RhoC is essential for angiogenesis induced by hepatocellular carcinoma cells via regulation of endothelial cell organization

GENE EXPRESSION WITHIN A HUMAN CHOROIDAL NEOVASCULAR MEMBRANE USING SPATIAL TRANSCRIPTOMICS

Macular neovascularization is a relatively common and potentially visually devastating complication of age-related macular degeneration. In macular neovascularization, pathologic angiogenesis can originate from either the choroid or the retina, but we have limited understanding of how different cell types become dysregulated in this dynamic process. In this study, we performed spatial RNA sequencing on a human donor eye with macular neovascularization as well as a healthy control donor. We identified genes enriched within the area of macular neovascularization and used deconvolution algorithms to predict the originating cell type of these dysregulated genes. Within the area of neovascularization, endothelial cells were predicted to increase expression of genes related to Rho family GTPase signaling and integrin signaling. Likewise, VEGF and TGFB1 were identified as potential upstream regulators that could drive the observed gene expression changes produced by endothelial and retinal pigment epithelium cells in the macular neovascularization donor. These spatial gene expression profiles were compared to previous single-cell gene expression experiments in human age-related macular degeneration as well as a model of laser-induced neovascularization in mice. As a secondary aim, we also investigated spatial gene expression patterns within the macular neural retina and between the macular and peripheral choroid. We recapitulated previously described regional-specific gene expression patterns across both tissues. Overall, this study spatially analyzes gene expression across the retina, retinal pigment epithelium, and choroid in health and describes a set of candidate molecules that become dysregulated in macular neovascularization.

RHO GTPase family in hepatocellular carcinoma

RHO GTPases are a subfamily of the RAS superfamily of proteins, which are highly conserved in eukaryotic species and have important biological functions, including actin cytoskeleton reorganization, cell proliferation, cell polarity, and vesicular transport. Recent studies indicate that RHO GTPases participate in the proliferation, migration, invasion and metastasis of cancer, playing an essential role in the tumorigenesis and progression of hepatocellular carcinoma (HCC). This review first introduces the classification, structure, regulators and functions of RHO GTPases, then dissects its role in HCC, especially in migration and metastasis. Finally, we summarize inhibitors targeting RHO GTPases and highlight the issues that should be addressed to improve the potency of these inhibitors.

Comparative transcriptomics of high-altitude Vulpes and their low-altitude relatives

The harsh environment of Qinghai-Tibet Plateau (QTP) imposes strong selective stresses (e.g., hypoxia, high UV-radiation, and extreme temperature) to the native species, which have driven striking phenotypic and genetic adaptations. Although the mechanisms of high-altitude adaptation have been explored for many plateau species, how the phylogenetic background contributes to genetic adaption to high-altitude of Vulpes is largely unknown. In this study, we sequenced transcriptomic data across multiple tissues of two high-altitude Vulpes (Vulpes vulpes montana and Vulpes ferrilata) and their low-altitude relatives (Vulpes corsac and Vulpes lagopus) to search the genetic and gene expression changes caused by high-altitude environment. The results indicated that the positive selection genes (PSGs) identified by both high-altitude Vulpes are related to angiogenesis, suggesting that angiogenesis may be the result of convergent evolution of Vulpes in the face of hypoxic selection pressure. In addition, more PSGs were detected in V. ferrilata than in V. v. montana, which may be related to the longer adaptation time of V. ferrilata to plateau environment and thus more genetic changes. Besides, more PSGs associated with high-altitude adaptation were identified in V. ferrilata compared with V. v. montana, indicating that the longer the adaptation time to the high-altitude environment, the more genetic alterations of the species. Furthermore, the result of expression profiles revealed a tissue-specific pattern between Vulpes. We also observed that differential expressed genes in the high-altitude group exhibited species-specific expression patterns, revealed a convergent expression pattern of Vulpes in high-altitude environment. In general, our research provides a valuable transcriptomic resource for further studies, and expands our understanding of high-altitude adaptation within a phylogenetic context.

Down-regulation of EGFL8 regulates migration, invasion and apoptosis of hepatocellular carcinoma through activating Notch signaling pathway

BACKGROUND

Our previous studies have reported the down-regulation of EGFL8 correlates to the development and prognosis of colorectal and gastric cancer. The present study is carried out to explore the expression pattern and role of EGFL8 in hepatocellular carcinoma (HCC).

