RESUMEN
Thioredoxin-interacting protein (TXNIP) is sensitive to oxidative stress and is involved in the pathogenesis of various metabolic, cardiovascular, and neurodegenerative disorders. Therefore, several studies have suggested that TXNIP is a promising therapeutic target for several diseases, particularly cancer and diabetes. However, the regulation of TXNIP expression under amino acid (AA)-restricted conditions is not well understood. In the present study, we demonstrated that TXNIP expression was promoted by the deprivation of AAs, especially arginine, glutamine, lysine, and methionine, in non-small cell lung cancer (NSCLC) cells. Interestingly, we determined that increased TXNIP expression induced by AA deprivation was associated with nuclear factor erythroid 2-related factor 2 (NRF2) downregulation, but not with activating transcription factor 4 (ATF4) activation. Furthermore, N-acetyl-l-cysteine (NAC), a scavenger of reactive oxygen species (ROS), suppressed TXNIP expression in NSCLC cells deprived of AA. Collectively, the induction of TXNIP expression by AA deprivation was mediated by ROS production, potentially through NRF2 downregulation. Our findings suggest that TXNIP expression may be associated with the redox homeostasis of AA metabolism and provide a possible rationale for a therapeutic strategy to treat cancer with AA restriction.
Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas , Neoplasias Pulmonares , Humanos , Especies Reactivas de Oxígeno/metabolismo , Factor 2 Relacionado con NF-E2/genética , Factor 2 Relacionado con NF-E2/metabolismo , Aminoácidos/metabolismo , Regulación hacia Abajo , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismoRESUMEN
Although endocrine therapy with tamoxifen has improved survival in breast cancer patients, resistance to this therapy remains one of the major causes of breast cancer mortality. In the present study, we found that the expression level of YAP/TAZ in tamoxifen-resistant MCF7 (MCF7-TR) breast cancer cells was significantly increased compared with that in MCF7 cells. Knockdown of YAP/TAZ with siRNA sensitized MCF7-TR cells to tamoxifen. Furthermore, siRNA targeting PSAT1, a downstream effector of YAP/TAZ, enhanced sensitivity to tamoxifen in MCF7-TR cells. Additionally, mTORC1 activity and survivin expression were significantly decreased during cell death induced by combination treatment with YAP/TAZ or PSAT1 siRNA and tamoxifen. In conclusion, targeting the YAP/TAZ-PSAT1 axis could sensitize tamoxifen-resistant MCF7 breast cancer cells by modulating the mTORC1-survivin axis.
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Neoplasias de la Mama , Tamoxifeno , Proteínas Coactivadoras Transcripcionales con Motivo de Unión a PDZ , Proteínas Señalizadoras YAP , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/genética , Neoplasias de la Mama/metabolismo , Línea Celular Tumoral , Resistencia a Antineoplásicos , Femenino , Humanos , Células MCF-7 , Diana Mecanicista del Complejo 1 de la Rapamicina , ARN Interferente Pequeño , Survivin/genética , Tamoxifeno/farmacología , Proteínas Coactivadoras Transcripcionales con Motivo de Unión a PDZ/metabolismo , Proteínas Señalizadoras YAP/metabolismoRESUMEN
Daphnetin is a dehydroxylated derivative of coumarin isolated from Daphne species. However, the effect of daphnetin on melanogenesis has not been elucidated. This study aims to investigate the inhibitory effect of daphnetin on melanogenesis in α-melanocyte stimulating hormone (α-MSH)-treated B16F10 cells and its potential mechanism. Melanin content analysis and cellular tyrosinase activity assay showed that daphnetin inhibited melanin biosynthesis in α-MSH-treated B16F10 cells. Immunoblotting and qRT-PCR also indicated that daphnetin suppressed the expression of microphthalmia-associated transcription factor, a mastering transcription factor of melanogenesis and its downstream melanogenic enzymes including tyrosinase and tyrosinase-related proteins. Moreover, daphnetin downregulated the phosphorylation of PKA, ERK, MSK1, and CREB. Additionally, daphnetin inhibited melanin synthesis in UVB-irradiated HaCaT conditioned medium system suggesting that daphnetin has potential as an antipigmentation activity in a physiological skin condition. Our data propose that daphnetin inhibits melanogenesis via modulating both the PKA/CREB and the ERK/MSK1/CREB pathways.
