Rab25 suppresses colon cancer cell invasion through upregulating claudin­7 expression.

Ras­related protein 25 (Rab25) is a member of small GTPase and is implicated in cancer cell progression of various types of cancer. Growing evidence suggests the context­dependent role of Rab25 in cancer invasiveness. Claudin­7 is a tight junction protein and has been known to suppress cancer cell invasion. Although Rab25 was reported to repress cancer aggressiveness through recycling ß1 integrin to the plasma membrane, the detailed underlying mechanism remains to be elucidated. The present study identified the critical role of claudin­7 in Rab25­induced suppression of colon cancer invasion. 3D Matrigel system and modified Boyden chamber analysis showed that enforced expression of Rab25 attenuated colon cancer cell invasion. In addition, Rab25 inactivated epidermal growth factor receptor (EGFR) and increased E­cadherin expression. Unexpectedly, it was observed that Rab25 induces claudin­7 expression through protein stabilization. In addition, ectopic claudin­7 expression reduced EGFR activity and Snail expression as well as colon cancer cell invasion. However, silencing of claudin­7 expression reversed the tumor suppressive role of Rab25, thereby increasing colon cancer cell invasiveness. Collectively, the present data indicated that Rab25 inactivates EGFR and colon cancer cell invasion by upregulating claudin­7 expression.

STAT3 mediates RCP-induced cancer cell invasion through the NF-κB/Slug/MT1-MMP signaling cascade.

Rab coupling protein (RCP) has been known to induce cancer invasion and metastasis, and STAT3 is one of major oncogenic factors. In the present study, we identify the critical role of STAT3 in RCP-induced cancer cell invasion. Immunohistochemical data of ovarian cancer tissues presented that levels of RCP expression are closely correlated with those of phospho-STAT3 (p-STAT3). In addition, ovarian cancer patients with high expression of both RCP and p-STAT3 had significantly lower progress-free and overall survival rates compared to those with low either RCP or p-STAT3 expression. Mechanistically, RCP induced STAT3 phosphorylation in both ovarian and breast cancer cells. Silencing or pharmacological inhibition of STAT3 significantly inhibited RCP-induced cancer cell invasion. In addition, we provide evidence that the ß1 integrin/EGFR axis is important for RCP-induced STAT3 phosphorylation. Furthermore, STAT3 activated NF-κB for Slug expression that in turn upregulated MT1-MMP expression for cancer cell invasion. Collectively, our present data demonstrate that STAT3 is located downstream of the ß1 integrin/EGFR axis and induces Slug and MT1-MMP expression for cancer cell invasion.

Ceria-Zirconia nanoparticles reduce intracellular globotriaosylceramide accumulation and attenuate kidney injury by enhancing the autophagy flux in cellular and animal models of Fabry disease.

BACKGROUND: Fabry disease (FD) is a lysosome storage disease (LSD) characterized by significantly reduced intracellular autophagy function. This contributes to the progression of intracellular pathologic signaling and can lead to organ injury. Phospholipid-polyethyleneglycol-capped Ceria-Zirconia antioxidant nanoparticles (PEG-CZNPs) have been reported to enhance autophagy flux. We analyzed whether they suppress globotriaosylceramide (Gb3) accumulation by enhancing autophagy flux and thereby attenuate kidney injury in both cellular and animal models of FD. RESULTS: Gb3 was significantly increased in cultured human renal proximal tubular epithelial cells (HK-2) and human podocytes following the siRNA silencing of α galactosidase A (α-GLA). PEG-CZNPs effectively reduced the intracellular accumulation of Gb3 in both cell models of FD and improved both intracellular inflammation and apoptosis in the HK-2 cell model of FD. Moreover these particles attenuated pro fibrotic cytokines in the human podocyte model of FD. This effect was revealed through an improvement of the intracellular autophagy flux function and a reduction in reactive oxygen species (ROS). An FD animal model was generated in which 4-week-old male B6;129-Glatm1Kul/J mice were treated for 8 weeks with 10 mg/kg of PEG-CZNPs (twice weekly via intraperitoneal injection). Gb3 levels were reduced in the kidney tissues of these animals, and their podocyte characteristics and autophagy flux functions were preserved. CONCLUSIONS: PEG-CZNPs alleviate FD associated kidney injury by enhancing autophagy function and thus provide a foundation for the development of new drugs to treat of storage disease.