METHODS AND MATERIALS

EGFL8 expression in 102 cases of HCC tissues matched with adjacent non-tumorous liver tissues, a normal liver cell line and three liver cancer cell lines with different metastatic capacity was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot. Moreover, the clinicopathological features and prognosis of HCC patients were correlated with expression of EGFL8. Subsequently, the gain-and loss-of-function experiments were carried out to investigate the biological function of EGFL8 in HCC. We also used N-[N-(3,5-Difluorophenacetyl-L-alanyl)]-(S)- phenylglycine t-butyl ester (DAPT), an inhibitor for Notch signaling pathway, in these experiments to verify the involvement of Notch signaling pathway in the effects of EGFL8. Additionally, a mouse model was established to investigate the effect of EGFL8 on metastasis of HCC cells. The expression of Notch signaling pathway in HCC cells and xenograft mouse tumors were detected by Western blot and immunohistochemistory.

RESULTS

The expression of EGFL8 was significantly decreased in HCC tissues and cell lines and EGFL8 down-regulation correlated to multiple nodules, vein invasion, high TNM stage and poor prognosis of HCC. Interestingly, the expression levels of EGFL8 in three liver cancer cell lines were negatively associated with their metastatic capacity. In vitro and in vivo experiments indicated that EGFL8 obviously suppressed metastasis and invasion of HCC cells but slightly promoted apoptosis. Meanwhile, the expression of Notch signaling pathway was obviously suppressed in EGFL8 overexpressed HCCLM3 cells and xenograft mouse tumors generated from these cells but markedly elevated in EGFL8 depleted Hep3B cells. Furthermore, the up-regulated expression of Notch signaling pathway and effects induced by EGFL8 knockdown in Hep3B cells could be counteracted by DAPT treatment.

CONCLUSION

The down-regulation of EGFL8 was correlated to progression and poor prognosis of HCC and regulates HCC cell migration, invasion and apoptosis through activating the Notch signaling pathway, suggesting EGFL8 as a novel therapeutic target and a potential prognostic marker for HCC.

Cytotoxic necrotizing factor 1 promotes bladder cancer angiogenesis through activating RhoC

Uropathogenic Escherichia coli (UPEC), a leading cause of urinary tract infections, is associated with prostate and bladder cancers. Cytotoxic necrotizing factor 1 (CNF1) is a key UPEC toxin; however, its role in bladder cancer is unknown. In the present study, we found CNF1 induced bladder cancer cells to secrete vascular endothelial growth factor (VEGF) through activating Ras homolog family member C (RhoC), leading to subsequent angiogenesis in the bladder cancer microenvironment. We then investigated that CNF1-mediated RhoC activation modulated the stabilization of hypoxia-inducible factor 1α (HIF1α) to upregulate the VEGF. We demonstrated in vitro that active RhoC increased heat shock factor 1 (HSF1) phosphorylation, which induced the heat shock protein 90α (HSP90α) expression, leading to stabilization of HIF1α. Active RhoC elevated HSP90α, HIF1α, VEGF expression, and angiogenesis in the human bladder cancer xenografts. In addition, HSP90α, HIF1α, and VEGF expression were also found positively correlated with the human bladder cancer development. These results provide a potential mechanism through which UPEC contributes to bladder cancer progression, and may provide potential therapeutic targets for bladder cancer.

The Role of Rho GTPases in VEGF Signaling in Cancer Cells

Vascular endothelial growth factors (VEGFs) consist of five molecules (VEGFA through D as well as placental growth factor) which are crucial for regulating key cellular and tissue functions. The role of VEGF and its intracellular signaling and downstream molecular pathways have been thoroughly studied. Activation of VEGF signal transduction can be initiated by the molecules' binding to two classes of transmembrane receptors: (1) the VEGF tyrosine kinase receptors (VEGF receptors 1 through 3) and (2) the neuropilins (NRP1 and 2). The involvement of Rho GTPases in modulating VEGFA signaling in both cancer cells and endothelial cells has also been well established. Additionally, different isoforms of Rho GTPases, namely, RhoA, RhoC, and RhoG, have been shown to regulate VEGF expression as well as blood vessel formation. This review article will explore how Rho GTPases modulate VEGF signaling and the consequences of such interaction on cancer progression.

Hypoxia and EGF Stimulation Regulate VEGF Expression in Human Glioblastoma Multiforme (GBM) Cells by Differential Regulation of the PI3K/Rho-GTPase and MAPK Pathways

