RESUMEN
Glycogen synthase kinase-3 (GSK-3) is a constitutively active kinase, involved in regulation of multiple physiological processes. In brain, changes in GSK-3 signaling are related to neurodegenerative issues, including Alzheimer's disease. Due to the wide range of GSK-3 cellular targets, a therapeutic use of the enzyme inhibitors entails significant risk of side effects. Thus, altering the ratio of specific pool of GSK-3 or specific substrates instead of changing the global activity of GSK-3 in brains might be a more appropriate strategy. This paper provides a comprehensive data on abundances of proteins involved in GSK-3 signaling in three regions of young and old mouse brains. It might help to identify novel protein targets with the highest therapeutic potential for treatment of age-related neurodegenerative diseases.
Asunto(s)
Envejecimiento/fisiología , Encéfalo/metabolismo , Cerebelo/metabolismo , Glucógeno Sintasa Quinasa 3/metabolismo , Animales , Encéfalo/efectos de los fármacos , Hipocampo/metabolismo , Ratones , Proteoma/metabolismo , Transducción de Señal/efectos de los fármacosRESUMEN
CK2 is a ubiquitously expressed, constitutively active Ser/Thr protein kinase, which is considered the most pleiotropic protein kinase in the human kinome. Such a pleiotropy explains the involvement of CK2 in many cellular events. However, its predominant roles are stimulation of cell growth and prevention of apoptosis. High levels of CK2 messenger RNA and protein are associated with CK2 pathological functions in human cancers. Over the last decade, basic and translational studies have provided evidence of CK2 as a pivotal molecule driving the growth of different blood malignancies. CK2 overexpression has been demonstrated in nearly all the types of hematological cancers, including acute and chronic leukemias, where CK2 is a key regulator of signaling networks critical for cell proliferation, survival and drug resistance. The findings that emerged from these studies suggest that CK2 could be a valuable therapeutic target in leukemias and supported the initiation of clinical trials using CK2 antagonists. In this review, we summarize the recent advances on the understanding of the signaling pathways involved in CK2 inhibition-mediated effects with a particular emphasis on the combinatorial use of CK2 inhibitors as novel therapeutic strategies for treating both acute and chronic leukemia patients.
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Quinasa de la Caseína II/metabolismo , Leucemia/tratamiento farmacológico , Leucemia/metabolismo , Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/uso terapéutico , Animales , Apoptosis/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Humanos , Transducción de Señal/efectos de los fármacosRESUMEN
Sorafenib, an oral multikinase inhibitor, is the only approved agent for the treatment of advanced hepatocellular carcinoma (HCC). However, its benefits are modest, and as its mechanisms of action remain elusive, a better understanding of its anticancer effects is needed. Based on our previous study results, we investigated here the implication of the nuclear protein 1 (NUPR1) in HCC and its role in sorafenib treatment. NUPR1 is a stress-inducible protein that is overexpressed in various malignancies, but its role in HCC is not yet fully understood. We found that NUPR1 expression was significantly higher in primary human HCC samples than in the normal liver. Knockdown of NUPR1 significantly increased cell sensitivity to sorafenib and inhibited the cell growth, migration and invasion of HCC cells, both in vitro and in vivo. Moreover, NUPR1 silencing influenced the expression of RELB and IER3 genes. Unsurprisingly, RELB and IER3 knockdown also inhibited HCC cell viability, growth and migration. Using gene expression profiling of HCC cells following stable NUPR1 knockdown, we found that genes functionally involved in cell death and survival, cellular response to therapies, lipid metabolism, cell growth and proliferation, molecular transport and cellular movement were mostly suppressed. Network analysis of dynamic gene expression identified NF-κB and ERK as downregulated gene nodes, and several HCC-related oncogenes were also suppressed. We identified Runt-related transcription factor 2 (RUNX2) gene as a NUPR1-regulated gene and demonstrated that RUNX2 gene silencing inhibits HCC cell viability, growth, migration and increased cell sensitivity to sorafenib. We propose that the NUPR1/RELB/IER3/RUNX2 pathway has a pivotal role in hepatocarcinogenesis. The identification of the NUPR1/RELB/IER3/RUNX2 pathway as a potential therapeutic target may contribute to the development of new treatment strategies for HCC management.
