RESUMEN
AMP-activated protein kinase (AMPK) is a critical cellular energy sensor at the interface of metabolism and cancer. However, the role of AMPK in carcinogenesis remains unclear. Here, through analysis of the TCGA melanoma dataset, we found that PRKAA2 gene that encodes the α2 subunit of AMPK is mutated in â¼9% of cutaneous melanomas, and these mutations tend to co-occur with NF1 mutations. Knockout of AMPKα2 promoted anchorage-independent growth of NF1-mutant melanoma cells, whereas ectopic expression of AMPKα2 inhibited their growth in soft agar assays. Moreover, loss of AMPKα2 accelerated tumor growth of NF1-mutant melanoma and enhanced their brain metastasis in immune-deficient mice. Our findings support that AMPKα2 serves as a tumor suppressor in NF1-mutant melanoma and suggest that AMPK could be a therapeutic target for treating melanoma brain metastasis.
RESUMEN
BACKGROUND AND PURPOSE: Previous work has focussed on changes in drug metabolism caused by altered activity of CYP3A in the presence of inflammation and, in particular, inflammation associated with malignancy. However, drug metabolism involves a number of other P450s, and therefore, we assessed the effect of cancer-related inflammation on multiple CYP enzymes using a validated drug cocktail. EXPERIMENTAL APPROACH: Patients with advanced stage ovarian cancer and healthy volunteers were recruited. Participants received caffeine, chlorzoxazone, dextromethorphan, and omeprazole as in vivo probes for CYP1A2, CYP2E1, CYP2D6, CYP3A, and CYP2C19. Blood was collected for serum C-reactive protein and cytokine analysis. KEY RESULTS: CYP2E1 activity was markedly up-regulated in cancer (6-hydroxychlorzoxazone/chlorzoxazone ratio of 1.30 vs. 2.75), while CYP3A phenotypic activity was repressed in cancer (omeprazole sulfone/omeprazole ratio of 0.23 vs. 0.49). Increased activity of CYP2E1 was associated with raised serum levels of IL-6, IL-8, and TNF-α. Repression of CYP3A correlated with raised levels of serum C-reactive protein, IL-6, IL-8, and TNF-α. CONCLUSIONS AND IMPLICATIONS: CYP enzyme activity is differentially affected by the presence of tumour-associated inflammation, affecting particularly CYP2E1- and CYP3A-mediated drug metabolism, and may have profound implications for drug development and prescribing in oncological settings.
Asunto(s)
Cafeína/farmacología , Clorzoxazona/análogos & derivados , Sistema Enzimático del Citocromo P-450/metabolismo , Dextrometorfano/farmacología , Omeprazol/análogos & derivados , Neoplasias Ováricas/inmunología , Neoplasias Ováricas/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Proteína C-Reactiva/análisis , Clorzoxazona/farmacología , Citocinas/sangre , Femenino , Humanos , Inflamación/inmunología , Inflamación/metabolismo , Persona de Mediana Edad , Omeprazol/farmacología , Neoplasias Ováricas/sangreRESUMEN
In humans, C-X-C chemokine receptor type 4 (CXCR4) is a protein that is encoded by the CXCR4 gene and binds the ligand CXCL12 (also known as SDF-1). The CXCR4-CXCL12 interaction in cancer elicits biological activities that result in tumor progression and has accordingly been the subject of significant investigation for detection and treatment of the disease. Peptidic antagonists have been labeled with a variety of radioisotopes for the detection of CXCR4, but the methodology utilizing small molecules has predominantly used radiometals. We report here the development of a 18F-radiolabeled cyclam-based small molecule radioprobe, [18F]MCFB, for imaging CXCR4 expression. The IC50 value of [19F]MCFB for CXCR4 was similar to that of AMD3465 (111.3 and 89.8 nM, respectively). In vitro binding assays show that the tracer depicted a differential CXCR4 expression, which was blocked in the presence of AMD3465, demonstrating the specificity of [18F]MCFB. Positron emission tomography (PET) imaging studies showed a distinct uptake of the radioprobe in lymphoma and breast cancer xenografts. High liver and kidney uptakes were seen with [18F]MCFB, leading us to further examine the basis of its pharmacokinetics in relation to the tracer's cationic nature and thus the role of organic cation transporters (OCTs). Substrate competition following the intravenous injection of metformin led to a marked decrease in the urinary excretion of [18F]MCFB, with moderate changes observed in other organs, including the liver. Our results suggest involvement of OCTs in the renal elimination of the tracer. In conclusion, the 18F-radiolabeled monocyclam, [18F]MCFB, has potential to detect tumor CXCR4 in nonhepatic tissues.
