RESUMO
Resistance to the BCR-ABL inhibitor imatinib mesylate (IM) poses a major problem for the treatment of chronic myeloid leukemia (CML). IM resistance often results from a secondary mutation in BCR-ABL that interferes with drug binding. However, in many instances, there is no mutation in BCR-ABL, and the basis of such BCR-ABL-independent IM resistance remains to be elucidated. To gain insight into BCR-ABL-independent IM resistance mechanisms, we performed a large-scale RNA interference screen and identified IM-sensitizing genes (IMSGs) whose knockdown renders BCR-ABL(+) cells IM-resistant. In these IMSG knockdown cells, RAF/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling is sustained after IM treatment because of up-regulation of PRKCH, which encodes the protein kinase C (PKC) family member PKCη, an activator of CRAF. PRKCH is also up-regulated in samples from CML patients with BCR-ABL-independent IM resistance. Combined treatment with IM and trametinib, a U.S. Food and Drug Administration-approved MEK inhibitor, synergistically kills BCR-ABL(+) IMSG knockdown cells and prolongs survival in mouse models of BCR-ABL-independent IM-resistant CML. Finally, we showed that CML stem cells contain high levels of PRKCH, and this contributes to their intrinsic IM resistance. Combined treatment with IM and trametinib synergistically kills CML stem cells with negligible effect on normal hematopoietic stem cells. Collectively, our results identify a therapeutically targetable mechanism of BCR-ABL-independent IM resistance in CML and CML stem cells.
Assuntos
Benzamidas/uso terapêutico , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Proteínas de Fusão bcr-abl/metabolismo , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Terapia de Alvo Molecular , Piperazinas/uso terapêutico , Pirimidinas/uso terapêutico , Animais , Benzamidas/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Modelos Animais de Doenças , Progressão da Doença , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Técnicas de Silenciamento de Genes , Genes Neoplásicos , Humanos , Mesilato de Imatinib , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Camundongos , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Células-Tronco Neoplásicas/efeitos dos fármacos , Células-Tronco Neoplásicas/patologia , Fosforilação/efeitos dos fármacos , Piperazinas/farmacologia , Proteína Quinase C/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Pirimidinas/farmacologia , RNA Interferente Pequeno/metabolismo , Análise de Sobrevida , Regulação para Cima/efeitos dos fármacos , Quinases raf/metabolismoRESUMO
BACKGROUND: The Modified Checklist for Autism in Toddlers (M-CHAT) is a screening tool for autism spectrum disorders in the clinic. However, the follow-up questions in the M-CHAT are difficult to implement on a paper format. OBJECTIVE: To compare the effectiveness of the M-CHAT on an electronic format versus paper format in an outpatient clinic setting. Methods. A prospective study used electronic M-CHAT on the iPad. A retrospective review of paper M-CHATs 6 months prior to implementation was used as the comparison group. RESULTS: A total of 176 participants completed the electronic M-CHAT format and 197 paper M-CHATs were retrospectively reviewed. The electronic format (3%) resulted in a significant difference in the frequency of children found to be at risk for autism compared with the paper version (11%); 99% of parents rated the experience as "good" or "excellent." CONCLUSION: The electronic format lowered both false at-risk screens and false not-at-risk screens and had higher parental satisfaction.
Assuntos
Lista de Checagem/tendências , Transtornos Globais do Desenvolvimento Infantil/diagnóstico , Computadores de Mão , Inquéritos e Questionários/normas , Instituições de Assistência Ambulatorial , Pré-Escolar , Documentação/tendências , Registros Eletrônicos de Saúde , Humanos , Lactente , Programas de Rastreamento/métodos , Programas de Rastreamento/tendências , Pediatria , Estudos Prospectivos , População UrbanaRESUMO
Ligand activation of peroxisome proliferator-activated receptor-ß/δ (PPARß/δ) and inhibition of cyclooxygenase-2 (COX2) activity by nonsteroidal anti-inflammatory drugs (NSAID) can both attenuate skin tumorigenesis. The present study examined the hypothesis that combining ligand activation of PPARß/δ with inhibition of COX2 activity will increase the efficacy of chemoprevention of chemically induced skin tumorigenesis over that observed with either approach alone. To test this hypothesis, wild-type and Pparß/δ-null mice were initiated with 7,12-dimethylbenz[a]anthracene (DMBA), topically treated with 12-O-tetradecanoylphorbol-13-acetate to promote tumorigenesis, and then immediately treated with topical application of the PPARß/δ ligand GW0742, dietary administration of the COX2 inhibitor nimesulide, or both GW0742 and nimesulide. Ligand activation of PPARß/δ with GW0742 caused a PPARß/δ-dependent delay in the onset of tumor formation. Nimesulide also delayed the onset of tumor formation and caused inhibition of tumor multiplicity (46%) in wild-type mice but not in Pparß/δ-null mice. Combining ligand activation of PPARß/δ with dietary nimesulide resulted in a further decrease of tumor multiplicity (58%) in wild-type mice but not in Pparß/δ-null mice. Biochemical and molecular analysis of skin and tumor samples show that these effects were due to the modulation of terminal differentiation, attenuation of inflammatory signaling, and induction of apoptosis through both PPARß/δ-dependent and PPARß/δ-independent mechanisms. Increased levels and activity of PPARß/δ by nimesulide were also observed. These studies support the hypothesis that combining ligand activation of PPARß/δ with inhibition of COX2 activity increases the efficacy of preventing chemically induced skin tumorigenesis as compared with either approach alone.