Asunto(s)
Melanoma Experimental , Melanoma , Animales , Línea Celular Tumoral , Melaninas , Melanoma/metabolismo , Factor de Transcripción Asociado a Microftalmía/genética , Factor de Transcripción Asociado a Microftalmía/metabolismo , Monofenol Monooxigenasa , Transducción de Señal , Umbeliferonas , alfa-MSH/farmacologíaRESUMEN
Ovarian cancer is a carcinoma that affects women and that has a high mortality rate. Overcoming paclitaxel resistance is important for clinical application. However, the effect of amino acid metabolism regulation on paclitaxel-resistant ovarian cancer is still unknown. In this study, the effect of an amino acid-deprived condition on paclitaxel resistance in paclitaxel-resistant SKOV3-TR cells was analyzed. We analyzed the cell viability of SKOV3-TR in culture conditions in which each of the 20 amino acids were deprived. As a result, the cell viability of the SKOV3-TR was significantly reduced in cultures deprived of arginine, glutamine, and lysine. Furthermore, we showed that the glutamine-deprived condition inhibited mTORC1/S6K signaling. The decreased cell viability and mTORC1/S6K signaling under glutamine-deprived conditions could be restored by glutamine and α-KG supplementation. Treatment with PF-4708671, a selective S6K inhibitor, and the selective glutamine transporter ASCT2 inhibitor V-9302 downregulated mTOR/S6K signaling and resensitized SKOV3-TR to paclitaxel. Immunoblotting showed the upregulation of Bcl-2 phosphorylation and a decrease in Mcl-1 expression in SKOV3-TR via the cotreatment of paclitaxel with PF-4708671 and V-9302. Collectively, this study demonstrates that the inhibition of glutamine uptake can resensitize SKOV3-TR to paclitaxel and represents a promising therapeutic target for overcoming paclitaxel resistance in ovarian cancer.
Asunto(s)
Neoplasias Ováricas , Paclitaxel , Carcinoma Epitelial de Ovario , Línea Celular Tumoral , Resistencia a Antineoplásicos , Femenino , Glutamina/farmacología , Humanos , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Neoplasias Ováricas/patología , Paclitaxel/farmacología , Paclitaxel/uso terapéutico , Proteínas Quinasas S6 Ribosómicas/metabolismo , Transducción de SeñalRESUMEN
BACKGROUND: Although the major anticancer effect of metformin involves AMPK-dependent or AMPK-independent mTORC1 inhibition, the mechanisms of action are still not fully understood. METHODS: To investigate the molecular mechanisms underlying the effect of metformin on the mTORC1 inhibition, MTT assay, RT-PCR, and western blot analysis were performed. RESULTS: Metformin induced the expression of ATF4, REDD1, and Sestrin2 concomitant with its inhibition of mTORC1 activity. Treatment with REDD1 or Sestrin2 siRNA reversed the mTORC1 inhibition induced by metformin, indicating that REDD1 and Sestrin2 are important for the inhibition of mTORC1 triggered by metformin treatment. Moreover, REDD1- and Sestrin2-mediated mTORC1 inhibition in response to metformin was independent of AMPK activation. Additionally, lapatinib enhances cell sensitivity to metformin, and knockdown of REDD1 and Sestrin2 decreased cell sensitivity to metformin and lapatinib. CONCLUSIONS: ATF4-induced REDD1 and Sestrin2 expression in response to metformin plays an important role in mTORC1 inhibition independent of AMPK activation, and this signalling pathway could have therapeutic value.