Discoidin Domain Receptor 2 Mediates Lysophosphatidic Acid-Induced Ovarian Cancer Aggressiveness.

Lysophosphatidic acid (LPA), a bioactive lipid produced extracellularly by autotaxin (ATX), has been known to induce various pathophysiological events, including cancer cell invasion and metastasis. Discoidin domain receptor 2 (DDR2) expression is upregulated in ovarian cancer tissues, and is closely associated with poor clinical outcomes in ovarian cancer patients. In the present study, we determined a critical role and signaling cascade for the expression of DDR2 in LPA-induced ovarian cancer cell invasion. We also found ectopic expression of ATX or stimulation of ovarian cancer cells with LPA-induced DDR2 expression. However, the silencing of DDR2 expression significantly inhibited ATX- and LPA-induced ovarian cancer cell invasion. In addition, treatment of the cells with pharmacological inhibitors of phosphoinositide 3-kinase (PI3K), Akt, and mTOR abrogated LPA-induced DDR2 expression. Moreover, we observed that HIF-1α, located downstream of the mTOR, is implicated in LPA-induced DDR2 expression and ovarian cancer cell invasion. Finally, we provide evidence that LPA-induced HIF-1α expression mediates Twist1 expression to upregulate DDR2 expression. Collectively, the present study demonstrates that ATX, and thereby LPA, induces DDR2 expression through the activation of the PI3K/Akt/mTOR/HIF-1α/Twist1 signaling axes, aggravating ovarian cancer cell invasion.

Ceria-Zirconia Antioxidant Nanoparticles Attenuate Hypoxia-Induced Acute Kidney Injury by Restoring Autophagy Flux and Alleviating Mitochondrial Damage.

Oxidative stress is one of the principal causes of hypoxia-induced kidney injury. The ceria nanoparticle (CNP) is known to exhibit free radical scavenger and catalytic activities. When zirconia is attached to CNPs (CZNPs), the ceria atom tends to remain in a Ce3+ form and its efficacy as a free radical scavenger thus increases. We determined the effectiveness of CNP and CZNP antioxidant activities against hypoxia-induced acute kidney injury (AKI) and observed that these nanoparticles suppress the apoptosis of hypoxic HK-2 cells by restoring autophagy flux and alleviating mitochondrial damage. In vivo experiments revealed that CZNPs effectively attenuate hypoxia-induced AKI by preserving renal structures and glomerulus function. These nanoparticles can successfully diffuse into HK-2 cells and effectively counteract reactive oxygen species (ROS) to block hypoxia-induced AKI. This suggests that these particles represent a novel approach to controlling this condition.

Zeb1 for RCP-induced oral cancer cell invasion and its suppression by resveratrol.

Rab coupling protein (RCP) is upregulated in head and neck squamous cell carcinoma (HNSCC) and is correlated with the progression and survival of patients. However, the role of RCP in one of the aggressive types of HNSCC, oral squamous cell carcinoma (OSCC), remains elusive. In the present study, we identified the important role of Zeb1 in RCP-induced OSCC epithelial-to-mesenchymal transition (EMT) and invasion. RCP induces Zeb1 expression, and silencing Zeb1 expression significantly inhibits RCP-induced OSCC invasion. In addition, Zeb1 upregulates MT1-MMP expression to promote OSCC EMT and invasion. Furthermore, we observed that the ß1 integrin/EGFR/ß-catenin signaling cascade mediates RCP-induced Zeb1 expression to promote OSCC invasion. Notably, we provide evidence that resveratrol (REV) strongly inhibits RCP-induced Zeb1 expression through blocking ß1 integrin endosome recycling and EGFR activation, leading to suppression of RCP-induced OSCC invasion, demonstrating the important role of RCP in OSCC invasion and its reversion by REV. Collectively, the present study provides evidence for the first time that RCP aggravates OSCC invasion through increasing Zeb1 expression and subsequently upregulating MT1-MMP expression and that this process is reversed by REV, providing novel biomarkers and indicating the therapeutic potential of REV in OSCC.

