RESUMO
Mutations in the genes encoding isocitrate dehydrogenase 1 and 2 (IDH1/2) occur in a variety of tumor types, resulting in production of the proposed oncometabolite, 2-hydroxyglutarate (2-HG). How mutant IDH and 2-HG alter signaling pathways to promote cancer, however, remains unclear. Additionally, there exist relatively few cell lines with IDH mutations. To examine the effect of endogenous IDH mutations and 2-HG, we created a panel of isogenic epithelial cell lines with either wild-type IDH1/2 or clinically relevant IDH1/2 mutations. Differences were noted in the ability of IDH mutations to cause robust 2-HG accumulation. IDH1/2 mutants that produce high levels of 2-HG cause an epithelial-mesenchymal transition (EMT)-like phenotype, characterized by changes in EMT-related gene expression and cellular morphology. 2-HG is sufficient to recapitulate aspects of this phenotype in the absence of an IDH mutation. In the cells types examined, mutant IDH-induced EMT is dependent on up-regulation of the transcription factor ZEB1 and down-regulation of the miR-200 family of microRNAs. Furthermore, sustained knockdown of IDH1 in IDH1 R132H mutant cells is sufficient to reverse many characteristics of EMT, demonstrating that continued expression of mutant IDH is required to maintain this phenotype. These results suggest mutant IDH proteins can reversibly deregulate discrete signaling pathways that contribute to tumorigenesis.
Assuntos
Transição Epitelial-Mesenquimal , Regulação Enzimológica da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Proteínas de Homeodomínio/metabolismo , Isocitrato Desidrogenase/biossíntese , MicroRNAs/biossíntese , Mutação de Sentido Incorreto , Proteínas de Neoplasias/metabolismo , Neoplasias/metabolismo , RNA Neoplásico/biossíntese , Fatores de Transcrição/metabolismo , Substituição de Aminoácidos , Linhagem Celular Tumoral , Glutaratos/metabolismo , Proteínas de Homeodomínio/genética , Humanos , Isocitrato Desidrogenase/genética , MicroRNAs/genética , Proteínas de Neoplasias/genética , Neoplasias/genética , Neoplasias/patologia , RNA Neoplásico/genética , Fatores de Transcrição/genética , Regulação para Cima/genética , Homeobox 1 de Ligação a E-box em Dedo de ZincoRESUMO
B-cell activating factor of the TNF family (BAFF) is critical for the survival and maturation of B cells. The molecular mechanisms by which BAFF regulates the survival of developing B cells are becoming better understood. Recent evidence has begun to emerge demonstrating a role for the PI3K/Akt signalling pathway in response to BAFF. However, the importance of the PI3K family for BAFF-signalling and the effects of loss of PI3K function on BAFF responses are still unknown. We therefore investigated the BAFF-mediated responses of B cells deficient for the PI3K catalytic subunit P110delta. We find that the loss of P110delta impairs the BAFF-mediated survival of cultured B cells demonstrating a direct role for this member of the PI3K family in regulating the survival of B cells in response to BAFF. P110delta was required for the growth of B cells in response to BAFF and was critical for the upregulation of the receptor for BAFF following BCR crosslinking. Our findings reveal an important role for p110delta in regulating B-cell responses to BAFF.