RESUMEN
Telomerase activation is a crucial step in melanomagenesis, often occurring because of ultraviolet radiation (UVR)-induced mutations at the telomerase gene (TERT) promoter and rendering TERT transcription in response to the activated Raf-MAP kinase pathway by BRAFV600E mutation. Due to the excessively long telomeres in mice, this process does not occur during melanomagenesis in mouse models. To investigate the impact of telomere dysfunction on melanomagenesis, BrafV600E was induced in generations 1 and 4 (G1 and G4) of Tert-/- mice. Our findings revealed that, regardless of UVR exposure, melanoma development was delayed in G4 mice, which had shorter telomeres compared to G1 and wild-type C57BL/6J (G0) mice. Moreover, many G4 tumors displayed an accumulation of excessive DNA damage, as evidenced by increased γH2A.X staining. Tumors from UVR-exposed mice exhibited elevated p53 protein expression. Cultured tumor cells isolated from G4 mice displayed abundant chromosomal fusions and rearrangements, indicative of telomere dysfunction in these cells. Additionally, tumor cells derived from UVB-exposed mice exhibited constitutively elevated expression of mutant p53 proteins, suggesting that p53 was a target of UVB-induced mutagenesis. Taken together, our findings suggest that telomere dysfunction hampers melanomagenesis, and targeting telomere crisis-mediated genomic instability may hold promise for the prevention and treatment of melanoma.
Asunto(s)
Melanoma , Proteínas Proto-Oncogénicas B-raf , Telomerasa , Animales , Ratones , Melanoma/genética , Melanoma/metabolismo , Ratones Endogámicos C57BL , Ratones Noqueados , Mutación , Proteínas Proto-Oncogénicas B-raf/genética , Proteínas Proto-Oncogénicas B-raf/metabolismo , Telomerasa/genética , Telomerasa/metabolismo , Telómero/metabolismo , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismo , Rayos Ultravioleta/efectos adversosRESUMEN
Current cancer therapy can be effective, but the development of drug resistant disease is the usual outcome. These drugs can eliminate most of the tumor burden but often fail to eliminate the rare, "Drug Tolerant Persister" (DTP) cell subpopulations in residual tumors, which can be referred to as "Persister" cells. Therefore, novel therapeutic agents specifically targeting or preventing the development of drug-resistant tumors mediated by the remaining persister cells subpopulations are needed. Since approximately ninety percent of cancer-related deaths occur because of the eventual development of drug resistance, identifying, and dissecting the biology of the persister cells is essential for the creation of drugs to target them. While there remains uncertainty surrounding all the markers identifying DTP cells in the literature, this review summarizes the drugs and therapeutic approaches that are available to target the persister cell subpopulations expressing the cellular markers ATP-binding cassette sub-family B member 5 (ABCB5), CD133, CD271, Lysine-specific histone demethylase 5 (KDM5), and aldehyde dehydrogenase (ALDH). Persister cells expressing these markers were selected as the focus of this review because they have been found on cells surviving following drug treatments that promote recurrent drug resistant cancer and are associated with stem cell-like properties, including self-renewal, differentiation, and resistance to therapy. The limitations and obstacles facing the development of agents targeting these DTP cell subpopulations are detailed, with discussion of potential solutions and current research areas needing further exploration.
Asunto(s)
Antineoplásicos , Resistencia a Antineoplásicos , Neoplasias , Humanos , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Neoplasias/patología , Animales , Resistencia a Antineoplásicos/efectos de los fármacos , Antineoplásicos/farmacología , Antineoplásicos/uso terapéutico , Células Madre Neoplásicas/efectos de los fármacos , Células Madre Neoplásicas/metabolismo , Tolerancia a Medicamentos , Biomarcadores de Tumor/metabolismo , Biomarcadores de Tumor/genéticaRESUMEN
Multiple independent sequence variants of the hTERT locus have been associated with telomere length and cancer risks in genome-wide association studies. Here, we identified an intronic variable number tandem repeat, VNTR2-1, as an enhancer-like element, which activated hTERT transcription in a cell in a chromatin-dependent manner. VNTR2-1, consisting of 42-bp repeats with an array of enhancer boxes, cooperated with the proximal promoter in the regulation of hTERT transcription by basic helix-loop-helix transcription factors and maintained hTERT expression during embryonic stem-cell differentiation. Genomic deletion of VNTR2-1 in MelJuSo melanoma cells markedly reduced hTERT transcription, leading to telomere shortening, cellular senescence, and impairment of xenograft tumor growth. Interestingly, VNTR2-1 lengths varied widely in human populations; hTERT alleles with shorter VNTR2-1 were underrepresented in African American centenarians, indicating its role in human aging. Therefore, this polymorphic element is likely a missing link in the telomerase regulatory network and a molecular basis for genetic diversities of telomere homeostasis and age-related disease susceptibilities.
