RESUMEN
The design and radiosynthesis of [18F]NT376, a high potency inhibitor of class-IIa histone deacetylases (HDAC) is reported. We utilized a three-step radiochemical approach that led to the radiosynthesis of [18F]NT376 in a good radiochemical yield, (17.0 ± 3%, decay corrected), high radiochemical purity (> 97%) and relatively high molar activity of 185.0 GBq/µmol (> 5.0 Ci/µmol). The repositioning of the 18F-radiolabel into a phenyl ring (18F-Fluoro-aryl) of the class-IIa HDAC inhibitor avoided the shortcomings of the direct radiolabeling of the 5-trifluoromethyl-1,2,4-oxadiazole moiety that was reported by us previously and was associated with low molar activity (0.74-1.51 GBq/µmol, 20-41 mCi/µmol). This radiochemical approach could find a wider application for radiolabeling similar molecules with good radiochemical yield and high molar activity.
Asunto(s)
Radioisótopos de Flúor , Inhibidores de Histona Desacetilasas , Radiofármacos , Inhibidores de Histona Desacetilasas/química , Inhibidores de Histona Desacetilasas/síntesis química , Inhibidores de Histona Desacetilasas/farmacología , Radioisótopos de Flúor/química , Radiofármacos/química , Radiofármacos/síntesis química , Diseño de Fármacos , Humanos , Radioquímica/métodos , Oxadiazoles/química , Oxadiazoles/síntesis químicaRESUMEN
The p63 transcription factor is critical for epidermis formation in embryonic development, but its role in the adult epidermis is poorly understood. In this study, we show that acute genetic ablation of ΔNp63, the main p63 isoform, in adult epidermis disrupts keratinocyte proliferation and self-maintenance and, unexpectedly, triggers an inflammatory psoriasis-like condition. Mechanistically, single-cell RNA sequencing revealed the downregulation of cell cycle genes, upregulation of differentiation markers, and induction of several proinflammatory pathways in ΔNp63-ablated keratinocytes. Intriguingly, ΔNp63-ablated cells disappear by 3 weeks after ablation, at the expense of the remaining nonablated cells. This is not associated with active cell death and is likely due to reduced self-maintenance and enhanced differentiation. Indeed, in vivo wound healing, a physiological readout of the epidermal stem cell function, is severely impaired upon ΔNp63 ablation. We found that the Wnt signaling pathway (Wnt10A, Fzd6, Fzd10) and the activator protein 1 (JunB, Fos, FosB) factors are the likely ΔNp63 effectors responsible for keratinocyte proliferation/stemness and suppression of differentiation, respectively, whereas IL-1a, IL-18, IL-24, and IL-36γ are the likely negative effectors responsible for suppression of inflammation. These data establish ΔNp63 as a critical node that coordinates epidermal homeostasis, stemness, and suppression of inflammation, upstream of known regulatory pathways.
Asunto(s)
Células Epidérmicas , Epidermis , Humanos , Adulto , Epidermis/metabolismo , Queratinocitos/metabolismo , Homeostasis , Inflamación/genética , Inflamación/metabolismoRESUMEN
We utilized positron emission tomography (PET) imaging in vivo to map the spatiotemporal biodistribution/expression of class-IIa histone deacetylases (class-IIa HDACs) in the central nervous system (CNS). Herein we report an improved radiosynthesis of [18F]NT160 using 4-hydroxy-TEMPO which led to a significant improvement in radiochemical yield and molar activity. PET imaging with [18F]NT160, a highly potent class-IIa HDAC inhibitor, led to high-quality and high-contrast images of the brain. [18F]NT160 displayed excellent pharmacokinetic and imaging characteristics: brain uptake is high in gray matter regions, tissue kinetics are appropriate for a 18F-tracer, and specific binding for class-IIa HDACs is demonstrated by self-blockade. Higher uptake with [18F]NT160 was observed in the hippocampus, thalamus, and cortex while the uptake in the cerebellum was relatively low. Overall, our current studies with [18F]NT160 will likely facilitate the development and clinical translation of PET tracers for imaging of class-IIa HDACs biodistribution/expression in cancer and the CNS.