Asunto(s)
Fluorodesoxiglucosa F18/química , Compuestos Heterocíclicos/química , Neoplasias/metabolismo , Radiofármacos/química , Receptores CXCR4/metabolismo , Animales , Línea Celular Tumoral , Quimiocina CXCL12/metabolismo , Femenino , Técnicas de Silenciamiento del Gen , Xenoinjertos , Humanos , Concentración 50 Inhibidora , Ratones , Ratones Endogámicos NOD , Ratones Desnudos , Ratones SCID , Neoplasias/diagnóstico por imagen , Proteínas de Transporte de Catión Orgánico/metabolismo , Tomografía de Emisión de Positrones/métodos , Piridinas , Receptores CXCR4/genética , Eliminación Renal , Distribución TisularRESUMEN
BACKGROUND: Aberrant activation of Axl is implicated in the progression of hepatocellular carcinoma (HCC). We explored the biologic significance and preclinical efficacy of Axl inhibition as a therapeutic strategy in sorafenib-naive and resistant HCC. METHODS: We evaluated Axl expression in sorafenib-naive and resistant (SR) clones of epithelial (HuH7) and mesenchymal origin (SKHep-1) using antibody arrays and confirmed tissue expression. We tested the effect of Axl inhibition with RNA-interference and pharmacologically with R428 on a number of phenotypic assays. RESULTS: Axl mRNA overexpression in cell lines (n = 28) and RNA-seq tissue datasets (n = 373) correlated with epithelial-to-mesenchymal transition (EMT). Axl was overexpressed in HCC compared to cirrhosis and normal liver. We confirmed sorafenib resistance to be associated with EMT and enhanced motility in both HuH7-SR and SKHep-1-SR cells documenting a 4-fold increase in Axl phosphorylation as an adaptive feature of chronic sorafenib treatment in SKHep-1-SR cells. Axl inhibition reduced motility and enhanced sensitivity to sorafenib in SKHep-1SR cells. In patients treated with sorafenib (n = 40), circulating Axl levels correlated with shorter survival. CONCLUSIONS: Suppression of Axl-dependent signalling influences the transformed phenotype in HCC cells and contributes to adaptive resistance to sorafenib, providing a pre-clinical rationale for the development of Axl inhibitors as a measure to overcome sorafenib resistance.
Asunto(s)
Antineoplásicos/uso terapéutico , Carcinoma Hepatocelular/tratamiento farmacológico , Resistencia a Antineoplásicos/genética , Neoplasias Hepáticas/tratamiento farmacológico , Proteínas Proto-Oncogénicas/genética , Proteínas Tirosina Quinasas Receptoras/genética , Sorafenib/uso terapéutico , Adulto , Anciano , Antineoplásicos/farmacología , Línea Celular Tumoral , Movimiento Celular , Transición Epitelial-Mesenquimal , Femenino , Humanos , Masculino , Persona de Mediana Edad , Proteínas Proto-Oncogénicas/antagonistas & inhibidores , ARN Mensajero/metabolismo , Proteínas Tirosina Quinasas Receptoras/antagonistas & inhibidores , Sorafenib/farmacología , Tirosina Quinasa del Receptor AxlRESUMEN
The hypoxic response underlies the pathogenesis and malignant behavior of PCC/PGL. Regulation of PD-1 receptor-ligand signaling, a therapeutically actionable driver of the anti-tumor immune response, is a hypoxic-driven trait across malignancies. We evaluated the prognostic role of PD ligands in association with biomarkers of hypoxia and angiogenesis in patients with PCC/PGL. Tissue microarrays sections including consecutive cases diagnosed between 1983-2011 were stained for PD-L1 and 2, hypoxia inducible factor 1a (Hif-1a), Carbonic Anhydrase IX (CaIX), Vascular Endothelial Growth Factor-A (VEGF-A). We explored the biologic significance of PD ligands expression using gene set enrichment analysis (GSEA) on The Cancer Genome Atlas (TCGA) for PCC/PGL (n = 184). In total, 100 patients, 10% malignant, 64% PCC, 29% familial with median tumor size of 4.7 cm (range 1-14) were included. Median follow-up was 4.7 y. We found PD-L1 expression in 18% of PCC/PGL, which was independent of adverse pathological features including capsular (CI), vascular invasion (VI), necrosis (N) and expression of biomarkers of hypoxia. PD-L2 expression (16%) strongly correlated with CI, VI, N and malignant behavior (p < 0.05) and was associated with stronger Hif-1a and CaIX immunolabeling (p < 0.01). PD-L2 was predictive of shorter survival (162 versus 309 months, HR 3.1 95%CI 1.1-9.2, p = 0.02). GSEA on TGCA samples confirmed enrichment of transcripts involved in hypoxia and anti-cancer immunity. We report for the first time PD ligands expression in PCC/PGL with a distinctive prognostic, clinico-pathologic and immuno-biologic