RESUMO
Hormones regulate hepatic gene expressions to maintain metabolic homeostasis. Ectonucleotide pyrophosphatase/phosphodiesterase 1 has been thought to interfere with insulin signaling. To determine its potential role in the regulation of metabolism, we analyzed its gene (Enpp1) expression in the liver of rats experiencing fasting and refeeding cycles, and in primary rat hepatocytes and human hepatoma HepG2 cells treated with insulin and dexamethasone using northern blot and real-time PCR techniques. Hepatic Enpp1 expression was induced by fasting and reduced by refeeding in the rat liver. In primary rat hepatocytes and HepG2 hepatoma cells, insulin reduced Enpp1 mRNA abundance, whereas dexamethasone induced it. Dexamethasone disrupted the insulin-reduced Enpp1 expression in primary hepatocytes. This is in contrast to the responses of the expression of the cytosolic form of phosphoenolpyruvate carboxykinase gene to the same hormones, where insulin reduced it significantly in the process. In addition, the dexamethasone-induced Enpp1 gene expression was attenuated in the presence of 8-Br-cAMP. In conclusion, we demonstrated for the first time that hepatic Enpp1 is regulated in the cycle of fasting and refeeding, a process that might be attributed to insulin-reduced Enpp1 expression. This insulin-reduced Enpp1 expression might play a role in the development of complications in diabetic patients.
Assuntos
Humanos , Animais , Masculino , Ratos , Pirofosfatases/genética , RNA Mensageiro/efeitos dos fármacos , Dexametasona/farmacologia , Diester Fosfórico Hidrolases/genética , Glucocorticoides/farmacologia , Hipoglicemiantes/farmacologia , Insulina/farmacologia , Fígado/enzimologia , Pirofosfatases/biossíntese , Pirofosfatases/efeitos dos fármacos , Resistência à Insulina , RNA Mensageiro/metabolismo , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Indução Enzimática/efeitos dos fármacos , Jejum/metabolismo , Ratos Sprague-Dawley , Diester Fosfórico Hidrolases/biossíntese , Diester Fosfórico Hidrolases/efeitos dos fármacos , Células Hep G2 , Reação em Cadeia da Polimerase em Tempo RealRESUMO
@# Objective: To explore the effect of shRNA interfering BAMBI (bone morphogenetic protein and activin membrane bound inhibitor) on the proliferation, apoptosis, invasion and migration of human colon cancer SW480 cells and the possible mechanisms. Methods: After successful transfection with sh-BAMBI in SW480 cells, the mRNA and protein epxressions of BAMBI were detected by qRT-PCR and Western blotting, respectively. Cell proliferation was measured by MTT; apoptosis was tested by Hoechst33258 staining; cell invasion was detected by transwell assay; and cell migration was measured by wound healing assay. The expressions of TGF-β/ Smad/2 signaling pathway related proteins were detected by Western blotting. Results: The mRNA and protein levels of BAMBI in shBAMBI group were lower than those of control group (P<0.05). Compared with control group, cell proliferation in sh-BAMBI group was obviously decreased (P<0.05), while apoptosis was obviously increased (P<0.01); in the meanwhile, cell invasion and migration in sh-BAMBI group were significantly reduced (P<0.05). In addition, the protein level of TGF-β and the ratio of p-Smad/2/ Smad/2 in shBAMBI group were significantly higher than those in control group (P<0.05). Conclusion: Interference of BAMBI by shRNA inhibits proliferation, invasion and migration but induces apoptosis of human colon cancer SW480 cells and activates TGF-β/Smad/2 pathway.