Asunto(s)
Factor de Transcripción Activador 4/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/antagonistas & inhibidores , Metformina/farmacología , Metformina/uso terapéutico , Proteínas Nucleares/metabolismo , Factores de Transcripción/metabolismo , Humanos , TransfecciónRESUMEN
Gain- or loss-of-function mutations in Janus kinase 3 (JAK3) contribute to the pathogenesis of various haematopoietic malignancies and immune disorders, suggesting that aberrant JAK3 signalling is an attractive therapeutic target to treat these disorders. In this study, we performed structure-based computational database screening using the 3D structure of the JAK3 kinase domain and the National Cancer Institute diversity set and identified tubulosine as a novel JAK3 inhibitor. Tubulosine directly blocked the catalytic activity of JAK3 by selective interacting with the JAK3 kinase domain. Consistently, tubulosine potently inhibited persistently activated and interleukin-2-dependent JAK3, and JAK3-mediated downstream targets. Importantly, it did not affect the activity of other JAK family members, particularly prolactin-induced JAK2/signal transducer and activator of transcription 5 and interferon alpha-induced JAK1-TYK2/STAT1. Tubulosine specifically decreased survival and proliferation of cancer cells, in which persistently active JAK3 is expressed, by inducing apoptotic and necrotic/autophagic cell death without affecting other oncogenic signalling. Collectively, tubulosine is a potential small-molecule compound that selectively inhibits JAK3 activity, suggesting that it may serve as a promising therapeutic candidate for treating disorders caused by aberrant activation of JAK3 signalling.
Asunto(s)
Adenosina Trifosfato/metabolismo , Emetina/análogos & derivados , Janus Quinasa 3/antagonistas & inhibidores , Transducción de Señal , Apoptosis/efectos de los fármacos , Autofagia/efectos de los fármacos , Sitios de Unión , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Emetina/química , Emetina/farmacología , Humanos , Janus Quinasa 3/metabolismo , Modelos Biológicos , Necrosis , Oncogenes , Factor de Transcripción STAT5/metabolismo , Transducción de Señal/efectos de los fármacosRESUMEN
Mechanistic target of rapamycincomplex 1 (mTORC1) integrates various environmental signals to regulate cell growth and metabolism. mTORC1 activity is sensitive to changes in amino acid levels. Here, we investigated the effect of lysine on mTORC1 activity in non-small cell lung cancer (NSCLC) cells. Lysine deprivation suppressed mTORC1 activity and lysine replenishment restored the decreased mTORC1 activity in lysine-deprived cells. Supplementing growth factors, such as insulin growth factor-1 or insulin restored the decreased mTORC1 activity in serum-deprived cells. However, in serum/lysine-deprived cells, supplementing growth factors was not sufficient to restore mTORC1 activity, suggesting thatgrowth factors could not activate mTORC1 efficiently in the absence of lysine. General control nonderepressible 2 and AMP-activated protein kinase were involved in lysine deprivation-mediated inhibition of mTORC1. Taken together, these results suggest that lysine might play role in the regulation of mTORC1 activation in NSCLC cells.
Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas/metabolismo , Neoplasias Pulmonares/metabolismo , Lisina/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Células A549 , Proteínas Quinasas Activadas por AMP/antagonistas & inhibidores , Proteínas Quinasas Activadas por AMP/genética , Proteínas Quinasas Activadas por AMP/metabolismo , Línea Celular Tumoral , Medio de Cultivo Libre de Suero , Técnicas de Silenciamiento del Gen , Humanos , Insulina/administración & dosificación , Factor I del Crecimiento Similar a la Insulina/administración & dosificación , Lisina/administración & dosificación , Lisina/deficiencia , Proteínas Serina-Treonina Quinasas/antagonistas & inhibidores , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/metabolismo , ARN Interferente Pequeño/genéticaRESUMEN
Ionizing radiation (IR) has been widely used in the treatment of cancer. Radiation-induced DNA damage triggers the DNA damage response (DDR), which can confer radioresistance and early local recurrence by activating DNA repair pathways. Since karyopherin-α2 (KPNA2), playing an important role in nucleocytoplasmic transport, was significantly increased by IR in our previous study, we aimed to determine the function of KPNA2 with regard to DDR. Exposure to radiation upregulated KPNA2 expression in human colorectal cancer HT29 and HCT116 cells and breast carcinoma MDA-MB-231 cells together with the increased expression of DNA repair protein BRCA1. The knockdown of KPNA2 effectively increased apoptotic cell death via inhibition of BRCA1 nuclear import following IR. Therefore, we propose that KPNA2 is a potential target for overcoming radioresistance via interruption to DDR.
