MiR-29c reduces the cisplatin resistance of non-small cell lung cancer cells by negatively regulating the PI3K/Akt pathway.

In previous studies, miR-29s showed tumor suppressor properties against lung cancer, which improved the survival of patients upon the administration of chemotherapy via an unknown mechanism. Here, we investigated the regulatory effects of miR-29s on the cisplatin resistance of NSCLC cells. The expression of miR-29s was assessed in 130 clinical patients and in cisplatin-treated NSCLS cell lines. MiR-29c expression was decreased in 77% of NSCLC patients. Cisplatin treatment increased the expression of miR-29c and decreased the expression of its oncogenic target AKT2 in NSCLC cell lines. A Kaplan-Meier survival analysis indicated that higher miR-29c levels led to a longer disease-free survival. In particular, patients who experienced cancer recurrences after cisplatin chemotherapy exhibited a lower level of miR-29c expression, suggesting that miR-29c activation may contribute to the chemotherapeutic efficiency of cisplatin. The enforced expression of miR-29c enhanced the cisplatin sensitivity of NSCLC cells, while the knocking down of miR-29c led to cisplatin resistance. MiR-29c amplified the therapeutic effects of cisplatin in vivo. Rescue experiments suggested that miR-29c regulates the cisplatin resistance of NSCLS cells by negatively regulating the PI3K/Akt pathway. Overall, our results demonstrated that miR-29c enhances the sensitivity of NSCLC cells to cisplatin by targeting the PI3K/Akt pathway.

Impaired myocardium energetics associated with the risk for new-onset atrial fibrillation after isolated coronary artery bypass graft surgery.

BACKGROUND: New-onset postoperative atrial fibrillation (POAF) is one of the most common complications occurring in 10-40% of patients after coronary artery bypass graft (CABG) surgery. Recent studies suggest that dysmetabolism may contribute to the pathogenesis of atrial fibrillation; however, the putative mechanism in patients undergoing CABG surgery is unknown. Peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) has been demonstrated as a master regulator of myocardial energy metabolism, and glucose transporter 3 (GLUT3) has both a higher affinity for glucose and a much greater transport capacity compared with GLUT1, GLUT2, and GLUT4. We sought to evaluate the role of energy metabolism, especially the glucose metabolism, on patients after isolated CABG surgery. METHODS AND RESULTS: Right atrial appendages were obtained from 79 patients who were in normal sinus rhythm and undergoing isolated CABG; those who exhibited new-onset POAF (n=22) or remained in sinus rhythm (n=57) were prospectively matched on the basis of preoperative, intraoperative, and postoperative characteristics. POAF was assessed by electrocardiogram and must have required the initiation of antiarrhythmic therapy or anticoagulation. Local PGC-1α and GLUT3 concentrations were quantified by enzyme-linked immunosorbent assay in tissue homogenates. The comparison of mRNA expression was tested by quantitative real-time PCR. PGC-1α and GLUT3 levels and the related protein mRNA expression were significantly reduced in POAF patients compared with controls (P<0.05). This selective reduction in PGC-1α was associated with the presence of diabetes mellitus (P<0.05). CONCLUSION: Patients who have low PGC-1α and GLUT3 levels are at increased risk for new-onset POAF. The myofibrillar energetic impairment may be important in the pathogenesis of atrial fibrillation.