role. These findings support a potential therapeutic role for PD-1/PD-L1 targeted checkpoint inhibitors in these tumors. KEY MESSAGE The molecular mechanisms underlying immune evasion in malignant phaeochromocytomas and paragangliomas (PCC/PGL) are poorly understood. This study demonstrates for the first time a distinctive immune-biologic and prognostic role of programmed death ligands 1 and 2 (PD-L1, PD-L2), two actionable drivers of the anti-cancer immune response. RNA-sequencing of tumor tissues reveals enrichment of transcripts relating to hypoxia and immune-exhaustion to explain the adverse clinical course observed in PD-L2 overexpressing tumors. These findings provide a rationale for the development of anti PD-1 therapies in malignant PCC/PGL.
RESUMEN
Biguanides, such as the diabetes therapeutics metformin and phenformin, have shown antitumor activity both in vitro and in vivo. However, their potential effects on the tumor microenvironment are largely unknown. Here we report that phenformin selectively inhibits granulocytic myeloid-derived suppressor cells in spleens of tumor-bearing mice and ex vivo. Phenformin induces production of reactive oxygen species in granulocytic myeloid-derived suppressor cells, whereas the antioxidant N-acetylcysteine attenuates the inhibitory effects of phenformin. Co-treatment of phenformin enhances the effect of anti-PD-1 antibody therapy on inhibiting tumor growth in the BRAF V600E/PTEN-null melanoma mouse model. Combination of phenformin and anti PD-1 cooperatively induces CD8+ T-cell infiltration and decreases levels of proteins that are critical for immune suppressive activities of myeloid-derived suppressor cells. Our findings show a selective, inhibitory effect of phenformin on granulocytic myeloid-derived suppressor cell-driven immune suppression and support that phenformin improves the anti-tumor activity of PD-1 blockade immunotherapy in melanoma.
Asunto(s)
Melanoma/tratamiento farmacológico , Células Supresoras de Origen Mieloide/efectos de los fármacos , Neoplasias Experimentales , Fenformina/farmacología , Receptor de Muerte Celular Programada 1/antagonistas & inhibidores , Neoplasias Cutáneas/tratamiento farmacológico , Animales , Línea Celular Tumoral , Femenino , Citometría de Flujo , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Hipoglucemiantes/farmacología , Inmunohistoquímica , Inmunoterapia , Melanoma/metabolismo , Melanoma/patología , Ratones , Células Supresoras de Origen Mieloide/metabolismo , Células Supresoras de Origen Mieloide/patología , Receptor de Muerte Celular Programada 1/biosíntesis , Receptor de Muerte Celular Programada 1/genética , ARN Neoplásico/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Neoplasias Cutáneas/metabolismo , Neoplasias Cutáneas/patología , Células Tumorales CultivadasRESUMEN
Inactivation of the tumor suppressor neurofibromin 1 (NF1) presents a newly characterized melanoma subtype, for which currently no targeted therapies are clinically available. Preclinical studies suggest that extracellular signal-regulated kinase (ERK) inhibitors are likely to provide benefit, albeit with limited efficacy as a single agent; therefore, there is a need for rationally designed combination therapies. Here, we evaluate the combination of the ERK inhibitor SCH772984 and the biguanide phenformin. A combination of both compounds showed potent synergy in cell viability assays and cooperatively induced apoptosis. Treatment with both drugs was required to fully suppress mechanistic target of rapamycin signaling, a known effector of NF1 loss. Mechanistically, SCH772984 increased the oxygen consumption rate, indicating that these cells relied more on oxidative phosphorylation upon treatment. Consistently, SCH772984 increased expression of the mitochondrial transcriptional coactivator peroxisome proliferator-activated receptor gamma, coactivator 1-α. In contrast, cotreatment with phenformin, an inhibitor of complex I of the respiratory chain, decreased the oxygen consumption rate. SCH772984 also promoted the expansion of the H3K4 demethylase KDM5B (also known as JARID1B)-positive subpopulation of melanoma cells, which are slow-cycling and treatment-resistant. Importantly, phenformin suppressed this KDM5B-positive population, which reduced the emergence of SCH772984-resistant clones in long-term cultures. Our results warrant the clinical investigation of this combination therapy in patients with NF1 mutant melanoma.