Asunto(s)
Repeticiones de Minisatélite/genética , Polimorfismo Genético , Telomerasa/genética , Activación Transcripcional , Negro o Afroamericano/genética , Anciano de 80 o más Años , Animales , Secuencia de Bases , Diferenciación Celular/genética , Línea Celular , Proliferación Celular/genética , Cromosomas Artificiales Bacterianos/genética , Elementos E-Box/genética , Genoma Humano , Células Madre Embrionarias Humanas/metabolismo , Humanos , Ratones Desnudos , Neoplasias/genética , Neoplasias/patología , Regiones Promotoras Genéticas , Unión Proteica/genética , Eliminación de Secuencia/genética , Homeostasis del Telómero/genéticaRESUMEN
Aldehyde dehydrogenases (ALDHs) are a family of enzymes that aid in detoxification and are overexpressed in several different malignancies. There is a correlation between increased expression of ALDH and a poor prognosis, stemness, and resistance to several drugs. Several ALDH inhibitors have been generated due to the crucial role that ALDH plays in cancer stem cells. All of these inhibitors, however, are either ineffective, very toxic, or have yet to be subjected to rigorous testing on their effectiveness. Although various drug-like compounds targeting ALDH have been reported in the literature, none have made it to routine use in the oncology clinic. As a result, new potent, non-toxic, bioavailable, and therapeutically effective ALDH inhibitors are still needed. In this study, we designed and synthesized potent multi-ALDH isoform inhibitors based on the isatin and indazole pharmacophore. Molecular docking studies and enzymatic tests revealed that among all of the synthesized analogs, compound 3 is the most potent inhibitor of ALDH1A1, ALDH3A1, and ALDH1A3, exhibiting 51.32%, 51.87%, and 36.65% inhibition, respectively. The ALDEFLUOR assay further revealed that compound 3 acts as an ALDH broad spectrum inhibitor at 500 nM. Compound 3 was also the most cytotoxic to cancer cells, with an IC50 in the range of 2.1 to 3.8 µM for ovarian, colon, and pancreatic cancer cells, compared to normal and embryonic kidney cells (IC50 7.1 to 8.7 µM). Mechanistically, compound 3 increased ROS activity due to potent multi-ALDH isoform inhibition, which increased apoptosis. Taken together, this study identified a potent multi-isoform ALDH inhibitor that could be further developed as a cancer therapeutic.
Asunto(s)
Aldehído Deshidrogenasa , Inhibidores Enzimáticos , Isatina , Simulación del Acoplamiento Molecular , Humanos , Isatina/química , Isatina/farmacología , Aldehído Deshidrogenasa/antagonistas & inhibidores , Aldehído Deshidrogenasa/metabolismo , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , Inhibidores Enzimáticos/síntesis química , Línea Celular Tumoral , Antineoplásicos/farmacología , Antineoplásicos/química , Antineoplásicos/síntesis química , Relación Estructura-Actividad , Isoenzimas/antagonistas & inhibidores , Isoenzimas/metabolismo , Estructura MolecularRESUMEN
High-risk B-cell acute lymphoblastic leukemia (B-ALL) is an aggressive disease, often characterized by resistance to chemotherapy. A frequent feature of high-risk B-ALL is loss of function of the IKAROS (encoded by the IKZF1 gene) tumor suppressor. Here, we report that IKAROS regulates expression of the BCL2L1 gene (encodes the BCL-XL protein) in human B-ALL. Gain-of-function and loss-of-function experiments demonstrate that IKAROS binds to the BCL2L1 promoter, recruits histone deacetylase HDAC1, and represses BCL2L1 expression via chromatin remodeling. In leukemia, IKAROS' function is impaired by oncogenic casein kinase II (CK2), which is overexpressed in B-ALL. Phosphorylation by CK2 reduces IKAROS binding and recruitment of HDAC1 to the BCL2L1 promoter. This results in a loss of IKAROS-mediated repression of BCL2L1 and increased expression of BCL-XL. Increased expression of BCL-XL and/or CK2, as well as reduced IKAROS expression, are associated with resistance to doxorubicin treatment. Molecular and pharmacological inhibition of CK2 with a specific inhibitor CX-4945, increases binding of IKAROS to the BCL2L1 promoter and enhances IKAROS-mediated repression of BCL2L1 in B-ALL. Treatment with CX-4945 increases sensitivity to doxorubicin in B-ALL, and reverses resistance to doxorubicin in multidrug-resistant B-ALL. Combination treatment with CX-4945 and doxorubicin show synergistic therapeutic effects in vitro and in preclinical models of high-risk B-ALL. Results reveal a novel signaling network that regulates chemoresistance in leukemia. These data lay the groundwork for clinical testing of a rationally designed, targeted therapy that combines the CK2 inhibitor, CX-4945, with doxorubicin for the treatment of hematopoietic malignancies.