Glioblastoma multiforme (GBM) is one of the most common and deadly cancers of the central nervous system (CNS). It is characterized by the presence of hypoxic regions, especially in the core, leading to an increase in vascularity. This increased vascularization is driven by the expression of the major angiogenic inducer VEGF and the indirect angiogenic inducer Epidermal growth factor (EGF), which stimulates VEGF expression. In this study, we examine the regulation of VEGF by both hypoxia and the EGF signaling pathway. We also examine the involvement of pathways downstream from EGF signaling, including the mitogen-activated protein kinase/extracellular regulated kinase (MAPK/ERK) pathway and the Phosphatidylinositol-3-kinase/RhoA/C (PI3K/RhoA/C) pathway in this regulation. Our results show that VEGF expression and secretion levels increase following either hypoxia or EGF stimulation, with the two stimuli signaling in parallel. We also observed an increase in ERK and protein kinase B (Akt) phosphorylation, in response to EGF stimulation, with kinetics that correlated with the kinetics of the effect on VEGF. Using pharmacological inhibitors against ERK and PI3K and small interfering RNAs (siRNAs) against RhoA and RhoC, we found that both the ERK and the PI3K/RhoA/C pathways have to cooperate in order to lead to an increase in VEGF expression, downstream from EGF. In response to hypoxia, however, only ERK was involved in the regulation of VEGF. Hypoxia also led to a surprising decrease in the activation of PI3K and RhoA/C. Finally, the decrease in the activation of these Rho-GTPases was found to be mediated through a hypoxia-driven overexpression of the Rho-GTPase GTPase activating protein (GAP), StarD13. Therefore, while under normoxic conditions, EGF stimulates the activation of both the PI3K and the MAPK pathways and the induction of VEGF, in glioblastoma cells, hypoxic conditions lead to the suppression of the PI3K/RhoA/C pathway and an exclusive switch to the MAPK pathway.

Expression And Biological Interaction Network Of RHOC For Hepatic Carcinoma With Metastasis In PBMC Samples

Objectives

Hepatic carcinoma with metastasis remains incurable, and clinical diagnostic methods lacked adequate sensitivity and specificity. Therefore, seeking effectively diagnostic biomarkers is still essential for it. RHOC was reported to be linked to metastasis of hepatic carcinoma. However, almost all of the studies used tissues as detection samples, which was not ideal for clinical course minoring. Therefore, here, it was aimed to use PBMC samples that were not only easily accessible but also minimally invasive to determine the expression and biological interaction network of RHOC for hepatic carcinoma with metastasis.

Methods

PBMC samples were isolated. Then, RNA-seq was performed to identify the DEGs between hepatic carcinoma with metastasis and hepatic carcinoma with solitary tumor. Subsequently, q-RT-PCR was used to verify the expression level of RHOC. Finally, bioinformatic analysis was used to present the biological interaction network of RHOC for hepatic carcinoma with metastasis in PBMC samples.

Results

The results of both RNA-seq and q-RT-PCR showed that the expression level of RHOC was significantly higher in the PBMC samples of hepatic carcinoma with metastasis than in those of hepatic carcinoma with solitary tumor. By using variety of bioinformatic analysis platforms, in PBMCs, 18 co-expression genes with RHOC were identified and their interaction network showed that MYL9 and RHOC had the highest edge evidence, and were involved in some cell migration-related pathways.

Conclusion

Our results indicated that RHOC in PBMCs could be potentially minimally invasive indicators for the diagnosis and clinical course supervision of hepatic carcinoma with metastasis, and its biological interaction network determined based on bioinformatic methods would lay a foundation for further study of the role of RHOC in tumor invasion and metastasis.

Building Blood Vessels-One Rho GTPase at a Time

Blood vessels are required for the survival of any organism larger than the oxygen diffusion limit. Blood vessel formation is a tightly regulated event and vessel growth or changes in permeability are linked to a number of diseases. Elucidating the cell biology of endothelial cells (ECs), which are the building blocks of blood vessels, is thus critical to our understanding of vascular biology and to the development of vascular-targeted disease treatments. Small GTPases of the Rho GTPase family are known to regulate several processes critical for EC growth and maintenance. In fact, many of the 21 Rho GTPases in mammals are known to regulate EC junctional remodeling, cell shape changes, and other processes. Rho GTPases are thus an attractive target for disease treatments, as they often have unique functions in specific vascular cell types. In fact, some Rho GTPases are even expressed with relative specificity in diseased vessels. Interestingly, many Rho GTPases are understudied in ECs, despite their known expression in either developing or mature vessels, suggesting an even greater wealth of knowledge yet to be gleaned from these complex signaling pathways. This review aims to provide an overview of Rho GTPase signaling contributions to EC vasculogenesis, angiogenesis, and mature vessel barrier function. A particular emphasis is placed on so-called "alternative" Rho GTPases, as they are largely understudied despite their likely important contributions to EC biology.

Effects of RhoC downregulation on the angiogenesis characteristics of myeloma vascular endothelial cells

Background

Tumor angiogenesis plays an important role in disease progression, and RhoC has been previously found to be expressed in vascular endothelial cells (VECs); however, its role in tumor angiogenesis requires clarification. This study aimed to explore the effects of RhoC downregulation on the cytoskeleton, pseudopod formation, migration ability, and canalization capacity of myeloma vascular endothelial cells (MVECs) in vitro.

