RESUMEN
Heart failure (HF) represents the terminal stage of cardiovascular diseases, with limited therapeutic options currently available. Calotropin (CAL), a cardenolide isolated from Calotropis gigantea, exhibits a similar chemical structure and inhibitory effect on Na+/K+-ATPase to digoxin, a positive inotropic drugs used in heart failure treatment. However, the specific effect of calotropin in ischemic HF (IHF) remains unknown. The objective of this study is to assess the anti-HF effect and clarify its underlying mechanisms. The left anterior descending (LAD) artery ligation on Male Sprague-Dawley (SD) rats was used to construct ischemic HF model. Daily administration of CAL at 0.05â¯mg/kg significantly enhanced ejection fraction (EF) and fractional shortening (FS), while inhibiting cardiac fibrosis in IHF rats. CAL reduced the OGD/R-induced H9c2 cell injury. Furthermore, CAL upregulated the expression of SERCA2a and SIRT1. The cardioprotective effect of CAL against IHF was abrogated in the presence of the SIRT1 inhibitor EX527. Notably, we identified FOXD3 as a pivotal transcription factor mediating CAL-induced SERCA2a regulation. CAL promoted the deacetylation and nuclear translocation of FOXD3 in a SIRT1-dependent manner. In conclusion, our study explores a novel mechanism of calotropin for improving cardiac dysfunction in ischemic heart failure by regulating SIRT1/FOXD3/SERCA2a pathway.
RESUMEN
The adhesion mediated drug resistance in cancer cells resulted from adhesion of the extracellular matrix is a major cause for multidrug resistance (MDR) and leads chemotherapeutic failure for colon cancer. In this study, we explored the role of 67-kDa laminin receptor (67LR) in chemotherapeutic drug resistance in colon cancer cells. SiRNA-mediated knockdown of 67LR decreased the cell adhesion when laminins were applied. Moreover, 67LR knockdown increased the expression of pro-apoptotic gene Bax but inhibited the expression of anti-apoptotic gene Bcl-2. Enhanced apoptosis was observed in 67LR siRNA-transfected SW480 cell when the cell was treated with doxorubicin for apoptosis induction. Furthermore, MTT assay revealed that the IC50 of chemotherapeutic toward SW480 cell adhesion to laminins was reduced after 67LR knockdown, indicating there was a significant increase of drug sensitivity in SW480 cell. In conclusion, our study demonstrated that 67LR plays a considerable role in the development of colon cancer MDR.