Asunto(s)
Quinasa de la Caseína II/genética , Resistencia a Antineoplásicos , Regulación Leucémica de la Expresión Génica , Factor de Transcripción Ikaros/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Proteína bcl-X/genética , Animales , Antibióticos Antineoplásicos/farmacología , Antibióticos Antineoplásicos/uso terapéutico , Línea Celular Tumoral , Doxorrubicina/farmacología , Doxorrubicina/uso terapéutico , Regulación Leucémica de la Expresión Génica/efectos de los fármacos , Humanos , Ratones , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamiento farmacológicoRESUMEN
Decreasing the levels of certain proteins has been shown to be important for controlling cancer but it is currently unknown whether proteins could potentially be targeted by the inhibiting of protein synthesis. Under this circumstance, targeting protein translation could preferentially affect certain pathways, which could then be of therapeutic advantage when treating cancer. In this report, eukaryotic elongation factor-2 kinase (EEF2K), which is involved in protein translation, was shown to regulate cholesterol metabolism. Targeting EEF2K inhibited key parts of the cholesterol pathway in cancer cells, which could be rescued by the addition of exogenous cholesterol, suggesting that it is a potentially important pathway modulated by targeting this process. Specifically, targeting EEF2K significantly suppressed tumour cell growth by blocking mRNA translation of the cholesterol biosynthesis transcription factor, sterol regulatory element-binding protein (SREBP) 2, and the proteins it regulates. The process could be rescued by the addition of LDL cholesterol taken into the cells via non-receptor-mediated-uptake, which negated the need for SREBP2 protein. Thus, the levels of SREBP2 needed for cholesterol metabolism in cancer cells are therapeutically vulnerable by targeting protein translation. This is the first report to suggest that targeting EEF2K can be used to modulate cholesterol metabolism to treat cancer.
Asunto(s)
Quinasa del Factor 2 de Elongación , Melanoma , Colesterol/metabolismo , Quinasa del Factor 2 de Elongación/genética , Quinasa del Factor 2 de Elongación/metabolismo , Humanos , Biosíntesis de Proteínas , Proteína 2 de Unión a Elementos Reguladores de Esteroles/genética , Proteína 2 de Unión a Elementos Reguladores de Esteroles/metabolismoRESUMEN
The role of aldehyde dehydrogenase (ALDH) in carcinogenesis and resistance to cancer therapies is well known. Mounting evidence also suggests a potentially important role for ALDH in the induction and function of regulatory T (Treg) cells. Treg cells are important cells of the immune system involved in promoting immune tolerance and preventing aberrant immune responses to beneficial or non-harmful antigens. However, Treg cells also impair tumor immunity, leading to the progression of various carcinomas. ALDH expression and the subsequent production of retinoic acid by numerous cells, including dendritic cells, macrophages, eosinophils and epithelial cells, seems important in Treg induction and function in multiple organ systems. This is particularly evident in the gastrointestinal tract, pulmonary tract and skin, which are exposed to a myriad of environmental antigens and represent interfaces between the human body and the outside world. Expression of ALDH in Treg cells themselves may also be involved in the proliferation of these cells and resistance to certain cytotoxic therapies. Hence, inhibition of ALDH expression may be useful to treat cancer. Besides the direct effect of ALDH inhibition on carcinogenesis and resistance to cancer therapies, inhibition of ALDH could potentially augment the immune response to tumor antigens by inhibiting Treg induction, function and ability to promote immune tolerance to tumor cells in multiple cancer types.
Asunto(s)
Aldehído Deshidrogenasa/metabolismo , Neoplasias/inmunología , Linfocitos T Reguladores/fisiología , Aldehído Deshidrogenasa/genética , Animales , Diferenciación Celular , Proliferación Celular , Humanos , Tolerancia Inmunológica , Inmunidad Celular , Microambiente TumoralRESUMEN
Drug combinations acting synergistically to kill cancer cells have become increasingly important in melanoma as an approach to manage the recurrent resistant disease. Protein kinase B (AKT) is a major target in this disease but its inhibitors are not effective clinically, which is a major concern. Targeting AKT in combination with WEE1 (mitotic inhibitor kinase) seems to have potential to make AKT-based therapeutics effective clinically. Since agents targeting AKT and WEE1 have been tested individually in the clinic, the quickest way to move the drug combination to patients would be to combine these agents sequentially, enabling the use of existing phase I clinical trial toxicity data. Therefore, a rapid preclinical approach is needed to evaluate whether simultaneous or sequential drug treatment has maximal therapeutic efficacy, which is based on a mechanistic rationale. To develop this approach, melanoma cell lines were treated with AKT inhibitor AZD5363 [4-amino-N-[(1S)-1-(4-chlorophenyl)-3-hydroxypropyl]-1-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)piperidine-4-carboxamide] and WEE1 inhibitor AZD1775 [2-allyl-1-(6-(2-hydroxypropan-2-yl)pyridin-2-yl)-6-((4-(4-methylpiperazin-1-yl)phenyl)amino)-1H-pyrazolo[3,4-d]pyrimidin-3(2H)-one] using simultaneous and sequential dosing schedules. Simultaneous treatment synergistically reduced melanoma cell survival and tumor growth. In contrast, sequential treatment was antagonistic and had a minimal tumor inhibitory effect compared with individual agents. Mechanistically, simultaneous targeting of AKT and WEE1 enhanced deregulation of the cell cycle and DNA damage repair pathways by modulating transcription factors p53 and forkhead box M1, which was not observed with sequential treatment. Thus, this study identifies a rapid approach to assess the drug combinations with a mechanistic basis for selection, which suggests that combining AKT and WEE1 inhibitors is needed for maximal efficacy.