Asunto(s)
Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Movimiento Celular/efectos de los fármacos , Resistencia a Antineoplásicos/efectos de los fármacos , Neoplasias Hepáticas/patología , Terapia Molecular Dirigida , Proteínas de Neoplasias/metabolismo , Niacinamida/análogos & derivados , Compuestos de Fenilurea/farmacología , Anciano , Anciano de 80 o más Años , Proteínas Reguladoras de la Apoptosis/genética , Proteínas Reguladoras de la Apoptosis/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/patología , Movimiento Celular/genética , Proliferación Celular/efectos de los fármacos , Proliferación Celular/genética , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/genética , Biología Computacional , Subunidad alfa 1 del Factor de Unión al Sitio Principal/metabolismo , Regulación hacia Abajo/efectos de los fármacos , Femenino , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Técnicas de Silenciamiento del Gen , Silenciador del Gen/efectos de los fármacos , Humanos , Neoplasias Hepáticas/genética , Masculino , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Persona de Mediana Edad , Invasividad Neoplásica , Proteínas de Neoplasias/genética , Niacinamida/farmacología , ARN Interferente Pequeño/metabolismo , Sorafenib , Factor de Transcripción ReIB/genética , Factor de Transcripción ReIB/metabolismo , Transcriptoma/genética , Adulto JovenRESUMEN
Sirtuins are class III deacetylases that regulate many essential processes, including cellular stress, genome stability and metabolism. Although these NAD(+)-dependent deacetylases control adaptive cellular responses, identification of sirtuin-regulated signaling targets remain under-studied. Here, we demonstrate that acetylation of the mitogen-activated protein kinase kinase-1 (MEK1) stimulates its kinase activity, and that acetylated MEK1 is under the regulatory control of the sirtuin family members SIRT1 and SIRT2. Treatment of cells with sirtuin inhibitors, or siRNA knockdown of SIRT1 or SIRT2 proteins, increases MEK1 acetylation and subsequent phosphorylation of the extracellular signal-regulated kinase. Generation of an acetyl-specific MEK1 antibody demonstrates that endogenous acetylated MEK1 is extensively enriched in the nucleus following epidermal growth factor stimulation. An acetyl-mimic of MEK1 increases inappropriate growth properties, suggesting that acetylation of MEK1 has oncogenic potential.
Asunto(s)
MAP Quinasa Quinasa 1/metabolismo , Neoplasias/genética , Sirtuina 1/biosíntesis , Sirtuina 2/biosíntesis , Acetilación , Línea Celular , Núcleo Celular/metabolismo , Inestabilidad Genómica , Humanos , MAP Quinasa Quinasa 1/genética , NAD/metabolismo , Neoplasias/patología , Fosforilación/genética , Sirtuina 1/genética , Sirtuina 2/metabolismoRESUMEN
Constitutively active phosphoinositide 3-kinase (PI3K) signaling is a common feature of T-cell acute lymphoblastic leukemia (T-ALL), where it upregulates cell proliferation, survival and drug resistance. These observations lend compelling weight to the application of PI3K inhibitors in the therapy of T-ALL. Here, we have analyzed the therapeutic potential of the pan-PI3K inhibitor NVP-BKM120 (BKM120), an orally bioavailable 2,6-dimorpholino pyrimidine derivative, which has entered clinical trials for solid tumors, on both T-ALL cell lines and patient samples. BKM120 treatment resulted in G2/M phase cell cycle arrest and apoptosis, being cytotoxic to a panel of T-ALL cell lines and patient T lymphoblasts, and promoting a dose- and time-dependent dephosphorylation of Akt and S6RP. BKM120 maintained its pro-apoptotic activity against Jurkat cells even when cocultured with MS-5 stromal cells, which mimic the bone marrow microenvironment. Remarkably, BKM120 synergized with chemotherapeutic agents currently used for treating T-ALL patients. Moreover, in vivo administration of BKM120 to a subcutaneous xenotransplant model of human T-ALL significantly delayed tumor growth, thus prolonging survival time. Taken together, our findings indicate that BKM120, either alone or in combination with chemotherapeutic drugs, may be an efficient treatment for T-ALLs that have aberrant upregulation of the PI3K signaling pathway.
Asunto(s)
Aminopiridinas/farmacología , Apoptosis/efectos de los fármacos , Ciclo Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Morfolinas/farmacología , Inhibidores de las Quinasa Fosfoinosítidos-3 , Leucemia-Linfoma Linfoblástico de Células T Precursoras/tratamiento farmacológico , Animales , Western Blotting , Citometría de Flujo , Humanos , Ratones , Ratones Endogámicos NOD , Ratones SCID , Leucemia-Linfoma Linfoblástico de Células T Precursoras/metabolismo , Leucemia-Linfoma Linfoblástico de Células T Precursoras/patología , Células Tumorales Cultivadas , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Glycogen synthase kinase-3 (GSK-3) is well documented to participate in a complex array of critical cellular processes. It was initially identified in rat skeletal muscle as a serine/threonine kinase that phosphorylated and inactivated glycogen synthase. This versatile protein is involved in numerous signaling pathways that influence metabolism, embryogenesis, differentiation, migration, cell cycle progression and survival. Recently, GSK-3 has been implicated in leukemia stem cell pathophysiology and may be an appropriate target for its eradication. In this review, we will discuss the roles that GSK-3 plays in hematopoiesis and leukemogenesis as how this pivotal kinase can interact with multiple signaling pathways such as: Wnt/ß-catenin, phosphoinositide 3-kinase (PI3K)/phosphatase and tensin homolog (PTEN)/Akt/mammalian target of rapamycin (mTOR), Ras/Raf/MEK/extracellular signal-regulated kinase (ERK), Notch and others. Moreover, we will discuss how targeting GSK-3 and these other pathways can improve leukemia therapy and may overcome therapeutic resistance. In summary, GSK-3 is a crucial regulatory kinase interacting with multiple pathways to control various physiological processes, as well as leukemia stem cells, leukemia progression and therapeutic resistance. GSK-3 and Wnt are clearly intriguing therapeutic targets.
