RESUMEN
Non-coding ribonucleic acids (ncRNAs) have been recently shown to contribute to tumorigenesis by mediating changes in metabolism. ncRNAs act as key molecules in metabolic pathways regulation. The dysregulation of ncRNAs during cancer progression contributes to altered metabolic phenotypes leading to reprogrammed metabolism. Since ncRNAs affect different tumor processes by regulating mitochondrial dynamics and metabolism, in the future ncRNAs can be exploited in disease detection, diagnosis, treatment, and resistance. The purpose of this review is to highlight the role of ncRNAs in mitochondrial metabolic reprogramming and to relate their therapeutic potential in the management of genitourinary cancer.
RESUMEN
Metabolic flexibility is a hallmark of many cancers where mitochondrial respiration is critically involved, but the molecular underpinning of mitochondrial control of cancer metabolic reprogramming is poorly understood. Here, we show that reverse electron transfer (RET) through respiratory chain complex I (RC-I) is particularly active in brain cancer stem cells (CSCs). Although RET generates ROS, NAD+/NADH ratio turns out to be key in mediating RET effect on CSC proliferation, in part through the NAD+-dependent Sirtuin. Mechanistically, Notch acts in an unconventional manner to regulate RET by interacting with specific RC-I proteins containing electron-transporting Fe-S clusters and NAD(H)-binding sites. Genetic and pharmacological interference of Notch-mediated RET inhibited CSC growth in Drosophila brain tumor and mouse glioblastoma multiforme (GBM) models. Our results identify Notch as a regulator of RET and RET-induced NAD+/NADH balance, a critical mechanism of metabolic reprogramming and a metabolic vulnerability of cancer that may be exploited for therapeutic purposes.
Asunto(s)
Complejo I de Transporte de Electrón/metabolismo , Células Madre Neoplásicas/metabolismo , Receptores Notch/metabolismo , Animales , Línea Celular Tumoral , Proliferación Celular/fisiología , Respiración de la Célula/fisiología , Modelos Animales de Enfermedad , Drosophila , Transporte de Electrón/fisiología , Complejo I de Transporte de Electrón/fisiología , Electrones , Glioblastoma/genética , Glioblastoma/metabolismo , Humanos , Ratones , Ratones Endogámicos NOD , Mitocondrias/metabolismo , NAD/metabolismo , Células Madre Neoplásicas/fisiología , Especies Reactivas de Oxígeno/metabolismoRESUMEN
Major fraction of the human genome is transcribed in to the RNA but is not translated in to any specific functional protein. These transcribed but not translated RNA molecules are called as non-coding RNA (ncRNA). There are thousands of different non-coding RNAs present inside the cells, each regulating different cellular pathway/pathways. Over the last few decades non-coding RNAs have been found to be involved in various diseases including cancer. Non-coding RNAs are reported to function both as tumor enhancer and/or tumor suppressor in almost each type of cancer. Urothelial carcinoma of the urinary bladder is the second most common urogenital malignancy in the world. Over the last few decades, non-coding RNAs were demonstrated to be linked with bladder cancer progression by modulating different signalling pathways and cellular processes such as autophagy, metastasis, drug resistance and tumor proliferation. Due to the heterogeneity of bladder cancer cells more in-depth molecular characterization is needed to identify new diagnostic and treatment options. This review emphasizes the current findings on non-coding RNAs and their relationship with various oncological processes such as autophagy, and their applicability to the pathophysiology of bladder cancer. This may offer an understanding of evolving non-coding RNA-targeted diagnostic tools and new therapeutic approaches for bladder cancer management in the future.
