RESUMEN

Skin ageing is characterized by features such as wrinkles, loss of elasticity, laxity, rough-textured appearance, melasma and freckles. Several researches have focused for preventing, and treating skin ageing by many natural ingredients. This study aimed to assess the anti-ageing activities for anti-skin ageing of the ethanolic extracts of Pink rambutan (PR) (Nephelium lappaceum Linn.) from leaves (L), branches (B), seeds (S), and peels from ripe (R) and young (Y) fruits. The extraction yields of all Pink Rambutan (PR) extracted by the Maceration (M) and the Soxhlet extraction (Sox) using 95% ethanol as a solvent, ranged from 10.62% to 30.63%. Flavonoids were found as the main phytochemicals in almost all the PR extracts. The PR-Y-M and PR-Y-Sox extracts gave the highest total phenolic contents by the Folin-Ciocalteu assay of 67.60 ± 4.38 mgGAE/g, and total flavonoid contents by the modified aluminum chloride colorimetric assay of 678.72 ± 23.59 mgQE/g, respectively. The PR-L-M extracts showed the highest three anti-oxidative activities; the free radical scavenging (SC50 of 0.320 ± 0.070 mg/mL), the lipid peroxidation inhibition (LC50 of 0.274 ± 0.029 mg/mL), and the metal chelation activity (MC50 of 0.203 ± 0.021 mg/mL). All the PR extracts at 0.01 and 0.1 mg/mL showed no cytotoxicity on B16F10 cells, and human skin fibroblasts, respectively. Likewise, the PR-R-Sox extract exhibited the highest anti-melanogenesis on B16F10 cells (52.7 ± 0.9%) and, the mushroom tyrosinase inhibition activity (IC50 of 0.04 ± 0.02 mg/mL), which was significantly comparable to kojic acid (p < 0.05). The PR-Y-Sox extract showed the collagen biosynthesis by the Sirius Red method, and the stimulation of anti-ageing genes (Sirt1 and Foxo1) on human skin fibroblasts by the RT-PCR method, which were similar to standards ʟ-ascorbic acid and resveratrol, respectively. This study suggests that the PR-R-Sox and PR-Y-Sox extracts can be further developed as natural anti-ageing agents for whitening and anti-wrinkle in the cosmetics, cosmeceutical, and pharmaceutical industries.

RESUMEN

CONTEXT: Bambara groundnut (BG), originally from Africa, is widely distributed in Asian countries, especially in southern Thailand, and is used for food and functional foods. There is no report on the use of BG for ethnomedicine or cosmetics. OBJECTIVE: To investigate collagen biosynthesis stimulation and anti-melanogenesis of the BG extracts. MATERIALS AND METHODS: The hulls (H) and seeds (S) of BG were collected from Trang province, Thailand and extracted by Soxhlet (S) and maceration (M) using ethanol, and boiled with distilled-water (B). Total phenolic (TPC) and total flavonoid (TFC) contents were quantified. The three antioxidant and tyrosinase inhibition activities were determined by DPPH, FIC and FTC; and the modified dopachrome methods, respectively. The collagen biosynthesis and the anti-melanogenesis activities were investigated by Sirius-Red and the melanin content assay. RESULTS: The yields of BG extracts ranged from 1.72% to 9.06%. The BG-SS extract gave the highest TPC and TFC. The BG-HM extract showed the highest antioxidant activities (SC50 of 0.87 ± 0.02 mg/mL, MC50 of 1.83 ± 0.09 mg/mL and LC50 of 0.70 ± 0.06 mg/mL), tyrosinase inhibition activity (IC50 of 0.45 ± 0.23 mg/mL), and anti-melanogenesis activities (72.9 ± 0.08%), whereas the BG-SB extract exhibited the highest stimulation of collagen biosynthesis (18.04 ± 0.03%). All BG extracts at 0.1 mg/mL showed no cytotoxicity on human dermal fibroblasts. DISCUSSION: The biological activities of BG extracts might be from their phytochemicals, especially phenolic and flavonoid contents. CONCLUSION: The BG-HB and BG-HM extracts might be promising novel active sources for anti-aging and whitening cosmeceuticals.