NADPH oxidase 4 mediates TGF-ß1/Smad signaling pathway induced acute kidney injury in hypoxia.

Hypoxia is an important cause of acute kidney injury (AKI) in various conditions because kidneys are one of the most susceptible organs to hypoxia. In this study, we investigated whether nicotinamide adenine dinucleotide 3-phosphate (NADPH) oxidase 4 (Nox4) plays a role in hypoxia induced AKI in a cellular and animal model. Expression of Nox4 in cultured human renal proximal tubular epithelial cells (HK-2) was significantly increased by hypoxic stimulation. TGF-ß1 was endogenously secreted by hypoxic HK-2 cells. SB4315432 (a TGF-ß1 receptor I inhibitor) significantly inhibited Nox4 expression in HK-2 cells through the Smad-dependent cell signaling pathway. Silencing of Nox4 using Nox4 siRNA and pharmacologic inhibition with GKT137831 (a specific Nox1/4 inhibitor) reduced the production of ROS and attenuated the apoptotic pathway. In addition, knockdown of Nox4 increased cell survival in hypoxic HK-2 cells and pretreatment with GKT137831 reproduce these results. This study demonstrates that hypoxia induces HK-2 cell apoptosis through a signaling pathway involving TGF-ß1 via Smad pathway induction of Nox4-dependent ROS generation. In an ischemia/reperfusion rat model, pretreatment of GKT137831 attenuated ischemia/reperfusion induced acute kidney injury as indicated by preserved kidney function, attenuated renal structural damage and reduced apoptotic cells. Therapies targeting Nox4 may be effective against hypoxia-induced AKI.

The YB-1/EZH2/amphiregulin signaling axis mediates LPA-induced breast cancer cell invasion.

Lysophosphatidic acid (LPA) has been known to induce epithelial-mesenchymal transition (EMT) to stimulate cancer cell invasion, and resveratrol (3,5,4'-trans-trihydroxystilbene; REV) suppresses the invasion and metastasis of various cancers. The current study aimed to identify the underlying mechanism by which LPA aggravates breast cancer cell invasion and the reversal of this phenomenon. Immunoblotting and quantitative RT-PCR analysis revealed that LPA induces amphiregulin (AREG) expression. Silencing of Y-box binding protein 1 (YB-1) or enhancer of zeste homolog 2 (EZH2) expression efficiently inhibited LPA-induced AREG expression. In addition, transfection of the cells with YB-1 siRNA abrogated LPA-induced EZH2 and AREG expression, leading to attenuation of breast cancer cell invasion. Furthermore, we observed that both REV and 5-fluorouracil (5-Fu) significantly reduce LPA-induced YB-1 phosphorylation and subsequent breast cancer invasion. Importantly, combined treatment of REV with 5-Fu showed more significant inhibition of LPA-induced breast cancer invasion compared to single treatment. Therefore, our data demonstrate that the YB-1/EZH2 signaling axis mediates LPA-induced AREG expression and breast cancer cell invasion and its inhibition by REV and 5-Fu, providing potential therapeutic targets and inhibition of breast cancer.

Author Correction: Rab25 augments cancer cell invasiveness through a ß1 integrin/EGFR/VEGF-A/Snail signaling axis and expression of fascin.

After online publication of this article, the authors noticed an error in the Figure 4c and Figure 5c section.

Correction to: Resveratrol attenuates norepinephrine-induced ovarian cancer invasiveness through downregulating hTERT expression.

Unfortunately, there are some errors in Fig. 1b and Fig. 3a of the article.

RCP induces FAK phosphorylation and ovarian cancer cell invasion with inhibition by curcumin.

Rab coupling protein (RCP) aggravates cancer cell metastasis and has been implicated in various cancer patient outcomes. Recently, we showed that RCP induces Slug expression and cancer cell invasion by stabilizing the ß1 integrin protein. In the present study, we demonstrated that FAK is implicated in RCP-induced EGFR phosphorylation and ovarian cancer cell invasion with inhibition by curcumin. Ectopic expression of RCP induced FAK phosphorylation, which links ß1 integrin with EGFR and participates in a positive regulation loop with EGFR. Interestingly, we observed for the first time that curcumin attenuates RCP-induced ovarian cancer cell invasion by blocking stabilization of ß1 integrin and consequently inhibiting FAK and EGFR activation, providing potential biomarkers for ovarian cancer and therapeutic approaches for this deadly disease.

