Next-generation sequencing analysis of exosomal microRNAs: Fusobacterium nucleatum regulates the expression profiling of exosomal microRNAs in human colorectal cancer cells

Colon cancer is one of the most common malignant tumors, but there are still a few validated biomarkers of colon cancer. Exosome-mediated microRNAs (miRNAs) have been recognized as potential biomarkers in cancers, and miRNAs can regulate a variety of genes. Recently, Fusobacterium nucleatum was discovered in the tissues of human colon cancer patients. Its role in colon cancer was highlighted. F. nucleatum may contribute to the progression of colon cancer through the mechanism of exosome-mediated miRNAs transfer. However, the exosomal miRNAs regulation mechanism by F. nucleatum in colon cancer is not well known. Thus, we performed next-generation sequencing to investigate the overall pattern of exosomal miRNAs expression in the colon cancer cell culture supernatant. We have confirmed the alterations of various exosomal miRNAs. In addition, to investigate the function of exosomal miRNAs, a Kyoto Encyclopedia of Genes and Genomes analysis was performed on the target genes of changed miRNAs. Potential target genes were associated with a variety of signaling pathways, and one of these pathways was related to colorectal cancer. These findings suggested that F. nucleatum can alter exosomal miRNAs released from colorectal cancer cells. Furthermore, exosomal miRNAs altered by F. nucleatum could be potential biomarkers for the diagnosis and therapy of colon cancer.

Antifibrotic Effect of BMP-7 in the Peritoneum and the Mechanism / 대한신장학회잡지

PURPOSE: Bone morphogenic protein (BMP)-7, a member of TGF-beta1 superfamily, is an endogenous antifibrotic protein highly expressed in normal kidney. It is not known, however, whether human peritoneal mesothelial cells (HPMC) express BMP-7 or if BMP-7 protects against peritoneal fibrosis and by what mechanism. We examined the effect of BMP-7 overexpression in TGF-beta1-induced epithelial-mesenchymal transition (EMT) of HPMC and in TGF-beta1 signaling in HPMC to elucidate the mechanisms of antifibrotic effect of BMP-7. METHODS: Growth arrested and synchronized HPMC were stimulated with 2 ng/mL of TGF-beta1 to induce EMT. HPMC were transiently transfected with adenovirus-mediated human BMP-7 (AdBMP-7) or with GFP (AdGFP). EMT was defined as downregulation of E-cadherin and upregulation of alpha-smooth muscle actin (SMA). RESULTS: HPMC constitutively expressed BMP-7 mRNA and protein. BMP-7 mRNA and protein expression were significantly inhibited by 50 mM D-glucose, 2x diluted commercial peritoneal dialysis solution, and 2 ng/ml of TGF-beta1. Transfection of AdBMP-7 resulted in 2.5-fold increase in BMP-7 mRNA expression in HPMC. TGF-beta1 significantly decreased E-cadherin and increased alpha-SMA expression in GFP transfected cells. BMP-7 overexpression effectively reversed TGF-beta1-induced E-cadherin and alpha-SMA expression and significantly suppressed TGF-beta1-induced phosphorylation of Smad2/3, ERK1/2, JNK, and p38 MAPK in HPMC as compared to GFP transfected cells. CONCLUSION: BMP-7 is an endogenous antifibrotic protein and downregulation of BMP-7 in HPMC by high glucose, PD solution, and TGF-beta1 may permit the development of peritoneal fibrosis during long-term PD. Our data demonstrate that BMP-7 overexpression reverses TGF-beta1-induced EMT of HPMC and consequent peritoneal fibrosis possibly through inhibition of Smad2/3 and MAPK phosphorylation.

Role of Reactive Oxygen Species and Mitogen-activated Protein Kinases in 2, 3, 7, 8-tetrachlorodibinzo-p-dioxin-induced Fibronectin Secretion by MDCK Cells / 대한신장학회잡지