Asunto(s)
Proteína BRCA1/metabolismo , Muerte Celular/efectos de la radiación , Supervivencia Celular/fisiología , alfa Carioferinas/metabolismo , Apoptosis/efectos de la radiación , Proteína BRCA1/genética , Western Blotting , Línea Celular Tumoral , Proliferación Celular/efectos de la radiación , Supervivencia Celular/genética , Ensayo Cometa , Daño del ADN/efectos de la radiación , Reparación del ADN/efectos de la radiación , Células HCT116 , Células HT29 , Humanos , Inmunoprecipitación , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Radiación IonizanteRESUMEN
Secretory clusterin (sCLU) is a stress-associated protein that confers resistance to therapy when overexpressed. In this study, we observed that the V-ATPase inhibitors bafilomycin A1 and concanamycin A significantly stimulated sCLU protein expression. Knockdown of sCLU with siRNA sensitized non-small cell lung cancer (NSCLC) cells to bafilomycin A1, suggesting that sCLU expression renders cells resistant to V-ATPase inhibitors. The dual PI3K/AKT and mTOR inhibitor BEZ235 suppressed sCLU expression and enhanced cell sensitivity induced by bafilomycin A1. Notably, sCLU knockdown further decreased the expression of the survivin protein by bafilomycin A1, and the ectopic expression of survivin alleviated the cell sensitivity by bafilomycin A1 and sCLU depletion, suggesting that increased sensitivity to sCLU depletion in the cells with V-ATPase inhibitors is due, at least in part, to the down-regulation of survivin. Taken together, we demonstrated that the depletion of sCLU expression enhances the sensitivity of NSCLC cells to V-ATPase inhibitors by decreasing survivin expression. Inhibition of the PI3K/AKT/mTOR pathway enhances the sensitivity of NSCLC cells to V-ATPase inhibitors, leading to decreased sCLU and survivin expression. Thus, we suggest that a combination of PI3K/AKT/mTOR inhibitors with V-ATPase inhibitors might be an effective approach for NSCLC treatment.
Asunto(s)
Antineoplásicos/administración & dosificación , Carcinoma de Pulmón de Células no Pequeñas/terapia , Clusterina/genética , Terapia Genética/métodos , Proteínas Inhibidoras de la Apoptosis/metabolismo , Neoplasias Pulmonares/terapia , ATPasas de Translocación de Protón Vacuolares/antagonistas & inhibidores , Células A549 , Apoptosis/efectos de los fármacos , Carcinoma de Pulmón de Células no Pequeñas/genética , Carcinoma de Pulmón de Células no Pequeñas/patología , Supervivencia Celular/efectos de los fármacos , Terapia Combinada/métodos , Regulación hacia Abajo/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/genética , Silenciador del Gen , Humanos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patología , SurvivinRESUMEN
HER family receptors are frequently deregulated in breast cancer and the deregulation of these receptors is associated with poor prognosis. Thus, these receptors are considered therapeutic targets. In the present study, we found that piperlongumine (PL) downregulates the expression of HER family receptors HER1, HER2, and HER3 in breast cancer cells. Downregulation of these receptors by PL is mediated through the generation of reactive oxygen species (ROS), as N-acetyl-cysteine blocks it. Interestingly, the HER2-overexpressing cell lines BT474 and SkBr3 are somewhat more sensitive to PL than the low HER2-expressing cell line MCF7. In addition, the overexpression of HER2 increases the sensitivity of MCF7 cells to PL. Collectively, our data indicate the therapeutic potential of PL in the treatment of breast cancer.