Asunto(s)
Histona Desacetilasas , Tomografía de Emisión de Positrones , Histona Desacetilasas/metabolismo , Distribución Tisular , Tomografía de Emisión de Positrones/métodos , Inhibidores de Histona Desacetilasas/farmacología , Encéfalo/metabolismo , Epigénesis Genética , Radioisótopos de Flúor/metabolismoRESUMEN
While pregnancy is known to reduce a woman's life-long risk of breast cancer, clinical data suggest that it can specifically promote HER2 (human EGF receptor 2)-positive breast cancer subtype (HER2+ BC). HER2+ BC, characterized by amplification of HER2, comprises about 20% of all sporadic breast cancers and is more aggressive than hormone receptor-positive breast cancer (the majority of cases). Consistently with human data, pregnancy strongly promotes HER2+ BC in genetic mouse models. One proposed mechanism of this is post-pregnancy accumulation of PIMECs (pregnancy-identified mammary epithelial cells), tumor-initiating cells for HER2+ BC in mice. We previously showed that p63, a homologue of the tumor suppressor p53, is required to maintain the post-pregnancy number of PIMECs and thereby promotes HER2+ BC. Here we set to test whether p63 also affects the intrinsic tumorigenic properties of PIMECs. To this end, we FACS-sorted YFP-labeled PIMECs from p63+/-;ErbB2 and control p63+/+;ErbB2 females and injected their equal amounts into immunodeficient recipients. To our surprise, p63+/- PIMECs showed increased, rather than decreased, tumorigenic capacity in vivo, i.e., significantly accelerated tumor onset and tumor growth, as well as increased self-renewal in mammosphere assays and proliferation in vitro and in vivo. The underlying mechanism of these phenotypes seems to be a specific reduction of the tumor suppressor TAp63 isoform in p63+/- luminal cells, including PIMECs, with concomitant aberrant upregulation of the oncogenic ΔNp63 isoform, as determined by qRT-PCR and scRNA-seq analyses. In addition, scRNA-seq revealed upregulation of several cancer-associated (Il-4/Il-13, Hsf1/HSP), oncogenic (TGFß, NGF, FGF, MAPK) and self-renewal (Wnt, Notch) pathways in p63+/-;ErbB2 luminal cells and PIMECs per se. Altogether, these data reveal a complex role of p63 in PIMECs and pregnancy-associated HER2+ BC: maintaining the amount of PIMECs while suppressing their intrinsic tumorigenic capacity.
Asunto(s)
Neoplasias de la Mama/patología , Células Madre Neoplásicas/fisiología , Embarazo/fisiología , Transactivadores/fisiología , Animales , Mama/patología , Neoplasias de la Mama/genética , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/patología , Células Epiteliales/patología , Células Epiteliales/fisiología , Femenino , Genes erbB-2 , Ratones , Ratones de la Cepa 129 , Ratones Endogámicos C57BL , Ratones Desnudos , Ratones Transgénicos , Células Madre Neoplásicas/patología , Transactivadores/genéticaRESUMEN
Breast cancer is the leading cause of cancer-related death in women worldwide. Human epidermal growth factor receptor 2 (HER2)-positive subtype comprises 20% of sporadic breast cancers and is an aggressive disease. While targeted therapies have greatly improved its management, primary and acquired resistance remain a major roadblock to making it a curable malignancy. Ganetespib, an Hsp90 (Heat shock protein 90) small molecule inhibitor, shows preferential efficacy in HER2-positive breast cancer, including therapy-refractory cases, and has an excellent safety profile in ongoing clinical trials (38 in total, six on breast cancer). However, Ganetespib itself evokes acquired resistance, which is a significant obstacle to its clinical advancement. Here, we show that Ganetespib potently, albeit temporarily, suppresses HER2-positive breast cancer in genetic mouse models, but the animals eventually succumb via acquired resistance. We found that Ganetespib-resistant tumors upregulate several compensatory HSPs, as well as a wide network of phospho-activated receptor tyrosine kinases (RTKs), many of which are HSP clients. Downstream of p-RTKs, the MAPK pathway remains suppressed in the resistant tumors, as is HER2 itself. In contrast, the p-RTK effector Akt is stabilized and phospho-activated. Notably, pharmacological inhibition of Akt significantly delays acquired Ganetespib resistance, by 50%. These data establish Akt as a unifying actionable node downstream of the broadly upregulated HSP/p-RTK resistance program and suggests that Akt co-targeting with Ganetespib may be a superior therapeutic strategy in the clinic.