RESUMEN
New strategies are needed to enhance the efficacy of anti-programmed cell death protein antibody (anti-PD-1 Ab) in cancer. Here, we report that inhibiting palmitoyl-protein thioesterase 1 (PPT1), a target of chloroquine derivatives like hydroxychloroquine (HCQ), enhances the antitumor efficacy of anti-PD-1 Ab in melanoma. The combination resulted in tumor growth impairment and improved survival in mouse models. Genetic suppression of core autophagy genes, but not Ppt1, in cancer cells reduced priming and cytotoxic capacity of primed T cells. Exposure of antigen-primed T cells to macrophage-conditioned medium derived from macrophages treated with PPT1 inhibitors enhanced melanoma-specific killing. Genetic or chemical Ppt1 inhibition resulted in M2 to M1 phenotype switching in macrophages. The combination was associated with a reduction in myeloid-derived suppressor cells in the tumor. Ppt1 inhibition by HCQ, or DC661, induced cyclic GMP-AMP synthase/stimulator of interferon genes/TANK binding kinase 1 pathway activation and the secretion of interferon-ß in macrophages, the latter being a key component for augmented T cell-mediated cytotoxicity. Genetic Ppt1 inhibition produced similar findings. These data provide the rationale for this combination in melanoma clinical trials and further investigation in other cancers.
Asunto(s)
Inhibidores Enzimáticos/farmacología , Hidroxicloroquina/farmacología , Inhibidores de Puntos de Control Inmunológico/uso terapéutico , Melanoma/tratamiento farmacológico , Receptor de Muerte Celular Programada 1/antagonistas & inhibidores , Tioléster Hidrolasas/antagonistas & inhibidores , Animales , Anticuerpos/inmunología , Protocolos de Quimioterapia Combinada Antineoplásica , Inhibidores Enzimáticos/administración & dosificación , Inhibidores Enzimáticos/uso terapéutico , Hidroxicloroquina/administración & dosificación , Hidroxicloroquina/uso terapéutico , Inhibidores de Puntos de Control Inmunológico/administración & dosificación , Inhibidores de Puntos de Control Inmunológico/farmacología , Interferón beta/metabolismo , Macrófagos/efectos de los fármacos , Macrófagos/inmunología , Melanoma/inmunología , Ratones , Ratones Endogámicos C57BL , Nucleotidiltransferasas/metabolismo , Receptor de Muerte Celular Programada 1/inmunología , Células RAW 264.7 , Linfocitos T/inmunología , Tioléster Hidrolasas/genética , Tioléster Hidrolasas/metabolismo , Células Tumorales CultivadasRESUMEN
Autophagy is being explored as a potential therapeutic target for enhancing the cytotoxic effects of chemotherapeutic regimens in various malignancies. Autophagy plays a very important role in cancer pathogenesis. Here, we discuss the updates on the modulation of autophagy via dynamic interactions with different organelles and the exploitation of selective autophagy for exploring therapeutic strategies. We further discuss the role of autophagy inhibitors in cancer preclinical and clinical trials, novel autophagy inhibitors, and challenges likely to be faced by clinicians while inducting autophagy modulators in clinical practice.
Asunto(s)
Autofagia/fisiología , Neoplasias/patología , Animales , Antineoplásicos/farmacología , Autofagia/efectos de los fármacos , Ensayos Clínicos como Asunto , Evaluación Preclínica de Medicamentos/métodos , Humanos , Terapia Molecular Dirigida/métodos , Neoplasias/tratamiento farmacológicoRESUMEN
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
RESUMEN
The c-Myc oncogene drives malignant progression and induces robust anabolic and proliferative programmes leading to intrinsic stress. The mechanisms enabling adaptation to MYC-induced stress are not fully understood. Here we reveal an essential role for activating transcription factor 4 (ATF4) in survival following MYC activation. MYC upregulates ATF4 by activating general control nonderepressible 2 (GCN2) kinase through uncharged transfer RNAs. Subsequently, ATF4 co-occupies promoter regions of over 30 MYC-target genes, primarily those regulating amino acid and protein synthesis, including eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1), a negative regulator of translation. 4E-BP1 relieves MYC-induced proteotoxic stress and is essential to balance protein synthesis. 4E-BP1 activity is negatively regulated by mammalian target of rapamycin complex 1 (mTORC1)-dependent phosphorylation and inhibition of mTORC1 signalling rescues ATF4-deficient cells from MYC-induced endoplasmic reticulum stress. Acute deletion of ATF4 significantly delays MYC-driven tumour progression and increases survival in mouse models. Our results establish ATF4 as a cellular rheostat of MYC activity, which ensures that enhanced translation rates are compatible with survival and tumour progression.