BACKGROUND: 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD: dioxin) is a potent environmental toxicant that alters various cell function. Both reactive oxygen species (ROS) and mitogen-activated protein kinases (MAPK) mediate dioxin-induced cytotoxicity. Since dioxin was shown to increase renal cell fibronectin secretion in a dose-dependent manner and ROS and MAPK also play roles in fibronectin upregulation in renal cells, the present study examined whether ROS and/or MAPK activation play a role in dioxin-induced fibronectin upregulation in tubular epithelial cells. METHODS: Madin-Darby canine kidney (MDCK) cells were cultured with minimum essential medium (MEM) containing 10% fetal bovine serum. Growth arrested and synchronized MDCK cells by serum deprivation were stimulated with dioxin 1 nM in the presence or absence of extracellular signal-regulated protein kinase (ERK) inhibitor PD98059 50 microM, p38 MAPK inhibitor 100 nM, trolox 500 microM, or taurine 500 microM for up to 48 hours. Dichlorofulorescein (DCF)-sensitive cellular ROS was measured by FACScan and fibronectin in the media and cellular MAPK by a Western blot analysis. RESULTS: Dioxin 1 nM significantly increased cellular ROS and fibronectin in MDCK cells. Antioxidants, trolox and taurine, effectively inhibited dioxin-induced cellular ROS and fibronectin secretion. Dioxin increased phosphorylation of ERK at 5 minutes and P38 MAPK at 48 hours. Dioxin did not affect c-Jun NH2-terminal kinase (JNK) activation for up to 48 hours. Both PD98059 and p38 MAPK inhibitor suppressed dioxin-induced fibronectin secretion by MDCK cells. CONCLUSION: These data suggest that dioxin increases fibronectin secretion by renal distal tubular epithelial cells through ROS and MAPK (ERK and p38 MAPK) and this may lead to renal fibrosis.

Role of Reactive Oxygen Species in Transforming Growth Factor - beta1 - inuduced Fibronectin Secretion and alpha - Smooth Muscle Actin Expression in Human Lung Fibroblasts / 결핵및호흡기질환

BACKGROUND: The transforming growth factor-beta1 (TGF-beta1) plays a key role in lung fibrosis. However, the mole?cular mechanisms involved in TGF-beta1-induced lung fibrosis are unclear. TGF-beta1 is the key inducer of myofibroblast transdifferentiation via de novo synthesis of alphasmooth muscle actin (alpha-SMA). Since TGF-beta1 signals through reactive oxygen species (ROS) and ROS have been shown to induce accumulation of extracellular matrix (ECM) in various tissues, this study examined if ROS play a role in TGF-beta1-induced fibronectin secretion and alpha-SMA expression in human lung fibroblasts, MRC-5 cells. METHODS: Growth arrested and synchronized MRC-5 cells were stimulated with TGF-beta1 (0.2-10 ng/ml) in the presence or absence of N-acetylcysteine (NAC) or diphenyleneiodonium (DPI) for up to 96 hours. Dichlorofluorescein (DCF)- sensitive cellular ROS were measured by FACScan and secreted fibronectin and cellular alpha-SMA by Western blot analysis. RESULTS: TGF-beta1 increased the level of fibronectin secretion and alpha-SMA expression in MRC-5 cells in a dose- dependent manner. Both NAC (20 and 30 mM) and DPI (1 and 5 microM significantly inhibited TGF-beta1-induced fibronectin and alpha-SMA upregulation. The TGF-beta1-induced cellular ROS level was also significantly reduced by NAC and DPI. CONCLUSIONS: The results suggest that NADPH oxidase-dependent ROS play an important role in TGF-beta1-induced fibronectin secretion and alpha-SMA expression in MRC-5 cells, which leads to myofibroblast transdifferentiation and progressive lung fibrosis.

Effects of 2,3,7,8-tetrachlorodibenzo- p-dioxin(TCDD) on Glomerular Mesangial and Tubular Epithelial Cell Activation / 대한신장학회잡지

BACKGROUND: 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a prototype compound of polyhalogenated aromatic hydrocarbons, produces diverse biologic effects. Although nephrotoxicity of aromatic hydrocarbons such as benzo[a]pyrene(BP) is well known, little is known about the effects of TCDD on renal function. Thus, the present study examined the effects of TCDD on cell viability, proliferation, and extracellular matrix(ECM) synthesis by glomerular mesangial cells, LLC-PK1 cells representing proximal tubular epithelial cells, and MDCK cells representing distal epithelial cells and compared with the effects of BP. METHODS: Quiescent cells were incubated with serum free media containing different concentrations of TCDD(1-100 nM) and BP(3 and 30 micro M) for 24- 96 hours. Cell viability and proliferation were assessed by lactate dehydrogenase(LDH) release and [3H]-thymidine incorporation, respectively. Secreted fibronectin was measured by Western blot analysis. RESULTS: When cells were continuously exposed to TCDD, LDH release significantly increased in MMC, LLC-PK1, and MDCK in a dose- and a time- dependent manner. [3H]-Thymidine incorporation was increased in MMC and LLC-PK1 but decreased in MDCK by TCDD. Contrary to TCDD, 30 micro BP significantly inhibited [3H]-thymidine incorporation in MMC and MDCK but not in LLC-PK1. Both TCDD and BP increased fibronectin secretion by MMC, LLC-PK1, and MDCK cells, suggesting that TCDD and BP may cause renal fibrosis leading to loss of renal function. CONCLUSION: These data provide experimental evidence that TCDD can alter cell viability and proliferation and increase ECM synthesis by renal cells which may lead to renal injury.

