RESUMO
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.
Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Humanos , Espécies Reativas de Oxigênio/metabolismo , Fator 2 Relacionado a NF-E2/genética , Fator 2 Relacionado a NF-E2/metabolismo , Aminoácidos/metabolismo , Regulação para Baixo , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismoRESUMO
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.
Assuntos
Neoplasias da Mama , Tamoxifeno , Proteínas com Motivo de Ligação a PDZ com Coativador Transcricional , Proteínas de Sinalização YAP , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos , Feminino , Humanos , Células MCF-7 , Alvo Mecanístico do Complexo 1 de Rapamicina , RNA Interferente Pequeno , Survivina/genética , Tamoxifeno/farmacologia , Proteínas com Motivo de Ligação a PDZ com Coativador Transcricional/metabolismo , Proteínas de Sinalização YAP/metabolismoRESUMO
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.
Assuntos
Neoplasias Ovarianas , Paclitaxel , Carcinoma Epitelial do Ovário , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos , Feminino , Glutamina/farmacologia , Humanos , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Neoplasias Ovarianas/patologia , Paclitaxel/farmacologia , Paclitaxel/uso terapêutico , Proteínas Quinases S6 Ribossômicas/metabolismo , Transdução de SinaisRESUMO
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.
Assuntos
Fator 4 Ativador da Transcrição/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/antagonistas & inibidores , Metformina/farmacologia , Metformina/uso terapêutico , Proteínas Nucleares/metabolismo , Fatores de Transcrição/metabolismo , Humanos , TransfecçãoRESUMO
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.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/metabolismo , Neoplasias Pulmonares/metabolismo , Lisina/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Células A549 , Proteínas Quinases Ativadas por AMP/antagonistas & inibidores , Proteínas Quinases Ativadas por AMP/genética , Proteínas Quinases Ativadas por AMP/metabolismo , Linhagem Celular Tumoral , Meios de Cultura Livres de Soro , Técnicas de Silenciamento de Genes , Humanos , Insulina/administração & dosagem , Fator de Crescimento Insulin-Like I/administração & dosagem , Lisina/administração & dosagem , Lisina/deficiência , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , RNA Interferente Pequeno/genéticaRESUMO
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.
Assuntos
Antineoplásicos/administração & dosagem , Carcinoma Pulmonar de Células não Pequenas/terapia , Clusterina/genética , Terapia Genética/métodos , Proteínas Inibidoras de Apoptose/metabolismo , Neoplasias Pulmonares/terapia , ATPases Vacuolares Próton-Translocadoras/antagonistas & inibidores , Células A549 , Apoptose/efeitos dos fármacos , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/patologia , Sobrevivência Celular/efeitos dos fármacos , Terapia Combinada/métodos , Regulação para Baixo/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/genética , Inativação Gênica , Humanos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patologia , SurvivinaRESUMO
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.
Assuntos
Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Dioxolanos/administração & dosagem , Receptores ErbB/biossíntese , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Antineoplásicos/administração & dosagem , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Regulação para Baixo/efeitos dos fármacos , Humanos , Células MCF-7RESUMO
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.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Ácido Dicloroacético/administração & dosagem , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Metformina/administração & dosagem , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/metabolismo , Apoptose/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Humanos , Células MCF-7 , Neoplasias Experimentais/patologia , Resultado do TratamentoRESUMO
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.
