Abstract
MicroRNA-21 (miR-21) has been found to promote cell proliferation and survival. It has also been shown to exhibit an increased expression in a number of forms of cardiovascular disease. However, the mechanisms underlying the involvement of miR-21 in atherosclerosis remain to be elucidated. In the present study, it was demonstrated that miR-21 was upregulated in a time-dependent manner in response to high-concentration glucose stimulation in Raw 264.7 macrophages. High concentrations of glucose induce macrophage apoptosis. miR-21-inhibited macrophages treated with a normal concentration of glucose exhibited increased levels of cell apoptosis and augmented levels of activated caspase-3, while cells treated with an miR-21 inhibitor and a high concentration of glucose, revealed significantly increased levels of apoptosis. In addition, inhibition of miR-21 increased mRNA and protein levels of programmed cell death 4 (PDCD4), which, by contrast, were reduced in miR-21-inhibited cells that had been treated with a high concentration of glucose. In conclusion, miR-21 is sensitive to high-concentration glucose treatment in macrophages, and appears to have a protective effect in macrophage apoptosis induced by high concentrations of glucose via PDCD4.