Materials and methods

The expression of RhoC in MVECs and human umbilical vein endothelial cells (HUVECs) was knocked down by shRNA, and the expression levels of RhoC mRNA were detected by quantitative reverse transcription polymerase chain reaction (qRT‐PCR). The cytoskeletal changes and pseudopods were observed by laser scanning confocal and scanning electron microscopy; VECs were incubated in two‐dimensional Matrigel and three‐dimensional microcarriers to observe tube‐like structures and budding status, respectively. The protein expression of RhoC, phosphorylation of mitogen‐activated protein kinase (p‐MAPK), and Rho‐associated coiled‐coil kinase (ROCK) was determined by Western blotting. The expression of RhoC in VECs was downregulated by RhoC shRNA, thereby decreasing the number of pseudopods, two‐dimensional tube‐like structures, and buds.

Results

When RhoC was downregulated, the expression levels of ROCK and phosphorylation of MAPK were both decreased (P < 0.05). Moreover, the expression levels of RhoC and phosphorylation of MAPK and three‐dimensional budding numbers were higher in MVECs than in HUVECs (P < 0.05). The downregulation of RhoC expression in MVECs and HUVECs inhibited pseudopod formation, migration, canalization ability, and angiogenesis (P < 0.05).

Conclusion

Our data indicated that MVECs and HUVECs were well suited for angiogenesis research, but the former cell type was shown to be more advantageous in terms of budding numbers. RhoC plays a pivotal role in MVECs angiogenesis, and the downregulation of RhoC expression could inhibit angiogenesis via the RhoC/MAPK and RhoC/ROCK signaling pathways.

RHOG Activates RAC1 through CDC42 Leading to Tube Formation in Vascular Endothelial Cells

Angiogenesis is a hallmark of cancer cell malignancy. The role of the RHO family GTPase RHOG in angiogenesis in vascular endothelial cells has recently been elucidated. However, the regulation of RHOG during this process, as well as its cross-talk with other RHO GTPases, have yet to be fully examined. In this study, we found that siRNA-mediated depletion of RHOG strongly inhibits tube formation in vascular endothelial cells (ECV cells), an effect reversed by transfecting dominant active constructs of CDC42 or RAC1 in the RHOG-depleted cells. We also found CDC42 to be upstream from RAC1 in these cells. Inhibiting either Phosphatidyl inositol (3) kinase (PI3K) with Wortmannin or the mitogen-activated protein kinase extracellular-regulated kinase (MAPK ERK) with U0126 leads to the inhibition of tube formation. While knocking down either RHO, GTPase did not affect p-AKT levels, and p-ERK decreased in response to the knocking down of RHOG, CDC42 or RAC1. Recovering active RHO GTPases in U0126-treated cells also did not reverse the inhibition of tube formation, placing ERK downstream from PI3K-RHOG-CDC42-RAC1 in vascular endothelial cells. Finally, RHOA and the Rho activated protein kinases ROCK1 and ROCK2 positively regulated tube formation independently of ERK, while RHOC seemed to inhibit the process. Collectively, our data confirmed the essential role of RHOG in angiogenesis, shedding light on a potential new therapeutic target for cancer malignancy and metastasis.

miR-330-5p targets SPRY2 to promote hepatocellular carcinoma progression via MAPK/ERK signaling

MicroRNAs (miRNAs) have been identified as critical modulators of cell proliferation and growth, which are the major causes of cancer progression including hepatocellular carcinoma (HCC). Our previous miRNA microarray data have shown that miR-330-5p was always upregulated in HCC. However, the accurate role of miR-330-5p in HCC is still uncertain. Here, we report that miR-330-5p expression is upregulated in HCC tissues and cell lines, and is associated with tumor size, tumor nodule number, capsule formation and Tumor Node Metastasis (TNM) stage in HCC patients. Overexpression of miR-330-5p promotes proliferation and growth of HCC cells in vitro and in vivo, while miR-330-5p knockdown has the inverse effect. Moreover, using miRNA databases and dual luciferase report assay, we find miR-330-5p directly binds to the 3′-untranslated region (3′-UTR) of Sprouty2 (SPRY2). Then we find the novel biofunctional role of SPRY2 inactivation in promoting HCC progression. Finally, we confirm that miR-330-5p suppresses SPRY2 to promote proliferation via mitogen-activated protein kinases (MAPK)/extracellular regulated kinase (ERK) signaling in HCC. Taken together, our findings demonstrate the critical role of miR-330-5p in promoting HCC progression via targeting SPRY2 to activate MAPK/ERK signaling, which may provide a novel and promising prognostic marker and therapeutic target for HCC.

