ERK1/2-Dependent Gene Expression Contributing to TGFβ-Induced Lens EMT

ELABELA-derived peptide ELA13 attenuates kidney fibrosis by inhibiting the Smad and ERK signaling pathways

Kidney fibrosis is an inevitable result of various chronic kidney diseases (CKDs) and significantly contributes to end-stage renal failure. Currently, there is no specific treatment available for renal fibrosis. ELA13 (amino acid sequence: RRCMPLHSRVPFP) is a conserved region of ELABELA in all vertebrates; however, its biological activity has been very little studied. In the present study, we evaluated the therapeutic effect of ELA13 on transforming growth factor-β1 (TGF-β1)-treated NRK-52E cells and unilateral ureteral occlusion (UUO) mice. Our results demonstrated that ELA13 could improve renal function by reducing creatinine and urea nitrogen content in serum, and reduce the expression of fibrosis biomarkers confirmed by Masson staining, immunohistochemistry, real-time polymerase chain reaction (RT-PCR), and western blot. Inflammation biomarkers were increased after UUO and decreased by administration of ELA13. Furthermore, we found that the levels of essential molecules in the mothers against decapentaplegic (Smad) and extracellular signal-regulated kinase (ERK) pathways were reduced by ELA13 treatment in vivo and in vitro. In conclusion, ELA13 protected against kidney fibrosis through inhibiting the Smad and ERK signaling pathways and could thus be a promising candidate for anti-renal fibrosis treatment.

Enhanced EGF receptor-signaling potentiates TGFβ-induced lens epithelial-mesenchymal transition

The ocular lens is exposed to numerous growth factors that influence its behavior in diverse ways. While many of these, such as FGF and EGF promote normal cell behavior, TGFβ is unique in that it can also induce lens cell pathology, namely, the epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) leading to fibrotic cataract formation. The present study explores how EGF impacts on TGFβ-induced EMT in the lens. LECs in explants prepared from 21-day-old Wistar rats were treated with either 200 pg/ml TGFβ2, 5 ng/ml EGF, or a combination of these, with or without a 2-h pre-treatment of an EGFR inhibitor (PD153035), MEK inhibitor (U0126) or Smad3 inhibitor (SIS3). Co-treatment of LECs with TGFβ2 and EGF, compared with TGFβ2 alone, resulted in a more pronounced elongation and transdifferentiation of the LECs into myofibroblastic cells, with higher protein levels of mesenchymal cell markers (α-SMA and tropomyosin). Combining EGF with a less potent lower dose of TGFβ2 (50 pg/ml) induced LECs to undergo EMT equivalent to treatment with a higher dose of TGFβ2 (200 pg/ml) within 5 days of culture. EGF alone, nor the lower dose of TGFβ2, were able to induce EMT in LECs within 5 days. Co-treatment of LECs with EGF and TGFβ2 induced a temporal shift in the phosphorylation levels of Smad2/3, ERK1/2 and EGFR and changed the expression patterns of downstream EMT target genes, compared to treatment of LECs with either growth factor alone. Inhibition of EGFR-signaling with PD153035 blocked the EMT response induced by co-treatment with EGF and TGFβ2. Taken together, our data demonstrate that EGF can potentiate TGFβ2 activity to enhance EMT in LECs, further highlighting the importance of EGFR-signaling in cataract formation. By directly blocking EGFR signaling, the activity of both EGF and TGFβ2 can be simultaneously reduced, thereby serving as a potential target for cataract prevention.

Bortezomib attenuates renal interstitial fibrosis in kidney transplantation via regulating the EMT induced by TNF-α-Smurf1-Akt-mTOR-P70S6K pathway

Allograft interstitial fibrosis was characterized by massive extracellular matrix deposition caused by activated fibroblasts and myofibroblasts. Epithelial‐mesenchymal transition (EMT) is recognized as an important source of myofibroblasts contributing to the pathogenesis of allograft interstitial fibrosis. Smad ubiquitination regulatory factor 1 (Smurf1) has been recently reported to be involved in the progression of EMT. Our study was to detect the effect of Bortezomib and Smurf1 in the EMT and allograft interstitial fibrosis. Biomarkers of EMT, as well as Smurf1, were examined in human proximal tubular epithelial cells (HK‐2) treated with tumour necrosis factor‐alpha (TNF‐α) in various doses or at various time points by Western Blotting or qRT‐PCR. We knockdown or overexpressed Smurf1 in HK‐2 cells. Furthermore, rat renal transplant model was established and intervened by Bortezomib. Allograft tissues from human and rats were also collected and prepared for HE, Masson's trichrome, immunohistochemical staining and western blotting assays. As a result, we found that TNF‐α significantly promoted the development of EMT in a time‐dependent and dose‐dependent manner through Smurf1/Akt/mTOR/P70S6K signalling pathway. More importantly, Bortezomib alleviated the progression of EMT and allograft interstitial fibrosis in vivo and in vitro by inhibiting the production of TNF‐α and expression of Smurf1. In conclusion, Smurf1 plays a critical role in the development of EMT induced by TNF‐α. Bortezomib can attenuate the Sumrf1‐mediated progression of EMT and renal allograft interstitial fibrosis, which could be suggested as a novel choice for the prevention and treatment of renal allograft interstitial fibrosis.

Increased SPK1 expression promotes cell growth by activating the ERK1/2 signaling in non-small-cell lung cancer

Lung cancer remains the leading cause of cancer-associated mortality in China and the world. Increasing numbers of studies have reported that sphingosine kinase 1 (SPK1) is frequently highly expressed in tumors of various origins, including lung cancer, and its high expression contributes toward tumor progression. However, the clinical significance of SPK1 and its role in the growth and metastasis of non-small-cell lung cancer (NSCLC) remain unclear. In the present study, we found that SPK1 expression was expressed highly in NSCLC tissues and cell lines. Knockdown of SPK1 suppressed cell growth, proliferation, migration, and invasion and increased apoptosis. Moreover, knocking down SPK1 expression inhibited the growth of tumors in nude mice. Mechanistically, silencing the expression of SPK1 inhibited the expression of p-extracellular signal-regulated kinase (ERK). Moreover, the ERK-specific inhibitor U0126 suppressed the expression of the epithelial-mesenchymal transition of lung cancer cells. Together, our findings indicated that SPK1 enhanced tumor growth in lung cancer and induced metastasis by activating the ERK1/2 signaling pathway, indicating its potential application in NSCLC diagnosis and therapy.