Asunto(s)

Colágeno/biosíntesis , Melaninas/metabolismo , Extractos Vegetales/farmacología , Vigna/química , Animales , Antioxidantes/aislamiento & purificación , Antioxidantes/farmacología , Colágeno/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Fibroblastos/efectos de los fármacos , Fibroblastos/metabolismo , Flavonoides/aislamiento & purificación , Flavonoides/farmacología , Humanos , Dosificación Letal Mediana , Ratones , Fenoles/aislamiento & purificación , Fenoles/farmacología , Extractos Vegetales/administración & dosificación , Extractos Vegetales/química , Tailandia

RESUMEN

Despite efforts to develop efficient chemotherapeutic drug strategies to treat cancer, acquired drug resistance is a commonly encountered problem. In the present study, to investigate this phenomenon, human A549 lung cancer cells resistant to the topoisomerase inhibitor etoposide (A549RT­eto) were used and compared with A549 parental cells. A549RT­eto cells demonstrated increased resistance to etoposide­induced apoptosis when compared with A549 parental cells. Notably, A549RT­eto cells were observed to exhibit greater levels of histone deacetylase 4 (HDAC4), phospho­Stat1 and P­glycoprotein [P­gp; encoded by the multidrug resistance 1 (MDR1) gene], compared with A549 cells. To address whether HDAC4 protein is involved in etoposide resistance in A549 cells, A549RT­eto cells were treated with trichostatin A (TSA; an HDAC inhibitor) during etoposide treatment. The combined treatment was demonstrated to enhance etoposide­induced apoptosis and reduce expression levels of HDAC4, P­gp and phospho­Stat1. In addition, the suppression of Stat1 with siRNA enhanced etoposide­induced apoptosis and reduced the expression levels of HDAC4 and P­gp, suggesting that Stat1 is essential in the regulation of resistance to etoposide, and in the upregulation of P­gp. Notably, TSA treatment reduced P­gp transcript levels but Stat1 siRNA treatment did not, suggesting that P­gp is regulated by HDAC at the transcriptional level and by Stat1 at the post­transcriptional level. These results suggest that the upregulation of Stat1 and HDAC4 determines etoposide resistance through P­gp expression in human A549 lung cancer cells.

Asunto(s)

Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/genética , Antineoplásicos Fitogénicos/farmacología , Resistencia a Antineoplásicos/genética , Etopósido/farmacología , Regulación Neoplásica de la Expresión Génica , Histona Desacetilasas/genética , Proteínas Represoras/genética , Factor de Transcripción STAT1/genética , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/metabolismo , Línea Celular Tumoral , Células Cultivadas , Resistencia a Antineoplásicos/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Inhibidores de Histona Desacetilasas/farmacología , Histona Desacetilasas/metabolismo , Humanos , Neoplasias Pulmonares/genética , Fosforilación , Interferencia de ARN , ARN Interferente Pequeño/genética , Proteínas Represoras/metabolismo , Factor de Transcripción STAT1/metabolismo , Transcripción Genética

RESUMEN

Since it has been known that shikonin derived from a medicinal plant possesses anti-cancer activity, we wonder whether acetylshikonin (ASK), a derivate of shikonin, can be used to treat hepatocellular carcinoma cells expressing hepatitis B virus X protein (HBX), an oncoprotein from hepatitis B virus. When ASK was added to Hep3B cells stably expressing HBX, it induced apoptosis in a dose-dependent manner. ASK induced upregulation and export of Nur77 to the cytoplasm and activation of JNK. Likewise, suppression of Nur77 and JNK inactivation protected the cells from ASK-induced apoptosis, indicating that Nur77 upregulation and JNK activation were required for ASK-mediated apoptosis. Furthermore, ASK increased the expression of Bip and ubiquitination levels of cellular proteins, features of endoplasmic reticulum (ER) stress, via the production of reactive oxygen species in a dose-dependent manner. Suppression of reactive oxygen species with N-acetylcysteine reduced levels of Bip protein and ubiquitination levels of cellular proteins during ASK treatment, leading to protection of cells from apoptosis. Cycloheximide treatment reduced ASK-induced ER stress, suggesting that protein synthesis is involved in ASK-induced ER stress. Moreover, we showed using salubrinal, an ER stress inhibitor that reactive oxygen species production, JNK activation, and Nur77 upregulation and its translocation to cytoplasm are necessary for ER-induced stress. Interestingly, we found that JNK inactivation suppresses ASK-induced ER stress, whereas Nur77 siRNA treatment does not, indicating that JNK is required for ASK-induced ER stress. Accordingly, we report that ASK induces ER stress, which is prerequisite for apoptosis of HBX-expressing hepatocellular carcinoma cells.