Asunto(s)
Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/metabolismo , Dioxolanos/administración & dosificación , Receptores ErbB/biosíntesis , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Antineoplásicos/administración & dosificación , Apoptosis/efectos de los fármacos , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Regulación hacia Abajo/efectos de los fármacos , Humanos , Células MCF-7RESUMEN
Heat shock protein 90 (HSP90) regulates the stability of various proteins and plays an essential role in cellular homeostasis. Many client proteins of HSP90 are involved in cell growth, survival, and migration; processes that are generally accepted as participants in tumorigenesis. HSP90 is also up-regulated in certain tumors. Indeed, the inhibition of HSP90 is known to be effective in cancer treatment. Recently, studies showed that HSP90 regulates transforming growth factor ß1 (TGF-ß1)-induced transcription by increasing the stability of the TGF-ß receptor. TGF-ß signaling also has been implicated in cancer, suggesting the possibility that TGF-ß1 and HSP90 function cooperatively during the cancer cell progression. Here in this paper, we investigated the role of HSP90 in TGF-ß1-stimulated Mv1Lu cells. Treatment of Mv1Lu cells with the HSP90 inhibitor, 17-allylamino-demethoxy-geldanamycin (17AAG), or transfection with truncated HSP90 (ΔHSP90) significantly reduced TGF-ß1-induced cell migration. Pretreatment with 17AAG or transfection with ΔHSP90 also reduced the levels of phosphorylated Smad2 and Smad3. In addition, the HSP90 inhibition interfered the nuclear localization of Smads induced by constitutively active Smad2 (S2EE) or Smad3 (S3EE). We also found that the HSP90 inhibition decreased the protein level of importin-ß1 which is known to regulate R-Smad nuclear translocation. These data clearly demonstrate a novel function of HSP90; HSP90 modulates TGF-ß signaling by regulating Smads localization. Overall, our data could provide a detailed mechanism linking HSP90 and TGF-ß signaling. The extension of our understanding of HSP90 would offer a better strategy for treating cancer.
Asunto(s)
Proteínas HSP90 de Choque Térmico/metabolismo , Proteína Smad2/metabolismo , Proteína smad3/metabolismo , Animales , Benzoquinonas/farmacología , Proteínas HSP90 de Choque Térmico/antagonistas & inhibidores , Proteínas HSP90 de Choque Térmico/genética , Lactamas Macrocíclicas/farmacología , Fosforilación/efectos de los fármacos , Receptores de Factores de Crecimiento Transformadores beta/metabolismo , Transducción de Señal/efectos de los fármacos , Factor de Crecimiento Transformador beta/metabolismo , Factor de Crecimiento Transformador beta1/metabolismoRESUMEN
Previous studies have shown that hypoxia can reverse DCA/metformin-induced cell death in breast cancer cells. Therefore, targeting hypoxia is necessary for therapies targeting cancer metabolism. In the present study, we found that TRAIL can overcome the effect of hypoxia on the cell death induced by treatment of DCA and metformin in breast cancer cells. Unexpectedly, DR5 is upregulated in the cells treated with DCA/metformin, and sustained under hypoxia. Blocking DR5 by siRNA inhibited DCA/metformin/TRAIL-induced cell death, indicating that DR5 upregulation plays an important role in sensitizing cancer cells to TRAIL-induced cell death. Furthermore, we found that activation of JNK and c-Jun is responsible for upregulation of DR5 induced by DCA/metformin. These findings support the potential application of combining TRAIL and metabolism-targeting drugs in the treatment of cancers under hypoxia.
