Insulin-like growth factor 2 promotes adipocyte proliferation, differentiation and lipid deposition in obese type 2 diabetes

Aim: Insulin-like growth factor-2 (IGF2) is known to regulate fetal development and differentiation, but its role in adults is still poorly understood compared with that of IGF1. This study evaluated the expression of IGF2 in obesity with type 2 diabetes mellitus (T2DM) and investigated the effects of IGF2 on adipocyte proliferation, differentiation and lipid deposition. Methods: A cross-sectional study with pair-matched controls was conducted on 50 adults with obese T2DM and 50 controls in Yuyao people's hospital, China. Serum levels of IGF2 were measured with a commercial ELISA kit. Pre-adipocytes of 3T3-L1 cell viability was determined by an MTS assay. Oil Red O staining and Nile Red staining were performed to evaluate the effects of IGF2 on 3T3-L1 differentiation and lipid deposition. Results: The expression of IGF2 is up-regulated in obese T2DM and correlates with lipid-related parameters like body mass index (r=0.315, p=0.002), waist circumference (r=0.271, p=0.008), triglyceride (r=0.262, p=0.008) and HDL-c (r=-0.324, p=0.002). Treatment of IGF2 could promote the proliferation of 3T3-L1 cells in a dose-dependent manner. High dose of IGF2 promoted 3T3-L1 differentiation by Oil Red O staining and enhanced the lipid accumulation in differentiated 3T3-L1 adipocytes by Nile Red staining and triglyceride assay. Conclusion: High level of IGF2 was positively correlated with lipid-related parameters in obeseT2DM. Furthermore, IGF2 could promote the proliferation and differentiation of 3T3-L1 cells and increase the lipid deposition of differentiated 3T3-L1 adipocytes.