RESUMEN
BACKGROUND & AIMS: Intratumoral lactate accumulation and acidosis impair T-cell function and antitumor immunity. Interestingly, expression of the lactate transporter monocarboxylate transporter (MCT) 4, but not MCT1, turned out to be prognostic for the survival of patients with rectal cancer, indicating that single MCT4 blockade might be a promising strategy to overcome glycolysis-related therapy resistance. METHODS: To determine whether blockade of MCT4 alone is sufficient to improve the efficacy of immune checkpoint blockade (ICB) therapy, we examined the effects of the selective MCT1 inhibitor AZD3965 and a novel MCT4 inhibitor in a colorectal carcinoma (CRC) tumor spheroid model co-cultured with blood leukocytes in vitro and the MC38 murine CRC model in vivo in combination with an antibody against programmed cell death ligand-1(PD-L1). RESULTS: Inhibition of MCT4 was sufficient to reduce lactate efflux in three-dimensional (3D) CRC spheroids but not in two-dimensional cell-cultures. Co-administration of the MCT4 inhibitor and ICB augmented immune cell infiltration, T-cell function and decreased CRC spheroid viability in a 3D co-culture model of human CRC spheroids with blood leukocytes. Accordingly, combination of MCT4 and ICB increased intratumoral pH, improved leukocyte infiltration and T-cell activation, delayed tumor growth, and prolonged survival in vivo. MCT1 inhibition exerted no further beneficial impact. CONCLUSIONS: These findings demonstrate that single MCT4 inhibition represents a novel therapeutic approach to reverse lactic-acid driven immunosuppression and might be suitable to improve ICB efficacy.
Asunto(s)
Neoplasias Colorrectales , Inhibidores de Puntos de Control Inmunológico , Animales , Humanos , Ratones , Línea Celular Tumoral , Neoplasias Colorrectales/tratamiento farmacológico , Glucólisis , Inhibidores de Puntos de Control Inmunológico/farmacología , Inhibidores de Puntos de Control Inmunológico/uso terapéutico , Ácido Láctico/metabolismo , Transportadores de Ácidos Monocarboxílicos/antagonistas & inhibidoresRESUMEN
Due to increased lactate production during glucose metabolism, tumor cells heavily rely on efficient lactate transport to avoid intracellular lactate accumulation and acidification. Monocarboxylate transporter 4 (MCT4/SLC16A3) is a lactate transporter that plays a central role in tumor pH modulation. The discovery and optimization of a novel class of MCT4 inhibitors (hit 9a), identified by a cellular screening in MDA-MB-231, is described. Direct target interaction of the optimized compound 18n with the cytosolic domain of MCT4 was shown after solubilization of the GFP-tagged transporter by fluorescence cross-correlation spectroscopy and microscopic studies. In vitro treatment with 18n resulted in lactate efflux inhibition and reduction of cellular viability in MCT4 high expressing cells. Moreover, pharmacokinetic properties of 18n allowed assessment of lactate modulation and antitumor activity in a mouse tumor model. Thus, 18n represents a valuable tool for investigating selective MCT4 inhibition and its effect on tumor biology.
Asunto(s)
Antineoplásicos/uso terapéutico , Transportadores de Ácidos Monocarboxílicos/antagonistas & inhibidores , Proteínas Musculares/antagonistas & inhibidores , Neoplasias/tratamiento farmacológico , Ácidos Picolínicos/uso terapéutico , Sulfonamidas/uso terapéutico , Animales , Antineoplásicos/síntesis química , Antineoplásicos/farmacología , Línea Celular Tumoral , Ensayos de Selección de Medicamentos Antitumorales , Femenino , Células HEK293 , Humanos , Ácido Láctico/metabolismo , Ratones Endogámicos C57BL , Ratones Desnudos , Ratones SCID , Estructura Molecular , Ácidos Picolínicos/síntesis química , Ácidos Picolínicos/farmacología , Relación Estructura-Actividad , Sulfonamidas/síntesis química , Sulfonamidas/farmacología , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
The PI3K/PTEN/Akt signal transduction pathway plays a key role in many tumors. Downstream targets of this pathway include the Forkhead family of transcription factors (FOXO1a, FOXO3a, FOXO4). In PTEN null cells, FOXO1a is inactivated by PI3K-dependent phosphorylation and mislocalization to the cytoplasm, yet still undergoes nucleocytoplasmic shuttling. Since forcible localization of FOXO1a to the nucleus can reverse tumorigenicity of PTEN null cells, a high-content, chemical genetic screen for inhibitors of FOXO1a nuclear export was performed. The compounds detected in the primary screen were retested in secondary assays, and structure-function relationships were identified. Novel general export inhibitors were found that react with CRM1 as well as a number of compounds that inhibit PI3K/Akt signaling, among which are included multiple antagonists of calmodulin signaling.
Asunto(s)
Transporte Activo de Núcleo Celular/efectos de los fármacos , Proteínas de Unión al ADN/metabolismo , Diseño de Fármacos , Inhibidores Enzimáticos/farmacología , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Fosfatidilinositol 3-Quinasas/metabolismo , Receptores Citoplasmáticos y Nucleares , Factores de Transcripción/metabolismo , Animales , Bencimidazoles/farmacología , Benzotiazoles/farmacología , Calmodulina/metabolismo , Núcleo Celular/metabolismo , Proteína Forkhead Box O1 , Factores de Transcripción Forkhead , Humanos , Carioferinas/metabolismo , Modelos Moleculares , Inhibidores de las Quinasa Fosfoinosítidos-3 , Monoéster Fosfórico Hidrolasas/deficiencia , Monoéster Fosfórico Hidrolasas/genética , Fosforilación , Transducción de Señal/efectos de los fármacos , Células Tumorales Cultivadas , Proteína Exportina 1RESUMEN
The mammalian DAF-16-like transcription factors, FKHR, FKHRL1, and AFX, function as key regulators of insulin signaling, cell cycle progression, and apoptosis downstream of phosphoinositide 3-kinase. Gene activation through binding to insulin response sequences (IRS) has been thought to be essential for mediating these functions. However, using transcriptional profiling, chromatin immunoprecipitation, and functional experiments, we demonstrate that rather than activation of IRS regulated genes (Class I transcripts), transcriptional repression of D-type cyclins (in Class III) is required for FKHR mediated inhibition of cell cycle progression and transformation. These data suggest that a novel mechanism of FKHR-mediated gene regulation is linked to its activity as a suppressor of tumor growth.