Asunto(s)
Quinasas MAP Reguladas por Señal Extracelular/antagonistas & inhibidores , Indazoles/farmacología , Melanoma/tratamiento farmacológico , Neurofibromina 1/genética , Fenformina/farmacología , Piperazinas/farmacología , Apoptosis/efectos de los fármacos , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Sinergismo Farmacológico , Humanos , Indazoles/administración & dosificación , Melanoma/genética , Melanoma/patología , Mutación , Consumo de Oxígeno/efectos de los fármacos , Fenformina/administración & dosificación , Piperazinas/administración & dosificaciónRESUMEN
The protein kinase B-Raf proto-oncogene, serine/threonine kinase (BRAF) is an oncogenic driver and therapeutic target in melanoma. Inhibitors of BRAF (BRAFi) have shown high response rates and extended survival in patients with melanoma who bear tumors that express mutations encoding BRAF proteins mutant at Val600, but a vast majority of these patients develop drug resistance. Here we show that loss of stromal antigen 2 (STAG2) or STAG3, which encode subunits of the cohesin complex, in melanoma cells results in resistance to BRAFi. We identified loss-of-function mutations in STAG2, as well as decreased expression of STAG2 or STAG3 proteins in several tumor samples from patients with acquired resistance to BRAFi and in BRAFi-resistant melanoma cell lines. Knockdown of STAG2 or STAG3 expression decreased sensitivity of BRAF(Val600Glu)-mutant melanoma cells and xenograft tumors to BRAFi. Loss of STAG2 inhibited CCCTC-binding-factor-mediated expression of dual specificity phosphatase 6 (DUSP6), leading to reactivation of mitogen-activated protein kinase (MAPK) signaling (via the MAPKs ERK1 and ERK2; hereafter referred to as ERK). Our studies unveil a previously unknown genetic mechanism of BRAFi resistance and provide new insights into the tumor suppressor function of STAG2 and STAG3.
Asunto(s)
Antígenos Nucleares/genética , Resistencia a Antineoplásicos/genética , Indoles/uso terapéutico , Melanoma/tratamiento farmacológico , Proteínas Nucleares/genética , Inhibidores de Proteínas Quinasas/uso terapéutico , Sulfonamidas/uso terapéutico , Factor de Unión a CCCTC , Proteínas de Ciclo Celular/genética , Línea Celular Tumoral , Proteínas Cromosómicas no Histona/genética , Fosfatasa 6 de Especificidad Dual/metabolismo , Humanos , Inmunohistoquímica , Sistema de Señalización de MAP Quinasas , Melanoma/genética , Melanoma/secundario , Metástasis de la Neoplasia , Recurrencia Local de Neoplasia/genética , Proto-Oncogenes Mas , Proteínas Proto-Oncogénicas B-raf/antagonistas & inhibidores , Proteínas Represoras/metabolismo , Vemurafenib , CohesinasRESUMEN
The glycerophospholipid phosphatidylcholine is the most abundant phospholipid species of eukaryotic membranes and essential for structural integrity and signaling function of cell membranes required for cancer cell growth. Inhibition of choline kinase alpha (CHKA), the first committed step to phosphatidylcholine synthesis, by the selective small-molecule ICL-CCIC-0019, potently suppressed growth of a panel of 60 cancer cell lines with median GI50 of 1.12 µM and inhibited tumor xenograft growth in mice. ICL-CCIC-0019 decreased phosphocholine levels and the fraction of labeled choline in lipids, and induced G1 arrest, endoplasmic reticulum stress and apoptosis. Changes in phosphocholine cellular levels following treatment could be detected non-invasively in tumor xenografts by [18F]-fluoromethyl-[1,2-2H4]-choline positron emission tomography. Herein, we reveal a previously unappreciated effect of choline metabolism on mitochondria function. Comparative metabolomics demonstrated that phosphatidylcholine pathway inhibition leads to a metabolically stressed phenotype analogous to mitochondria toxin treatment but without reactive oxygen species activation. Drug treatment decreased mitochondria function with associated reduction of citrate synthase expression and AMPK activation. Glucose and acetate uptake were increased in an attempt to overcome the metabolic stress. This study indicates that choline pathway pharmacological inhibition critically affects the metabolic function of the cell beyond reduced synthesis of phospholipids.
