Heat shock protein 70 protects rat peritoneal mesothelial cells from advanced glycation end-products-induced epithelial-to-mesenchymal transition through mitogen-activated protein kinases/extracellular signal-regulated kinases and transforming growth factor-β/Smad pathways

Epithelial-to-mesenchymal transition (EMT) may result in damage to the peritoneum and the development of fibrosis in peritoneal mesothelial cells (PMCs). However, the mechanism underlying EMT in peritoneal mesothelial cells is not well understood. Heat shock proteins (HSPs) were initially identified as proteins that are expressed following exposure of cells to environmental stress. However, their function in the development of EMT in PMCs remains to be fully elucidated. In the present study, the effect of HSP70 on advanced glycation end-products (AGEs)-induced EMT in peritoneal mesothelial cells was investigated by overexpression of this protein using a plasmid and knockdown of HSP70 using small interfering RNA. In addition, the underlying molecular mechanisms were explored. The results demonstrated that AGEs activated changes associated with EMT, including the loss of E-cadherin and the increase in a-smooth muscle actin. Furthermore, AGEs also induced the upregulation of HSP70, which led to the partial inhibition of EMT in PMCs. HSP70 inhibits EMT by modulating transforming growth factor-beta (TGF-beta)/Smad expression and the mitogen-activated protein kinases (MAPK)/extracellular signal-regulated kinases (ERK) signaling pathways. The findings suggested that HSP70 augments the cellular defense capacity through inhibition of TGF-beta/Smad and MAPK/ERK signaling pathways, thereby protecting PMCs from AGEs-induced EMT.