Asunto(s)
Factor de Transcripción Activador 4/genética , Genes myc/genética , Activación Transcripcional/fisiología , Proteínas Adaptadoras Transductoras de Señales/genética , Animales , Proteínas de Ciclo Celular , Estrés del Retículo Endoplásmico/genética , Humanos , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Ratones Transgénicos , Fosfoproteínas/genética , Fosforilación , Biosíntesis de Proteínas/fisiología , Serina-Treonina Quinasas TOR/metabolismoRESUMEN
Resistance to BRAF and MEK inhibitors (BRAFi + MEKi) in BRAF-mutant tumors occurs through heterogeneous mechanisms, including ERK reactivation and autophagy. Little is known about the mechanisms by which ERK reactivation or autophagy is induced by BRAFi + MEKi. Here, we report that in BRAF-mutant melanoma cells, BRAFi + MEKi induced SEC61-dependent endoplasmic reticulum (ER) translocation of the MAPK pathway via GRP78 and KSR2. Inhibition of ER translocation prevented ERK reactivation and autophagy. Following ER translocation, ERK exited the ER and was rephosphorylated by PERK. Reactivated ERK phosphorylated ATF4, which activated cytoprotective autophagy. Upregulation of GRP78 and phosphorylation of ATF4 were detected in tumors of patients resistant to BRAFi + MEKi. ER translocation of the MAPK pathway was demonstrated in therapy-resistant patient-derived xenografts. Expression of a dominant-negative ATF4 mutant conferred sensitivity to BRAFi + MEKi in vivo. This mechanism reconciles two major targeted therapy resistance pathways and identifies druggable targets, whose inhibition would likely enhance the response to BRAFi + MEKi. SIGNIFICANCE: ERK reactivation and autophagy are considered distinct resistance pathways to BRAF + MEK inhibition (BRAFi + MEKi) in BRAF V600E cancers. Here, we report BRAFi + MEKi-induced ER translocation of the MAPK pathway is necessary for ERK reactivation, which drives autophagy. The ER translocation mechanism is a major druggable driver of resistance to targeted therapy.This article is highlighted in the In This Issue feature, p. 305.
Asunto(s)
Retículo Endoplásmico/metabolismo , Sistema de Señalización de MAP Quinasas , Melanoma/tratamiento farmacológico , Melanoma/metabolismo , Mutación , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Proto-Oncogénicas B-raf/genética , Animales , Autofagia , Línea Celular Tumoral , Resistencia a Antineoplásicos , Retículo Endoplásmico/efectos de los fármacos , Retículo Endoplásmico/patología , Chaperón BiP del Retículo Endoplásmico , Proteínas de Choque Térmico/metabolismo , Humanos , Quinasas Quinasa Quinasa PAM/antagonistas & inhibidores , Masculino , Melanoma/genética , Melanoma/patología , Ratones , Ratones Endogámicos NOD , Ratones SCID , Transporte de Proteínas , Proteínas Proto-Oncogénicas B-raf/antagonistas & inhibidores , Proteínas Proto-Oncogénicas B-raf/metabolismo , Células Tumorales Cultivadas , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Clinical trials repurposing lysosomotropic chloroquine (CQ) derivatives as autophagy inhibitors in cancer demonstrate encouraging results, but the underlying mechanism of action remains unknown. Here, we report a novel dimeric CQ (DC661) capable of deacidifying the lysosome and inhibiting autophagy significantly better than hydroxychloroquine (HCQ). Using an in situ photoaffinity pulldown strategy, we identified palmitoyl-protein thioesterase 1 (PPT1) as a molecular target shared across monomeric and dimeric CQ derivatives. HCQ and Lys05 also bound to and inhibited PPT1 activity, but only DC661 maintained activity in acidic media. Knockout of PPT1 in cancer cells using CRISPR/Cas9 editing abrogates autophagy modulation and cytotoxicity of CQ derivatives, and results in significant impairment of tumor growth similar to that observed with DC661. Elevated expression of PPT1 in tumors correlates with poor survival in patients in a variety of cancers. Thus, PPT1 represents a new target in cancer that can be inhibited with CQ derivatives. SIGNIFICANCE: This study identifies PPT1 as the previously unknown lysosomal molecular target of monomeric and dimeric CQ derivatives. Genetic suppression of PPT1 impairs tumor growth, and PPT1 levels are elevated in cancer and associated with poor survival. These findings provide a strong rationale for targeting PPT1 in cancer. This article is highlighted in the In This Issue feature, p. 151.