Assuntos
Ácido Dicloroacético/farmacologia , Metformina/farmacologia , Ligante Indutor de Apoptose Relacionado a TNF/farmacologia , Neoplasias da Mama/patologia , Morte Celular/efeitos dos fármacos , Hipóxia Celular/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Células MCF-7 , Receptores de Morte Celular/metabolismo , Regulação para Cima/efeitos dos fármacosRESUMO
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.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Carcinoma Pulmonar de Células não Pequenas/enzimologia , Receptores ErbB/antagonistas & inibidores , Neoplasias Pulmonares/enzimologia , ATPases Vacuolares Próton-Translocadoras/antagonistas & inibidores , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/patologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Resistencia a Medicamentos Antineoplásicos , Receptores ErbB/metabolismo , Cloridrato de Erlotinib , Gefitinibe , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Lapatinib , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patologia , Macrolídeos/farmacologia , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Quinazolinas/farmacologia , Interferência de RNA , Transfecção , ATPases Vacuolares Próton-Translocadoras/metabolismoRESUMO
The PI3K/Akt/mTOR axis in lung cancer is frequently activated and implicated in tumorigenesis. Specific targeting of this pathway is therefore an attractive therapeutic approach for lung cancer. However, non-small cell lung cancer cells are resistant to BEZ235, a dual inhibitor of PI3K and mTOR. Interestingly, blockage of Stat3 with a selective inhibitor, S3I-201, or siRNA dramatically sensitized the BEZ235-induced cell death, as evident from increased PARP cleavage. Furthermore, inhibition of Stat3 led to enhancement of cell death induced by LY294002, a PI3K inhibitor. Treatment of cells with a combination of BEZ235 and S3I-201 significantly induced the proapoptotic transcription factor, CHOP, and its targets, Bim and DR4. Knockdown of CHOP or Bim suppressed cell death stimulated by the combination treatment, implicating the involvement of these BEZ235/S3I-201-induced factors in pronounced cell death. Moreover, the BEZ235/S3I-201 combination enhanced TRAIL-induced cell death. Our results collectively suggest that blockage of Stat3 presents an effective strategy to overcome resistance to PI3K/Akt/mTOR inhibition.
Assuntos
Benzenossulfonatos/farmacologia , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Imidazóis/farmacologia , Neoplasias Pulmonares/tratamento farmacológico , Inibidores de Fosfoinositídeo-3 Quinase , Inibidores de Proteínas Quinases/farmacologia , Quinolinas/farmacologia , Fator de Transcrição STAT3/antagonistas & inibidores , Serina-Treonina Quinases TOR/antagonistas & inibidores , Ácidos Aminossalicílicos/farmacologia , Antineoplásicos/farmacologia , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Carcinoma Pulmonar de Células não Pequenas/patologia , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Humanos , Pulmão/efeitos dos fármacos , Pulmão/metabolismo , Pulmão/patologia , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Fosfatidilinositol 3-Quinases/metabolismo , Interferência de RNA , RNA Interferente Pequeno/genética , Fator de Transcrição STAT3/genética , Transdução de Sinais/efeitos dos fármacos , Serina-Treonina Quinases TOR/metabolismoRESUMO
Although epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) have been effective targeted therapies for non-small cell lung cancer (NSCLC), most advanced NSCLC inevitably develop resistance to these therapies. Combination therapies emerge as valuable approach to preventing, delaying, or overcoming disease progression. Duloxetine, an antidepressant known as a serotonin-noradrenaline reuptake inhibitor, is commonly prescribed for the treatment of chemotherapy-induced peripheral neuropathy. In the present study, we investigated the combined effects of duloxetine and EGFR-TKIs and their possible mechanism in NSCLC cells. Compared with either monotherapy, the combination of duloxetine and EGFR-TKIs leads to synergistic cell death. Mechanistically, duloxetine suppresses 70-kDa ribosomal protein S6 kinase 1 (p70S6K1) activity through mechanistic target of rapamycin complex 1 (mTORC1), and this effect is associated with the synergistic induction of cell death of duloxetine combined with EGFR-TKIs. More importantly, activating transcription factor 4 (ATF4)-induced regulated in development and DNA damage response 1 (REDD1) is responsible for the suppression of mTORC1/S6K1 activation. Additionally, we found that the combination effect was significantly attenuated in REDD1 knockout NSCLC cells. Taken together, our findings reveal that the ATF4/REDD1/mTORC1/S6K1 signaling axis, as a novel mechanism, is responsible for the synergistic therapeutic effect of duloxetine with EGFR-TKIs. These results suggest that combining EGFR-TKIs with duloxetine appears to be a promising way to improve EGFR-TKI efficacy against NSCLC.
