RESUMO
We set up a screening system to detect low-molecular-weight compounds that induce insulin expression in pancreatic acinar carcinoma AR42J cells. They can differentiate into insulin-producing cells with neuron-like morphological change when treated with activin A. We employed this morphological change for the screening of beta-cell inducers among various signal transduction inhibitors. As a result, a vinca alkaloid, conophylline, induced neurite formation at 0.1 approximately 0.3 microg/ml in 72 h, like activin A. Conophylline-treated cells were found to express insulin as measured at both mRNA and protein levels. By RT-PCR analysis, conophylline-treated cells were shown to express neurogenin3 strongly. They also expressed Beta2/NeuroD and Nkx2.2, but not Pax4 and PP. Although activin A induces nuclear translocation of Smad2, conophylline did not. But the latter induced p38 activation, like activin A, as detected by phosphorylation. Pretreatment with a p38-specific inhibitor, SB203580, lowered the conophylline-induced insulin production. Therefore, p38 activation would be involved in the differentiation of AR42J cells into insulin-producing cells. Studies on structure-activity relationship with conophyllidine, conofoline, conophyllinine, and related monomer alkaloids showed that the dimeric aspidosperma structure with the dihydrofuran unit in its center was essential for the differentiation-inducing activity.
Assuntos
Diferenciação Celular/efeitos dos fármacos , Insulina/biossíntese , Ilhotas Pancreáticas/efeitos dos fármacos , Alcaloides de Vinca/farmacologia , Animais , Carcinoma de Células Acinares/metabolismo , Carcinoma de Células Acinares/patologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Proteína Homeobox Nkx-2.2 , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/patologia , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patologia , Ratos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Relação Estrutura-Atividade , Fatores de Transcrição/biossíntese , Alcaloides de Vinca/química , Proteínas Quinases p38 Ativadas por MitógenoRESUMO
Three new 12beta-hydroxymultiflorane triterpenoid acids, sandorinic acids A-C (1-3), were isolated from the stem bark of Sandoricum indicum together with five known triterpenes (4-8). The structures of 1-3 were elucidated by spectral data interpretation. Compounds 1-8 were evaluated for their inhibiting activity against several tumor cell lines and for their effects on lymphocyte proliferation.