Asunto(s)
Antimaláricos/farmacología , Biomarcadores de Tumor/metabolismo , Cloroquina/farmacología , Proteínas de la Membrana/metabolismo , Neoplasias/patología , Tioléster Hidrolasas/metabolismo , Aminoquinolinas/farmacología , Apoptosis , Biomarcadores de Tumor/genética , Proliferación Celular , Humanos , Proteínas de la Membrana/genética , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Poliaminas/farmacología , Pronóstico , Tasa de Supervivencia , Tioléster Hidrolasas/genética , Células Tumorales Cultivadas , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
BACKGROUND: Renal cell carcinoma (RCC) is the most common kidney neoplasm and requires an early diagnosis because of poor response to conventional cancer treatments. However, till date, there is no reliable tumor marker available for the diagnosis of RCC. OBJECTIVE: The aim of the study was to evaluate the expression of speckle-type POZ protein (SPOP) as a biomarker in patients with RCC. MATERIALS AND METHODS: Blood samples were collected from fifty patients with RCC and ten healthy controls. Tumor tissue samples were obtained from nephrectomy specimen. Adjoining normal renal parenchyma of these fifty patients and eight normal renal tissue samples from normal kidney served as controls. Reverse transcriptase-polymerase chain reaction assay was performed for SPOP and mammalian target of rapamycin expression. RESULTS: SPOP was significantly increased in blood of patients with RCC as compared to controls (0.754 ± 0.32 vs. 0.224 ± 0.14; P < 0.001). Twenty-two patients (44%) had SPOP value more than mean + 2 standard deviation (SD) of controls. In RCC tissue, 42 (84%) patients had increased expression of SPOP more than 0.523 (mean + 2 SD value of SPOP expression in controls). SPOP expression was high in blood of 60% patients and in tumor tissue of 90% patients with clear cell RCC. SPOP was higher in high grade and high stage of RCC. CONCLUSIONS: Our result suggests that SPOP expression in blood might have a sensitivity that is low for routine diagnostic use and for screening for RCC. However, SPOP could be a potential tissue diagnostic biomarker in RCC.
Asunto(s)
Biomarcadores de Tumor/sangre , Proteínas Nucleares/sangre , Proteínas Represoras/sangre , Adulto , Anciano , Carcinoma de Células Renales/sangre , Carcinoma de Células Renales/diagnóstico , Carcinoma de Células Renales/patología , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Autophagy is a conserved, self-degradation system that is critical for maintaining cellular homeostasis during stress conditions. Dysregulated autophagy has implications in health and disease. Specifically, in cancer, autophagy plays a dichotomous role by inhibiting tumor initiation but supporting tumor progression. Early results from clinical trials that repurposed hydroxychloroquine for cancer have suggested that autophagy inhibition may be a promising approach for advanced cancers. In this review of the literature, the authors present fundamental advances in the biology of autophagy, approaches to targeting autophagy, the preclinical rationale and clinical experience with hydroxychloroquine in cancer clinical trials, the potential role of autophagy in tumor immunity, and recent developments in next-generation autophagy inhibitors that have clinical potential. Autophagy is a promising target for drug development in cancer. Cancer 2018. © 2018 American Cancer Society.