Asunto(s)
Aminopiridinas/farmacología , Transformación Celular Neoplásica/efectos de los fármacos , Colina Quinasa/antagonistas & inhibidores , Puntos de Control de la Fase G1 del Ciclo Celular/efectos de los fármacos , Mitocondrias/efectos de los fármacos , Fosfatidilcolinas/metabolismo , Inhibidores de Proteínas Quinasas/farmacología , Compuestos de Piridinio/farmacología , Transducción de Señal/efectos de los fármacos , Animales , Apoptosis/efectos de los fármacos , Línea Celular Tumoral , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Colina/metabolismo , Citrato (si)-Sintasa/metabolismo , Estrés del Retículo Endoplásmico/efectos de los fármacos , Femenino , Técnica del Anticuerpo Fluorescente , Humanos , Metabolómica , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Mitocondrias/metabolismo , Tomografía de Emisión de Positrones , Especies Reactivas de Oxígeno/metabolismo , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
In this issue Kang et al. (2015) show that oncogenic BRAF(V600E) stimulates expression of ketogenic enzyme 3-hydroxy-3-methylglutaryl-CoA lyase and promotes the formation of the ketone body acetoacetate, which subsequently enhances BRAF(V600E)/MEK/ERK signaling.
Asunto(s)
Leucemia de Células Pilosas/metabolismo , MAP Quinasa Quinasa 1/metabolismo , Melanoma/metabolismo , Factor 1 de Transcripción de Unión a Octámeros/metabolismo , Oxo-Ácido-Liasas/metabolismo , Proteínas Proto-Oncogénicas B-raf/metabolismo , Transducción de Señal , HumanosRESUMEN
AIMS: Malignant transformation results in overexpression of choline-kinase (CHK) and altered choline metabolism, which is potentially detectable by immunohistochemistry (IHC). We investigated the utility of CHK-alpha (CHKA) IHC as a complement to current diagnostic investigation of prostate cancer by analysing expression patterns in normal (no evidence of malignancy) and malignant human prostate tissue samples. METHODS: As an initial validation, paraffin-embedded prostatectomy specimen blocks with both normal and malignant prostate tissue were analysed for CHKA protein and mRNA expression by western blot and quantitative reverse transcriptase PCR (qRT-PCR), respectively. Subsequently, 100 paraffin-embedded malignant prostate tumour and 25 normal prostate cores were stained for both Ki67 (labelling-index: LI) and CHKA expression. RESULTS: The validity of CHKA-antibody was verified using CHKA-transfected cells and siRNA knockdown. Immunoblotting of tissues showed good resolution of CHKA protein in malignant prostate, verifying use of the antibody for IHC. There was minimal qRT-PCR detectable CHKA mRNA in normal tissue, and conversely high expression in malignant prostate tissues. IHC of normal prostate cores showed mild (intensity) CHKA expression in only 28% (7/25) of samples with no Ki67 expression. In contrast, CHKA was expressed in all malignant prostate cores along with characteristically low proliferation (median 2% Ki67-LI; range 1-17%). Stratification of survival according to CHK intensity showed a trend towards lower progression-free survival with CHK score of 3. CONCLUSIONS: Increased expression of CHKA, detectable by IHC, is seen in malignant lesions. This relatively simple cost-effective technique (IHC) could complement current diagnostic procedures for prostate cancer and, therefore, warrants further investigation.