Asunto(s)
Carcinogénesis , Glucógeno Sintasa Quinasa 3/metabolismo , Hematopoyesis , Leucemia/patología , Proteínas Wnt/metabolismo , beta Catenina/metabolismo , Animales , Humanos , Leucemia/enzimología , Leucemia/metabolismo , Leucemia/terapiaRESUMEN
Signal transducer and activator of transcription (STAT) proteins comprise a family of transcription factors that are activated by cytokines, hormones and growth factors. The activation of STAT proteins plays a key role in the production of mature hematopoietic cells via effects on cellular proliferation, survival and lineage-specific differentiation. Emerging evidence also demonstrates frequent, constitutive activation of STATs in primary leukemia specimens. Moreover, roles for STATs in promoting leukemia development have been delineated in numerous preclinical studies. This review summarizes our current understanding of STAT protein involvement in normal hematopoiesis and leukemogenesis, as well as recent advances in the development and testing of novel STAT inhibitors.
Asunto(s)
Transformación Celular Neoplásica/metabolismo , Hematopoyesis , Leucemia/metabolismo , Factores de Transcripción STAT/metabolismo , Empalme Alternativo , Animales , Transformación Celular Neoplásica/genética , Hematopoyesis/genética , Humanos , Leucemia/tratamiento farmacológico , Leucemia/genética , Terapia Molecular Dirigida , Factores de Transcripción STAT/antagonistas & inhibidores , Factores de Transcripción STAT/genética , Transducción de Señal/efectos de los fármacosRESUMEN
B-precursor acute lymphoblastic leukemia (B-pre ALL) is a malignant disorder characterized by the abnormal proliferation of B-cell progenitors. The prognosis of B-pre ALL has improved in pediatric patients, but the outcome is much less successful in adults. Constitutive activation of the phosphatidylinositol 3-kinase (PI3K), Akt and the mammalian target of rapamycin (mTOR) (PI3K/Akt/mTOR) network is a feature of B-pre ALL, where it strongly influences cell growth and survival. RAD001, a selective mTORC1 inhibitor, has been shown to be cytotoxic against many types of cancer including hematological malignancies. To investigate whether mTORC1 could represent a target in the therapy of B-pre ALL, we treated cell lines and adult patient primary cells with RAD001. We documented that RAD001 decreased cell viability, induced cell cycle arrest in G0/G1 phase and caused apoptosis in B-pre ALL cell lines. Autophagy was also induced, which was important for the RAD001 cytotoxic effect, as downregulation of Beclin-1 reduced drug cytotoxicity. RAD001 strongly synergized with the novel allosteric Akt inhibitor MK-2206 in both cell lines and patient samples. Similar results were obtained with the combination CCI-779 plus GSK 690693. These findings point out that mTORC1 inhibitors, either as a single agent or in combination with Akt inhibitors, could represent a potential therapeutic innovative strategy in B-pre ALL.
Asunto(s)
Inhibidores de las Quinasa Fosfoinosítidos-3 , Leucemia-Linfoma Linfoblástico de Células Precursoras B/tratamiento farmacológico , Proteínas Proto-Oncogénicas c-akt/antagonistas & inhibidores , Transducción de Señal/efectos de los fármacos , Serina-Treonina Quinasas TOR/antagonistas & inhibidores , Apoptosis/efectos de los fármacos , Autofagia/efectos de los fármacos , Puntos de Control del Ciclo Celular/efectos de los fármacos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Everolimus , Compuestos Heterocíclicos con 3 Anillos/farmacología , Humanos , Diana Mecanicista del Complejo 1 de la Rapamicina , Complejos Multiproteicos/antagonistas & inhibidores , Oxadiazoles/farmacología , Sirolimus/análogos & derivados , Sirolimus/farmacologíaRESUMEN
Constitutively active casein kinase 2 (CK2) signaling is a common feature of T-cell acute lymphoblastic leukemia (T-ALL). CK2 phosphorylates PTEN (phosphatase and tensin homolog) tumor suppressor, resulting in PTEN stabilization and functional inactivation. Downregulation of PTEN activity has an impact on PI3K/Akt/mTOR signaling, which is of fundamental importance for T-ALL cell survival. These observations lend compelling weight to the application of CK2 inhibitors in the therapy of T-ALL. Here, we have analyzed the therapeutic potential of CX-4945-a novel, highly specific, orally available, ATP-competitive inhibitor of CK2α. We show that CX-4945 treatment induced apoptosis in T-ALL cell lines and patient T lymphoblasts. CX-4945 downregulated PI3K/Akt/mTOR signaling in leukemic cells. Notably, CX-4945 affected the unfolded protein response (UPR), as demonstrated by a significant decrease in the levels of the main UPR regulator GRP78/BIP, and led to apoptosis via upregulation of the ER stress/UPR cell death mediators IRE1α and CHOP. In vivo administration of CX-4945 to a subcutaneous xenotransplant model of human T-ALL significantly delayed tumor growth. Our findings indicate that modulation of the ER stress/UPR signaling through CK2 inhibition could be exploited for inducing apoptosis in T-ALL cells and that CX-4945 may be an efficient treatment for those T-ALLs displaying upregulation of CK2α/PI3K/Akt/mTOR signaling.