Inhibition of Phosphatidylinositol 3-kinease suppresses formation and progression of experimental abdominal aortic aneurysms

Accumulating evidence suggests an important role of Phosphatidylinositol 3-kinease (PI3K) pathway in inflammatory cells infiltration. Given  the essential role of inflammatory cells infiltration during the formation and progression of abdominal aortic aneurysm (AAA), to investigate the possibility of preventing AAA formation and progression via targeting PI3K is anticipated. Here, experimental AAAs was created in rats by transient intraluminal porcine pancreatic elastase (PPE) infusion into the infrarenal aorta firstly. AAAs rats were administrated with vehicle or Wortmannin during the period of day 0 to day 28 after PPE infusion. The aortic diameter of rats treated with Wortmannin was significantly smaller than those treated with vehicle. Meanwhile, Elastin destruction score and SMC destruction score were significantly decreased in rats treated with Wortmannin. Furthermore, histological analysis revealed infiltration of inflammatory cells were significantly reduced in rats treated with Wortmannin. Finally, the mRNA expression of PI3K and protein expression of pAKT in human abdominal aneurismal aorta tissues was elevated as compare to normal aorta. Our study revealed that PI3K inhibitor suppresses experimental AAAs formation and progression, through mechanisms likely related to impairing inflammation cells infiltration and median elastin degradation. These findings indicated that PI3K inhibitor may hold substantial translation value for AAA diseases.

Ack1 overexpression promotes metastasis and indicates poor prognosis of hepatocellular carcinoma

Despite the substantial data supporting the oncogenic role of Ack1, the predictive value and biologic role of Ack1 in hepatocellular carcinoma (HCC) metastasis remains unknown. In this study, both correlations of Ack1 expression with prognosis of HCC, and the role of Ack1 in metastasis of HCC were investigated in vitro and in vivo. Our results showed that Ack1 was overexpressed in human HCC tissues and cell lines. High Ack1 expression was associated with HCC metastasis and determined as a significant and independent prognostic factor for HCC after liver resection. Ack1 promoted HCC invasion and metastasis in vitro and in vivo. Mechanistically, we confirmed that Ack1 enhanced invasion and metastasis of HCC via EMT by mediating AKT phosphorylation. In conclusion, our study shows Ack1 is a novel prognostic biomarker for HCC and promotes metastasis of HCC via EMT by activating AKT signaling.

Extrauterine growth restriction on pulmonary vascular endothelial dysfunction in adult male rats: the role of epigenetic mechanisms

Objective:

Early postnatal life is considered as a critical time window for the determination of long-term metabolic states and organ functions. Extrauterine growth restriction (EUGR) causes the development of adult-onset chronic diseases, including pulmonary hypertension. However, the effects of nutritional disadvantages during the early postnatal period on pulmonary vascular consequences in later life are not fully understood. Our study was designed to test whether epigenetics dysregulation mediates the cellular memory of this early postnatal event.

Methods and results:

To test this hypothesis, we isolated pulmonary vascular endothelial cells by magnetic-activated cell sorting from EUGR and control rats. A postnatal insult, nutritional restriction-induced EUGR caused development of an increased pulmonary artery pressure at 9 weeks of age in male Sprague–Dawley rats. Methyl-DNA immune precipitation chip, genome-scale mapping studies to search for differentially methylated loci between control and EUGR rats, revealed significant difference in cytosine methylation between EUGR and control rats. EUGR changes the cytosine methylation at approximately 500 loci in male rats at 9 weeks of age, preceding the development of pulmonary hypertension and these represent the candidate loci for mediating the pathogenesis of pulmonary vascular disease that occurs later in life. Gene ontology analysis on differentially methylated genes showed that hypermethylated genes in EUGR are vascular development-associated genes and hypomethylated genes in EUGR are late-differentiation-associated and signal transduction genes. We validated candidate dysregulated loci with the quantitative assays of cytosine methylation and gene expressions.

Conclusion:

These results demonstrate that epigenetics dysregulation is a strong mechanism for propagating the cellular memory of early postnatal events, causing changes in the expression of genes and long-term susceptibility to pulmonary hypertension, and further providing a new insight into the prevention and treatment of EUGR-related pulmonary hypertension.