Asunto(s)
Biomarcadores de Tumor/análisis , Colina Quinasa/biosíntesis , Neoplasias de la Próstata/enzimología , Western Blotting , Colina Quinasa/análisis , Supervivencia sin Enfermedad , Humanos , Inmunohistoquímica , Estimación de Kaplan-Meier , Masculino , Pronóstico , Neoplasias de la Próstata/mortalidad , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Metabolic rearrangements subsequent to malignant transformation are not well characterized in endometrial cancer. Identification of altered metabolites could facilitate imaging-guided diagnosis, treatment surveillance, and help to identify new therapeutic options. Here, we used high-resolution magic angle spinning magnetic resonance mass spectroscopy on endometrial cancer surgical specimens and normal endometrial tissue to investigate the key modulators that might explain metabolic changes, incorporating additional investigations using qRT-PCR, Western blotting, tissue microarrays (TMA), and uptake assays of [(3)H]-labeled choline. Lipid metabolism was severely dysregulated in endometrial cancer with various amino acids, inositols, nucleobases, and glutathione also altered. Among the most important lipid-related alterations were increased phosphocholine levels (increased 70% in endometrial cancer). Mechanistic investigations revealed that changes were not due to altered choline transporter expression, but rather due to increased expression of choline kinase α (CHKA) and an activated deacylation pathway, as indicated by upregulated expression of the catabolic enzymes LYPLA1, LYPLA2, and GPCPD1. We confirmed the significance of CHKA overexpression on a TMA, including a large series of endometrial hyperplasia, atypical hyperplasia, and adenocarcinoma tissues, supporting a role for CHKA in malignant transformation. Finally, we documented several-fold increases in the uptake of [(3)H]choline in endometrial cancer cell lines compared with normal endometrial stromal cells. Our results validate deregulated choline biochemistry as an important source of noninvasive imaging biomarkers for endometrial cancer.
Asunto(s)
Colina Quinasa/biosíntesis , Colina/metabolismo , Neoplasias Endometriales/metabolismo , Fosfolípidos/metabolismo , Adenocarcinoma/metabolismo , Línea Celular , Línea Celular Tumoral , Colina Quinasa/metabolismo , Neoplasias Endometriales/enzimología , Femenino , Humanos , Hiperplasia/metabolismo , Metabolismo de los Lípidos , Persona de Mediana Edad , Fosfolipasas/metabolismo , Fosforilcolina/metabolismo , Transducción de Señal , Tioléster Hidrolasas/metabolismoRESUMEN
UNLABELLED: Deregulated cellular metabolism is a hallmark of many cancers. In addition to increased glycolytic flux, exploited for cancer imaging with (18)F-FDG, tumor cells display aberrant lipid metabolism. Pivalic acid is a short-chain, branched carboxylic acid used to increase oral bioavailability of prodrugs. After prodrug hydrolysis, pivalic acid undergoes intracellular metabolism via the fatty acid oxidation pathway. We have designed a new probe, 3-(18)F-fluoro-2,2-dimethylpropionic acid, also called (18)F-fluoro-pivalic acid ((18)F-FPIA), for the imaging of aberrant lipid metabolism and cancer detection. METHODS: Cell intrinsic uptake of (18)F-FPIA was measured in murine EMT6 breast adenocarcinoma cells. In vivo dynamic imaging, time course biodistribution, and radiotracer stability testing were performed. (18)F-FPIA tumor retention was further compared in vivo to (18)F-FDG uptake in several xenograft models and inflammatory tissue. RESULTS: (18)F-FPIA rapidly accumulated in EMT6 breast cancer cells, with retention of intracellular radioactivity predicted to occur via a putative (18)F-FPIA carnitine-ester. The radiotracer was metabolically stable to degradation in mice. In vivo imaging of implanted EMT6 murine and BT474 human breast adenocarcinoma cells by (18)F-FPIA PET showed rapid and extensive tumor localization, reaching 9.1% ± 0.5% and 7.6% ± 1.2% injected dose/g, respectively, at 60 min after injection. Substantial uptake in the cortex of the kidney was seen, with clearance primarily via urinary excretion. Regarding diagnostic utility, uptake of (18)F-FPIA was comparable to that of (18)F-FDG in EMT6 tumors but superior in the DU145 human prostate cancer model (54% higher uptake; P = 0.002). Furthermore, compared with (18)F-FDG, (18)F-FPIA had lower normal-brain uptake resulting in a superior tumor-to-brain ratio (2.5 vs. 1.3 in subcutaneously implanted U87 human glioma tumors; P = 0.001), predicting higher contrast for brain cancer imaging. Both radiotracers showed increased localization in inflammatory tissue. CONCLUSION: (18)F-FPIA shows promise as an imaging agent for cancer detection and warrants further investigation.
