HGF-induced capillary morphogenesis of endothelial cells is regulated by Src.

The signal transduction pathway involved in hepatocyte growth factor (HGF)-induced capillary morphogenesis of endothelial cells was investigated. HGF-induced capillary morphogenesis of the murine spleen endothelial cell line MSS31 was inhibited by a Src family kinase inhibitor, PP2. Stable expression of kinase-inactive Src in MSS31 cells inhibited HGF-induced activation of Src as well as capillary morphogenesis. The HGF-induced capillary morphogenesis of human umbilical vein endothelial cells was also inhibited by PP2 and was reduced by the downregulation of Src by small interfering RNA. These results suggest that HGF induces capillary morphogenesis of endothelial cells through Src

Tributyltin Inhibits Neural Induction of Human Induced Pluripotent Stem Cells

Tributyltin (TBT), one of the organotin compounds, is a well-known environmental pollutant. In our recent study, we reported that TBT induces mitochondrial dysfunction, in human-induced pluripotent stem cells (iPSCs) through the degradation of mitofusin1 (Mfn1), which is a mitochondrial fusion factor. However, the effect of TBT toxicity on the developmental process of iPSCs was not clear. The present study examined the effect of TBT on the differentiation of iPSCs into the ectodermal, mesodermal, and endodermal germ layers. We found that exposure to nanomolar concentration of TBT (50 nM) selectively inhibited the induction of iPSCs into the ectoderm, which is the first step in neurogenesis. We further assessed the effect of TBT on neural differentiation and found that it reduced the expression of several neural differentiation marker genes, which were also downregulated by Mfn1 knockdown in iPSCs. Taken together, these results indicate that TBT induces developmental neurotoxicity via Mfn1-mediated mitochondrial dysfunction in iPSCs

Downregulation of Fes inhibits VEGF-A-induced chemotaxis and capillary-like morphogenesis by cultured endothelial cells.

The aim of this study was to determine whether the downregulation of endogenous Fes by siRNA in cultured endothelial cells affects vascular endothelial growth factor-A (VEGF-A)-induced chemotaxis and capillary-like morphogenesis, which are considered as angiogenic cellular responses in vitro. VEGF-A-treatment induced autophosphorylation of Fes in cultured endothelial cells. LY294002, a phosphoinositide 3-kinase inhibitor, significantly inhibited VEGF-A-induced chemotaxis and capillary-like morphogenesis. Downregulation of Fes attenuated these VEGF-A-induced cellular responses but LY294002 did not produce further inhibition of these responses. Downregulation of Fes neither affected VEGF-A-induced autophosphorylation of VEGF receptor 2 nor mitogen-activated protein kinase activation, but markedly decreased Akt activation. Taken together, our novel results indicate the involvement of Fes in VEGF-A-induced cellular responses by cultured endothelial cells

Fibroblast growth factor-2 induces the activation of Src through Fes, which regulates focal adhesion disassembly.

Cell migration is regulated by focal adhesion (FA) turnover. Fibroblast growth factor-2 (FGF-2) induces FA disassembly in the murine brain capillary endothelial cell line IBE, leading to FGF-2-directed chemotaxis. We previously showed that activation of Src and Fes by FGF-2 was involved in chemotaxis of IBE cells. In this study, we examined the interplay between Src and Fes. FGF-2 treatment decreased the number of FA in IBE cells, but not in cells expressing dominant-negative Fes (denoted KE5-15 cells). FGF-2 induced the activation of Src and subsequent binding to and phosphorylation of Cas in IBE cells, but not in KE5-15 cells. Focal adhesion kinase (FAK) activation and tyrosine phosphorylation by Src were also delayed in KE5-15 cells compared to parental cells. FGF-2 induced activation of Src within FA in IBE cells, but not in KE5-15 cells. Downregulation of Fes or FAK using small interfering RNA diminished Src activation by FGF-2 within FA. These findings suggest that activation of Fes by FGF-2 enhances FAK-dependent activation of Src within FA, promoting FGF-2-induced disassembly of focal adhesions

Upregulation of CA 19-9 in the Mouse Kidney Following Unilateral Ureteral Obstruction

High serum levels of carbohydrate antigen19-9 (CA19-9) have been detected in patients with pancreatic cancer and described in several recent case reports of patients with hydronephrosis. However, the mechanism of high serum levels of CA19-9 among hydronephrosis cases remains to be elucidated. In this study, we established a mouse unilateral ureteral obstruction (UUO) model to investigate the expression of CA19-9 protein in renal tissue. To investigate the progression of hydronephrosis following UUO, MR urography and pathological analysis were performed. CA19-9 expression was examined by immunohistochemistry and western blot analysis. MR urography revealed that the grade of pelvic dilatation increased in a time dependent manner. Pathologically, both interstitial cellular infiltration and fibrosis were detected from the second to the fourteenth day after surgery in UUO mice. CA19-9 was detected in the UUO kidney after the second day. The immunoblot analysis revealed that the elevated expression of CA19-9 was demonstrated at an early stage of obstructive nephropathy. Our study shows that the ureteral obstructed kidney is dominated by cell infiltration and induced fibrosis. The selective expression of CA19-9 was detected in renal fibrous tissue. Based on these findings, the level of CA19-9 might be a good indicator for onset of renal fibrosis induced by obstruction

Role of Src in angiopoietin 1-induced capillary morphogenesis of endothelial cells: Effect of chronic hypoxia on Src inhibition by PP2.

