STC2 Modulates ERK1/2 Signaling to Suppress Adipogenic Differentiation of Human Bone Marrow Mesenchymal Stem Cells

Stanniocalcin-2 (STC2) is a glycoprotein that has been found to play key roles in the regulation of cancer, diabetes mellitus, and osteogenesis. Herein we sought to extend these past studies by examining the importance of STC2 in the context of human mesenchymal stem cell (hMSC) adipogenic differentiation and exploring the mechanisms underlying such importance. We found that STC2 expression was significantly reduced on day 7 of hMSC adipogenesis. When we deliberately overexpressed STC2 in these cells, this resulted in significantly decreased expression of both peroxisome proliferator-activated receptor γ (PPARγ) and Fatty Acid Binding Protein-4 (FABP4) together with increased extracellular-signal regulated kinase 1/2 (ERK1/2) phosphorylation and markedly reduced lipid droplet formation within cells. Treatment of cells using the ERK inhibitor U0126 disrupted this ERK1/2 phosphorylation and restored the adipogenic differentiation of these hMSCs. When we instead knocked down STC2 expression, the opposite phenotypes were observed. Together these findings thus reveal that STC2 modulates ERK1/2 signaling in hMSCs so as to suppress their adipogenic differentiation.