Curcumin Alters Iron Regulation in C2C12 Skeletal Muscle Cells and Prevents Iron Accumulation in a Model of Elevated Oxidative Stress

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The Centers for Disease Control and Prevention have stated that as of 2017, 30.3 million people in the United States have diabetes (9.6% of total population), with an additional 84.1 million who have prediabetes (33.9% of total population). Patients with diabetes show signs of iron dysregulation, and recent studies indicate a correlation between iron dysregulation and insulin sensitivity suggesting that iron dysregulation plays a role in diabetes. Unbound cellular iron is highly reactive and can cause increased amounts of free radicals. Curcumin is a naturally occurring compound in the spice, turmeric, and has been shown to be effective in improving insulin sensitivity, although the mechanisms by which it does so are not entirely understood. Curcumin has been shown to bind iron and is very likely to have an effect on iron regulation. The purpose of this study is to understand the effects of curcumin on iron regulation and its ability to prevent iron dysregulation. Differentiated C2C12 mouse skeletal muscle cells were used in normal and high iron conditions, and protein expression and total iron content were analyzed to assess curcumin's effects on iron regulation. Cells were treated with 40 μM curcumin for 12 hours, and then harvested for analysis of protein expression and total iron content. Protein expression of transferrin receptor (TfR) and ferritin heavy chain (FHC) were measured by western blot analysis. Total iron content was measured by using a total iron colorimetric assay. C2C12 cells treated with 40 μM curcumin for 12 hours caused a reduction in TfR protein expression by 19±10% (p=0.02), as well as a reduction in FHC protein expression by 55±16% (p=0.01). The decrease in TfR expression correlated with a reduction in total cellular iron level, although the reduction in total iron was not significant. We then examined the effect of curcumin on iron regulation in high iron conditions to reflect the stress caused by elevated circulating iron levels associated with insulin resistance. In a model of high iron, pre‐treatment of 40 μM curcumin for 12 hours followed by treatment of 10 μM FeCl3 for 24 hours caused a reduction in TfR expression by 23±11% (p=0.008). Curcumin's effects on FHC expression were reversed in this high iron model, as FHC expression increased by 30±17% (p=0.04). Curcumin did not significantly alter total iron levels in this high iron model. Finally, we used a model of elevated oxidative stress to cause iron dysregulation in C2C12 cells, and analyzed curcumin's ability to prevent iron dysregulation. Cells were treated with 10 μM FeCl3 for 24 hours, with 200 μM hydrogen peroxide added during the final 12 hours of treatment. Pre‐treatment with curcumin prevented iron accumulation in cells treated with both iron and hydrogen peroxide (p=0.006). Our results show that curcumin's alteration of iron regulation is dependent upon extracellular iron levels. Results also show that curcumin has the potential to prevent iron dysregulation in an environment of elevated oxidative stress, providing a possible mechanism to its ability to improve insulin sensitivity.Support or Funding InformationThis work was supported by a BYU Mentoring Enhancement Grant.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.