Downregulation of miR-4284 can Inhibit the Apoptosis of Human Arterial Smooth Muscle Cells (HASMCs) in Arteriosclerosis Obliterans (ASO).

Abstract

The disease arteriosclerosis obliterans (ASO) affects the lower extremities. ASO's mechanism involves the proliferation and migration of vascular smooth muscle cells (VSMCs). The miR-4284 is involved in several biological processes of the cardiovascular system, including VSMC proliferation, migration, and death. However, it is unknown if the miR-4284 gene is involved in the control of ASO. Furthermore, the molecular processes behind the contribution of human arterial smooth muscle cells (HASMCs), one of the most significant components of the arterial wall, to arteriosclerosis obliterans (ASO) pathogenesis remain unknown. Previously, we explored the alterations of miRNAs in the blood of ASO patients, and now we wanted to test further whether these changes also take place in the HASMCs that are responsible for the pathogenesis of ASO. The expression levels of miR-29a in arterial walls were analyzed via a real-time polymerase chain reaction. An ASO cell model was established to investigate the expression of miR- 4284 on HASMCs. The Transwell system and CCK-8 detection were used to assess the migration and proliferation of HASMCs. The proportion of apoptotic cells as well as the concentrations of apoptotic signal protein production were assessed using flow cytometry. A Western blot technique was used to identify B cell lymphoma-2 (Bcl2), Bcl2-associated X protein (BAX), as well as Xlinked inhibitors of apoptosis protein (XIAP). The results showed that PCR confirmed that the qualified production or expression of miR-4284 was significantly reduced in HASMCs after they were cultured without FBS and in an atmosphere of 1% O2 + 5% CO2 + 94% N2 and that glucose had no effect on its expression. MiR- 4284 has no effect on migration and proliferation, but downregulation of miR-4284 can decrease the apoptotic rate of HASMCs, as revealed by flow cytometry. Furthermore, western blot experiments showed that the expression of BAX was low, while the expression of the other two proteins, viz., Bcl2 and XIAP, was over-expressed. We found that miR-4284 downregulation enhanced Bcl2, as well as XIAP, and decreased Bax. This shows that downregulated miR-4284 regulates apoptosis-related protein expression in HASMCs. The mechanism is not clear, and we need further study to confirm it.