PKN3 is the major regulator of angiogenesis and tumor metastasis in mice

PKN, a conserved family member related to PKC, was the first protein kinase identified as a target of the small GTPase Rho. PKN is involved in various functions including cytoskeletal arrangement and cell adhesion. Furthermore, the enrichment of PKN3 mRNA in some cancer cell lines as well as its requirement in malignant prostate cell growth suggested its involvement in oncogenesis. Despite intensive research efforts, physiological as well as pathological roles of PKN3 in vivo remain elusive. Here, we generated mice with a targeted deletion of PKN3. The PKN3 knockout (KO) mice are viable and develop normally. However, the absence of PKN3 had an impact on angiogenesis as evidenced by marked suppressions of micro-vessel sprouting in ex vivo aortic ring assay and in vivo corneal pocket assay. Furthermore, the PKN3 KO mice exhibited an impaired lung metastasis of melanoma cells when administered from the tail vein. Importantly, PKN3 knock-down by small interfering RNA (siRNA) induced a glycosylation defect of cell-surface glycoproteins, including ICAM-1, integrin β1 and integrin α5 in HUVECs. Our data provide the first in vivo genetic demonstration that PKN3 plays critical roles in angiogenesis and tumor metastasis, and that defective maturation of cell surface glycoproteins might underlie these phenotypes.

RhoC maintains vascular homeostasis by regulating VEGF-induced signaling in endothelial cells

Vasculogenesis and angiogenesis are controlled by vascular endothelial growth factor A (VEGF-A). Dysregulation of these physiological processes contributes to the pathologies of heart disease, cancer and stroke. Rho GTPase proteins play an integral role in VEGF-mediated formation and maintenance of blood vessels. The regulatory functions of RhoA and RhoB in vasculogenesis and angiogenesis are well defined, whereas the purpose of RhoC remains poorly understood. Here, we describe how RhoC promotes vascular homeostasis by modulating endothelial cell migration, proliferation and permeability. RhoC stimulates proliferation of human umbilical vein endothelial cells (HUVECs) by stabilizing nuclear β-catenin, which promotes transcription of cyclin D1 and subsequently drives cell cycle progression. RhoC negatively regulates endothelial cell migration through MAPKs and downstream MLC2 signaling, and decreases vascular permeability through downregulation of the phospholipase Cγ (PLCγ)-Ca(2+)-eNOS cascade in HUVECs. Using a VEGF-inducible zebrafish (Danio rerio) model, we observed significantly increased vascular permeability in RhoC morpholino (MO)-injected zebrafish compared with control MO-injected zebrafish. Taken together, our findings suggest that RhoC is a key regulator of vascular homeostasis in endothelial cells.

The role of RhoC in epithelial-to-mesenchymal transition of ovarian carcinoma cells

Background

RhoC is a small G protein/GTPase and involved in tumor mobility, invasion and metastasis. Previously, up-regulated RhoC expression is found to play an important role in ovarian carcinogenesis and subsequent progression by modulating proliferation, apoptosis, migration and invasion.

Methods

We transfected RhoC-expressing plasmid and RhoC siRNA into CAOV3 and OVCAR3 cells respectively. These cells and transfectants were exposed to vascular epithelial growth factor (VEGF), transforming growth factor (TGF)-β1 or their receptor inhibitors with the phenotypes and their related-molecules examined.

Results

TGF-β1R or VEGFR inhibitor suppressed the proliferation, migration, invasion and lamellipodia formation, the expression of N-cadherin, α-SMA, snail and Notch1 mRNA or protein, and enhanced E-cadherin mRNA and protein expression in CAOV3 and its RhoC-overexpressing transfectants, whereas both growth factors had the opposite effects in OVCAR3 cells and their RhoC-hypoexpressing transfectants. Ectopic RhoC expression enhanced migration, invasion, lamellipodia formation and the alteration in epithelial to mesenchymal transition (EMT) markers of CAOV3 cells regardless of the treatment of VEGFR or TGF-β1R inhibitor, whereas RhoC knockdown resulted in the converse in OVCAR3 cells even with the exposure to VEGF or TGF-β1.

Conclusion

RhoC expression might be involved in EMT of ovarian epithelial carcinoma cells, stimulated by TGF-β1 and VEGF.

Small Rho GTPases in the control of cell shape and mobility

Rho GTPases are a class of evolutionarily conserved proteins comprising 20 members, which are predominantly known for their role in regulating the actin cytoskeleton. They are primarily regulated by binding of GTP/GDP, which is again controlled by regulators like GEFs, GAPs, and RhoGDIs. Rho GTPases are thus far well known for their role in the regulation of actin cytoskeleton and migration. Here we present an overview on the role of Rho GTPases in regulating cell shape and plasticity of cell migration. Finally, we discuss the emerging roles of ubiquitination and sumoylation in regulating Rho GTPases and cell migration.

Inhibition of rho-kinase by fasudil suppresses formation and progression of experimental abdominal aortic aneurysms

Objective

Accumulating evidence suggests that inflammatory cell infiltration is crucial pathogenesis during the initiation and progression of abdominal aortic aneurysm (AAA). Given Rho-kinase (ROCK), an important kinase control the actin cytoskeleton, regulates the inflammatory cell infiltration, thus, we investigate the possibility and mechanism of preventing experimental AAA progression via targeting ROCK in mice porcine pancreatic elastase (PPE) model.