Oxidative stress caused by activation of NADPH oxidase 4 promotes contrast-induced acute kidney injury.

Contrast-induced acute kidney injury (CIAKI) is a leading cause of acute kidney injury following radiographic procedures. Intrarenal oxidative stress plays a critical role in CIAKI. Nicotinamide adenine dinucleotide 3-phosphate (NADPH) oxidases (Noxs) are important sources of reactive oxygen species (ROS). Among the various types of Noxs, Nox4 is expressed predominantly in the kidney in rodents. Here, we evaluated the role of Nox4 and benefit of Nox4 inhibition on CIAKI using in vivo and in vitro models. HK-2 cells were treated with iohexol, with or without Nox4 knockdown, or the most specific Nox1/4 inhibitor (GKT137831). Effects of Nox4 inhibition on CIAKI mice were examined. Expression of Nox4 in HK-2 cells was significantly increased following iohexol exposure. Silencing of Nox4 rescued the production of ROS, downregulated pro-inflammatory markers (particularly phospho-p38) implicated in CIAKI, and reduced Bax and caspase 3/7 activity, which resulted in increased cellular survival in iohexol-treated HK-2 cells. Pretreatment with GKT137831 replicated these effects by decreasing levels of phospho-p38. In a CIAKI mouse model, even though the improvement of plasma blood urea nitrogen was unclear, pretreatment with GKT137831 resulted in preserved structure, reduced expression of 8-hydroxy-2'-deoxyguanosine (8OHdG) and kidney injury molecule-1 (KIM-1), and reduced number of TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling)-positive cells. These results suggest Nox4 as a key source of reactive oxygen species responsible for CIAKI and provide a novel potential option for prevention of CIAKI.

TGF-ß-mediated NADPH oxidase 4-dependent oxidative stress promotes colistin-induced acute kidney injury.

Background: Colistin (polymyxin E) is an important constituent of the polymyxin class of cationic polypeptide antibiotics. Intrarenal oxidative stress can contribute to colistin-induced nephrotoxicity. Nicotinamide adenine dinucleotide 3-phosphate oxidases (Noxs) are important sources of reactive oxygen species. Among the various types of Noxs, Nox4 is predominantly expressed in the kidney. Objectives: We investigated the role of Nox4 and benefit of Nox4 inhibition in colistin-induced acute kidney injury using in vivo and in vitro models. Methods: Human proximal tubular epithelial (HK-2) cells were treated with colistin with or without NOX4 knockdown, or GKT137831 (most specific Nox1/4 inhibitor). Effects of Nox4 inhibition on colistin-induced acute kidney injury model in Sprague-Dawley rats were examined. Results: Nox4 expression in HK-2 cells significantly increased following colistin exposure. SB4315432 (transforming growth factor-ß1 receptor I inhibitor) significantly inhibited Nox4 expression in HK-2 cells. Knockdown of NOX4 transcription reduced reactive oxygen species production, lowered the levels of pro-inflammatory markers (notably mitogen-activated protein kinases) implicated in colistin-induced nephrotoxicity and attenuated apoptosis by altering Bax and caspase 3/7 activity. Pretreatment with GKT137831 replicated these effects mediated by downregulation of mitogen-activated protein kinase activities. In a rat colistin-induced acute kidney injury model, administration of GKT137831 resulted in attenuated colistin-induced acute kidney injury as indicated by attenuated impairment of glomerulus function, preserved renal structures, reduced expression of 8-hydroxyguanosine and fewer apoptotic cells. Conclusions: Collectively, these findings identify Nox4 as a key source of reactive oxygen species responsible for kidney injury in colistin-induced nephrotoxicity and highlight a novel potential way to treat drug-related nephrotoxicity.

Rab25 augments cancer cell invasiveness through a ß1 integrin/EGFR/VEGF-A/Snail signaling axis and expression of fascin.