Asunto(s)
Proteína Forkhead Box M1/metabolismo , Mieloma Múltiple/tratamiento farmacológico , Pirazoles/administración & dosificación , Pirimidinas/administración & dosificación , Pirroles/administración & dosificación , Proteína p53 Supresora de Tumor/metabolismo , Animales , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Esquema de Medicación , Antagonismo de Drogas , Ensayos de Selección de Medicamentos Antitumorales , Sinergismo Farmacológico , Quimioterapia Combinada , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Ratones , Mieloma Múltiple/metabolismo , Pirazoles/farmacología , Pirimidinas/farmacología , Pirimidinonas , Pirroles/farmacología , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Drug resistance and toxicity are major limitations of cancer treatment and frequently occurs during melanoma therapy. Nanotechnology can decrease drug resistance by improving drug delivery, with limited toxicity. This study details the development of nanoparticles containing arachidonyl trifluoromethyl ketone (ATK), a cytosolic phospholipase A2 inhibitor, which can inhibit multiple key pathways responsible for the development of recurrent resistant disease. Free ATK is toxic, limiting its efficacy as a therapeutic agent. Hence, a novel nanoliposomal delivery system called NanoATK was developed, which loads 61.7% of the compound and was stable at 4oC for 12 weeks. The formulation decreased toxicity-enabling administration of higher doses, which was more effective at inhibiting melanoma cell growth compared to free-ATK. Mechanistically, NanoATK decreased cellular proliferation and triggered apoptosis to inhibit melanoma xenograft tumor growth without affecting animal weight. Functionally, it inhibited the cPLA2, AKT, and STAT3 pathways. Our results suggest the successful preclinical development of a unique nanoliposomal formulation containing ATK for the treatment of melanoma.
Asunto(s)
Ácidos Araquidónicos/farmacología , Sistemas de Liberación de Medicamentos , Liposomas/administración & dosificación , Melanoma/tratamiento farmacológico , Nanopartículas/administración & dosificación , Inhibidores de Fosfolipasa A2/farmacología , Fosfolipasas A2 Citosólicas/antagonistas & inhibidores , Animales , Ácidos Araquidónicos/administración & dosificación , Proliferación Celular/efectos de los fármacos , Femenino , Humanos , Liposomas/química , Melanoma/enzimología , Melanoma/patología , Ratones , Ratones Desnudos , Nanopartículas/química , Inhibidores de Fosfolipasa A2/administración & dosificación , Células Tumorales CultivadasRESUMEN
BACKGROUND: Demand for cholesterol is high in certain cancers making them potentially sensitive to therapeutic strategies targeting cellular cholesterol homoeostasis. A potential approach involves disruption of intracellular cholesterol transport, which occurs in Niemann-Pick disease as a result of acid sphingomyelinase (ASM) deficiency. Hence, a class of lysosomotropic compounds that were identified as functional ASM inhibitors (FIASMAs) might exhibit chemotherapeutic activity by disrupting cancer cell cholesterol homoeostasis. METHODS: Here, the chemotherapeutic utility of ASM inhibition was investigated. The effect of FIASMAs on intracellular cholesterol levels, cholesterol homoeostasis, cellular endocytosis and signalling cascades were investigated. The in vivo efficacy of ASM inhibition was demonstrated using melanoma xenografts and a nanoparticle formulation was developed to overcome dose-limiting CNS-associated side effects of certain FIASMAs. RESULTS: Functional ASM inhibitors inhibited intracellular cholesterol transport leading to disruption of autophagic flux, cellular endocytosis and receptor tyrosine kinase signalling. Consequently, major oncogenic signalling cascades on which cancer cells were reliant for survival were inhibited. Two tested ASM inhibitors, perphenazine and fluphenazine that are also clinically used as antipsychotics, were effective in inhibiting xenografted tumour growth. Nanoliposomal encapsulation of the perphenazine enhanced its chemotherapeutic efficacy while decreasing CNS-associated side effects. CONCLUSIONS: This study suggests that disruption of intracellular cholesterol transport by targeting ASM could be utilised as a potential chemotherapeutic approach for treating cancer.