Signal transduction pathways leading to angiopoietin 1 (Ang1)-induced capillary morphogenesis by endothelial cells remain poorly defined. Angiogenic cellular responses by endothelial cells may be modulated in vivo by chronic hypoxia, such as that induced by tumors. Here, we studied Ang1-induced capillary morphogenesis in human umbilical-vein endothelial cells (HUVECs) cultured chronically under normoxic (21% oxygen) or hypoxic (1.5% oxygen) conditions. Downregulation of Src using a small interfering RNA (siRNA) inhibited Ang1-induced capillary morphogenesis of HUVECs cultured under both conditions by blocking cell spreading and protrusion. Ang1 upregulated the Src-dependent secretion of vascular endothelial growth factor-A (VEGF-A). Blockade of endogenous VEGF-A also inhibited Ang1-induced capillary morphogenesis. Addition of exogenous VEGF-A restored cell spreading and protrusion, leading to Ang1-induced capillary morphogenesis of Src siRNA-treated HUVECs, suggesting that Ang1-induced VEGF-A secretion through Src was required for capillary morphogenesis. PP2 inhibited both Ang1-induced capillary morphogenesis and Src activation in HUVECs cultured under normoxic conditions, but the PP2 activity was significantly impaired in HUVECs cultured under hypoxic conditions. Expression of multidrug resistance-associated protein 1 (MRP 1) was upregulated in hypoxic HUVECs, and treatment with MRP 1 siRNA restored the inhibitory action of PP2. Taken together, our results suggest that Ang1 induces capillary morphogenesis in HUVECs through Src-dependent upregulation of endogenous VEGF-A. Conditions of chronic hypoxia impaired the effect of PP2, possibly via MRP 1

High expression of Twist is associated with tumor aggressiveness and poor prognosis in patients with renal cell carcinoma

Aims: Twist has been reported to play crucial roles for malignant aggressiveness; however, detailed pathological significance of Twist in renal cell carcinoma (RCC) is not fully understood. The present study was to clarify clinical significance and molecular functions of Twist in patients with RCC. Methods: Twist expression was examined by immunohistochemical techniques in 156 formalin-fixed specimens. Cell proliferation, angiogenesis, and apoptosis were measured as the percentage of Ki-67-positive cells (proliferation index, PI), CD31-stained vessels (microvessel density, MVD), and TUNEL-positive cells (apoptotic index, AI). In addition, semi-quantification of matrix metalloproteinase (MMP)-2 was performed. Macrophages were identified with anti-CD68 antibody, and the tumor associated macrophage (TAM) density was calculated as CD68-positive cells per high-power field. Results: Twist expression was positively associated with grade, pT stage, and metastasis (p<0.001). We also noticed that its expression was considerably higher in cancer cells of sarcomatoid RCC and in those at the edge of the tumors. Twist expression was positively correlated with PI, MVD, MMP2 expression, and TAM density (P<0.001), but not with AI, and MMP-2 expression and TAM density were independently correlate by multi-variate analyses. Kaplan-Meir survival curves showed high Twist expression was a worse predictor for cause-specific survival (P<0.001). Conclusions: Twist plays important roles in tumor growth, progression, and survival in patients with RCC patients. Such pathological mechanisms are significantly associated with increased cancer cell proliferation, angiogenesis, MMP2 expression, and macrophage recruitment. These findings are important information for discussion of treatment and observation strategies in these patients

Elevated expression of ERK 2 in human tumor cells chronically treated with PD98059.

We examined the effect of chronic exposure of tumor cells to a mitogen-activated protein kinase/extracellular signal-regulated kinases (ERK) kinase inhibitor, PD98059, on cell proliferation was investigated. Human renal carcinoma cells (ACHN) and prostatic carcinoma cells (DU145) were cultured in the presence of PD98059 for more than 4 weeks (denoted ACHN (PD) cells and DU145 (PD) cells, respectively) and proliferation and signal transduction pathways were examined. PD98059 significantly inhibited the proliferation of parental cells. However, PD98059 failed to inhibit proliferation of ACHN (PD) and DU145 (PD) cells significantly. Expression of ERK 1 and 2 was elevated in these cells. These phenotypes were reversible. Downregulation of ERK 2, but not ERK 1, by small interfering RNA significantly inhibited the proliferation of ACHN (PD) and DU145 (PD) cells. Taken together, chronic exposure of tumor cells to PD98059 induced elevated expression of ERK 2, which was associated with decreased sensitivity of cellular proliferation to PD98059