The small GTP-binding protein Rab25 is associated with tumor formation and progression. However, recent studies have shown discordant effects of Rab25 on cancer cell progression depending on cell lineage. In the present study, we elucidate the underlying mechanisms by which Rab25 induces cellular invasion. We demonstrate that Rab25 increases ß1 integrin levels and subsequent activation of EGFR and upregulation of VEGF-A expression, leading to increased Snail expression, epithelial-to-mesenchymal transition and cancer cell invasiveness. Strikingly, we identify that Snail mediates Rab25-induced cancer cell invasiveness through fascin expression and that ectopic expression of Rab25 aggravates metastasis of ovarian cancer cells to the lung. We thus demonstrate a novel role of a ß1 integrin/EGFR/VEGF-A/Snail signaling cascade in Rab25-induced cancer cell aggressiveness through induction of fascin expression, thus providing novel biomarkers and potential therapeutic targets for Rab25-expressing cancer cells.

Resveratrol suppresses breast cancer cell invasion by inactivating a RhoA/YAP signaling axis.

Hippo/YAP signaling is implicated in tumorigenesis and progression of various cancers. By inhibiting a plethora signaling cascades, resveratrol has strong anti-tumorigenic and anti-metastatic activity. In the present study, we demonstrate that resveratrol decreases the expression of YAP target genes. In addition, our data showed that resveratrol attenuates breast cancer cell invasion through the activation of Lats1 and consequent inactivation of YAP. Strikingly, we also demonstrate that resveratrol inactivates RhoA, leading to the activation of Lats1 and induction of YAP phosphorylation. Further, resveratrol in combination with other agents that inactivate RhoA or YAP showed more marked suppression of breast cancer cell invasion compared with single treatment. Collectively, these findings indicate the beneficial effects of resveratrol on breast cancer patients by suppressing the RhoA/Lats1/YAP signaling axis and subsequently inhibiting breast cancer cell invasion.

Homeobox A9 directly targeted by miR-196b regulates aggressiveness through nuclear Factor-kappa B activity in non-small cell lung cancer cells.

MicroRNAs (miRNAs) are recognized as crucial posttranscriptional regulators of gene expression, and play critical roles as oncogenes or tumor suppressors in various cancers. Here, we show that miR-196b is upregulated in mesenchymal-like-state non-small cell lung cancer (NSCLC) cells and lung cancer tissues. Moreover, miR-196b upregulation stimulates cell invasion and a change in cell morphology to a spindle shape via loss of cell-to-cell contacts. We identified homeobox A9 (HOXA9) as a target gene of miR-196b by using public databases such as TargetScan, miRDB, and microRNA.org. HOXA9 expression is inversely correlated with miR-196b levels in clinical NSCLC samples as compared to that in corresponding control samples, and with the migration and invasion of NSCLC cells. Ectopic expression of HOXA9 resulted in a suppression of miR-196b-induced cell invasion, and HOXA9 reexpression increased E-cadherin expression. Furthermore, HOXA9 potently attenuated the expression of snail family zinc finger 2 (SNAI2/SLUG) and matrix metallopeptidase 9 (MMP9) by controlling the binding of nuclear factor-kappa B to the promoter of SLUG and MMP9 genes, respectively. Therefore, we suggest that HOXA9 plays a central role in controlling the aggressive behavior of lung cancer cells and that miR-196b can serve as a potential target for developing anticancer agents. © 2015 Wiley Periodicals, Inc.

Resveratrol attenuates norepinephrine-induced ovarian cancer invasiveness through downregulating hTERT expression.

Stress hormone norepinephrine (NE) has been associated with acquisition of cancer progression, and naturally occurring phytoalexin resveratrol (REV) has been known to suppress cancer growth and progression. In the present study, we determine the effect of REV on NE-induced ovarian cancer invasiveness. Pretreatment of REV significantly inhibited NE-induced ovarian cancer cell epithelial-to-mesenchymal transition with concomitant recovery of E-cadherin expression. In addition, our data showed that REV downregulates NE-induced human telomerase reverse transcriptase (hTERT) expression through inhibiting Src phosphorylation and HIF-1α expression. Further, REV reduced NE-induced Slug expression and subsequent ovarian cancer invasion. More importantly, combined treatment of REV with a pharmacological inhibitor of beta adrenergic receptor significantly attenuated NE-induced ovarian cancer invasion compared to single treatment. Therefore, we demonstrate interference of a Src and HIF-1α/hTERT/Slug signaling cascade by REV, providing potential therapeutic targets and inhibition of ovarian cancer.