Asunto(s)
Antineoplásicos/uso terapéutico , Quinasa de la Caseína II/antagonistas & inhibidores , Naftiridinas/uso terapéutico , Proteínas de Neoplasias/metabolismo , Leucemia-Linfoma Linfoblástico de Células T Precursoras/tratamiento farmacológico , Transducción de Señal , Respuesta de Proteína Desplegada , Animales , División Celular , Chaperón BiP del Retículo Endoplásmico , Humanos , Ratones , Ratones Endogámicos NOD , Ratones SCID , Proteínas de Neoplasias/química , Fenazinas , Leucemia-Linfoma Linfoblástico de Células T Precursoras/patologíaRESUMEN
The mechanisms responsible for the switch of prostate cancer from androgen-sensitive (AS) to androgen-insensitive (AI) form are not well understood. Regulation of androgen receptor (AR), through which androgens control the expression of genes involved in prostate cells proliferation, migration and death also involves its cross-talk with the other signaling pathways, transcription factors and coregulatory proteins, such as ß-catenin. With the aim to determine their possible contribution in triggering the switch from AS to AI form, which occurs upon androgen deprivation therapy - AR, Akt and ß-catenin expression were knocked-down with respective siRNAs. Treatment of LNCaP prostate cells with siRNA for AR significantly reduced their proliferation (45-70%), expression of nuclear ß- catenin, cyclin-D1, cyclin-G1, c-Myc as well as activity of metalloproteinases (MMPs) -2,-7,-9 and cell migration. Surprisingly, after longer (over 72 hrs) silencing of AR in LNCaP cells, elevated levels of p-Akt were detected and enhanced proliferation as well as expression of nuclear ß-catenin, cyclin-D1, c-Myc and activity of MMPs were observed. Such effects were not observed in either PC-3 or DU145 AI cells. However, silencing of Akt and /or ß-catenin in those as well as in LNCaP cells led to their decreased proliferation and migration. Our findings suggest that in prostate cancer cells, either AR or Akt signaling prevails, depending on their initial androgen sensitivity and its availability. In AI prostate cancer cells, Akt takes over the role of AR and more effectively contributes through the same signaling molecule, ß-catenin, to AI cancer progression.
Asunto(s)
Andrógenos/metabolismo , Neoplasias de la Próstata/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Receptores Androgénicos/metabolismo , Transducción de Señal , Andrógenos/genética , Línea Celular Tumoral , Proliferación Celular , Ciclina D1/genética , Ciclina D1/metabolismo , Regulación Neoplásica de la Expresión Génica , Humanos , Masculino , Metaloproteinasas de la Matriz Secretadas/genética , Metaloproteinasas de la Matriz Secretadas/metabolismo , Próstata/metabolismo , Próstata/patología , Neoplasias de la Próstata/genética , Neoplasias de la Próstata/patología , Proteínas Proto-Oncogénicas c-akt/genética , Proteínas Proto-Oncogénicas c-myc/genética , Proteínas Proto-Oncogénicas c-myc/metabolismo , Interferencia de ARN , ARN Interferente Pequeño/genética , Receptores Androgénicos/genética , beta Catenina/genética , beta Catenina/metabolismoRESUMEN
The phosphatidylinositol 3-kinase (PI3K) and the mammalian target of rapamycin (mTOR) are two major signaling molecules in the PI3K/Akt/mTOR signal transduction cascade. This pathway is a key regulator of a wide range of physiological cell processes which include proliferation, differentiation, survival, metabolism, exocytosis, motility, and autophagy. However, aberrantly upregulated PI3K/Akt/mTOR signaling characterizes many types of cancers where it negatively influences response to therapeutic treatments. Therefore, targeting PI3K/Akt/mTOR signaling with small molecule inhibitors could improve cancer patient outcome. The PI3K/Akt/mTOR signaling network is activated in acute leukemias of both myelogenous and lymphoid lineage, where it correlates with poor prognosis and enhanced drug-resistance. The catalytic sites of PI3K and mTOR share a high degree of sequence homology. This feature has allowed the synthesis of ATP-competitive compounds that targeted the catalytic site of both PI3K and mTOR (e.g. PI-103, NVP-BEZ235). In preclinical settings, dual PI3K/mTOR inhibitors displayed a much stronger cytotoxicity against leukemic cells than either PI3K inhibitors or allosteric mTOR inhibitors, such as rapamycin and its derivatives (rapalogs). At variance with rapamycin/rapalogs, dual PI3K/mTOR inhibitors targeted both mTOR complex 1 and mTOR complex 2, and inhibited the rapamycin-resistant phosphorylation of eukaryotic initiation factor 4E-binding protein 1, resulting in a marked inhibition of oncogenetic protein translation in leukemic cells. Hence, they strongly reduced the proliferation rate and induced an important apoptotic response. Here, we reviewed the evidence documenting that dual PI3K/mTOR inhibitors represent a promising option for future targeted therapies of leukemic patients.