Asunto(s)

Antraquinonas/farmacología , Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Estrés del Retículo Endoplásmico , Transactivadores/genética , Carcinoma Hepatocelular/tratamiento farmacológico , Carcinoma Hepatocelular/genética , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Humanos , Neoplasias Hepáticas/tratamiento farmacológico , Neoplasias Hepáticas/genética , MAP Quinasa Quinasa 4/metabolismo , Miembro 1 del Grupo A de la Subfamilia 4 de Receptores Nucleares/genética , Miembro 1 del Grupo A de la Subfamilia 4 de Receptores Nucleares/metabolismo , ARN Interferente Pequeño/genética , Regulación hacia Arriba , Proteínas Reguladoras y Accesorias Virales

RESUMEN

During the screening of natural chemicals that can reverse multidrug resistance in human A549 lung cancer cells resistant to etoposide (A549RT-eto), we discovered that Feroniellin A (FERO), a novel furanocoumarin, shows toxicity toward A549RT-eto cells in a dose- and time-dependent manner. FERO reduced the expression of NF-κB, leading to downregulation of P-glycoprotein (P-gp), encoded by MDR1, which eventually sensitized A549RT-eto cells to apoptosis. FERO specifically diminished transcription and promoter activity of MDR1 but did not inhibit the expression of other multidrug resistance genes MRP2 and BCRP. Moreover, co-administration of FERO with Bay11-7802, an inhibitor of NF-κB, accelerated apoptosis of A549RT-eto cells through decreased expression of P-gp, indicating that NF-κB is involved in multidrug resistance. Conversely, addition of Z-VAD, a pan-caspase inhibitor, blocked FERO-induced apoptosis in A549RT-eto cells but did not block downregulation of P-gp, indicating that a decrease in P-gp expression is necessary but not sufficient for FERO-induced apoptosis. Interestingly, we found that FERO also induces autophagy, which is characterized by the conversion of LC3 I to LC3 II, induction of GFP-LC3 puncta, enhanced expression of Beclin-1 and ATG5, and inactivation of mTOR. Furthermore, suppression of Beclin-1 by siRNA reduced FERO-induced apoptosis in A549RT-eto cells and activation of autophagy by rapamycin accelerated FERO-induced apoptosis, suggesting that autophagy plays an active role in FERO-induced apoptosis. Herein, we report that FERO reverses multidrug resistance in A549RT-eto cells and exerts its cytotoxic effect by induction of both autophagy and apoptosis, which suggests that FERO can be a useful anticancer drug for multidrug-resistant lung cancer.

Asunto(s)

Apoptosis/efectos de los fármacos , Cumarinas/farmacología , Furanos/farmacología , Glicósidos/farmacología , Neoplasias Pulmonares/tratamiento farmacológico , Factor de Transcripción ReIA/biosíntesis , Subfamilia B de Transportador de Casetes de Unión a ATP/biosíntesis , Antineoplásicos/farmacología , Apoptosis/genética , Proteínas Reguladoras de la Apoptosis/genética , Autofagia/efectos de los fármacos , Beclina-1 , Línea Celular Tumoral , Resistencia a Antineoplásicos/efectos de los fármacos , Etopósido/farmacología , Humanos , Proteínas de la Membrana/genética , Proteínas de Microfilamentos , Nitrilos/farmacología , Regiones Promotoras Genéticas , Interferencia de ARN , ARN Interferente Pequeño , Sirolimus/farmacología , Sulfonas/farmacología , Factor de Transcripción ReIA/antagonistas & inhibidores , Transcripción Genética