Asunto(s)
Autofagia/genética , Carcinogénesis/genética , Terapia Molecular Dirigida , Neoplasias/tratamiento farmacológico , Autofagia/efectos de los fármacos , Carcinogénesis/efectos de los fármacos , Desarrollo de Medicamentos , Humanos , Neoplasias/epidemiología , Neoplasias/genéticaRESUMEN
Lysosomal autophagy inhibitors (LAI) such as hydroxychloroquine (HCQ) have significant activity in a subset of cancer cell lines. LAIs are being evaluated in cancer clinical trials, but genetic determinants of sensitivity to LAIs are unknown, making it difficult to predict which tumors would be most susceptible. Here we characterize differentially expressed genes in HCQ-sensitive (-S) and -resistant (-R) cancer cells. Notably, expression of canonical macroautophagy/autophagy genes was not associated with sensitivity to HCQ. Expression patterns of ALDH1A1 (aldehyde dehydrogenase 1 family member A1) and HLTF (helicase like transcription factor) identified HCQ-S (ALDH1A1high HLTFlow; ALDH1A1low HLTFlow) and HCQ-R (ALDH1A1low HLTFhigh) cells. ALDH1A1 overexpression was found to enhance LAI cell entry and cytotoxicity without directly affecting lysosome function or autophagic flux. Expression of HLTF allows repair of DNA damage caused by LAI-induced reactive oxygen species, leading to HCQ resistance. Sensitivity to HCQ is increased in cells where HLTF is silenced by promoter methylation. HLTF overexpression blunted the antitumor efficacy of chloroquine derivatives in vitro and in vivo. Analysis of tumor RNA sequencing data from >700 patients in the Cancer Genome Atlas identified cancers including colon cancer, renal cell carcinoma, and gastric cancers, that were enriched for the HCQ-S or HCQ-R signature. These results provide mechanistic insights into LAI efficacy, and guidance for LAI clinical development.
Asunto(s)
Aldehído Deshidrogenasa/metabolismo , Autofagia , Proteínas de Unión al ADN/metabolismo , Lisosomas/metabolismo , Factores de Transcripción/metabolismo , Familia de Aldehído Deshidrogenasa 1 , Animales , Autofagia/efectos de los fármacos , Línea Celular Tumoral , Cloroquina/farmacología , Daño del ADN , Resistencia a Antineoplásicos/efectos de los fármacos , Epigénesis Genética/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Hidroxicloroquina/farmacología , Lisosomas/efectos de los fármacos , Ratones Desnudos , Especies Reactivas de Oxígeno/metabolismo , Reproducibilidad de los Resultados , Retinal-DeshidrogenasaRESUMEN
Lysosomes serve dual roles in cancer metabolism, executing catabolic programs (i.e., autophagy and macropinocytosis) while promoting mTORC1-dependent anabolism. Antimalarial compounds such as chloroquine or quinacrine have been used as lysosomal inhibitors, but fail to inhibit mTOR signaling. Further, the molecular target of these agents has not been identified. We report a screen of novel dimeric antimalarials that identifies dimeric quinacrines (DQ) as potent anticancer compounds, which concurrently inhibit mTOR and autophagy. Central nitrogen methylation of the DQ linker enhances lysosomal localization and potency. An in situ photoaffinity pulldown identified palmitoyl-protein thioesterase 1 (PPT1) as the molecular target of DQ661. PPT1 inhibition concurrently impairs mTOR and lysosomal catabolism through the rapid accumulation of palmitoylated proteins. DQ661 inhibits the in vivo tumor growth of melanoma, pancreatic cancer, and colorectal cancer mouse models and can be safely combined with chemotherapy. Thus, lysosome-directed PPT1 inhibitors represent a new approach to concurrently targeting mTORC1 and lysosomal catabolism in cancer.Significance: This study identifies chemical features of dimeric compounds that increase their lysosomal specificity, and a new molecular target for these compounds, reclassifying these compounds as targeted therapies. Targeting PPT1 blocks mTOR signaling in a manner distinct from catalytic inhibitors, while concurrently inhibiting autophagy, thereby providing a new strategy for cancer therapy. Cancer Discov; 7(11); 1266-83. ©2017 AACR.See related commentary by Towers and Thorburn, p. 1218This article is highlighted in the In This Issue feature, p. 1201.