RESUMEN
T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive neoplastic disorder arising from T-cell progenitors. T-ALL accounts for 15% of newly diagnosed ALL cases in children and 25% in adults. Although the prognosis of T-ALL has improved, due to the use of polychemotherapy schemes, the outcome of relapsed/chemoresistant T-ALL cases is still poor. A signaling pathway that is frequently upregulated in T-ALL, is the phosphatidylinositol 3-kinase/Akt/mTOR network. To explore whether Akt could represent a target for therapeutic intervention in T-ALL, we evaluated the effects of the novel allosteric Akt inhibitor, MK-2206, on a panel of human T-ALL cell lines and primary cells from T-ALL patients. MK-2206 decreased T-ALL cell line viability by blocking leukemic cells in the G(0)/G(1) phase of the cell cycle and inducing apoptosis. MK-2206 also induced autophagy, as demonstrated by an increase in the 14-kDa form of LC3A/B. Western blotting analysis documented a concentration-dependent dephosphorylation of Akt and its downstream targets, GSK-3α/ß and FOXO3A, in response to MK-2206. MK-2206 was cytotoxic to primary T-ALL cells and induced apoptosis in a T-ALL patient cell subset (CD34(+)/CD4(-)/CD7(-)), which is enriched in leukemia-initiating cells. Taken together, our findings indicate that Akt inhibition may represent a potential therapeutic strategy in T-ALL.
Asunto(s)
Compuestos Heterocíclicos con 3 Anillos/farmacología , Leucemia-Linfoma Linfoblástico de Células T Precursoras/patología , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Proto-Oncogénicas c-akt/antagonistas & inhibidores , Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Autofagia/efectos de los fármacos , Western Blotting , Ciclo Celular/efectos de los fármacos , Doxorrubicina/farmacología , Sinergismo Farmacológico , Humanos , Fosforilación , Leucemia-Linfoma Linfoblástico de Células T Precursoras/enzimología , Transducción de SeñalRESUMEN
The mammalian target of rapamycin (mTOR) serine/threonine kinase is the catalytic subunit of two multi-protein complexes, referred to as mTORC1 and mTORC2. Signaling downstream of mTORC1 has a critical role in leukemic cell biology by controlling mRNA translation of genes involved in both cell survival and proliferation. mTORC1 activity can be downmodulated by upregulating the liver kinase B1/AMP-activated protein kinase (LKB1/AMPK) pathway. Here, we have explored the therapeutic potential of the anti-diabetic drug, metformin (an LKB1/AMPK activator), against both T-cell acute lymphoblastic leukemia (T-ALL) cell lines and primary samples from T-ALL patients displaying mTORC1 activation. Metformin affected T-ALL cell viability by inducing autophagy and apoptosis. However, it was much less toxic against proliferating CD4(+) T-lymphocytes from healthy donors. Western blot analysis demonstrated dephosphorylation of mTORC1 downstream targets. Unlike rapamycin, we found a marked inhibition of mRNA translation in T-ALL cells treated with metformin. Remarkably, metformin targeted the side population of T-ALL cell lines as well as a putative leukemia-initiating cell subpopulation (CD34(+)/CD7(-)/CD4(-)) in patient samples. In conclusion, metformin displayed a remarkable anti-leukemic activity, which emphasizes future development of LKB1/AMPK activators as clinical candidates for therapy in T-ALL.
Asunto(s)
Adenilato Quinasa/metabolismo , Leucemia-Linfoma Linfoblástico de Células T Precursoras/metabolismo , Proteínas/metabolismo , Transducción de Señal , Apoptosis , Secuencia de Bases , Línea Celular Tumoral , Cartilla de ADN , Citometría de Flujo , Humanos , Diana Mecanicista del Complejo 1 de la Rapamicina , Metformina/farmacología , Complejos Multiproteicos , Fosforilación , Leucemia-Linfoma Linfoblástico de Células T Precursoras/patología , Biosíntesis de Proteínas/efectos de los fármacos , ARN Mensajero/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Serina-Treonina Quinasas TORRESUMEN
Cancer stem cells (CSCs) comprise a subset of hierarchically organized, rare cancer cells with the ability to initiate cancer in xenografts of genetically modified murine models. CSCs are thought to be responsible for tumor onset, self-renewal/maintenance, mutation accumulation, and metastasis. The existence of CSCs could explain the high frequency of neoplasia relapse and resistance to all of currently available therapies, including chemotherapy. The phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway is a key regulator of physiological cell processes which include proliferation, differentiation, apoptosis, motility, metabolism, and autophagy. Nevertheless, aberrantly upregulated PI3K/Akt/mTOR signaling characterizes many types of cancers where it negatively influences prognosis. Several lines of evidence indicate that this signaling system plays a key role also in CSC biology. Of note, CSCs are more sensitive to pathway inhibition with small molecules when compared to healthy stem cells. This observation provides the proof-of-principle that functional differences in signaling transduction pathways between CSCs and healthy stem cells can be identified. Here, we review the evidence which links the signals deriving from the PI3K/Akt/mTOR network with CSC biology, both in hematological and solid tumors. We then highlight how therapeutic targeting of PI3K/Akt/mTOR signaling with small molecule inhibitors could improve cancer patient outcome, by eliminating CSCs.