Asunto(s)
Radioisótopos de Flúor , Neoplasias Experimentales/diagnóstico por imagen , Ácidos Pentanoicos , Radiofármacos , Animales , Línea Celular Tumoral , Humanos , Ratones , Tomografía de Emisión de PositronesRESUMEN
PURPOSE: Expression of HER2 has profound implications on treatment strategies in various types of cancer. We investigated the specificity of radiolabeled HER2-targeting ZHER2:2891 Affibody, [(18)F]GE-226, for positron emission tomography (PET) imaging. EXPERIMENTAL DESIGN: Intrinsic cellular [(18)F]GE-226 uptake and tumor-specific tracer binding were assessed in cells and xenografts with and without drug treatment. Specificity was further determined by comparing tumor localization of a fluorescently labeled analogue with DAKO HercepTest. RESULTS: [(18)F]GE-226 uptake was 11- to 67-fold higher in 10 HER2-positive versus HER2-negative cell lines in vitro independent of lineage. Uptake in HER2-positive xenografts was rapid with net irreversible binding kinetics making possible the distinction of HER2-negative [MCF7 and MCF7-p95HER2: NUV60 (%ID/mL) 6.1 ± 0.7; Ki (mL/cm(3)/min) 0.0069 ± 0.0014] from HER2-positive tumors (NUV60 and Ki: MCF7-HER2, 10.9 ± 1.5 and 0.015 ± 0.0035; MDA-MB-361, 18.2 ± 3.4 and 0.025 ± 0.0052; SKOV-3, 18.7 ± 2.4 and 0.036 ± 0.0065) within 1 hour. Tumor uptake correlated with HER2 expression determined by ELISA (r(2) = 0.78), and a fluorophore-labeled tracer analogue colocalized with HER2 expression. Tracer uptake was not influenced by short-term or continuous treatment with trastuzumab in keeping with differential epitope binding, but reflected HER2 degradation by short-term NVP-AUY922 treatment in SKOV-3 xenografts (NUV60: 13.5 ± 2.1 %ID/mL vs. 9.0 ± 0.9 %ID/mL for vehicle or drug, respectively). CONCLUSIONS: [(18)F]GE-226 binds with high specificity to HER2 independent of cell lineage. The tracer has potential utility for HER2 detection, irrespective of prior trastuzumab treatment, and to discern HSP90 inhibitor-mediated HER2 degradation.
Asunto(s)
Radioisótopos de Flúor/farmacocinética , Neoplasias/diagnóstico por imagen , Tomografía de Emisión de Positrones/métodos , Radiofármacos/farmacocinética , Receptor ErbB-2/análisis , Proteínas Recombinantes de Fusión/farmacocinética , Animales , Línea Celular Tumoral , Femenino , Xenoinjertos , Humanos , Ratones Endogámicos BALB C , Ratones Desnudos , Neoplasias/genética , Neoplasias/metabolismoRESUMEN
Choline kinase alpha is hyperactivated in many solid tumours and regulates malignant progression, making it a promising cancer drug target. The successful design and synthesis of novel inhibitors with high cellular activity are described.
RESUMEN
Epidemiological studies have shown an association between statin use and a decreased risk of dementia. However, the mechanism by which this beneficial effect is brought about is unclear. In the context of Alzheimer's disease, at least three possibilities have been studied; reduction in amyloid beta peptide (Abeta) production, the promotion of alpha-secretase cleavage and positive effects on neurite outgrowth. By investigating the effects of mevalonate pathway blockade on neurite outgrowth using real-time imaging, we found that rather than promote the production of neurite extensions, inhibition rapidly induced cell rounding. Crucially, neurite-like structures were generated through the persistence of cell-cell and cell-substrate adhesions and not through a mechanism of positive outgrowth. This effect can be strikingly enhanced by the over-expression of human amyloid precursor protein and is isoprenoid rather than cholesterol dependent.