RESUMEN

We showed in our previous study that cancer upregulated gene (CUG) 2, a novel oncogene, confers resistance to infection of oncolytic vesicular stomatitis virus (VSV) by activating Stat1-mediated signal transduction. Since many studies have reported that autophagy is involved in virus replication, we investigated whether autophagy also plays a role in the antiviral activity in A549 cells overexpressing CUG2 (A549-CUG2). We suppressed Atg5 or Beclin 1 expression using siRNA and examined its effect on the susceptibility of cells to infection by oncolytic VSV. We found that A549-CUG2 cells treated with Atg5 or Beclin 1 siRNA became susceptible to VSV infection, whereas A549-CUG2 cells treated with control siRNA were resistant. This result suggests that autophagy is involved in the antiviral response of A549-CUG2 cells. Further investigation revealed that autophagy impairment enhanced the generation of reactive oxygen species (ROS), which resulted in inactivation of S6 kinase. Under these conditions, the levels of ISG15 transcript and protein decreased, which conferred on A549-CUG2 cell susceptibility to VSV infection. Finally, we found that overloading of H2O2 sensitized control A549-CUG2 cells to VSV-induced apoptosis. Taken together, these results indicate that autophagy impairment induces excessive ROS formation, which decreases S6 kinase activity and ISG15 expression, ultimately rendering the A549-CUG2 cells susceptible to VSV infection. We propose that autophagy impairment is a potential strategy for successful VSV virotherapy of CUG2-overexpressing tumors.

Asunto(s)

Apoptosis/genética , Autofagia/genética , Proteínas Cromosómicas no Histona/genética , Citocinas/genética , Ubiquitinas/genética , Virus de la Estomatitis Vesicular Indiana/patogenicidad , Animales , Proteínas Reguladoras de la Apoptosis/genética , Proteína 5 Relacionada con la Autofagia , Beclina-1 , Línea Celular Tumoral , Proteínas Cromosómicas no Histona/biosíntesis , Citocinas/biosíntesis , Humanos , Neoplasias Pulmonares/virología , Proteínas de la Membrana/genética , Ratones , Proteínas Asociadas a Microtúbulos/genética , Virus Oncolíticos/genética , Virus Oncolíticos/patogenicidad , Interferencia de ARN , ARN Interferente Pequeño , Especies Reactivas de Oxígeno/metabolismo , Infecciones por Rhabdoviridae/genética , Infecciones por Rhabdoviridae/patología , Proteínas Quinasas S6 Ribosómicas/antagonistas & inhibidores , Factor de Transcripción STAT1/genética , Transducción de Señal , Ubiquitinas/biosíntesis , Virus de la Estomatitis Vesicular Indiana/genética , Replicación Viral

RESUMEN

Since multidrug resistance (MDR) is one of the main reasons for failure in cancer treatment, its suppression may increase the efficacy of cancer therapy. In the present study we attempted to identify a new and effective anticancer drug against MDR cancer cells. We first found that lung cancer A549 cells resistant to etoposide (A549RT-eto) exhibit upregulation of NF-κB and SIRT1 in comparison to A549 parental cells. During a search for anticancer drug candidates from medicinal plant sources, we found that an extract fraction (F14) of Bryophyllum laetivirens leaves downregulated expression of NF-κB and SIRT1, sensitizing the levels of A549RT-eto cells to apoptosis through downregulation of P-glycoprotein (P-gp), which is encoded by the MDR1 gene. To address whether NF-κB is involved in resistance to etoposide through P-gp, we treated A549RT-eto cells with Bay11-7802, an inhibitor of NF-κB. We then observed that Bay11-7802 treatment reduced P-gp expression levels, and furthermore combined treatment with the F14 extract and Bay11-7802 accelerated apoptosis through a decrease in P-gp levels, suggesting that NF-κB is involved in MDR. To address whether upregulation of SIRT1 is involved in resistance to etoposide through P-gp, we treated A549RT-eto cells with SIRT1 siRNA or nicotinamide (NAM), an inhibitor of SIRT1. we found that suppression of SIRT1 did not reduce P-gp levels. furthermore, the combined treatment with the F14 extract, and SIRT1 siRNA or NAM did not accelerate apoptosis, indicating that SIRT1 is not involved in the regulation of P-gp levels in A549RT-eto cells. Taken together, we suggest that upregulation of NF-κB determines etoposide resistance through P-gp expression in human A549 lung cancer cells. We herein demonstrated that B. laetivirens extract reverses etoposide resistance in human A549 lung cancer cells through downregulation of NF-κB.