Asunto(s)
Ácido Dicloroacético/farmacología , Metformina/farmacología , Ligando Inductor de Apoptosis Relacionado con TNF/farmacología , Neoplasias de la Mama/patología , Muerte Celular/efectos de los fármacos , Hipoxia de la Célula/efectos de los fármacos , Activación Enzimática/efectos de los fármacos , Humanos , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Células MCF-7 , Receptores de Muerte Celular/metabolismo , Regulación hacia Arriba/efectos de los fármacosRESUMEN
Ornithine decarboxylase 1 (ODC1), a metabolic enzyme critically involved in the polyamine biosynthesis, is commonly upregulated in hepatocellular carcinoma (HCC). Despite its altered expression in human HCC tissues, the molecular mechanism by which ODC1 alters the course of HCC progression and functions in HCC cell survival is unknown. Here we identified that silencing of ODC1 expression with small interfering (si) RNA causes inhibition of HCC cell growth through blockade of cell cycle progression and induction of apoptosis. Next, to obtain insights into the molecular changes in response to ODC1 knockdown, global changes in gene expression were examined using RNA sequencing. It revealed that 119 genes show same directional regulation (76 up- and 43 down-regulated) in both Huh1 and Huh7 cells and were considered as a common ODC1 knockdown signature. Particularly, we found through a network analysis that KLF2, which is known to inhibit PPARγ expression and adipogenesis, was commonly up-regulated. Subsequent Western blotting affirmed that the downregulation of ODC1 was accompanied by a decrease in the levels of PPARγ as well as of PARP-1, cyclin E1 and pro-caspase 9 delaying cell cycle progression and accelerating apoptotic signaling. Following the down-regulation of PPARγ expression, ODC1 silencing resulted in a strong inhibition in the expression of important regulators of glucose transport and lipid biogenesis, and caused a marked decrease in lipid droplet accumulation. In addition, ODC1 silencing significantly inhibited the growth of human HCC xenografts in nude mice. These findings indicate that the function of ODC1 is correlated with HCC lipogenesis and suggest that targeting ODC1 could be an attractive option for molecular therapy of HCC.
Asunto(s)
Carcinoma Hepatocelular/genética , Proliferación Celular/genética , Metabolismo de los Lípidos/genética , Neoplasias Hepáticas/genética , Ornitina Descarboxilasa/genética , Interferencia de ARN , Animales , Apoptosis/genética , Western Blotting , Carcinoma Hepatocelular/enzimología , Carcinoma Hepatocelular/patología , Caspasa 9/genética , Caspasa 9/metabolismo , Ciclo Celular/genética , Línea Celular Tumoral , Ciclina E/genética , Ciclina E/metabolismo , Regulación Neoplásica de la Expresión Génica , Redes Reguladoras de Genes , Humanos , Factores de Transcripción de Tipo Kruppel/genética , Factores de Transcripción de Tipo Kruppel/metabolismo , Neoplasias Hepáticas/enzimología , Neoplasias Hepáticas/patología , Masculino , Ratones Endogámicos BALB C , Ratones Desnudos , Proteínas Oncogénicas/genética , Proteínas Oncogénicas/metabolismo , Ornitina Descarboxilasa/metabolismo , PPAR gamma/genética , PPAR gamma/metabolismo , Poli(ADP-Ribosa) Polimerasa-1/genética , Poli(ADP-Ribosa) Polimerasa-1/metabolismo , Tratamiento con ARN de Interferencia/métodos , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Ensayos Antitumor por Modelo de Xenoinjerto/métodosRESUMEN
Recently, targeting deregulated energy metabolism is an emerging strategy for cancer therapy. In the present study, combination of DCA and metformin markedly induced cell death, compared with each drug alone. Furthermore, the expression levels of glycolytic enzymes including HK2, LDHA and ENO1 were downregulated by two drugs. Interestingly, HIF-1α activation markedly suppressed DCA/metformin-induced cell death and recovered the expressions of glycolytic enzymes that were decreased by two drugs. Based on these findings, we propose that targeting HIF-1α is necessary for cancer metabolism targeted therapy.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/administración & dosificación , Ácido Dicloroacético/administración & dosificación , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Metformina/administración & dosificación , Neoplasias Experimentales/tratamiento farmacológico , Neoplasias Experimentales/metabolismo , Apoptosis/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Humanos , Células MCF-7 , Neoplasias Experimentales/patología , Resultado del TratamientoRESUMEN