Asunto(s)
Antidepresivos Tricíclicos/farmacología , Antipsicóticos/farmacología , Colesterol/metabolismo , Melanoma/tratamiento farmacológico , Melanoma/metabolismo , Perfenazina/administración & dosificación , Administración Intravenosa , Administración Oral , Animales , Antidepresivos Tricíclicos/uso terapéutico , Antipsicóticos/administración & dosificación , Autofagia/efectos de los fármacos , Transporte Biológico/efectos de los fármacos , Transporte Biológico/genética , Supervivencia Celular/efectos de los fármacos , Desipramina/farmacología , Desipramina/uso terapéutico , Endocitosis/efectos de los fármacos , Endosomas/metabolismo , Femenino , Flupentixol/farmacología , Flupentixol/uso terapéutico , Flufenazina/farmacología , Flufenazina/uso terapéutico , Regulación de la Expresión Génica/efectos de los fármacos , Técnicas de Silenciamiento del Gen , Células HCT116 , Homeostasis/efectos de los fármacos , Homeostasis/genética , Humanos , Concentración 50 Inhibidora , Liposomas , Lisosomas/metabolismo , Lisosomas/ultraestructura , Células MCF-7 , Melanoma/genética , Ratones , Nortriptilina/farmacología , Nortriptilina/uso terapéutico , Perfenazina/farmacología , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Factor de Transcripción STAT3/metabolismo , Transducción de Señal/efectos de los fármacos , Esfingomielina Fosfodiesterasa/genética , Proteína X Asociada a bcl-2/metabolismoRESUMEN
Ikaros (IKZF1) is a tumor suppressor that binds DNA and regulates expression of its target genes. The mechanism of Ikaros activity as a tumor suppressor and the regulation of Ikaros function in leukemia are unknown. Here, we demonstrate that Ikaros controls cellular proliferation by repressing expression of genes that promote cell cycle progression and the phosphatidylinositol-3 kinase (PI3K) pathway. We show that Ikaros function is impaired by the pro-oncogenic casein kinase II (CK2), and that CK2 is overexpressed in leukemia. CK2 inhibition restores Ikaros function as transcriptional repressor of cell cycle and PI3K pathway genes, resulting in an antileukemia effect. In high-risk leukemia where one IKZF1 allele has been deleted, CK2 inhibition restores the transcriptional repressor function of the remaining wild-type IKZF1 allele. CK2 inhibition demonstrated a potent therapeutic effect in a panel of patient-derived primary high-risk B-cell acute lymphoblastic leukemia xenografts as indicated by prolonged survival and a reduction of leukemia burden. We demonstrate the efficacy of a novel therapeutic approach for high-risk leukemia: restoration of Ikaros tumor suppressor activity via inhibition of CK2. These results provide a rationale for the use of CK2 inhibitors in clinical trials for high-risk leukemia, including cases with deletion of one IKZF1 allele.
Asunto(s)
Quinasa de la Caseína II/antagonistas & inhibidores , Genes Supresores de Tumor , Factor de Transcripción Ikaros/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras B/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras B/patología , Animales , Apoptosis/efectos de los fármacos , Quinasa de la Caseína II/genética , Quinasa de la Caseína II/metabolismo , Proliferación Celular/efectos de los fármacos , Inmunoprecipitación de Cromatina , Inhibidores Enzimáticos/farmacología , Femenino , Humanos , Factor de Transcripción Ikaros/genética , Ratones , Ratones Endogámicos NOD , Fosfatidilinositol 3-Quinasas , Leucemia-Linfoma Linfoblástico de Células Precursoras B/tratamiento farmacológico , ARN Mensajero/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transducción de Señal/efectos de los fármacos , Células Tumorales Cultivadas , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Weak bases that readily penetrate through the lipid bilayer and accumulate inside the acidic organelles are known as lysosomotropic molecules. Many lysosomotropic compounds exhibit therapeutic activity and are commonly used as antidepressant, antipsychotic, antihistamine, or antimalarial agents. Interestingly, studies also have shown increased sensitivity of cancer cells to certain lysosomotropic agents and suggested their mechanism of action as a promising approach for selective destruction of cancer cells. However, their chemotherapeutic utility may be limited due to various side effects. Hence, understanding the homeostatic alterations mediated by lysosomotropic compounds has significant importance for revealing their true therapeutic potential as well as toxicity. In this review, after briefly introducing the concept of lysosomotropism and classifying the lysosomotropic compounds into two major groups according to their cytotoxicity on cancer cells, we focused on the subcellular alterations mediated by class-II lysosomotropic compounds. Briefly, their effect on intracellular cholesterol homeostasis, autophagy and lysosomal sphingolipid metabolism was discussed. Accordingly, class-II lysosomotropic molecules inhibit intracellular cholesterol transport, leading to the accumulation of cholesterol inside the late endosomal-lysosomal cell compartments. However, the accumulated lysosomal cholesterol is invisible to the cellular homeostatic circuits, hence class-II lysosomotropic molecules also upregulate cholesterol synthesis pathway as a downstream event. Considering the fact that Niemann-Pick disease, a lysosomal cholesterol storage disorder, also triggers similar pathologic abnormalities, this review combines the knowledge obtained from the Niemann-Pick studies and lysosomotropic compounds. Taken together, this review is aimed at allowing readers a better understanding of subcellular alterations mediated by lysosomotropic drugs, as well as their potential therapeutic and/or toxic activities.
Asunto(s)
Homeostasis/efectos de los fármacos , Lisosomas/efectos de los fármacos , Preparaciones Farmacéuticas/administración & dosificación , Animales , Colesterol/metabolismo , Humanos , Lisosomas/metabolismo , Neoplasias/metabolismoRESUMEN
Malaria caused by the Plasmodium parasites continues to be an enormous global health problem owing to wide spread drug resistance of parasites to many of the available antimalarial drugs. Therefore, development of new classes of antimalarial agents is essential to effectively treat malaria. In this study, the efficacy of naturally occurring diterpenoids, dehydroabietylamine and abietic acid, and their synthetic derivatives was assessed for antimalarial activity. Dehydroabietylamine and its N-trifluoroacetyl, N-tribromoacetyl, N-benzoyl, and N-benzyl derivatives showed excellent activity against P. falciparum parasites with IC50 values of 0.36 to 2.6 µM. Interestingly, N-dehydroabietylbenzamide showed potent antimalarial activity (IC50 0.36), and negligible cytotoxicity (IC50 >100 µM) to mammalian cells; thus, this compound can be an important antimalarial drug. In contrast, abietic acid was only marginally effective, exhibiting an IC50 value of ~82 µM. Several carboxylic group-derivatives of abietic acid were moderately active with IC50 values of ~8.2 to ~13.3 µM. These results suggest that a detailed understanding of the structure-activity relationship of abietane diterpenoids might provide strategies to exploit this class of compounds for malaria treatment.