Asunto(s)

Resistencia a Antineoplásicos/efectos de los fármacos , Etopósido/farmacología , Kalanchoe/química , Extractos Vegetales/farmacología , Sirtuina 1/genética , Factor de Transcripción ReIA/antagonistas & inhibidores , Subfamilia B de Transportador de Casetes de Unión a ATP , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/biosíntesis , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/genética , Antineoplásicos/farmacología , Antineoplásicos Fitogénicos/farmacología , Apoptosis/efectos de los fármacos , Apoptosis/genética , Línea Celular Tumoral , Regulación hacia Abajo , Resistencia a Múltiples Medicamentos/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Niacinamida/farmacología , Nitrilos/farmacología , Interferencia de ARN , ARN Interferente Pequeño , Sirtuina 1/antagonistas & inhibidores , Sirtuina 1/biosíntesis , Sulfonas/farmacología , Factor de Transcripción ReIA/biosíntesis , Transcripción Genética/efectos de los fármacos

RESUMEN

Cancer upregulated gene (CUG) 2, as a novel oncogene, has been predominantly detected in various cancer tissues, such as ovary, liver, lung and colon. We recently showed that CUG2 elevates STAT1 activity, leading to resistance to infection by oncolytic vesicular stomatitis virus. To investigate a possible role for CUG2-induced activation of STAT1 in oncogenesis, we first established a colon cancer cell line stably expressing CUG2 (Colon26L5-CUG2). Colon26L5-CUG2 exhibited higher levels not only in phosphorylation of STAT1, but also phosphorylation of Jak1/Tyk2 compared to that of the control (Colon26L5-Vec) cell line. Inhibition of Akt or ERK activity reduced phosphorylation of STAT1 in Colon26L5-CUG2 cells whereas inhibition of p38 MAPK did not significantly decrease levels of STAT1 phosphorylation, indicating that cell proliferation signals may be involved in CUG2-mediated activation of STAT1. Suppression of STAT1 expression diminished cell migration and wound healing compared to the control cells. In addition, since CUG2 expression conferred resistance to DNA damage caused by doxorubicin treatment, we investigated whether STAT1 is involved in resistance to doxorubicin-induced cell death. We found that STAT1 was not activated in Colon26L5-Vec cells while phosphorylated STAT1 was maintained in Colon26L5-CUG2 cells during doxorubicin treatment. Furthermore, suppression of STAT1 expression sensitized Colon26L5-CUG2 cells to doxorubicin-induced apoptosis whereas the control cells exhibited resistance to doxorubicin. Taken together, our results suggest that CUG2 enhances metastasis and drug resistance through STAT1 activation, which eventually contributes to tumor progression.