The function of PSMC5 (proteasome 26S subunit, ATPase 5) in tumors, particularly with respect to cancer radioresistance, is not known. Here, we identified PSMC5 as a novel radiosensitivity biomarker, demonstrating that radiosensitive H460 cells were converted to a radioresistance phenotype by PSMC5 depletion. Exposure of H460 cells to radiation induced a marked accumulation of cell death-promoting reactive oxygen species, but this effect was blocked in radiation-treated H460 PSMC5-knockdown cells through downregulation of the p53-p21 pathway. Interestingly, PSMC5 depletion in H460 cells enhanced both AKT activation and MDM2 transcription, thereby promoting the degradation of p53 and p21 proteins. Furthermore, specific inhibition of AKT with triciribine or knockdown of MDM2 with small interfering RNA largely restored p21 expression in PSMC5-knockdown H460 cells. Our data suggest that PSMC5 facilitates the damaging effects of radiation in radiation-responsive H460 cancer cells and therefore may serve as a prognostic indicator for radiotherapy and molecular targeted therapy in lung cancer patients.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Apoptosis/efectos de la radiación , Proteínas con Dominio LIM/metabolismo , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/radioterapia , Tolerancia a Radiación , Factores de Transcripción/metabolismo , ATPasas Asociadas con Actividades Celulares Diversas , Línea Celular Tumoral , Relación Dosis-Respuesta en la Radiación , Humanos , Neoplasias Pulmonares/patología , Complejo de la Endopetidasa Proteasomal , Dosificación Radioterapéutica , Resultado del TratamientoRESUMEN
UNLABELLED: Enhanced expression of the cancer stem cell (CSC) marker, CD133, is closely associated with a higher rate of tumor formation and poor prognosis in hepatocellular carcinoma (HCC) patients. Despite its clinical significance, the molecular mechanism underlying the deregulation of CD133 during tumor progression remains to be clarified. Here, we report on a novel mechanism by which interleukin-6/signal transducer and activator of transcription 3 (IL-6/STAT3) signaling up-regulates expression of CD133 and promotes HCC progression. STAT3 activated by IL-6 rapidly bound to CD133 promoter and increased protein levels of CD133 in HCC cells. Reversely, in hypoxic conditions, RNA interference silencing of STAT3 resulted in decrease of CD133 levels, even in the presence of IL-6, with a concomitant decrease of hypoxia-inducible factor 1 alpha (HIF-1α) expression. Active STAT3 interacted with nuclear factor kappa B (NF-κB) p65 subunit to positively regulate the transcription of HIF-1α providing a mechanistic explanation on how those three oncogenes work together to increase the activity of CD133 in a hypoxic liver microenvironment. Activation of STAT3 and its consequent induction of HIF-1α and CD133 expression were not observed in Toll-like receptor 4/IL-6 double-knockout mice. Long-term silencing of CD133 by a lentiviral-based approach inhibited cancer cell-cycle progression and suppressed in vivo tumorigenicity by down-regulating expression of cytokinesis-related genes, such as TACC1, ACF7, and CKAP5. We also found that sorafenib and STAT3 inhibitor nifuroxazide inhibit HCC xenograft formation by blocking activation of STAT3 and expression of CD133 and HIF-1α proteins. CONCLUSION: IL-6/STAT3 signaling induces expression of CD133 through functional cooperation with NF-κB and HIF-1α during liver carcinogenesis. Targeting STAT3-mediated CD133 up-regulation may represent a novel, effective treatment by eradicating the liver tumor microenvironment.