Asunto(s)
Abietanos/farmacología , Antimaláricos/farmacología , Plasmodium falciparum/efectos de los fármacos , Abietanos/química , Benzamidas , Benzotiazoles , Línea Celular , Línea Celular Tumoral , Diaminas , Relación Dosis-Respuesta a Droga , Eritrocitos/parasitología , Fibroblastos/efectos de los fármacos , Colorantes Fluorescentes , Humanos , Concentración 50 Inhibidora , Compuestos Orgánicos , Plasmodium falciparum/crecimiento & desarrollo , Quinolinas , Relación Estructura-ActividadRESUMEN
The UDP-glucuronosyltransferase (UGT) 1A enzymes are involved in the phase II metabolism of many important endogenous and exogenous compounds. The nine UGT1A isoforms exhibit high interindividual differences in expression, but their epigenetic regulation is not well understood. The purpose of the present study was to examine microRNA (miRNA) regulation of hepatic UGT1A enzymes and determine whether or not that regulation impacts enzymatic activity. In silico analysis identified miRNA 491-3p (miR-491-3p) as a potential regulator of the UGT1A gene family via binding to the shared UGT1A 3'-untranslated region common to all UGT1A enzymes. Transfection of miR-491-3p mimic into HuH-7 cells significantly repressed UGT1A1 (P < 0.001), UGT1A3 (P < 0.05), and UGT1A6 (P < 0.05) mRNA levels. For UGT1A1, this repression correlated with significantly reduced metabolism of raloxifene into raloxifene-6-glucuronide (ral-6-gluc; P < 0.01) and raloxifene-4'-glucuronide (ral-4'-gluc; P < 0.01). In HuH-7 cells with repressed miR-491-3p expression, there was a significant increase (~80%; P < 0.01) in UGT1A1 mRNA and a corresponding increase in glucuronidation of raloxifene into ral-6-gluc (50%; P < 0.05) and ral-4'-gluc (22%; P < 0.01). Knockdown of endogenous miR-491-3p in HepG2 cells did not significantly alter UGT1A1 mRNA levels but did increase the formation of ral-6-gluc (50%; P < 0.05) and ral-4'-gluc (34%; P < 0.001). A significant inverse correlation between miR-491-3p expression and both UGT1A3 (P < 0.05) and UGT1A6 (P < 0.01) mRNA levels was observed in a panel of normal human liver specimens, with a significant (P < 0.05) increase in UGT1A3 and UGT1A6 mRNA levels observed in miR-491-3p nonexpressing versus expressing liver specimens. These results suggest that miR-491-3p is an important factor in regulating the expression of UGT1A enzymes in vivo.
Asunto(s)
Glucuronosiltransferasa/metabolismo , Hígado/enzimología , MicroARNs/metabolismo , Línea Celular Tumoral , Simulación por Computador , Epirrubicina/metabolismo , Glucurónidos/metabolismo , Glucuronosiltransferasa/química , Glucuronosiltransferasa/genética , Células HEK293 , Humanos , Luciferasas de Renilla/genética , Luciferasas de Renilla/metabolismo , MicroARNs/química , Especificidad de Órganos , Unión Proteica , ARN Mensajero/química , Clorhidrato de Raloxifeno/metabolismoRESUMEN
BRAF is the most mutated gene in melanoma, with approximately 50% of patients containing V600E mutant protein. (V600E)B-RAF can be targeted using pharmacological agents, but resistance develops in patients by activating other proteins in the signaling pathway. Identifying downstream members in this signaling cascade is important to design strategies to avoid the development of resistance. Unfortunately, downstream proteins remain to be identified and therapeutic potential requires validation. A kinase screen was undertaken to identify downstream targets in the (V600E)B-RAF signaling cascade. Involvement of aurora kinase B (AURKB) and Wee1-like protein kinase (WEE1) as downstream proteins in the (V600E)B-RAF pathway was validated in xenografted tumors, and mechanisms of action were characterized in size- and time-matched tumors. Levels of only AURKB and WEE1 decreased in melanoma cells, when (V600E)B-RAF, mitogen-activated protein kinase 1/2, or extracellular signal-regulated kinase 1/2 protein levels were reduced using siRNA compared with other identified kinases. AURKB and WEE1 were expressed in tumors of patients with melanoma at higher levels than observed in normal human melanocytes. Targeting these proteins reduced tumor development by approximately 70%, similar to that observed when inhibiting (V600E)B-RAF. Furthermore, protein or activity levels of AURKB and WEE1 decreased in melanoma cells when pharmacological agents targeting upstream (V600E)B-RAF or mitogen-activated protein kinase were used to inhibit the (V600E)B-RAF pathway. Thus, AURKB and WEE1 are targets and biomarkers of therapeutic efficacy, lying downstream of (V600E)B-RAF in melanomas.
