Pollen typhae total flavone suppresses A7r5 cell proliferation promoted by insulin involving the MEK1/2-ERK1/2 cascades.

ABSTRACT

Pollen typhae, a traditional medicine in China, performs an anti-diabetic function and has anti-atherosclerosis effects involving suppression of vascular smooth muscle cell proliferation. However, the potential mechanisms keep to be revealed. The present study intended to investigate the influences of Pollen typhae extract named Pollen typhae total flavone (PTF) on A7r5 cell proliferation promoted by insulin and to uncover the underlying mechanisms. Proliferation and viability were evaluated by CCK-8 method. Western blotting was adopted to analyze the protein expression. Insulin promoted A7r5 cell proliferation, while PTF suppressed insulin-promoted proliferation in a concentration-dependent fashion. Although PTF did not change c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (p38MAPK) or MAPK kinase 1/2 (MEK1/2) protein expression and failed to affect the phosphorylation of JNK and p38MAPK, PTF remarkably inhibited extracellular signal-regulated kinase 1 and 2 (ERK1/2) protein expression and reduced ERK1/2 and MEK1/2 phosphorylation in A7r5 cells stimulated by insulin. Insulin-induced proliferation of A7r5 cells was abolished by inhibiting ERK1/2, which was in line with PTF. These findings indicate that PTF suppresses insulin-promoted proliferation of A7r5 cells involving the MEK1/2-ERK1/2 cascades, providing new insight into the potential uses of PTF for treatment of diabetic atherosclerosis.