RESUMEN
The CDK4/6 inhibitor, palbociclib (PAL), significantly improves progression-free survival in HR+/HER2- breast cancer when combined with anti-hormonals. We sought to discover PAL resistance mechanisms in preclinical models and through analysis of clinical transcriptome specimens, which coalesced on induction of MYC oncogene and Cyclin E/CDK2 activity. We propose that targeting the G1 kinases CDK2, CDK4, and CDK6 with a small-molecule overcomes resistance to CDK4/6 inhibition. We describe the pharmacodynamics and efficacy of PF-06873600 (PF3600), a pyridopyrimidine with potent inhibition of CDK2/4/6 activity and efficacy in multiple in vivo tumor models. Together with the clinical analysis, MYC activity predicts (PF3600) efficacy across multiple cell lineages. Finally, we find that CDK2/4/6 inhibition does not compromise tumor-specific immune checkpoint blockade responses in syngeneic models. We anticipate that (PF3600), currently in phase 1 clinical trials, offers a therapeutic option to cancer patients in whom CDK4/6 inhibition is insufficient to alter disease progression.
Asunto(s)
Ciclo Celular/efectos de los fármacos , Quinasa 2 Dependiente de la Ciclina/antagonistas & inhibidores , Quinasa 4 Dependiente de la Ciclina/antagonistas & inhibidores , Quinasa 6 Dependiente de la Ciclina/antagonistas & inhibidores , Neoplasias/tratamiento farmacológico , Femenino , Humanos , Masculino , Neoplasias/inmunologíaRESUMEN
c-Jun NH(2)-terminal kinase (JNK) plays an important role in insulin resistance; however, identification of pharmacologically potent and selective small molecule JNK inhibitors has been limited. Compound A has a cell IC(50) of 102 nM and is at least 100-fold selective against related kinases and 27-fold selective against glycogen synthase kinase-3beta and cyclin-dependent kinase-2. In C57BL/6 mice, compound A reduced LPS-mediated increases in both plasma cytokine levels and phosphorylated c-Jun in adipose tissue. Treatment of mice fed a high-fat diet with compound A for 3 wk resulted in a 13.1 +/- 1% decrease in body weight and a 9.3 +/- 1.5% decrease in body fat, compared with a 6.6 +/- 2.1% increase in body weight and a 6.7 +/- 2.1% increase in body fat in vehicle-treated mice. Mice pair fed to those that received compound A exhibited a body weight decrease of 7 +/- 1% and a decrease in body fat of 1.6 +/- 1.3%, suggesting that reductions in food intake could not account solely for the reductions in adiposity observed. Compound A dosed at 30 mg/kg for 13 days in high-fat fed mice resulted in a significant decrease in phosphorylated c-Jun in adipose tissue accompanied by a decrease in weight and reductions in glucose and triglycerides and increases in insulin sensitivity to levels comparable with those in lean control mice. The ability of compound A to reduce the insulin-stimulated phosphorylation of insulin receptor substrate-1 (IRS-1) von Ser307 and partially reverse the free fatty acid inhibition of glucose uptake in 3T3L1 adipocytes, suggests that enhancement of insulin signaling in addition to weight loss may contribute to the effects of compound A on insulin sensitization in vivo. Pharmacological inhibition of JNK using compound A may therefore offer an effective therapy for type 2 diabetes mediated at least in part via weight reduction.
Asunto(s)
Aminopiridinas/farmacología , Proteínas Quinasas JNK Activadas por Mitógenos/antagonistas & inhibidores , Inhibidores de Proteínas Quinasas/farmacología , Células 3T3-L1 , Tejido Adiposo Blanco/efectos de los fármacos , Tejido Adiposo Blanco/metabolismo , Aminopiridinas/farmacocinética , Animales , Glucemia/metabolismo , Peso Corporal/efectos de los fármacos , Citocinas/sangre , Grasas de la Dieta/administración & dosificación , Grasas de la Dieta/farmacología , Ingestión de Alimentos/efectos de los fármacos , Humanos , Insulina/sangre , Insulina/farmacología , Proteínas Sustrato del Receptor de Insulina/metabolismo , Resistencia a la Insulina , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Lipopolisacáridos/farmacología , Masculino , Ratones , Ratones Endogámicos C57BL , Proteína Quinasa 8 Activada por Mitógenos/antagonistas & inhibidores , Proteína Quinasa 8 Activada por Mitógenos/metabolismo , Obesidad/tratamiento farmacológico , Obesidad/etiología , Obesidad/patología , Fosforilación/efectos de los fármacos , Inhibidores de Proteínas Quinasas/farmacocinética , Proteínas Proto-Oncogénicas c-jun/metabolismo , Factor de Necrosis Tumoral alfa/farmacología , Células U937RESUMEN
The contribution of nutrient overload and associated inflammation to insulin resistance has highlighted several therapeutic targets including c-Jun N-terminal kinase (JNK) and S6 kinase (S6K). To investigate how a lipopolysaccharide (LPS)-mediated inflammatory response may modulate pathways implicated in insulin resistance, we characterized the LPS-induced changes in key biomarkers. Administration of 0.06-4 mg/kg LPS to C57BL/6 mice stimulated increases in plasma levels of TNFalpha, IL-12p40, IL-6 and MCP-1 and in JNK activity as measured by phosphorylated c-Jun in fat. For the first time, we show that LPS induces S6K activity by up to 6.1-fold, as measured by the phosphorylation of S6 ribosomal protein in liver, and increases by up to 1.8-fold, plasma levels of the novel pro-inflammatory cytokine osteopontin which is implicated in the pathogenesis of insulin resistance. These novel findings suggest that LPS administration may form the basis of an acute in vivo pharmacodynamic model for therapies targeting multiple pathways implicated in insulin resistance.