Asunto(s)
Mamíferos/metabolismo , Células Madre Neoplásicas/patología , Inhibidores de las Quinasa Fosfoinosítidos-3 , Proteínas Proto-Oncogénicas c-akt/antagonistas & inhibidores , Transducción de Señal/efectos de los fármacos , Sirolimus/farmacología , Animales , Antibióticos Antineoplásicos/farmacología , Humanos , Células Madre Neoplásicas/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Serina-Treonina Quinasas TOR/antagonistas & inhibidores , Serina-Treonina Quinasas TOR/metabolismoRESUMEN
The Ras/Raf/mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway is often implicated in sensitivity and resistance to leukemia therapy. Dysregulated signaling through the Ras/Raf/MEK/ERK pathway is often the result of genetic alterations in critical components in this pathway as well as mutations at upstream growth factor receptors. Unrestricted leukemia proliferation and decreased sensitivity to apoptotic-inducing agents and chemoresistance are typically associated with activation of pro-survival pathways. Mutations in this pathway and upstream signaling molecules can alter sensitivity to small molecule inhibitors targeting components of this cascade as well as to inhibitors targeting other key pathways (for example, phosphatidylinositol 3 kinase (PI3K)/phosphatase and tensin homologue deleted on chromosome 10 (PTEN)/Akt/mammalian target of rapamycin (mTOR)) activated in leukemia. Similarly, PI3K mutations can result in resistance to inhibitors targeting the Ras/Raf/MEK/ERK pathway, indicating important interaction points between the pathways (cross-talk). Furthermore, the Ras/Raf/MEK/ERK pathway can be activated by chemotherapeutic drugs commonly used in leukemia therapy. This review discusses the mechanisms by which abnormal expression of the Ras/Raf/MEK/ERK pathway can contribute to drug resistance as well as resistance to targeted leukemia therapy. Controlling the expression of this pathway could improve leukemia therapy and ameliorate human health.
Asunto(s)
Antineoplásicos/farmacología , Quinasas MAP Reguladas por Señal Extracelular/fisiología , Leucemia/tratamiento farmacológico , Sistema de Señalización de MAP Quinasas/fisiología , Quinasas de Proteína Quinasa Activadas por Mitógenos/fisiología , Terapia Molecular Dirigida , Proteínas de Neoplasias/fisiología , Quinasas raf/fisiología , Proteínas ras/fisiología , Antineoplásicos/uso terapéutico , Apoptosis/efectos de los fármacos , Apoptosis/fisiología , División Celular/efectos de los fármacos , División Celular/genética , Diseño de Fármacos , Resistencia a Antineoplásicos/efectos de los fármacos , Resistencia a Antineoplásicos/genética , Resistencia a Antineoplásicos/fisiología , Quinasas MAP Reguladas por Señal Extracelular/antagonistas & inhibidores , Quinasas MAP Reguladas por Señal Extracelular/genética , Regulación Leucémica de la Expresión Génica/efectos de los fármacos , Regulación Leucémica de la Expresión Génica/genética , Humanos , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Sistema de Señalización de MAP Quinasas/genética , Quinasas de Proteína Quinasa Activadas por Mitógenos/antagonistas & inhibidores , Quinasas de Proteína Quinasa Activadas por Mitógenos/genética , Modelos Biológicos , Proteínas de Neoplasias/antagonistas & inhibidores , Proteínas de Neoplasias/genética , Fosfatidilinositol 3-Quinasas/genética , Fosfatidilinositol 3-Quinasas/fisiología , Inhibidores de las Quinasa Fosfoinosítidos-3 , Quinasas raf/antagonistas & inhibidores , Quinasas raf/genética , Proteínas ras/antagonistas & inhibidores , Proteínas ras/genéticaRESUMEN
It has become apparent that regulation of protein translation is an important determinant in controlling cell growth and leukemic transformation. The phosphoinositide 3-kinase (PI3K)/phosphatase and tensin homologue deleted on chromosome ten (PTEN)/Akt/mammalian target of rapamycin (mTOR) pathway is often implicated in sensitivity and resistance to therapy. Dysregulated signaling through the PI3K/PTEN/Akt/mTOR pathway is often the result of genetic alterations in critical components in this pathway as well as mutations at upstream growth factor receptors. Furthermore, this pathway is activated by autocrine transformation mechanisms. PTEN is a critical tumor suppressor gene and its dysregulation results in the activation of Akt. PTEN is often mutated, silenced and is often haploinsufficient. The mTOR complex1 (mTORC1) regulates the assembly of the eukaryotic initiation factor4F complex, which is critical for the translation of mRNAs that are important for cell growth, prevention of apoptosis and transformation. These mRNAs have long 5'-untranslated regions that are G+C rich, rendering them difficult to translate. Elevated mTORC1 activity promotes the translation of these mRNAs via the phosphorylation of 4E-BP1. mTORC1 is a target of rapamycin and novel active-site inhibitors that directly target the TOR kinase activity. Although rapamycin and novel rapalogs are usually cytostatic and not cytotoxic for leukemic cells, novel inhibitors that target the kinase activities of PI3K and mTOR may prove more effective for leukemia therapy.