Asunto(s)
Lisosomas/efectos de los fármacos , Melanoma/tratamiento farmacológico , Proteínas de la Membrana/antagonistas & inhibidores , Serina-Treonina Quinasas TOR/genética , Tioléster Hidrolasas/antagonistas & inhibidores , Animales , Antimaláricos/administración & dosificación , Antineoplásicos/administración & dosificación , Autofagia/efectos de los fármacos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Cloroquina/administración & dosificación , Humanos , Lisosomas/genética , Diana Mecanicista del Complejo 1 de la Rapamicina/antagonistas & inhibidores , Diana Mecanicista del Complejo 1 de la Rapamicina/genética , Melanoma/genética , Melanoma/patología , Proteínas de la Membrana/genética , Ratones , Terapia Molecular Dirigida , Proteolisis/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Tioléster Hidrolasas/genéticaRESUMEN
Cancer cells are exposed to various intrinsic and extrinsic factors that disrupt protein homeostasis, producing endoplasmic reticulum (ER) stress. To cope with these situations, cancer cells evoke a highly conserved adaptive mechanism called the unfolded protein response (UPR) to restore the ER homeostasis. Recently, several pharmacological agents have been found to exhibit anti-tumor activity by targeting the UPR components. The development of potent and specific compounds that target the UPR components has not only shed light on the regulation of the UPR in cancer cells, but also brought the field closer to clinical drug candidates. Here we present an overview of the milestones in the field of UPR biology in cancer with a focus on new strategies for pharmacological inhibition.
Asunto(s)
Antineoplásicos/farmacología , Neoplasias/tratamiento farmacológico , Respuesta de Proteína Desplegada/efectos de los fármacos , Animales , Descubrimiento de Drogas/métodos , Estrés del Retículo Endoplásmico/efectos de los fármacos , Humanos , Terapia Molecular Dirigida/métodos , Neoplasias/metabolismo , Neoplasias/patologíaRESUMEN
BACKGROUND: Renal cell carcinoma (RCC) is one of the most common neoplasms that occurs in the kidney and is marked by a unique biology, with a long history of poor response to conventional cancer treatments. In recent years, there have been significant advancements implemented to understanding the biology of RCC, which has led to the introduction of novel targeted therapies in the management of patients with metastatic disease. OBJECTIVE: The present study was designed to evaluate the effects of p38 MAPK inhibitor (SB203580), alone and in combination with mTOR inhibitor (CCI779) on apoptosis and cell proliferation. METHOD: Subtoxic concentrations of inhibitors were selected by MTT assay using A-498, ACHN and primary culture of RCC. RESULTS: All the three types of RCC cells had almost similar response towards these inhibitors. The results revealed that 25µM of SB203580 and 20µM of CCI779 at 48 hrs decreased cell viability by 20% and 30%, respectively, whereas the combination of both inhibitors showed a maximum of 40% reduction in cell viability. CONCLUSION: The study concludes that the combination of SB203580 and CCI779 inhibitors may induce cellular senescence in A-498 cells with higher potency than that of individual inhibitors.