Methods and Results

AAA was created in 10-week-old male C57BL/6 mice by transient intraluminal porcine pancreatic elastase infusion into the infrarenal aorta. The mRNA level of RhoA, RhoC, ROCK1 and ROCK2 were elevated in aneurismal aorta. Next, PPE infusion mice were orally administrated with vehicle or ROCK inhibitor (Fasudil at dose of 200 mg/kg/day) during the period of day 1 prior to PPE infusion to day 14 after PPE infusion. PPE infusion mice treated with Fasudil produced significantly smaller aneurysms as compare to PPE infusion mice treated with vehicle. AAAs developed in all vehicle-treated groups within 14 days, whereas AAAs developed in six mice (66%, 6/9) treated with Fasudil within 14 days. Furthermore, our semi-quantitative histological analysis revealed that blood vessels and macrophages were significantly reduced in Fasudil treated mice during the AAA progression. Finally, when mice with existing AAAs were treated with Fasudil, the enlargement was nearly completely suppressed.

Conclusion

Fasudil inhibits experimental AAA progression and stabilize existing aneurysms, through mechanisms likely related to impaired mural macrophage infiltration and angiogenesis. These findings suggest that ROCK inhibitor may hold substantial translational value for AAA diseases.

Role of the angiogenic components, VEGFA, FGF2, OPN and RHOC, in urothelial cell carcinoma of the urinary bladder

The objective of this study was to analyze the expression profile of the angiogenic components, vascular endothelial growth factor-A (VEGFA), basic fibroblast growth factor-2 (FGF2), osteopontin (OPN) and ras homolog gene family, member C (RHOC), in urothelial cell carcinoma (UCC) of the urinary bladder and to examine their role as candidate diagnostic biomarkers. Using qPCR, 77 samples of UCC of the urinary bladder and 77 matched tumor-associated normal samples were investigated to determine the expression of the four angiogenic components. The correlation between gene expression, patient survival and pathological features of the tumors was also examined. The VEGFA and OPN transcript levels were greater in the bladder cancer tissue than in the normal urothelium (P<0.001). Patients with higher VEGFA mRNA levels showed a tendency towards shorter cancer-specific survival. OPN levels showed a gradual increase, the lowest levels being found in non-invasive carcinoma and the highest in muscle invasive tumors. Elevated OPN levels indicated poor prognosis in connection with advanced disease stage (P<0.001). Both superficially invasive and muscle invasive tumors had significantly higher FGF2 levels compared to the control tissues (P=0.018 and P=0.050, respectively). Moreover, FGF2 was significantly higher in the metastatic vs. the non-metastatic tumors (P=0.0097). FGF2 levels exhibited a trend towards a correlation with worse patient survival. RHOC mRNA levels were higher in muscle invasive compared to superficially invasive tumors, as well as in grade III vs. grade I/II tumors. Furthermore, we detected worse overall survival for patients with high RHOC expression levels. VEGFA and FGF2 exhibited the best linear combination in the ROC curves for specificity and sensitivity. Thus, VEGFA and FGF2 may serve as candidate biomarkers for diagnostic purposes. Higher OPN expression may be used as a potential biomarker to predict patient survival relative to advanced tumor stage. However, further studies are required to investigate its role in urinary bladder carcinogenesis.

RhoB controls endothelial cell morphogenesis in part via negative regulation of RhoA

Recent studies have suggested a role for the small GTPase RhoB in the control of processes required for angiogenesis. However, the mechanisms whereby RhoB exerts control over these processes are not well understood. Given the role of vascular endothelial growth factor (VEGF) in pathological angiogenesis, we were interested in examining whether RhoB contributed to VEGF-induced angiogenic processes. To assess this, RhoB was specifically depleted in human umbilical vein endothelial cells (HUVEC), using siRNA-targeted strategies. The effects of RhoB depletion on VEGF-induced angiogenic activities were assessed using a variety of standard in vitro angiogenesis assays to assess endothelial cell viability, migration and capillary morphogenesis. Effects of RhoB depletion on signaling from other Rho family member proteins was also assessed using specific activity assays for RhoA and RhoC. We observed that although RhoB appeared dispensable for HUVEC viability, RhoB was required for endothelial cell migration, sprouting, and capillary morphogenesis. We also observed that siRNA-mediated depletion of RhoB in HUVEC resulted in increased RhoA activation in response to VEGF stimulation. This increased RhoA activation contributed to the cellular morphogenesis defects observed in RhoB-depleted cells, as inhibition of RhoA activity using C3 transferase, or inhibition of the activity of the downstream RhoA effectors Rho-dependent kinases I and II (ROCK I and II) led to a partial restoration of capillary morphogenesis in the absence of RhoB. Thus our data indicate that RhoB plays a significant role in VEGF-induced endothelial cell morphogenesis in part by negatively regulating the activity of RhoA and the RhoA/ROCK pathway.

