Assuntos
Antineoplásicos/farmacologia , Proliferação de Células/efeitos dos fármacos , Clorambucila/farmacologia , Leucemia Linfocítica Crônica de Células B/tratamento farmacológico , Piperazinas/farmacologia , Pirimidinas/farmacologia , Triazenos/farmacologia , Antineoplásicos Alquilantes/farmacologia , Benzamidas , Dano ao DNA/efeitos dos fármacos , Humanos , Mesilato de Imatinib , Técnicas In Vitro , Fosforilação/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-abl/antagonistas & inibidores , Pirimidinas/síntese química , Triazenos/síntese química , Células Tumorais CultivadasRESUMO
Hypothesis-generating epidemiological research has suggested that cancer burden is reduced in diabetics treated with metformin and experimental work has raised questions regarding the role of direct adenosine monophosphate-activated protein kinase (AMPK)-mediated anti-neoplastic effects of metformin as compared with indirect effects attributable to reductions in circulating insulin levels in the host. We treated both tumor LKB1 expression and host diet as variables, and observed that metformin inhibited tumor growth and reduced insulin receptor activation in tumors of mice with diet-induced hyperinsulinemia, independent of tumor LKB1 expression. In the absence of hyperinsulinemia, metformin inhibited only the growth of tumors transfected with short hairpin RNA against LKB1, a finding attributable neither to an effect on host insulin level nor to activation of AMPK within the tumor. Further investigation in vitro showed that cells with reduced LKB1 expression are more sensitive to metformin-induced adenosine triphosphate depletion owing to impaired ability to activate LKB1-AMPK-dependent energy-conservation mechanisms. Thus, loss of function of LKB1 can accelerate proliferation in contexts where it functions as a tumor suppressor, but can also sensitize cells to metformin. These findings predict that any clinical utility of metformin or similar compounds in oncology will be restricted to subpopulations defined by host insulin levels and/or loss of function of LKB1.
Assuntos
Antineoplásicos/farmacologia , Dieta , Metformina/farmacologia , Neoplasias Experimentais/tratamento farmacológico , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Quinases Ativadas por AMP , Animais , Western Blotting , Carcinoma Pulmonar de Lewis , Resistencia a Medicamentos Antineoplásicos/genética , Genes Supressores de Tumor , Hiperinsulinismo/tratamento farmacológico , Hipoglicemiantes/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neoplasias Experimentais/metabolismo , Proteínas Serina-Treonina Quinases/genética , Transdução de Sinais/efeitos dos fármacos , TransfecçãoRESUMO
The nm23 gene family is thought to be involved in physiopathological processes such as growth, differentiation and cancer promotion, progression or metastasis. We report here the mouse nm23-M3 and nm23-M4 complementary DNA sequences and the genomic cloning, characterization and tissue expression pattern of the nm23-M2, nm23-M3 and nm23-M4 genes, in comparison with their human and rat orthologs and with the human nm23-H1 and mouse nm23-M1 genes. The organization and structure of the members of this gene family are remarkably similar in human and rodents. Accordingly, the striking similarities between the human and mouse nm23 genes enable the use of mouse transgenic and knock-out models for studying the role of nucleoside diphosphate kinase isoforms in human physiopathology.
Assuntos
Proteínas Monoméricas de Ligação ao GTP/genética , Núcleosídeo-Difosfato Quinase/genética , Fatores de Transcrição/genética , Sequência de Aminoácidos , Animais , Northern Blotting , Clonagem Molecular , DNA/química , DNA/genética , DNA Complementar/química , DNA Complementar/genética , Embrião de Mamíferos/enzimologia , Embrião de Mamíferos/metabolismo , Éxons , Regulação da Expressão Gênica no Desenvolvimento , Regulação Enzimológica da Expressão Gênica , Genes/genética , Humanos , Hibridização In Situ , Íntrons , Isoenzimas/genética , Camundongos , Dados de Sequência Molecular , Nucleosídeo NM23 Difosfato Quinases , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Alinhamento de Sequência , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Sítio de Iniciação de TranscriçãoRESUMO
Neuroblastoma and its benign differentiated counterpart, ganglioneuroma, are paediatric neuroblastic tumours arising in the sympathetic nervous system. Their broad spectrum of clinical virulence is mainly related to heterogeneous biologic background and tumour differentiation. Neuroblastic tumours synthesize various neuropeptides acting as neuromodulators. Previous studies suggested that galanin plays a role in sympathetic tissue where it could be involved in differentiation and development. We investigated the expression and distribution of galanin and its three known receptors (Gal-R1, Gal-R2, Gal-R3) in 19 samples of neuroblastic tumours tissue by immunohistochemistry, in situ hybridization and fluorescent-ligand binding. This study provides clear evidence for galanin and galanin receptor expression in human neuroblastic tumours. The messengers coding for galanin, Gal-R1 and -R3 were highly expressed in neuroblastoma and their amount dramatically decreased in ganglioneuroma. In contrast, Gal-R2 levels remained unchanged. Double labelling studies showed that galanin was mainly co-expressed with its receptors whatever the differentiation stage. In neuroblastic tumours, galanin might promote cell-survival or counteract neuronal differentiation through the different signalling pathways mediated by galanin receptors. Finally, our results suggest that galanin influences neuroblastoma growth and development as an autocrine/paracrine modulator. These findings suggest potential critical implications for galanin in neuroblastic tumours development.