expression levels were summarized as the means ± standard deviation. The statistical significance of BIBW2992 in vivo the difference Inositol monophosphatase 1 in expression levels between the two groups was examined by Welch’s t-test using R (http://www.r-project.org/). The expression data were also used for a Jonckheere–Terpstra trend test to examine the correlation between the expression pattern of genes and the allele pattern of rs6983267. The trend analysis was performed using the “SAGx” package of

the Bioconductor project (http://www.bioconductor.org/). The study group was subdivided according to SNP genotype. There were 18 risk allele cases (GG) and 89 non-risk allele cases (GT or TT). From the array-CGH data, we selected 38 genes related to diabetes or fat metabolism. Table 2 shows the coefficient of correlation between the genome copy number of the region of the SNP at 8q24 and that of each gene. In the risk allele cases, no gene had a significant association with 8q24 at the genomic level. However, in the non-risk allele cases, there were 10 genes indicating a coefficient correlation with the genomic copy number of 8q24. We next extracted the 10 genes from the c-DNA array data. Table 3 shows the correlation between the genome copy number of the region where SNP at 8q24 was located and the average expression level of each gene. Three genes had a positive correlation in both risk allele cases and non-risk allele cases (IGF-2 receptor [IGF2R]: P = 0.016 in risk allele cases and P < 0.

The most successful therapeutic regimen is the combination of spironolactone at 100 mg/day and furosemide at 40 mg/day, and the doses are increased in a stepwise fashion, maintaining the same ratio of doses in order to maintain normal potassium Enzalutamide in vitro levels.[4-7] However, these titration therapies cannot be easily used due to the risk of adverse events or refractory ascites. Also, use of diuretics

is associated with several complications such as renal failure and electrolyte disorders despite beneficial drug administration. Thus, a novel, orally available diuretic has been desired to be introduced into clinical practice; however, no drug has been launched. Tolvaptan, an arginine vasopressin V2 receptor antagonist, is a diuretic agent with an aquaretic effect that promotes electrolyte-free water excretion without disrupting electrolyte balance.[8, 9] It was approved for the treatment of hyponatremia in the USA and for the treatment of hyponatremia secondary to inappropriate antidiuretic hormone syndrome in the EU.[10] In 2010, tolvaptan was approved for the treatment of volume overload in patients with heart failure in Japan.[11] Now, tolvaptan is prescribed to patients who are non-responders to conventional diuretic therapy CH5424802 for treatment of edema due to heart failure in Japan. Thus, tolvaptan is already prescribed worldwide; therefore,

its benefits and risks due to occurrence of adverse events are well known. Therefore, tolvaptan can be prescribed in comfort when a new indication is added. This is desirable information Low-density-lipoprotein receptor kinase in cirrhotic patients, and whole body management of hepatic edema may be possible. In this issue of Hepatology Research, Sakaida et al. conducted a multicenter, randomized, double-blinded, placebo-controlled phase 3 study to verify the efficacy and safety of tolvaptan in cirrhotic patients with edema.[12] They set the study based on the result of a previous dose-finding trial that showed significant difference in bodyweight change between tolvaptan and placebo for 7 days in participating

patients who had insufficient response to combination therapy of spironolactone and furosemide.[12] This study demonstrated that tolvaptan at 7.5 mg/day improved hepatic edema compared with placebo. Tolvaptan dose was 7.5 mg/day, and the treatment period was 7 days. The primary end-point was change in bodyweight from baseline on the final dosing day to that was considered to reflect improvement of hepatic edema. The surrogate end-point was improvement of hepatic edema status which is assumed as a total of changes in ascites, lower limb edema and pleural effusion volumes. Change in bodyweight from baseline on the final dosing day was −0.44 kg in the placebo group and −1.95 kg in the tolvaptan group. Difference between the two groups was statistically significant (−1.51 kg, P < 0.0001). Change in ascites volume, calculated by performing computed tomography (CT), was −191.8 mL in the placebo group and −492.4 mL in the tolvaptan group.

7, 8 More importantly, DNROL and DOXOL have also been reported to be responsible for the cardiotoxicity of DNR and DOX, respectively.9, Afatinib supplier 10 In humans, the conversion of DNR and DOX to DNROL and DOXOL is mainly catalyzed by carbonyl reductase 1 (CBR1).11 CBR1 belongs to the short-chain dehydrogenase/reductase (SDR) family and is ubiquitously expressed in human tissues with particularly high levels in the liver.12 CBR1 is believed to contribute

significantly to the development of resistance toward DNR and DOX. This is supported by the finding that CBR1 overexpression results in DNR resistance in tumor cells.13, 14 DNR resistance in human stomach carcinoma cells has also been shown to result mainly from an induction of CBR1.15 Furthermore, the role of CBR1 in the severe cardiotoxicity associated with anthracycline treatment has been documented. Mice heterozygous for the null allele of CBR1 have shown reduced sensitivity to anthracycline-induced cardiotoxicity because reduced CBR1 expression produces lower levels of DOXOL.16 Because of CBR1′s role in the resistance to and toxicity of anthracyclines,

it has been speculated that the inhibition of CBR1 to prevent carbonyl reduction may be an effective approach to enhancing the efficiency and reducing the toxicity of anthracyclines.17 selleck kinase inhibitor In the SDR family, several enzymes are sensitive to inhibition by flavonoids, a group of natural products of plant origin. Flavonoids were first identified as lens aldose CBR inhibitors

in the 1970s.18, 19 More recently, hydroxy-PP has also been reported very to inhibit CBR1 and increase the sensitivity of cancer cell lines to DNR treatment (Fig. 1A).20 Flavonoids with different chemical structures are widely distributed in plants, vegetables, fruits, and beverages, particularly in tea and red wine. The major flavonoids of green tea extracts are catechins. Among them, (−)-epigallocatechin gallate (EGCG) is most abundant. EGCG has been shown to possess a wide range of pharmacological properties, including chemopreventive, anticarcinogenic, and antioxidant activity.21, 22 We have noticed a structural similarity between catechins and known inhibitors of CBR1, such as quercetin and quercitrin (Fig. 1A). In this report, evidence is presented that EGCG has a previously unknown inhibitory effect on CBR1 and CBR1-mediated tumor resistance to DNR, and this makes EGCG a potential chemotherapeutic agent for HCC.