Metformin reduces fibrosis factors in insulin resistant and hypertrophied adipocyte via integrin/ERK, collagen VI, apoptosis, and necrosis reduction

Aims: Fibrosis as the hallmark of adipose tissue dysfunction which is associated with insulin resistance and type 2 diabetes, results from deposition of excess extra cellular matrix components like collagen and increased cell death. Here we investigated the effect of antidiabetic drug, Metformin, on the factors that play role in fibrosis such as; integrin/ERK pathway, collagen VI, MMP2, MMP9, apoptosis markers including DAPK1, DAPK3, DAP, SIVA, necrosis markers including RIPK1, RIPK3, and MLKL in insulin resistant and hypertrophied adipocytes. Methods: 3T3-L1 adipocytes after differentiation to insulin resistant and hypertrophied cells, treated with Metformin, and the gene expression of aforementioned factors assayed by real time PCR. The protein expression of collagen VI and ERK assayed by western blotting. Key findings: The expression of integrins changed from 0.5 to 6-fold in hypertrophied adipocyte versus adipocyte. Apoptosis and necrosis markers increased >1.5-fold in insulin resistant and hypertrophied adipocytes. Also ECM components and ERK activation increased >2-fold and 1.5-fold, respectively in insulin resistant and hypertrophied adipocytes. Metformin caused reduction of activity of integrin/ERK pathway in Metformin treated insulin resistant and hypertrophied adipocytes compared to untreated group. Metformin also reduced collagen VI in both gene and protein expression level, MMP2 and MMP9 in gene expression, and also the expression of apoptosis and necrosis gene. Significance: Metformin with reduction of ECM component as collagen VI, MMP2 and MMP9, integrin/ERK pathway, necrosis markers as RIPK1, RIPK3 and MLKL, and apoptosis markers including DAP, DAPK1, DAPK3 and SIVA effects on fibrosis in insulin resistant and hypertrophied adipocytes in vitro.