Cinnamon extract increases tristetraprolin and decreases vascular endothelial growth factor gene expression in mouse adipocytes

Abstract

Cinnamon is proposed to improve the metabolic syndrome due to its insulin‐like activity (Khan et al., 2003, Diabetes, 26:3215–8; Cao et al., 2008, AgroFood Industry Hi‐tech, 19:14–17). Insulin increases tristetraprolin (TTP, a RNA binding and destabilizing protein) and decreases vascular endothelial growth factor (VEGF, a proangiogenic cytokine) gene expression in cultured adipocytes (Cao et al., 2008, Obesity, 16:1208–18). This study tested the hypothesis that CE has insulin‐like and insulin‐independent effects on the regulation of TTP, VEGF, and related gene expression in cultured adipocytes. Quantitative real‐time PCR was used to estimate mRNA levels in mouse 3T3‐L1 adipocytes. CE (100 μg/ml), like insulin, increased TTP mRNA levels by several‐fold in the adipocytes, but unlike insulin, its stimulation on TTP expression sustained over a much longer time. The levels of VEGF mRNA, a putative target of TTP, were decreased approximately 50% by CE. CE also affected the expression of a number of other genes in the adipocytes. This study demonstrates that CE has insulin‐like effects including rapid induction of TTP mRNA and reduction of VEGF mRNA, and that CE has insulin‐independent effects on sustained increases in TTP expression (Supported in part by USDA‐ARS Human Nutrition and Quality and Utilization of Agricultural Products Research Programs).