Asunto(s)
Antineoplásicos/farmacología , Carcinoma de Células Renales/tratamiento farmacológico , Imidazoles/farmacología , Neoplasias Renales/tratamiento farmacológico , Inhibidores de Proteínas Quinasas/farmacología , Piridinas/farmacología , Sirolimus/análogos & derivados , Proteína p53 Supresora de Tumor/metabolismo , Antineoplásicos/síntesis química , Antineoplásicos/química , Apoptosis/efectos de los fármacos , Carcinoma de Células Renales/patología , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Imidazoles/química , Neoplasias Renales/patología , Estructura Molecular , Inhibidores de Proteínas Quinasas/síntesis química , Inhibidores de Proteínas Quinasas/química , Piridinas/química , Sirolimus/química , Sirolimus/farmacología , Relación Estructura-Actividad , Serina-Treonina Quinasas TOR/antagonistas & inhibidores , Serina-Treonina Quinasas TOR/metabolismo , Células Tumorales Cultivadas , Proteínas Quinasas p38 Activadas por Mitógenos/antagonistas & inhibidores , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
Heat shock protein-70kDa (Hsp70) is a member of molecular chaperone family, involved in the proper folding of various proteins. Hsp70 is important for tumor cell survival and is also reported to be involved in enhancing the drug resistance of various cancer types. Hsp70 controls apoptosis both upstream and downstream of the mitochondria by regulating the mitochondrial membrane permeabilization (MMP) and apoptosome formation respectively. In the present study, we have elucidated the role of Hsp70 in Gambogic acid (GA) induced apoptosis in bladder cancer cells. We observed that functional inhibition of Hsp70 by Pifithrin-µ switches GA induced caspase dependent (apoptotic) cell death to caspase independent cell death. However, this cell death was not essentially necrotic in nature, as shown by the observations like intact plasma membranes, cytochrome-c release and no significant effect on nuclear condensation/fragmentation. Inhibition of Hsp70 by Pifithrin-µ shows differential effect on MMP. GA induced MMP and cytochrome-c release was inhibited by Pifithrin-µ at 12h but enhanced at 24h. Pifithrin-µ also reverted back GA inhibited autophagy which resulted in the degradation of accumulated ubiquitinated proteins. Our results demonstrate that Hsp70 plays an important role in GA induced apoptosis by regulating caspase activation. Therefore, inhibition of Hsp70 may hamper with the caspase dependent apoptotic pathways induced by most anti-cancer drugs and reduce their efficacy. However, the combination therapy with Pifithrin-µ may be particularly useful in targeting apoptotic resistant cancer cells as Pifithrin-µ may initiate alternative cell death program in these resistant cells.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Apoptosis/efectos de los fármacos , Carcinoma/tratamiento farmacológico , Caspasas/metabolismo , Proteínas HSP70 de Choque Térmico/antagonistas & inhibidores , Sulfonamidas/farmacología , Neoplasias de la Vejiga Urinaria/tratamiento farmacológico , Xantonas/farmacología , Anciano , Autofagia/efectos de los fármacos , Carcinoma/enzimología , Carcinoma/genética , Carcinoma/patología , Línea Celular Tumoral , Citocromos c/metabolismo , Relación Dosis-Respuesta a Droga , Resistencia a Antineoplásicos/efectos de los fármacos , Activación Enzimática , Femenino , Proteínas HSP70 de Choque Térmico/metabolismo , Humanos , Masculino , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Persona de Mediana Edad , Necrosis , Proteolisis , Especies Reactivas de Oxígeno/metabolismo , Transducción de Señal/efectos de los fármacos , Células Tumorales Cultivadas , Ubiquitinación , Neoplasias de la Vejiga Urinaria/enzimología , Neoplasias de la Vejiga Urinaria/genética , Neoplasias de la Vejiga Urinaria/patologíaRESUMEN
Urothelial carcinoma (UC) is characterized by therapeutic resistance and frequent tumor relapse. It has been suggested that UC are driven by a rare subset of cancer stem cells (CSCs). In order to understand UC recurrence post therapy, we investigated the behavior of urothelial CSCs after exposure to commonly used chemotherapeutic agents, gemcitabine (GC) and mitomycin (MM). Although, the role of autophagy in CSC maintenance is well documented, the relationship of autophagy and CSCs with respect to drug resistance remains elusive. In the present study, we found that both GC and MM increased the percentage of CSCs in primary cultured urothelial carcinoma cells (UCC). These CSCs exhibited higher autophagy flux and higher expression of glycolytic genes. Inhibition of autophagy led to decrease in the expression of glycolysis genes. Inhibition of autophagy and glycolysis caused decrease in expression of stemness genes (Oct-4, Nanog), drug resistance genes (ABCG2, MDR1) and sensitized CSCs to GC and MM induced apoptosis. This finding suggests that autophagy and glycolysis may play a central role in drug resistance. Altogether, we conclude that autophagy may support cell survival by buffering bioenergetic demands for maintenance of high glycolytic flux in CSCs. Therefore, autophagy-based, "customized" combinatorial approaches may provide a new method to counter CSC-driven resistance and may prevent relapse in UC. The synergistic cytotoxic effect of GC/ MM with autophagy inhibitor (chloroquine) or with glycolytic inhibitor (2-deoxyglucose) may be of help in improving the outcome in patients with urothelial carcinoma of urinary bladder.