Monocyte Chemoattractant Protein-1 Upregulates Fibronectin Secretion by Human Peritoneal Fibroblasts / 대한신장학회잡지

BACKGROUND: High glucose upregulates MCP-1 expression in rat glomerular mesangial cells and in human peritoneal mesothelial cells. However, the role of high glucose-induced MCP-1 on the development and progression of diabetic renal injury and peritoneal injury during peritoneal dialysis(PD) using high glucose PD solutions are not clear. Since MCP-1 was shown to upregulate transforming growth factor-beta1(TGF-beta1) and collagen expression in lung fibroblasts, the present study investigated the effects of MCP-1 on fibronectin secretion by mouse mesangial cells(MMC), human peritoneal mesothelial cells (HPMC), and human peritoneal fibroblasts(HPFB). METHODS: Synchronized cells were stimulated by different concentrations of MCP-1(0.1-100 ng/mL) or TGF-beta1(0.1-10 ng/mL) for 48 hours. Fibronectin protein secreted into the media was analyzed by Western blot analysis. RESULTS: MCP-1 up to 100 ng/mL did not affect fibronectin secretion by MMC. TGF-beta1 10 ng/mL, however, increased fibronectin secretion by MMC 2.8 fold that of control. MCP-1 up to 100 ng/mL did not affect fibronectin secretion by HPMC. But, TGF-beta1 0.1 ng/mL increased fibronectin secretion by HPMC 1.8 fold compared to control. On the other hand, MCP-1 increased fibronectin secretion by HPFB in a dose-dependent manner. MCP-1 at 1-10 ng/mL significantly increased fibronectin when compared to M199 control. 100 ng/mL MCP-1 further increased fibronectin secretion by HPFB compared to 0.1-10 ng/mL MCP-1. CONCLUSION: These results suggest a possible role for MCP-1 in the development and progression of peritoneal fibrosis and support the view that in addition to recruiting inflammatory cells MCP-1 may play a role in tissue fibrosis in other organs.

Effects of Osmolality and Osmotic Agents on Viability and Proliferation of Human Peritoneal Mesothelial Cells / 대한신장학회잡지

High glucose activates protein kinase C, induces reactive oxygen species generation, and upregulates expression of transforming growth factor-beta1(TGF-beta1) and fibronectin by human peritoneal mesothelial cells(HPMC). High glucose also induces premature senescence in mesothelial cells. Mesothelial cells shrink after exposure to hypertonic medium and intracellular uptake of amino acids increase to ensure subsequent volume increase. Based on these observations, new and more biocompatible peritoneal dialysis solutions that are glucose free and/or iso-osmolar have been developed. We investigated the effects of different osmolality and different osmotic agents including glucose, mannitol, and icodextrin on viability and proliferation of HPMC. HPMC were obtained from the omental tissues of consenting patients undergoing Cesarean section or elective abdominal surgery. All experiments were performed using cells in the 2nd or 3rd passage. Near-confluent HPMC grown in culture dishes were incubated with serum-free medium for 48 hours to arrest and synchronize cell growth. Lactate dehydrogenase(LDH) release was measured for cell viability and [3H]-thymidine incorporation for proliferation of cultured HPMC, after exposing HPMC to different concentrations of glucose, mannitol, and icodextrin for up to 96 hours. High glucose and mannitol at concentrations up to 100 mM(375 mOsm) did not increase LDH release up to 96 hours compared to control M199. When HPMC were exposed to 2, 4, 7.5, and 9% of icodextrin for 24-96 hours, LDH release did not increase. Glucose at 30, 50, and 100 mM significantly inhibited [3H]-thymidine incorporation by HPMC at 24 and 48 hours. Mannitol at 30, 50, and 100 mM for 24 hours and at only 100 mM for 48 hours also significantly inhibited cell proliferation. Icodextrin 9% (305 mOsm) inhibited cell proliferation compared with control M-199 at 24 hours. In conclusion, high osmolality per se dose not appear to increase HPMC death. However, high osmolality appears to inhibit HPMC proliferation at early stage. In addition, high glucose appears to inhibit HPMC proliferation independent of osmolality since high glucose continues to inhibit cell proliferation at 48 and 72 hours when mannitol at the same concentration did not. Icodextrin 9% of which osmolality is 305 mOsm inhibits HPMC proliferation at early stage but does not appear to increase HPMC death.