Asunto(s)

Neoplasias del Colon/genética , Metástasis de la Neoplasia/genética , Proteínas Nucleares/genética , Factor de Transcripción STAT1/biosíntesis , Apoptosis/genética , Línea Celular Tumoral , Movimiento Celular , Proteínas Cromosómicas no Histona , Neoplasias del Colon/patología , Resistencia a Antineoplásicos , Regulación Neoplásica de la Expresión Génica , Humanos , Metástasis de la Neoplasia/patología , Proteínas Nucleares/biosíntesis , Factor de Transcripción STAT1/genética , Transducción de Señal , Cicatrización de Heridas/genética , Proteínas Quinasas p38 Activadas por Mitógenos/genética , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismo

RESUMEN

We previously showed that SIRT1 deacetylase inhibits proliferation of hepatocellular carcinoma cells expressing hepatitis B virus (HBV) X protein (HBX), by destabilization of ß-catenin. Here, we report another role for SIRT1 in HBX-mediated resistance to oxidative stress. Ectopic expression and enhanced activity of SIRT1 sensitize Hep3B cells stably expressing HBX to oxidative stress-induced apoptosis. SIRT1 mutant analysis showed that nuclear localization of SIRT1 is not required for sensitization of oxidation-mediated apoptosis. Furthermore, ectopic expression of SIRT1 and treatment with resveratrol (a SIRT1 activator) attenuated JNK phosphorylation, which is a prerequisite for resistance to oxidative stress-induced apoptosis. Conversely, suppression of SIRT1 activity with nicotinamide inhibited the effect of resveratrol on JNK phosphorylation, leading to restoration of resistance to oxidation-induced apoptosis. Taken together, these results suggest that up-regulation of SIRT1 under oxidative stress may be a therapeutic strategy for treatment of hepatocellular carcinoma cells related to HBV through inhibition of JNK activation.

Asunto(s)

Apoptosis , Carcinoma Hepatocelular/enzimología , Neoplasias Hepáticas/enzimología , Estrés Oxidativo , Sirtuina 1/metabolismo , Transactivadores/biosíntesis , Regulación hacia Arriba , Antioxidantes/farmacología , Línea Celular Tumoral , Núcleo Celular/metabolismo , Humanos , MAP Quinasa Quinasa 4/metabolismo , Fosforilación , ARN Interferente Pequeño/genética , Resveratrol , Sirtuina 1/genética , Estilbenos/farmacología , Proteínas Reguladoras y Accesorias Virales

RESUMEN

Because we found in a recent study that pancreatic adenocarcinoma up-regulated factor (PAUF), a novel oncogene, induces a rapid proliferation of pancreatic cells by up-regulation of ß-catenin, we postulated that ß-catenin might be a target molecule for pancreatic cancer treatment. We thus speculated whether SIRT1, known to target ß-catenin in a colon cancer model, suppresses ß-catenin in those pancreatic cancer cells that express PAUF (Panc-PAUF). We further evaluated whether such suppression would lead to inhibition of the proliferation of these cells. The ectopic expression of either SIRT1 or resveratrol (an activator of SIRT1) suppressed levels of ß-catenin protein and its transcriptional activity in Panc-PAUF cells. Conversely, suppression of SIRT1 expression by siRNA enhanced ß-catenin expression and transcriptional activity. SIRT1 mutant analysis showed that nuclear localization of SIRT1 is not required for reduction of ß-catenin. Treatment with MG132, a proteasomal inhibitor, restored ß-catenin protein levels, suggesting that SIRT1-mediated degradation of ß-catenin requires proteasomal activity. It was reported that inhibition of GSK-3ß or Siah-1 stabilizes ß-catenin in colon cancer cells, but suppression of GSK-3ß or Siah-1 using siRNA in the presence of resveratrol instead diminished ß-catenin protein levels in Panc-PAUF cells. This suggests that GSK-3ß and Siah-1 are not involved in SIRT1-mediated degradation of ß-catenin in the cells. Finally, activation of SIRT1 inhibited the proliferation of Panc-PAUF cells by down-regulation of cyclin-D1, a target molecule of ß-catenin. These results suggest that SIRT1 activation may be a therapeutic strategy for treatment of pancreatic cancer cells that express PAUF via the down-regulation of ß-catenin.