Asunto(s)
Antineoplásicos/farmacología , Regulación Leucémica de la Expresión Génica/efectos de los fármacos , Leucemia/tratamiento farmacológico , Terapia Molecular Dirigida , Proteínas de Neoplasias/fisiología , Fosfohidrolasa PTEN/fisiología , Fosfatidilinositol 3-Quinasas/fisiología , Biosíntesis de Proteínas/efectos de los fármacos , Proteínas Proto-Oncogénicas c-akt/fisiología , Transducción de Señal/efectos de los fármacos , Serina-Treonina Quinasas TOR/fisiología , Antineoplásicos/uso terapéutico , Apoptosis/efectos de los fármacos , Apoptosis/genética , Diseño de Fármacos , Resistencia a Antineoplásicos/efectos de los fármacos , Resistencia a Antineoplásicos/genética , Regulación Leucémica de la Expresión Génica/genética , Humanos , Leucemia/genética , Diana Mecanicista del Complejo 1 de la Rapamicina , MicroARNs/genética , Complejos Multiproteicos/antagonistas & inhibidores , Complejos Multiproteicos/efectos de los fármacos , Complejos Multiproteicos/fisiología , Proteínas de Neoplasias/antagonistas & inhibidores , Proteínas de Neoplasias/genética , Células Madre Neoplásicas/efectos de los fármacos , Fosfohidrolasa PTEN/antagonistas & inhibidores , Fosfohidrolasa PTEN/genética , Fosfatidilinositol 3-Quinasas/genética , Inhibidores de las Quinasa Fosfoinosítidos-3 , Fosforilación/efectos de los fármacos , Procesamiento Proteico-Postraduccional/efectos de los fármacos , Proteínas/antagonistas & inhibidores , Proteínas/efectos de los fármacos , Proteínas/fisiología , Proteínas Proto-Oncogénicas c-akt/antagonistas & inhibidores , Proteínas Proto-Oncogénicas c-akt/genética , Seudogenes , ARN Mensajero/genética , ARN Neoplásico/genética , Serina-Treonina Quinasas TOR/antagonistas & inhibidores , Serina-Treonina Quinasas TOR/genética , Factores de Transcripción/antagonistas & inhibidores , Factores de Transcripción/efectos de los fármacos , Factores de Transcripción/fisiologíaRESUMEN
The mammalian Target Of Rapamycin (mTOR) serine/threonine kinase belongs to two multi-protein complexes, referred to as mTORC1 and mTORC2. mTOR-generated signals have critical roles in leukemic cell biology by controlling mRNA translation of genes that promote proliferation and survival. However, allosteric inhibition of mTORC1 by rapamycin has only modest effects in T-cell acute lymphoblastic leukemia (T-ALL). Recently, ATP-competitive inhibitors specific for the mTOR kinase active site have been developed. In this study, we have explored the therapeutic potential of active-site mTOR inhibitors against both T-ALL cell lines and primary samples from T-ALL patients displaying activation of mTORC1 and mTORC2. The inhibitors affected T-ALL cell viability by inducing cell-cycle arrest in G(0)/G(1) phase, apoptosis and autophagy. Western blot analysis demonstrated a Ser 473 Akt dephosphorylation (indicative of mTORC2 inhibition) and a dephosphorylation of mTORC1 downstream targets. Unlike rapamycin, we found a marked inhibition of mRNA translation in T-ALL cell lines treated with active-site mTOR inhibitors. The inhibitors strongly synergized with both vincristine and the Bcl-2 inhibitor, ABT-263. Remarkably, the drugs targeted a putative leukemia-initiating cell sub-population (CD34(+)/CD7(-)/CD4(-)) in patient samples. In conclusion, the inhibitors displayed remarkable anti-leukemic activity, which emphasizes their future development as clinical candidates for therapy in T-ALL.
Asunto(s)
Apoptosis/efectos de los fármacos , Autofagia/efectos de los fármacos , Leucemia-Linfoma Linfoblástico de Células T Precursoras/tratamiento farmacológico , Leucemia-Linfoma Linfoblástico de Células T Precursoras/patología , Inhibidores de Proteínas Quinasas/farmacología , Proteínas/antagonistas & inhibidores , Factores de Transcripción/antagonistas & inhibidores , Animales , Western Blotting , Dominio Catalítico , Ciclo Celular/efectos de los fármacos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Citometría de Flujo , Humanos , Inmunosupresores/farmacología , Diana Mecanicista del Complejo 1 de la Rapamicina , Ratones , Complejos Multiproteicos , Fosforilación/efectos de los fármacos , Leucemia-Linfoma Linfoblástico de Células T Precursoras/metabolismo , Proteínas/metabolismo , ARN Mensajero/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Sirolimus/farmacología , Serina-Treonina Quinasas TOR , Factores de Transcripción/metabolismoRESUMEN
Alkylphospholipids and alkylphosphocholines (APCs) are promising antitumor agents, which target the plasma membrane and affect multiple signal transduction networks. We investigated the therapeutic potential of erucylphosphohomocholine (ErPC3), the first intravenously applicable APC, in human acute myelogenous leukemia (AML) cells. ErPC3 was tested on AML cell lines, as well as AML primary cells. At short (6-12 h) incubation times, the drug blocked cells in G2/M phase of the cell cycle, whereas, at longer incubation times, it decreased survival and induced cell death by apoptosis. ErPC3 caused JNK 1/2 activation as well as ERK 1/2 dephosphorylation. Pharmacological inhibition of caspase-3 or a JNK 1/2 inhibitor peptide markedly reduced ErPC3 cytotoxicity. Protein phosphatase 2A downregulation by siRNA opposed ERK 1/2 dephosphorylation and blunted the cytotoxic effect of ErPC3. ErPC3 was cytotoxic to AML primary cells and reduced the clonogenic activity of CD34(+) leukemic cells. ErPC3 induced a significant apoptosis in the compartment (CD34(+) CD38(Low/Neg) CD123(+)) enriched in putative leukemia-initiating cells. This conclusion was supported by ErPC3 cytotoxicity on AML blasts showing high aldehyde dehydrogenase activity and on the side population of AML cell lines and blasts. These findings indicate that ErPC3 might be a promising therapeutic agent for the treatment of AML patients.
