Abstract
The present study aimed to investigate the expression of microRNA (miR)‑133a in patients with or without acute myocardial infarction (AMI) following radical surgery for gastric cancer, and to explore its underlying mechanisms. Blood samples were collected from patients with or without AMI in order to detect the expression levels of miR‑133a and endothelial injury markers. In addition, an AMI rat model was established. Reverse transcription‑quantitative polymerase chain reaction was used to detect the mRNA expression levels of miR‑133a and B‑cell lymphoma 2‑like 1 (Bcl2l1). In addition, an ELISA assay was used for endothelial injury marker analysis. To investigate the effects of miR‑133a on human umbilical vein endothelial cells (HUVECs), a miR‑133a inhibitor was used. Cell proliferation and apoptosis were subsequently detected using an MTT assay and flow cytometry. Western blot analysis was also conducted to detect Bcl2l1 protein expression. The results suggested that patients with AMI exhibited significantly increased expression of endothelial injury markers (von Willebrand factor, heart‑type fatty acid‑binding protein and cardiac troponin I) and miR‑133a in blood samples compared with patients without AMI. In addition, treatment with a miR‑133a mimic was able to upregulate the expression of endothelial injury markers in an AMI rat model, whereas treatment with a miR‑133a inhibitor had the opposite effect. Furthermore, cellular experiments indicated that a miR‑133a inhibitor could promote HUVEC proliferation and reduce cell apoptosis. The present results also confirmed that miR‑133a directly targets Bcl2l1 and negatively regulates Bcl2l1 expression. In conclusion, the results of the present study suggested that miR‑133a was involved in the endothelial injury process after AMI by targeting Bcl2l1.