Asunto(s)
Neoplasias de la Mama/tratamiento farmacológico , Proteínas HSP90 de Choque Térmico/uso terapéutico , Triazoles/uso terapéutico , Animales , Neoplasias de la Mama/patología , Femenino , Proteínas HSP90 de Choque Térmico/farmacología , Humanos , Ratones , Triazoles/farmacologíaRESUMEN
While the extracellular matrix (ECM) is known to regulate neural stem cell quiescence in the adult subventricular zone (SVZ), the function of ECM in the developing SVZ remains unknown. Here, we report that the ECM receptor dystroglycan regulates a unique developmental restructuring of ECM in the early postnatal SVZ. Dystroglycan is furthermore required for ependymal cell differentiation and assembly of niche pinwheel structures, at least in part by suppressing Notch activation in radial glial cells, which leads to the increased expression of MCI, Myb, and FoxJ1, transcriptional regulators necessary for acquisition of the multiciliated phenotype. Dystroglycan also regulates perinatal radial glial cell proliferation and transition into intermediate gliogenic progenitors, such that either acute or constitutive loss of function in dystroglycan results in increased oligodendrogenesis. These findings reveal a role for dystroglycan in orchestrating both the assembly and function of the SVZ neural stem cell niche.
Asunto(s)
Distroglicanos/genética , Ventrículos Laterales/metabolismo , Células-Madre Neurales/metabolismo , Neurogénesis/genética , Nicho de Células Madre/genética , Animales , Diferenciación Celular/genética , Proliferación Celular/genética , Distroglicanos/metabolismo , Matriz Extracelular/genética , Matriz Extracelular/metabolismo , Ventrículos Laterales/crecimiento & desarrollo , Ratones , Neuroglía/metabolismo , Neuronas/metabolismo , Ratas , Receptores Notch/biosíntesis , Receptores Notch/genéticaRESUMEN
The cell surface receptor dystroglycan mediates interactions between oligodendroglia and laminin-211, an extracellular matrix protein that regulates timely oligodendroglial development. However, dystroglycan's precise role in oligodendroglial development and the potential mechanisms to regulate laminin-dystroglycan interactions remain unknown. Here we report that oligodendroglial dystroglycan is cleaved by metalloproteinases, thereby uncoupling oligodendroglia from laminin binding. Dystroglycan cleavage is selectively stimulated by oligodendrocyte progenitor cell attachment to laminin-211, but not laminin-111 or poly-D-lysine. In addition, dystroglycan cleavage occurs most prominently in oligodendrocyte progenitor cells, with limited dystroglycan cleavage observed in differentiating oligodendrocytes. When dystroglycan cleavage is blocked by metalloproteinase inhibitors, oligodendrocyte progenitor cell proliferation is substantially decreased. Conversely, expression of the intracellular portion of cleaved dystroglycan results in increased oligodendrocyte progenitor cell proliferation, suggesting that endogenous dystroglycan cleavage may promote oligodendrocyte progenitor cell cycle progression. Intriguingly, while matrix metalloproteinase-2 and/or -9 have been reported to be responsible for dystroglycan cleavage, we find that these two metalloproteinases are neither necessary nor sufficient for cleavage of oligodendroglial dystroglycan. In summary, laminin-211 stimulates metalloproteinase-mediated dystroglycan cleavage in oligodendrocyte progenitor cells (but not in differentiated oligodendrocytes), which in turn promotes oligodendrocyte progenitor cell proliferation. This novel regulation of oligodendroglial laminin-dystroglycan interactions may have important consequences for oligodendroglial differentiation, both during development and during disease when metalloproteinase levels become elevated.