Breast cancer metastasis suppressor 1 (BRMS1) attenuates TGF-ß1-induced breast cancer cell aggressiveness through downregulating HIF-1α expression.

BACKGROUND: Cancer metastasis is a multi-step event including epithelial-to-mesenchymal transition (EMT). Breast cancer metastasis suppressor 1 (BRMS1) is a novel metastasis suppressor protein without anti-proliferating activity. However, a detailed underlying mechanism by which BRMS1 attenuates cancer cell EMT and invasion remained to be answered. In the present study, we report an additional mechanism by which BRMS1 attenuates Transforming growth factor-beta1 (TGF-ß1)-induced breast cancer cell EMT and invasion. METHODS: Experimental analysis involving chromosome immunoprecipitation (ChIP) and luciferase reporter assays were used to validate hypoxia inducible factor-1alpha (HIF-1α) as a transcriptional regulator of TWIST1 and Snail. Quantitative RT-PCR was used to analyze transcript expression. Immunoblotting and immunofluorescence were used to analyze protein expression. Matrigel-coated in vitro invasion insert was used to analyze cancer cell invasion. RESULTS: BRMS1 strongly inhibited TGF-ß1-induced breast cancer cell EMT and invasion. Unexpectedly, we observed that BRMS1 downregulates not only TWIST1 but also Snail expression, thereby inhibiting breast cancer cell invasion. In addition, we provide evidence that HIF-1α is required for Snail and TWIST1 expression. Further, BRMS1 reduced TGF-ß1-induced HIF-1α transcript expression through inactivation of nuclear factor kappaB (NF-κB). CONCLUSION: Collectively, the present study demonstrates a mechanical cascade of BRMS1 suppressing cancer cell invasion through downregulating HIF-1α transcript and consequently reducing Snail and TWIST1 expression.

A ROS/STAT3/HIF-1α signaling cascade mediates EGF-induced TWIST1 expression and prostate cancer cell invasion.

BACKGROUND: Epidermal growth factor (EGF) has been known to induce epithelial-mesenchymal transition (EMT) and prostate cancer cell progression. However, a detailed underlying mechanism by which EGF induces EMT and prostate cancer cell progression remained to be answered. Hypoxia-inducible factor (HIF)-1α and TWIST1 are transcription factors implicated in EMT and cancer metastasis. The purpose of this study is to determine the underlying mechanism of EGF-induced TWIST1 expression and prostate cancer invasion. METHODS: siRNAs were used to silence genes. Immunoblotting, quantitative RT-PCR and immunofluorescence analysis were used to examine protein or mRNA expression. Modified Boyden chamber and invasion assay kit with Matrigel-coated inserts were used to determine prostate cancer cell migration and invasion, respectively. RESULTS: We observed that EGF induced HIF-1α expression and morphological change of prostate cancer epithelial cells to mesenchymal cells. Silencing HIF-1α expression dramatically reduced EGF-induced TWIST1 expression and prostate cancer cell EMT. Conversely, transfection of the cells with HIF-1α siRNA reversed the reduced E-cadherin expression by EGF. Pretreatment of the cells with pharmacological inhibitors of reactive oxygen species [ROS, N-acetylcysteine (NAC)] and STAT3 (WP1066) but not p38 MAPK (SB203580) significantly reduced EGF-induced HIF-1α mRNA and protein expression. Further, pretreatment of the cells with NAC attenuated EGF-induced STAT3 phosphorylation. In addition, we showed that TWIST1 mediated EGF-induced N-cadherin expression, leading to prostate cancer invasion. CONCLUSIONS: We demonstrate a mechanism by which EGF promotes prostate cancer cell progression through a ROS/STAT3/HIF-1α/TWIST1/N-cadherin signaling cascade, providing novel biomarkers and promising therapeutic targets for prostate cancer cell progression.