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Apoptosis/efectos de los fármacos , Ácidos Erucicos/farmacología , Leucemia Mieloide Aguda/tratamiento farmacológico , MAP Quinasa Quinasa 4/metabolismo , Fosforilcolina/análogos & derivados , Células Precursoras de Linfocitos B/efectos de los fármacos , Proteína Fosfatasa 2/metabolismo , Animales , Western Blotting , Ciclo Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Citometría de Flujo , Técnica del Anticuerpo Fluorescente , Humanos , Técnicas para Inmunoenzimas , Leucemia Mieloide Aguda/metabolismo , Leucemia Mieloide Aguda/patología , Ratones , Proteína Quinasa 1 Activada por Mitógenos/antagonistas & inhibidores , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Proteína Quinasa 3 Activada por Mitógenos/antagonistas & inhibidores , Proteína Quinasa 3 Activada por Mitógenos/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Inhibidores de las Quinasa Fosfoinosítidos-3 , Fosforilcolina/farmacología , Células Precursoras de Linfocitos B/metabolismo , Proteína Fosfatasa 2/antagonistas & inhibidores , Proteína Fosfatasa 2/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transducción de SeñalRESUMEN
Since the discovery of leukemic stem cells (LSCs) over a decade ago, many of their critical biological properties have been elucidated, including their distinct replicative properties, cell surface phenotypes, their increased resistance to chemotherapeutic drugs and the involvement of growth-promoting chromosomal translocations. Of particular importance is their ability to transfer malignancy to non-obese diabetic-severe combined immunodeficient (NOD-SCID) mice. Furthermore, numerous studies demonstrate that acute myeloid leukemia arises from mutations at the level of stem cell, and chronic myeloid leukemia is also a stem cell disease. In this review, we will evaluate the main characteristics of LSCs elucidated in several well-documented leukemias. In addition, we will discuss points of therapeutic intervention. Promising therapeutic approaches include the targeting of key signal transduction pathways (for example, PI3K, Rac and Wnt) with small-molecule inhibitors and specific cell surface molecules (for example, CD33, CD44 and CD123), with effective cytotoxic antibodies. Also, statins, which are already widely therapeutically used for a variety of diseases, show potential in targeting LSCs. In addition, drugs that inhibit ATP-binding cassette transporter proteins are being extensively studied, as they are important in drug resistance-a frequent characteristic of LSCs. Although the specific targeting of LSCs is a relatively new field, it is a highly promising battleground that may reveal the Holy Grail of cancer therapy.
Asunto(s)
Leucemia/tratamiento farmacológico , Leucemia/patología , Células Madre Neoplásicas/patología , Sistemas de Liberación de Medicamentos/métodos , Humanos , Leucemia/etiología , Células Madre Neoplásicas/efectos de los fármacos , Resultado del TratamientoRESUMEN
A cytokine-dependent (FL5.12), drug-sensitive, p53 wild type (WT) and a doxorubicin-resistant derivative line (FL/Doxo) were used to determine the mechanisms that could result in drug resistance of early hematopoietic precursor cells. Drug resistance was associated with decreased p53 induction after doxorubicin treatment, which was due to a higher level of proteasomal degradation of p53. Dominant-negative (DN) p53 genes increased the resistance to chemotherapeutic drugs, MDM-2 and MEK inhibitors, further substantiating the role of p53 in therapeutic sensitivity. The involvement of signal transduction and apoptotic pathways was examined, as drug resistance did not appear to be due to increased drug efflux. Drug-resistant FL/Doxo cells had higher levels of activated Raf/MEK/ERK signaling and decreased induction of apoptosis when cultured in the presence of doxorubicin than drug-sensitive FL5.12 cells. Introduction of DN MEK1 increased drug sensitivity, whereas constitutively active (CA) MEK1 or conditionally active BRAF augmented resistance, documenting the importance of the Raf/MEK/ERK pathway in drug resistance. MEK inhibitors synergized with chemotherapeutic drugs to reduce the IC(50). Thus the p53 and Raf/MEK/ERK pathways play key roles in drug sensitivity. Targeting these pathways may be effective in certain drug-resistant leukemias that are WT at p53.