Asunto(s)
Autofagia/efectos de los fármacos , Desoxicitidina/análogos & derivados , Mitomicina/farmacología , Células Madre Neoplásicas/efectos de los fármacos , Adulto , Anciano , Antineoplásicos/farmacología , Autofagia/genética , Proteína 7 Relacionada con la Autofagia , Western Blotting , Carcinoma de Células Transicionales/genética , Carcinoma de Células Transicionales/metabolismo , Carcinoma de Células Transicionales/patología , Desoxicitidina/farmacología , Resistencia a Antineoplásicos/genética , Femenino , Citometría de Flujo , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Glucólisis/efectos de los fármacos , Glucólisis/genética , Humanos , Masculino , Persona de Mediana Edad , Células Madre Neoplásicas/metabolismo , Interferencia de ARN , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Células Tumorales Cultivadas , Enzimas Activadoras de Ubiquitina/genética , Enzimas Activadoras de Ubiquitina/metabolismo , Neoplasias de la Vejiga Urinaria/genética , Neoplasias de la Vejiga Urinaria/metabolismo , Neoplasias de la Vejiga Urinaria/patología , Adulto Joven , GemcitabinaRESUMEN
In the last decade, it has been well established that programmed cell death (PCD) is not confined to apoptosis (type-I PCD) but cells may use different mechanisms of active self-destruction. One such mechanism is autophagy also called as type-II PCD, which is characterized by different morphological and biochemical features. It is not surprising that the demise of a cell either by PCD-I or by PCD-II is a well-controlled and complex process. The functional role of autophagy is not confined to the cell death through PCD-II, but interestingly it can also lead to cell death through apoptosis by enhancing the caspase activation. Autophagy may also act as a cell survival process by acting as a stress response, delaying caspase activation, and removing damaged organelles. Therefore, the crosstalk between apoptosis and autophagy is quite complex and sometimes contradictory as well, but unquestionably it is decisive to the overall fate of the cell. The molecular regulators of both pathways are inter-connected, and both share some factors that are critical for their respective execution. B-cell lymphoma-2, which was well known as an anti-apoptotic protein is now also considered as an anti-autophagic. Beyond the simplistic view of caspases in apoptosis, recent studies have uncovered unexpected functions of caspases in the regulation of autophagy, indicative of the novel frontiers lying ahead in the science of autophagy.
Asunto(s)
Apoptosis/genética , Autofagia/genética , Caspasas/genética , Neoplasias/genética , Caspasas/metabolismo , Supervivencia Celular , Humanos , Neoplasias/patología , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Transducción de SeñalRESUMEN
Cancer cells require an uninterrupted nutritional supply for maintaining their proliferative needs and this high demand in concurrence with inadequate supply of blood and nutrition induces stress in these cells. These cells utilize various strategies like high glycolytic flux, redox signaling, and modulation of autophagy to avoid cell death and overcome nutritional deficiency. Autophagy allows the cell to generate ATP and other essential biochemical building blocks necessary under such adverse conditions. It is emerging as a decisive process in the development and progression of pathophysiological conditions that are associated with increased cancer risk. However, the precise role of autophagy in tumorigenesis is still debatable. Autophagy is a novel cytoprotective process to augment tumor cell survival under nutrient or growth factor starvation, metabolic stress, and hypoxia. The tumor hypoxic environment may provide site for the enrichment/expansion of the cancer stem cells (CSCs) and successive rapid tumor progression. CSCs are characteristically resistant to conventional anticancer therapy, which may contribute to treatment failure and tumor relapse. CSCs have the potential to regenerate for an indefinite period, which can impel tumor metastatic invasion. From last decade, preclinical research has focused on the diversity in CSC content within tumors that could affect their chemo- or radio-sensitivity by impeding with mechanisms of DNA repair and cell cycle progression. The aim of this review is predominantly directed on the recent developments in the CSCs during cancer treatment, role of autophagy in maintenance of CSC populations and their implications in the development of promising new cancer treatment options in future.