Résumé
Pancreatic adenocarcinoma (PAAD) is one of the most lethal malignancies. Although gemcitabine (GEM) is a standard treatment for PAAD, resistance limits its application and therapy. Secoemestrin C (Sec C) is a natural compound from the endophytic fungus Emericella, and its anticancer activity has not been investigated since it was isolated. Our research is the first to indicate that Sec C is a broad-spectrum anticancer agent and could exhibit potently similar anticancer activity both in GEM-resistant and GEM-sensitive PAAD cells. Interestingly, Sec C exerted a rapid growth-inhibiting effect (80% death at 6 h), which might be beneficial for patients who need rapid tumor shrinkage before surgery. Liquid chromatography/mass spectrometry and N-acetyl-l-cysteine (NAC) reverse assays show that Sec C sulfates cysteines to disrupt disulfide-bonds formation in endoplasmic reticulum (ER) proteins to cause protein misfolding, leading to ER stress and disorder of lipid biosynthesis. Microarray data and subsequent assays show that ER stress-mediated ER-associated degradation (ERAD) ubiquitinates and downregulates YAP to enhance ER stress via destruction complex (YAP-Axin-GSK-βTrCP), which also elucidates a unique degrading style for YAP. Potent anticancer activity in GEM-resistant cells and low toxicity make Sec C a promising anti-PAAD candidate.
Résumé
Aim To investigate the time-dependent effect of insulin on the expression of SREBP-1(sterol regulatory element binding protein-1),FAS(fat acid synthase)and lipid droplet formation in HKC cells(human renal proximal tubular epithelial cells line).MethodsHKC cells were respectively treated with 100 nmol·L~(-1) insulin for 0,2,4,6,12 h and 24 h.The analysis of SREBP-1 and FAS mRNA was performed by RT-PCR and the expression of SREBP-1 protein was detected by Western blot and immunocytochemistry.Furthermore,Oil Red O staining was used to determine cellular lipid droplet formation.ResultsCompared with HKC cells of 0 h group,there was no difference of SREBP-1 and FAS mRNA in HKC cells of 2 h group.However,the expression of SREBP-1 and FAS mRNA was significantly increased in HKC cells of 4,6 h and 12 h group.Further,the most expression of SREBP-1 and FAS mRNA was at 6 h group and was respectively increased by 3.578 and 4.272 times compared with 0 h group.The results of Western blot showed that the precursor and mature segments of SREBP-1 protein in 4,6 h and 12 h group HKC cells were increased and those of 6 h group HKC cells were the highest and about 4.106 and 5.167 times than those of 0 h group HKC cells.Immunocytochemistry presented the result that SREBP-1 protein was located in the plasma and the expression of 4,6 h and 12 h group HKC cells was significantly higher than that of 0,2 h and 24 h group HKC cells.The result of Oil Red O staining showed that lipid droplet markedly deposited in 6 h group HKC cells,contrarily,no lipid droplet was found in HKC cells of other groups.ConclusionAbove results suggested that insulin up-regulated SREBP-1 and FAS in time-dependent manner that led to cellular lipid droplet deposit,which may play an important role in the pathogenesis of renal lipid accumulation in metabolism syndrome.