MicroRNA-29b upregulation improves myocardial fibrosis and cardiac function in myocardial infarction rats through targeting SH2B3.

OBJECTIVE: Myocardial fibrosis (MF) seriously affects normal cardiac function. Meanwhile, MF at post-myocardial infarction (MI) is the leading cause of cardiac dysfunction in patients with acute myocardial infarction (AMI). Therefore, the aim of this study was to investigate the potential effect of microRNA-29b on MF and cardiac function after MI in rats. MATERIALS AND METHODS: In vivo MI model was constructed by ligation of the left anterior descending coronary artery in Sprague-Dawley rats. Lentivirus overexpressing microRNA-29b was established and transfected to up-regulate microRNA-29b expression in rat myocardial tissues. The effect of microRNA-29b on luciferase activity of SH2B3 3'UTR was detected by the luciferase reporter gene assay. The mRNA levels of microRNA-29b, SH1B3, COL1A1, and α-SMA in the infarct border zone and cardiomyocytes were detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Meanwhile, the protein levels of SH1B3, COL1A1, and α-SMA in the MI border zone and cardiomyocytes were determined by Western blot. In addition, cardiac function and MF in MI rats were evaluated by echocardiography, hematoxylin and eosin (HE) and Masson staining, respectively. RESULTS: MicroRNA-29b expression decreased significantly in the infarct border zone at day 28 after MI (p<0.05). In addition, microRNA-29b overexpression in myocardial tissues of MI rats significantly improved impaired cardiac function, reduced collagen volume fraction and down-regulated the expressions of COL1A1 and ɑ-SMA. Subsequent luciferase reporter gene assay verified the binding relation between microRNA-29b and SH2B3. Furthermore, the expressions of COL1A1 and ɑ-SMA were confirmed negatively regulated by SH2B3. CONCLUSIONS: MicroRNA-29b overexpression alleviates MF and cardiac dysfunction in MI rats through targeting SH2B3.

Apatinib resensitizes cisplatin-resistant non-small cell lung carcinoma A549 cell through reversing multidrug resistance and suppressing ERK signaling pathway.

OBJECTIVE: To observe the reversal effect of apatinib on the resistance to cisplatin (DDP) of A549/cisplatin (A549/DDP) cells and its relevant mechanism. MATERIALS AND METHODS: A549/DDP cells were treated with the control method, apatinib alone, DDP alone and DDP combined with apatinib. The cell proliferation was detected by the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and the cell clone formation assay. The cell apoptosis was detected by Hoechst 33258 staining and annexin V and propidium iodide (PI) double labeling. The changes in apoptotic proteins, multidrug resistance protein 1 (MDR1) and extracellular signal-regulated kinase (ERK) signaling pathway proteins in each group after treatment were detected by Western blotting. RESULTS: MTT assay results showed that compared with A549 cells, A549/DDP cells had obvious resistance to DDP. MTT assay and cell clone formation assay revealed that the tumor inhibition rate of the sub-lethal dose of apatinib (10 µM) combined with DDP was higher than that of DDP alone. The apoptosis detection results indicated that the proportion of apoptotic cells in the apatinib (10 µM) combined with DDP group was significantly increased. Western blotting results revealed that compared with that in parental A549 cells, the expression level of MDR1 in A549/DDP cells was significantly increased, and the ERK signaling pathway was activated. In the apatinib combined with DDP group, the levels of cleaved caspase-3, cleaved caspase-9 and B-cell lymphoma-2 (Bcl-2)-associated X (BAX) proteins were significantly upregulated, while the level of Bcl-2 proteins was downregulated. Apatinib could inhibit the expression of MDR1 and the activity of the ERK signaling pathway in a dose-dependent manner. CONCLUSIONS: Apatinib can restore the sensitivity of A549/DDP cells to DDP by down-regulating the expression level of MDR1 and inhibiting the activity of the ERK signaling pathway.