RESUMO
Therapeutic engineering of glucagon-like peptide 1 (GLP-1) has enabled development of new medicines to treat type 2 diabetes. These injectable analogs achieve robust glycemic control by increasing concentrations of "GLP-1 equivalents" (â¼50 pmol/L). Similar levels of endogenous GLP-1 occur after gastric bypass surgery, and mechanistic studies indicate glucose lowering by these procedures is driven by GLP-1. Therefore, because of the remarkable signaling and secretory capacity of the GLP-1 system, we sought to discover mechanisms that increase GLP-1 pharmacologically. To study active GLP-1, glucose-dependent insulinotropic polypeptide receptor (Gipr)-deficient mice receiving background dipeptidyl peptidase 4 (DPP4) inhibitor treatment were characterized as a model for evaluating oral agents that increase circulating GLP-1. A somatostatin receptor 5 antagonist, which blunts inhibition of GLP-1 release, and agonists for TGR5 and GPR40, which stimulate GLP-1 secretion, were investigated alone and in combination with the DPP4 inhibitor sitagliptin; these only modestly increased GLP-1 (â¼5-30 pmol/L). However, combining molecules to simultaneously intervene at multiple regulatory nodes synergistically elevated active GLP-1 to unprecedented concentrations (â¼300-400 pmol/L), drastically reducing glucose in Gipr null and Leprdb/db mice in a GLP-1 receptor-dependent manner. Our studies demonstrate that complementary pathways can be engaged to robustly increase GLP-1 without invasive surgical or injection regimens.
Assuntos
Diabetes Mellitus Tipo 2/tratamento farmacológico , Inibidores da Dipeptidil Peptidase IV/uso terapêutico , Drogas em Investigação/uso terapêutico , Peptídeo 1 Semelhante ao Glucagon/análogos & derivados , Modelos Biológicos , Receptores Acoplados a Proteínas G/agonistas , Administração Oral , Animais , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/metabolismo , Inibidores da Dipeptidil Peptidase IV/administração & dosagem , Desenho de Fármacos , Avaliação Pré-Clínica de Medicamentos , Resistência a Medicamentos , Sinergismo Farmacológico , Quimioterapia Combinada , Drogas em Investigação/administração & dosagem , Peptídeo 1 Semelhante ao Glucagon/administração & dosagem , Peptídeo 1 Semelhante ao Glucagon/sangue , Peptídeo 1 Semelhante ao Glucagon/uso terapêutico , Hiperglicemia/prevenção & controle , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Mutantes , Estudo de Prova de Conceito , Receptores Acoplados a Proteínas G/metabolismo , Receptores dos Hormônios Gastrointestinais/genética , Receptores dos Hormônios Gastrointestinais/metabolismo , Fosfato de Sitagliptina/uso terapêuticoRESUMO
Environmental-mediated drug-resistance (EM-DR) presents a major challenge for therapeutic development. Tissue microenvironment in the form of extracellular matrix, soluble factors, and stroma contribute to EM-DR. In multiple myeloma (MM), drug-resistance has hindered treatment success with 5-year survival rates remaining <50%. Here we evaluated IMGN901, a maytansinoid immunoconjugate, for its ability to overcome EM-DR alone or in combination with lenalidomide or dexamethasone. We show that while adhesion of MM cells to the extracellular matrix reduces potency of IMGN901, it remains cytotoxic with an average LC50=43 nM. However, only a combination of IMGN901, lenalidomide, and dexamethasone was able to overcome drug-resistance arising from the direct contact between MM and stromal cells. We demonstrate that multi-drug resistance protein-1 (MDR-1) was upregulated in MM cells grown in contact with stroma, likely responsible for the observed resistance. This study emphasizes the importance of incorporating the elements of tumor microenvironment during preclinical testing of novel therapeutics.
RESUMO
Multiple myeloma (MM) is an incurable plasma cell malignancy where nearly all patients succumb to a relapse. The current preclinical models of MM target the plasma cells, constituting the bulk of the tumor, leaving the cancer stem cells to trigger a relapse. Utilizing a three-dimensional tissue culture system where cells were grown in extracellular matrix designed to reconstruct human bone marrow, we tested the anti-multiple myeloma cancer stem cell (MM-CSC) potential of two natural product inhibitors of nuclear factor κB (NFκB). Here we show that parthenolide and andrographolide are potent anti-MM-CSC agents. Both natural products demonstrated preferential toxicity toward MM-CSCs over non-tumorigenic MM cells. Addition of the bone marrow stromal compartment abrogated andrographolide activity while having no effect on parthenolide cytoxicity. This is the first report of a natural product with anti-CSC activity in myeloma, suggesting that it has the potential to improve the survival of patients with MM by eliminating the relapse-causing MM-CSCs.