Asunto(s)
Sustitución de Aminoácidos/genética , Proteínas de Ciclo Celular/metabolismo , Melanoma/enzimología , Melanoma/patología , Proteínas Nucleares/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Tirosina Quinasas/metabolismo , Proteínas Proto-Oncogénicas B-raf/genética , Animales , Antineoplásicos/farmacología , Antineoplásicos/uso terapéutico , Apoptosis/efectos de los fármacos , Aurora Quinasa B , Aurora Quinasas , Biomarcadores de Tumor/metabolismo , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Transformación Celular Neoplásica/metabolismo , Transformación Celular Neoplásica/patología , Citometría de Flujo , Fase G2/efectos de los fármacos , Glucógeno Sintasa Quinasa 3/metabolismo , Humanos , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Melanoma/tratamiento farmacológico , Ratones , Ratones Desnudos , Mitosis/efectos de los fármacos , Terapia Molecular Dirigida , Estadificación de Neoplasias , ARN Interferente Pequeño/metabolismo , Transducción de Señal/efectos de los fármacosRESUMEN
CD47 is a "self marker" that is usually overexpressed on the surface of cancer cells to enable them to escape immunosurveillance. Recognition of CD47 by its receptor, signal regulatory protein α (SIRPα), which is expressed in the macrophages, inhibits phagocytic destruction of cancer cells by the macrophages. In this study, we have first shown that clinical isolates of human melanoma significantly upregulate CD47, possibly as a mechanism to defend themselves against the macrophages. We then exploited RNA interference (RNAi) technology to test the hypothesis that knocking down CD47 in the tumor cells will render them targets for macrophage destruction; hence, creating a novel anti-cancer therapy. Anti-CD47 siRNA was encapsulated in a liposome-protamine-hyaluronic acid (LPH) nanoparticle (NP) formulation to address the challenge of targeted delivery of siRNA-based therapeutics in vivo. Efficient silencing of CD47 in tumor tissues with systemic administration of LPH(CD47) also significantly inhibited the growth of melanoma tumors. In a lung metastasis model, LPH(CD47) efficiently inhibited lung metastasis to about 27% of the untreated control. Moreover, no hematopoietic toxicity was observed in the animals that received multiple doses of LPH(CD47). Our findings indicate CD47 as a potential prognostic marker for melanoma development as well as a target for therapeutic intervention with RNAi-based nanomedicines.
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Neoplasias Pulmonares/secundario , Melanoma Experimental/patología , Melanoma/tratamiento farmacológico , ARN Interferente Pequeño/administración & dosificación , Animales , Biomarcadores de Tumor , Antígeno CD47/genética , Línea Celular Tumoral , Células Cultivadas , Femenino , Técnicas de Silenciamiento del Gen , Humanos , Inyecciones Intravenosas , Liposomas/administración & dosificación , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/patología , Macrófagos/inmunología , Melanoma/patología , Melanoma/secundario , Melanoma Experimental/tratamiento farmacológico , Melanoma Experimental/inmunología , Melanoma Experimental/secundario , Ratones Endogámicos C57BL , Nanopartículas/administración & dosificación , Fagocitosis , Pronóstico , Interferencia de ARN , ARN Interferente Pequeño/uso terapéutico , ARN Interferente Pequeño/toxicidadRESUMEN
Telomeres undergo shortening with each cell division, serving as biomarkers of human aging, which is characterized by short telomeres and restricted telomerase expression in adult tissues. Contrarily, mice, featuring their longer telomeres and widespread telomerase activity, present limitations as models for understanding telomere-related human biology and diseases. To bridge this gap, we engineered a mouse strain with a humanized mTert gene, hmTert, wherein specific non-coding sequences were replaced with their human counterparts. The hmTert gene, encoding the wildtype mTert protein, was repressed in adult tissues beyond the gonads and thymus, closely resembling the regulatory pattern of the human TERT gene. Remarkably, the hmTert gene rescued telomere dysfunction in late generations of mTert-knockout mice. Through successive intercrosses of Terth/- mice, telomere length progressively declined, stabilizing below 10-kb. Terth/h mice achieved a human-like average telomere length of 10-12 kb, contrasting with the 50-kb length in wildtype C57BL/6J mice. Despite shortened telomeres, Terth/h mice maintained normal body weight and cell homeostasis in highly proliferative tissues. Notably, colonocyte proliferation decreased significantly in Terth/h mice during dextran sodium sulfate-induced ulcerative colitis-like pathology, suggesting limitations on cellular renewal due to short telomeres. Our findings underscore the genetic determination of telomere homeostasis in mice by the Tert gene. These mice, exhibiting humanized telomere homeostasis, serve as a valuable model for exploring fundamental questions related to human aging and cancer.