RESUMO
Tribbles pseudokinase 3 (TRIB3), a member of the mammalian Tribbles family, is implicated in multiple biological processes. This study aimed to investigate the biological functions of TRIB3 in lung cancer and its effect on amino acid-deprived lung cancer cells. TRIB3 mRNA expression was elevated in lung cancer tissues and cell lines compared to normal lung tissues and cells. TRIB3 knockdown markedly reduced the viability and proliferation of H1299 lung cancer cells. Deprivation of amino acids, particularly arginine, glutamine, lysine, or methionine, strongly increased TRIB3 expression via ATF4 activation in H1299 lung cancer cells. Knockdown of TRIB3 led to transcriptional downregulation of ATF4 and reduced AKT activation induced by amino acid deprivation, ultimately increasing the sensitivity of H1299 lung cancer cells to amino acid deprivation. Additionally, TRIB3 knockdown enhanced the sensitivity of H1299 cells to V-9302, a competitive antagonist of transmembrane glutamine flux. These results suggest that TRIB3 is a pro-survival regulator of cell viability in amino acid-deficient tumor microenvironments and a promising therapeutic target for lung cancer treatment.
RESUMO
Nutrient-limiting conditions are frequently encountered by tumor cells in poorly vascularized microenvironments. These stress conditions may facilitate the selection of tumor cells with an inherent ability to decrease apoptotic potential. Therefore, selective targeting of tumor cells under glucose deprivation conditions may provide an effective alternative strategy for cancer therapy. In the present study, we investigated the effects of S6 kinase 1 (S6K1) inhibition on glucose deprivation-induced cell death and the underlying mechanisms in MCF-7 breast cancer cells. PF4708671, a selective inhibitor of S6K1, and knockdown of S6K1 with specific siRNA enhanced cell death induced under glucose deprivation conditions. Moreover, inhibition of S6K1 led to apoptosis in glucose-starved MCF-7 cells via downregulation of the anti-apoptotic proteins, Mcl-1 and survivin. Further experiments revealed that sorafenib, shown to be involved in Mcl-1 and survivin downregulation via mTOR/S6K1 inhibition significantly promotes cell death under glucose deprivation conditions. These findings collectively suggest that S6K1 plays an important role in tumor cell survival under stress conditions, and thus inhibition of S6K1 may be an effective strategy for sensitizing cells to glucose deprivation.
Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Neoplasias da Mama/metabolismo , Glucose/deficiência , Proteínas Quinases S6 Ribossômicas 70-kDa/antagonistas & inibidores , Apoptose/efeitos dos fármacos , Neoplasias da Mama/enzimologia , Regulação para Baixo , Feminino , Técnicas de Silenciamento de Genes , Humanos , Imidazóis/farmacologia , Proteínas Inibidoras de Apoptose/metabolismo , Células MCF-7 , Proteína de Sequência 1 de Leucemia de Células Mieloides , Niacinamida/análogos & derivados , Niacinamida/farmacologia , Compostos de Fenilureia/farmacologia , Piperazinas/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Proteínas Quinases S6 Ribossômicas 70-kDa/genética , Sorafenibe , Survivina , Serina-Treonina Quinases TOR/antagonistas & inibidoresRESUMO
Resistance of estrogen receptor-positive breast cancer cells to tamoxifen represents a major barrier to the successful treatment of breast cancer. In the present study, we found that vacuolar H+ ATPase (vATPase) inhibitors, bafilomycin A1 and concanamycin A, sensitize tamoxifen-induced cell death. siRNA targeting ATP6V0C, a 16-kDa hydrophobic proteolipid subunit of vATPase that plays a central role in H+ transport, markedly increased cell death induced by tamoxifen. Interestingly, bafilomycin A1 induced up-regulation of DR4/DR5 and CHOP. Knock-down of CHOP by siRNA suppressed the cell death induced by bafilomycin A1 and tamoxifen, suggesting that bafilomycin A1-mediated CHOP activation sensitizes to tamoxifen. In addition, we found that bafilomycin A1 enhances TRAIL-induced cell death in breast cancer cells. Furthermore, we showed that combination of vATPase inhibitors with tamoxifen also effectively induced cell death in HER2- and ERα-overexpressing breast cancer cells. Overall, our results demonstrate that inhibition of vATPase can potentiate the apoptotic effects of tamoxifen through up-regulation of CHOP.
