Phenotype-specific inhibition of the vascular smooth muscle cell cycle by high glucose treatment

Abstract

Aims/hypothesis Diabetes accelerates the development of atherosclerosis, which critically involves the proliferation of vascular smooth muscle cells (SMCs). However, how high glucose treatment regulates SMC proliferation is controversial. Considering the established SMC heterogeneity, we hypothesised that glucose treatment may have distinct effects on proliferation of the various phenotypic SMCs. Materials and methods We tested this possibility using cloned spindle-shaped and epithelioid SMCs and laser scanning cytometry. Results Our results showed that glucose treatment significantly inhibited the serum-independent proliferation of epithelioid SMCs, but had no effect on the proliferation of spindle-shaped cells either with or without serum stimulation. Furthermore, glucose treatment inhibited DNA synthesis, as detected by bromodeoxyuridine (BrdU) incorporation, and increased the production of reactive oxygen species in epithelioid SMCs. The inhibition of BrdU incorporation by glucose treatment was mimicked by glucosamine and phorbol 2,13-dibutyrate, a protein kinase C (PKC) activator, and reversed by azaserine, an inhibitor of the hexosamine pathway. In addition, the inhibitory effects of glucose treatment were blocked by GF 109203X (a PKC inhibitor) and PD98058 (a MAPK/ERK kinase, MEK inhibitor), and by knockdown of MEK1 by small interfering RNA (siRNA). The addition of either GF 109203X or PD98058 also reduced the phosphorylation of MAP kinase induced by glucose treatment. Conclusions/interpretation Glucose treatment inhibits the proliferation of epithelioid, but not spindle-shaped, vascular SMCs through the activation of PKC and the MAP kinase pathway, suggesting that the effects of hyperglycaemia on vascular disease depend on the phenotype of SMCs involved.

Induction of MicroRNA-1 by Myocardin in Smooth Muscle Cells Inhibits Cell Proliferation

“…Western blot analysis was performed as described previously 26. Briefly, protein was extracted from cells with RIPA buffer and equal amounts of protein from each sample (20 μg) were separated by 9% SDS-PAGE and transferred to nitrocellulose membranes.…”

Clinical Update: Cardiovascular Disease in Diabetes Mellitus

“…55,56 Vascular smooth muscle cells (VSMC) undergo phenotypic switching from a quiescent, contractile state to an activated, proliferative, migratory, dedifferentiated state in the setting of hyperglycemia. 57 High glucose concentrations lead to macrophage inflammation and enhancement of response to inflammation, 58 and even transient hyperglycemia leads to epigenetic changes with activation of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway that persists even after return to normoglycemia. 59 Under experimental conditions to simulate glycemic variability in individuals with diabetes, 6 hours of hyperglycemia alternating with normoglycemia within a 24 hour period promotes worsening of endothelial function and increased oxidative stress as compared with continuous hyperglycemia even at serum glucose concentrations as high as 282 mg/dL (15.6 mmol/L).…”

Hyperglycemia enhances function and differentiation of adult rat cardiac fibroblasts

“…Interestingly, Peiro et al (2001) and Zheng et al (2007) reported contradictory results that high glucose inhibited SMC proliferation (Peiro et al, 2001; Zheng et al, 2007). Varma et al (2005) reported that hyperglycemic concentrations of 20 mM and 40 mM glucose significantly decreased human umbilical vein endothelial cell (HUVEC) proliferation compared to 5 mM glucose media(Varma et al, 2005).…”