Asunto(s)
Proliferación Celular/fisiología , Distroglicanos/metabolismo , Laminina/farmacología , Metaloproteasas/fisiología , Oligodendroglía/fisiología , Células Madre/fisiología , Animales , Animales Recién Nacidos , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Femenino , Ratones , Oligodendroglía/efectos de los fármacos , Embarazo , Ratas , Ratas Sprague-Dawley , Células Madre/efectos de los fármacosRESUMEN
During central nervous system (CNS) development, individual oligodendrocytes myelinate multiple axons, thus requiring the outgrowth and extensive branching of oligodendroglial processes. Laminin (Lm)-deficient mice have a lower percentage of myelinated axons, which may indicate a defect in the ability to properly extend and branch processes. It remains unclear, however, to what extent extracellular matrix (ECM) receptors contribute to oligodendroglial process remodeling itself. In the current study, we report that the ECM receptor dystroglycan is necessary for Lm enhancement of filopodial formation, process outgrowth, and process branching in differentiating oligodendroglia. During early oligodendroglial differentiation, the disruption of dystroglycan-Lm interactions, via blocking antibodies or dystroglycan small interfering RNA (siRNA), resulted in decreased filopodial number and length, decreased process length, and decreased numbers of primary and secondary processes. Later in oligodendrocyte differentiation, dystroglycan-deficient cells developed fewer branches, thus producing less complex networks of processes as determined by Sholl analysis. In newly differentiating oligodendroglia, dystroglycan was localized in filopodial tips, whereas, in more mature oligodendrocytes, dystroglycan was enriched in focal adhesion kinase (FAK)-positive focal adhesion structures. These results suggest that dystroglycan-Lm interactions influence oligodendroglial process dynamics and therefore may regulate the myelination capacity of individual oligodendroglia.
Asunto(s)
Diferenciación Celular/fisiología , Distroglicanos/metabolismo , Oligodendroglía/citología , Oligodendroglía/metabolismo , Seudópodos/fisiología , 2',3'-Nucleótido Cíclico 3'-Fosfodiesterasa , Actinas/metabolismo , Animales , Animales Recién Nacidos , Anticuerpos/farmacología , Diferenciación Celular/efectos de los fármacos , Células Cultivadas , Corteza Cerebral/citología , Corteza Cerebral/crecimiento & desarrollo , Distroglicanos/genética , Distroglicanos/inmunología , Quinasa 1 de Adhesión Focal/metabolismo , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Inmunoprecipitación , Interferón beta/inmunología , Interferón beta/metabolismo , Laminina/farmacología , Oligodendroglía/efectos de los fármacos , Hidrolasas Diéster Fosfóricas/metabolismo , Seudópodos/efectos de los fármacos , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Ratas , Estadísticas no Paramétricas , Células Madre , Factores de Tiempo , TransfecciónRESUMEN
The adhesion receptor dystroglycan positively regulates terminal differentiation of oligodendrocytes, but the mechanism by which this occurs remains unclear. Using primary oligodendrocyte cultures, we identified and examined a connection between dystroglycan and the ability of insulin-like growth factor-1 (IGF-1) to promote oligodendrocyte differentiation. Consistent with previous reports, treatment with exogenous IGF-1 caused an increase in MBP protein that was preceded by activation of PI3K (AKT) and MAPK (ERK) signaling pathways. The extracellular matrix protein laminin was further shown to potentiate the effect of IGF-1 on oligodendrocyte differentiation. Depletion of the laminin receptor dystroglycan using siRNA, however, blocked the ability of IGF-1 to promote oligodendrocyte differentiation of cells grown on laminin, suggesting a role for dystroglycan in IGF-1-mediated differentiation. Indeed, loss of dystroglycan led to a reduction in the ability of IGF-1 to activate MAPK, but not PI3K, signaling pathways. Pharmacological inhibition of MAPK signaling also prevented IGF-1-induced increases in myelin basic protein (MBP), indicating that MAPK signaling was necessary to drive IGF-1-mediated enhancement of oligodendrocyte differentiation. Using immunoprecipitation, we found that dystroglycan, the adaptor protein Grb2, and insulin receptor substrate-1 (IRS-1), were associated in a protein complex. Taken together, our results suggest that the positive regulatory effect of laminin on oligodendrocyte differentiation may be attributed, at least in part, to dystroglycan's ability to promote IGF-1-induced differentiation.