Assuntos
Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Tamoxifeno/farmacologia , Fator de Transcrição CHOP/biossíntese , Regulação para Cima/efeitos dos fármacos , ATPases Vacuolares Próton-Translocadoras/antagonistas & inibidores , Apoptose/efeitos dos fármacos , Apoptose/fisiologia , Neoplasias da Mama/patologia , Morte Celular/efeitos dos fármacos , Morte Celular/fisiologia , Linhagem Celular Tumoral , Sinergismo Farmacológico , Feminino , Técnicas de Silenciamento de Genes , Humanos , Células MCF-7 , Tamoxifeno/toxicidade , Fator de Transcrição CHOP/antagonistas & inibidores , Fator de Transcrição CHOP/genética , Regulação para Cima/fisiologiaRESUMO
S6 kinase 1 (S6K1) was suggested to be a marker for endocrine therapy resistance in breast cancer. We examined whether tamoxifen's effect can be modulated by S6K1 inhibition. S6K1 inhibition by PF4708671, a selective inhibitor of S6K1, acts synergistically with tamoxifen in S6K1-high MCF-7 cells. Similarly, the knockdown of S6K1 with small interfering RNA (siRNA) significantly sensitized MCF-7 cells to tamoxifen. Inhibition of S6K1 by PF4708671 led to a marked decrease in the expression levels of the anti-apoptotic proteins Mcl-1 and survivin, which was not related to mRNA levels. In addition, suppression of Mcl-1 or survivin, using specific siRNA, further enhanced cell sensitivity to tamoxifen. These results showed that inhibition of S6K1 acts synergistically with tamoxifen, via translational modulation of Mcl-1 and survivin. Based on these findings, we propose that targeting S6K1 may be an effective strategy to overcome tamoxifen resistance in breast cancer.
Assuntos
Apoptose/efeitos dos fármacos , Proteínas Inibidoras de Apoptose/metabolismo , Proteína de Sequência 1 de Leucemia de Células Mieloides/metabolismo , Proteínas Quinases S6 Ribossômicas 70-kDa/antagonistas & inibidores , Tamoxifeno/farmacologia , Neoplasias da Mama/tratamento farmacológico , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Feminino , Expressão Gênica/efeitos dos fármacos , Humanos , Imidazóis/farmacologia , Proteínas Inibidoras de Apoptose/biossíntese , Proteínas Inibidoras de Apoptose/genética , Células MCF-7 , Proteína de Sequência 1 de Leucemia de Células Mieloides/biossíntese , Proteína de Sequência 1 de Leucemia de Células Mieloides/genética , Piperazinas/farmacologia , Interferência de RNA , RNA Interferente Pequeno , Receptores de Estrogênio/efeitos dos fármacos , Proteínas Quinases S6 Ribossômicas 70-kDa/genética , SurvivinaRESUMO
BACKGROUND/AIM: The fibroblast growth factor receptor (FGFR) signaling pathway is abnormally activated in human cancers, including breast cancer. Therefore, targeting the FGFR signaling pathway is a potent strategy to treat breast cancer. The purpose of this study was to find drugs that could increase sensitivity to FGFR inhibitor effects in BT-474 breast cancer cells, and to investigate the combined effects and underlying mechanisms of these combinations for BT-474 breast cancer cell survival. MATERIALS AND METHODS: Cell viability was measured by MTT assay. Protein expression was determined by western blot analysis. mRNA expression was detected by Real-time PCR. Drug synergy effect was determined by isobologram analysis. RESULTS: Nebivolol, a third generation ß1-blocker, synergistically increased the sensitivity of BT-474 breast cancer cells to the potent and selective FGFR inhibitors erdafitinib (JNJ-42756493) and AZD4547. A combination of nebivolol and erdafitinib markedly reduced AKT activation. Suppression of AKT activation using specific siRNA and a selective inhibitor further enhanced cell sensitivity to combined treatment with nebivolol and erdafitinib, whereas SC79, a potent activator of AKT, reduced cell sensitivity to nebivolol and erdafitinib. CONCLUSION: Enhanced sensitivity of BT-474 breast cancer cells to nebivolol and erdafitinib was probably associated with down-regulation of AKT activation. Combined treatment with nebivolol and erdafitinib is a promising strategy for breast cancer treatment.