Asunto(s)

Proliferación Celular , Ciclina D1/genética , Regulación Neoplásica de la Expresión Génica , Lectinas/genética , Oncogenes , Neoplasias Pancreáticas/patología , Sirtuina 1/fisiología , beta Catenina/metabolismo , Línea Celular Tumoral , Núcleo Celular/metabolismo , Células HEK293 , Humanos , Péptidos y Proteínas de Señalización Intercelular , Leupeptinas/farmacología , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/metabolismo , Complejo de la Endopetidasa Proteasomal/metabolismo , Proteolisis , Sirtuina 1/genética

RESUMEN

Hepatitis B virus X (HBX) protein has been reported to induce upregulation of ß-catenin, a known proto-oncogene, in p53-knockout and p53-mutant hepatic cell lines both in a GSK-3ß-dependent manner and via interaction with adenomatous polyposis coli, which results in protection from ß-catenin degradation. In this study, we describe a novel mechanism for HBX-mediated upregulation of ß-catenin. We observed that HBX interacts with SIRT1, a class III histone deacetylase. Furthermore, the presence of HBX attenuated the interaction between SIRT1 and ß-catenin, leading to protection of ß-catenin from the inhibitory action of SIRT1. Reduction of SIRT1 with siRNA or suppression of SIRT1 activity with nicotinamide upregulated ß-catenin protein levels. In contrast, enhancement of SIRT1 activity with resveratrol reduced ß-catenin protein levels. Furthermore, in Hep3B cells stably expressing HBX, overexpression of SIRT1 or treatment with resveratrol enhanced sensitivity to doxorubicin-induced apoptosis, indicating that upregulation of SIRT1 could be a therapeutic strategy for HBV-related hepatocellular carcinoma. Based on these results, we propose that HBX upregulates ß-catenin by sequestering SIRT1, which leads to anticancer drug treatment resistance.

Asunto(s)

Sirtuina 1/metabolismo , Transactivadores/fisiología , Regulación hacia Arriba , beta Catenina/genética , Antibióticos Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Carcinoma Hepatocelular , Línea Celular Tumoral , Doxorrubicina/farmacología , Regulación Neoplásica de la Expresión Génica , Células HEK293 , Humanos , Neoplasias Hepáticas , Unión Proteica , Proto-Oncogenes Mas , Transactivadores/metabolismo , Proteínas Reguladoras y Accesorias Virales , Vía de Señalización Wnt , beta Catenina/metabolismo

RESUMEN

We have previously shown that hepatitis B virus (HBV) protein X (HBX), a regulatory protein of HBV, activates Stat1, leading to type I interferon (IFN) production. Type I IFN secreted from HBX-expressing hepatic cells enforces antiviral signals through its binding to the cognate type I IFN receptor. We therefore investigated how cells handle this detrimental situation. Interestingly, compared to Chang cells stably expressing an empty vector (Chang-Vec), Chang cells stably expressing HBX (Chang-HBX) showed lower levels of IFN-α receptor 1 (IFNAR1) protein, a subunit of type I IFN receptor. The levels of IFNAR1 transcripts detected in Chang-HBX cells were lower than the levels in Chang-Vec cells, indicating that HBX regulates IFNAR1 at the transcriptional level. Moreover, we observed that HBX induced the translocation of IFNAR1 to the cytoplasm. Consistent with these observations, HBX also downregulated Tyk2, which is required for the stable expression of IFNAR1 on the cell surface. Eventually, Chang-HBX cells consistently maintained a lower level of IFNAR1 expression and displayed no proper response to IFN-α, while Chang-Vec cells exhibited a proper response to IFN-α treatment. Taken together, we propose that HBX downregulates IFNAR1, leading to the avoidance of extracellular IFN-α signal transduction.

Asunto(s)

Interferón-alfa/metabolismo , Receptor de Interferón alfa y beta/metabolismo , Transducción de Señal , Transactivadores/metabolismo , Línea Celular , Regulación hacia Abajo , Virus de la Hepatitis B , Humanos , Interferón-alfa/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Receptor de Interferón alfa y beta/genética , Factor de Transcripción STAT1/genética , Factor de Transcripción STAT1/metabolismo , TYK2 Quinasa/genética , TYK2 Quinasa/metabolismo , Transactivadores/genética , Transfección , Proteínas Reguladoras y Accesorias Virales