Asunto(s)
Antígenos CD/fisiología , Carcinoma Hepatocelular/etiología , Glicoproteínas/fisiología , Interleucina-6/fisiología , Neoplasias Hepáticas/etiología , Péptidos/fisiología , Factor de Transcripción STAT3/fisiología , Regulación hacia Arriba , Antígeno AC133 , Animales , Hipoxia de la Célula , Humanos , Ratones , Ratones Endogámicos C57BLRESUMEN
Despite excellent initial clinical responses of non-small cell lung cancer (NSCLC) patients to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), many patients eventually develop resistance. According to a recent report, vacuolar H+ ATPase (vATPase) is overexpressed and is associated with chemotherapy drug resistance in NSCLC. We investigated the combined effects of EGFR TKIs and vATPase inhibitors and their underlying mechanisms in the regulation of NSCLC cell death. We found that combined treatment with EGFR TKIs (erlotinib, gefitinib, or lapatinib) and vATPase inhibitors (bafilomycin A1 or concanamycin A) enhanced synergistic cell death compared to treatments with each drug alone. Treatment with bafilomycin A1 or concanamycin A led to the induction of Bnip3 expression in an Hif-1α dependent manner. Knock-down of Hif-1α or Bnip3 by siRNA further enhanced cell death induced by bafilomycin A1, suggesting that Hif-1α/Bnip3 induction promoted resistance to cell death induced by the vATPase inhibitors. EGFR TKIs suppressed Hif-1α and Bnip3 expression induced by the vATPase inhibitors, suggesting that they enhanced the sensitivity of the cells to these inhibitors by decreasing Hif-1α/Bnip3 expression. Taken together, we conclude that EGFR TKIs enhance the sensitivity of NSCLC cells to vATPase inhibitors by decreasing Hif-1α/Bnip3 expression. We suggest that combined treatment with EGFR TKIs and vATPase inhibitors is potentially effective for the treatment of NSCLC.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Carcinoma de Pulmón de Células no Pequeñas/enzimología , Receptores ErbB/antagonistas & inhibidores , Neoplasias Pulmonares/enzimología , ATPasas de Translocación de Protón Vacuolares/antagonistas & inhibidores , Carcinoma de Pulmón de Células no Pequeñas/genética , Carcinoma de Pulmón de Células no Pequeñas/patología , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Resistencia a Antineoplásicos , Receptores ErbB/metabolismo , Clorhidrato de Erlotinib , Gefitinib , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia/genética , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Lapatinib , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patología , Macrólidos/farmacología , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/metabolismo , Quinazolinas/farmacología , Interferencia de ARN , Transfección , ATPasas de Translocación de Protón Vacuolares/metabolismoRESUMEN
Cyclin A1 is an A-type cyclin that directly binds to CDK2 to regulate cell-cycle progression. In the present study, we found that doxorubicin decreased the expression of cyclin A1 at the protein level in A549 lung cancer cells, while markedly downregulating its mRNA levels. Interestingly, doxorubicin upregulated caspase-1 in a concentration-dependent manner, and z-YAVD-fmk, a specific inhibitor of caspase-1, reversed the doxorubicin-induced decrease in cyclin A1 in A549 lung cancer and MCF7 breast cancer cells. Active caspase-1 effectively cleaved cyclin A1 at D165 into two fragments, which in vitro cleavage assays showed were further cleaved by caspase-3. Finally, we found that overexpression of cyclin A1 significantly reduced the cytotoxicity of doxorubicin, and knockdown of cyclin A1 by RNA interference enhanced the sensitivity of cells to ionizing radiation. Our data suggest a new mechanism for the downregulation of cyclin A1 by DNA-damaging stimuli that could be intimately involved in the cell death induced by DNA damage-inducing stimuli, including doxorubicin and ionizing radiation.
Asunto(s)
Caspasas/metabolismo , Muerte Celular/genética , Ciclina A1/metabolismo , Daño del ADN , Secuencia de Bases , Línea Celular Tumoral , Cartilla de ADN , Humanos , Proteolisis , Reacción en Cadena en Tiempo Real de la PolimerasaRESUMEN
TWIST1 is implicated in the process of epithelial mesenchymal transition, metastasis, stemness, and drug resistance in cancer cells, and therefore is a potential target for cancer therapy. In the present study, we found that knockdown of TWIST1 by small interfering RNA (siRNA) enhanced arsenic trioxide (ATO)- and ionizing radiation (IR)-induced cell death in non-small-cell lung cancer cells. Interestingly, intracellular reactive oxygen species levels were increased in cells treated with TWIST1 siRNA and further increased by co-treatment with ATO or IR. Pretreatment of lung cancer cells with the antioxidant N-acetyl-cysteine markedly suppressed the cell death induced by combined treatment with TWIST1 siRNA and ATO or IR. Moreover, treatment of cells with TWIST1 siRNA induced mitochondrial membrane depolarization and significantly increased mitochondrial fragmentation (fission) and upregulated the fission-related proteins FIS1 and DRP1. Collectively, our results demonstrate that siRNA-mediated TWIST1 knockdown induces mitochondrial dysfunction and enhances IR- and ATO-induced cell death in lung cancer cells.