Assuntos
Neoplasias da Mama , Humanos , Feminino , Nebivolol/farmacologia , Nebivolol/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptores de Fatores de Crescimento de Fibroblastos/metabolismo , Transdução de Sinais , Inibidores de Proteínas Quinases/farmacologia , Linhagem Celular TumoralRESUMO
BACKGROUND/AIM: Metformin is a widely used drug for type 2 diabetes mellitus and has recently attracted broad attention for its therapeutic effects on many cancers. This study aimed to investigate the molecular mechanism of metformin's anticancer activity. MATERIALS AND METHODS: Cell viability was measured by MTT assay. Gene and protein expression levels were determined by reverse transcription-polymerase chain reaction and western blot analyses, respectively. RESULTS: Metformin and phenformin markedly induced NUPR1 expression in a dose- and time-dependent manner in H1299 non-small-cell lung cancer (NSCLC) cells. The silencing of NUPR1 in H1299 NSCLC cells enhanced cell sensitivity to metformin or ionizing radiation. Our previous report showed that metformin induces AKT serine/threonine kinase (AKT) activation in an activating transcription factor 4 (ATF4)-dependent manner and that the inhibition of AKT promotes cell sensitivity to metformin in H1299 NSCLC cells. Interestingly, ATF4-induced AKT activation in H1299 NSCLC cells treated with metformin was suppressed by the knockdown of NUPR1. CONCLUSION: Targeting NUPR1 could enhance the sensitivity of H1299 NSCLC cells to metformin by AKT inhibition.
Assuntos
Carcinoma Pulmonar de Células não Pequenas , Diabetes Mellitus Tipo 2 , Neoplasias Pulmonares , Metformina , Fator 4 Ativador da Transcrição , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/genética , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/genética , Metformina/farmacologia , Proteínas Proto-Oncogênicas c-akt/genéticaRESUMO
Myeloid cell leukemia sequence 1 (MCL1), an antiapoptotic Bcell lymphoma 2 (BCL2) family molecule frequently amplified in various human cancer cells, is known to be critical for cancer cell survival. MCL1 has been recognized as a target molecule for cancer treatment. While various agents have emerged as potential MCL1 blockers, the present study presented acriflavine (ACF) as a novel MCL1 inhibitor in triplenegative breast cancer (TNBC). Further evaluation of its treatment potential on lung adenocarcinoma and glioblastoma multiforme (GBM) was also investigated. The anticancer effect of ACF on TNBC cells was demonstrated when MDAMB231 and HS578T cells were treated with ACF. ACF significantly induced typical intrinsic apoptosis in TNBCs in a dose and timedependent manner via MCL1 downregulation. MCL1 downregulation by ACF treatment was revealed at each phase of protein expression. Initially, transcriptional regulation via reverse transcriptionquantitative PCR was validated. Then, posttranslational regulation was explained by utilizing an inhibitor against protein biosynthesis and proteasome. Lastly, immunoprecipitation of ubiquitinated MCL1 confirmed the posttranslational downregulation of MCL1. In addition, the synergistic treatment efficacy of ACF with the wellknown MCL1 inhibitor ABT263 against the TNBC cells was explored [combination index (CI)<1]. Conjointly, the anticancer effect of ACF was assessed in GBM (U87, U251 and U343), and lung cancer (A549 and NCIH69) cell lines as well, using immunoblotting, cytotoxicity assay and FACS. The effect of the combination treatment using ACF and ABT263 was estimated in GBM (U87, U343 and U251), and nonsmall cell lung cancer (A549) cells likewise. The present study suggested a novel MCL1 inhibitory function of ACF and the synergistic antitumor effect with ABT263.