RESUMEN
Fibrin (Fn) deposition defines several type 1 immune responses, including delayed-type hypersensitivity and autoimmunity in which polymorphonuclear leukocytes (PMNs) are involved. Fn monomer and fibrinogen are multivalent ligands for a variety of cell receptors during cell adhesion. These cell receptors provide critical linkage among thrombosis, inflammation, and cancer metastasis under venous flow conditions. However, the mechanisms of Fn-mediated interactions among immune cells and circulating tumor cells remain elusive. By using a cone-plate viscometer shear assay and dual-color flow cytometry, we demonstrated that soluble fibrinogen and Fn had different abilities to enhance heterotypic aggregation between PMNs and Lu1205 melanoma cells in a shear flow, regulated by thrombin levels. In addition, the involvement of integrin α(v)ß(3), ICAM-1, and CD11b/CD18 (Mac-1) in fibrin(ogen)-mediated melanoma-PMN aggregations was explored. Kinetic studies provided evidence that ICAM-1 mediated initial capture of melanoma cells by PMNs, whereas α(v)ß(3) played a role in sustained adhesion of the two cell types at a shear rate of 62.5 s(-1). Quantitative analysis of the melanoma-PMN interactions conducted by a parallel-plate flow chamber assay further revealed that at a shear rate of 20 s(-1), α(v)ß(3) had enough contact time to form bonds with Mac-1 via Fn, which could not otherwise occur at a shear rate higher than 62.5 s(-1). Our studies have captured a novel finding that leukocytes could be recruited to tumor cells via thrombin-mediated Fn formation within a tumor microenvironment, and α(v)ß(3) and ICAM-1 may participate in multistep fibrin(ogen)-mediated melanoma cell adhesion within the circulation.
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Antígeno CD11b/sangre , Antígenos CD18/sangre , Fibrina/fisiología , Integrina alfaVbeta3/metabolismo , Molécula 1 de Adhesión Intercelular/sangre , Melanoma/inmunología , Infiltración Neutrófila/inmunología , Animales , Velocidad del Flujo Sanguíneo/inmunología , Adhesión Celular/inmunología , Comunicación Celular/inmunología , Línea Celular Tumoral , Fibrinógeno/fisiología , Humanos , Mediadores de Inflamación/metabolismo , Mediadores de Inflamación/fisiología , Integrina alfaVbeta3/fisiología , Molécula 1 de Adhesión Intercelular/fisiología , Melanoma/sangre , Melanoma/secundario , Ratones , Trombosis/sangre , Trombosis/inmunología , Trombosis/patologíaRESUMEN
In order to effectively treat melanoma, targeted inhibition of key m-echanistic events regulating melanoma development such as cell proliferation, survival, angiogenesis and invasion or metastasis needs to be accomplished. The Mitogen Activated Protein Kinase (MAPK) pathway has been identified as a key player in melanoma development making this cascade an important therapeutic target. However, identification of the ideal pathway member to therapeutically target for maximal clinical benefit remains a challenge. In normal cells, the MAPK pathway relays extracellular signals from the cell membrane to the nucleus via a cascade of phosphorylation events, which promote cancer development. Dysregulation of the MAPK pathway occurs frequently in many human cancers including melanoma. Mutations in the B-RAF and RAS genes, genetic or epigenetic modifications are the key aberrations observed in this signaling cascade. Constitutive activation of this pathway causes oncogenic transformation of cells by promoting cell proliferation, invasion, metastasis, migration, survival and angiogenesis. This review provides an overview of (a) key members of MAPK signaling regulating melanoma development; (b) key proteins which can serve as biomarkers to assess disease progression; (c) the clinical efficacy of various pharmacological agents targeting MAPK pathway; (d) current clinical trials evaluating downstream targets of the MAPK pathway; (e) issues associated with pharmacological agents such as drug resistance, induction of cancers; and finally (e) various strategies overcoming drug resistance.
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Melanoma/tratamiento farmacológico , Neoplasias Cutáneas/tratamiento farmacológico , Ensayos Clínicos como Asunto , Sistemas de Liberación de Medicamentos , Resistencia a Antineoplásicos , Humanos , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Sistema de Señalización de MAP Quinasas/fisiologíaRESUMEN
One of the current stumbling blocks in our fight against cancer is the development of acquired resistance to therapy, which is attributable to approximately 90% of cancer-related deaths. Undercutting this process during treatment could significantly improve cancer management. In many cases, drug resistance is mediated by a drug-tolerant persister (DTP) cell subpopulation present in tumors, often referred to as persister cells. This review provides a summary of currently known persister cell subpopulations and approaches to target them. A specific DTP cell subpopulation with elevated levels of aldehyde dehydrogenase (ALDH) activity has stem cell-like characteristics and a high level of plasticity, enabling them to switch rapidly between high and low ALDH activity. Further studies are required to fully elucidate the functions of ALDH-high DTP cells, how they withstand drug concentrations that kill other cells, and how they rapidly adapt under levels of high cellular stress and eventually lead to more aggressive, recurrent, and drug-resistant cancer. Furthermore, this review addresses the processes used by the ALDH-high persister cell subpopulation to enable cancer progression, the ALDH isoforms important in these processes, interactions of ALDH-high DTPs with the tumor microenvironment, and approaches to therapeutically modulate this subpopulation in order to more effectively manage cancer.