Targeting RhoC by Way of Ribozyme Trangene in Human Breast Cancer Cells and its Impact on Cancer Invasion

Background

Cell motility and migration are known to be regulated by the Rho family of GTPases through their effects on the actin cytoskeleton. In breast cancer studies, RhoC has been identified as a highly specific marker in detecting tumors that developed metastases. This study aims to investigate the impact of targeting RhoC in human breast cancer cells by utilising ribozyme transgene technology and to assess its effect on cancer cell invasion.

Methods

Retroviral hammerhead ribozyme transgenes, regulated by doxycycline, were designed to specifically target human RhoC mRNA. The breast cancer cell line MDA-MB-231 was transfected with either a retroviral RhoC transgene or a control retroviral transgene. Stably transfected cells were tested for their invasiveness and migratory properties in vitro.

Results

In vitro testing of the invasiveness of wild type, plasmid control and the RhoC knockdown cells showed that MDA-MB-231^DRHOC cells had significantly reduced invasiveness compared with MDA-MB-231^WT (p < 0.038 RHOC2 knockdown cells; p < 0.006 RHOC3 knockdown cells) and MDA-MB-231^pRevTRE control plasmid cells (p < 0.07 RHOC2 knockdown cells; p < 0.002 RHOC3 knockdown cells). An even greater reduction in invasiveness of the MDA-MB-231^DRHOC cells compared with the MDA-MB-231^WT cells was seen in response to hepatocyte growth factor (HGF/SF) (p < 0.009 RHOC1 knockdown; p = 0.004 RHOC2 knockdown; p = 0.00007 RHOC3 knockdown). The addition of doxycycline significantly improved the effectiveness of the ribozyme transgenes (p < 0.04 for all three Rho ribozymes), but did not improve the effectiveness of these knockdown cells when treated with HGF/SF (p > 0.1 for all three ribozymes).

Conclusions

This data would indicate that targeting RhoC may be an effective way to reduce the invasive potential of human breast cancer cells.

Notch1 regulates the functional contribution of RhoC to cervical carcinoma progression

BACKGROUND

The role of Notch signalling in human epithelial cancers is of immense interest. In this study, we examine the interplay between Notch signalling and RhoC, a well-established molecular factor in metastasis. By linking the function of Notch and RhoC, we further strengthen the notion that there is a pro-oncogenic role of Notch signalling in human cervical cancers.

METHODS

RhoC protein expression in cervical carcinoma cell lines was assessed by western blotting. Using CaSki and SiHa cells (cervical carcinoma cells lines), we show that RhoC contributes to wound healing, invasion and migration, anoikis resistance, colony formation, in vitro tube formation and tumour formation. Immunohistochemical studies were carried out to assess the co-expression of RhoC, pAkt and Notch1 in clinical sections.

RESULTS

An assessment of the changes associated with epithelial-to-mesenchymal transition (EMT) shows that both Notch1 and RhoC have similar phenotypic contribution to EMT. Rho activity assessment on Notch1 inhibition with DAPT shows decreased RhoC activity. We further show that constitutively active RhoC rescues the phenotypic effect of Notch1 inactivation, and a comparison of Notch1 with RhoC expression shows an overlap between the two proteins in the same areas of the tissue.

CONCLUSION

This study has provided evidence to suggest that RhoC is an effector of Notch1 in cervical carcinoma.

RhoC expression and head and neck cancer metastasis

RhoC protein, a known marker of metastases in aggressive breast cancers and melanoma, has also been found to be overexpressed in certain head and neck cancers, thus we investigated the correlation between RhoC expression and the metastatic behavior of head and neck squamous cell carcinoma. Selective inhibition of RhoC expression was achieved using lentiviral small hairpin RNA (shRNA) transduced and tracked with green fluorescent protein to achieve 70% to 80% RhoC inhibition. Fluorescence microscopy of the RhoC knockdown stable clones showed strong green fluorescence in the majority of cells, signifying a high efficiency of transduction. Importantly, quantitative real-time PCR showed no significant decrease in the mRNA expression levels of other members of the Ras superfamily. Cell motility and invasion were markedly diminished in RhoC-depleted cell lines as compared with control transduced lines. H&E staining of lung tissue obtained from severe combined immunodeficiency mice, which had been implanted with RhoC knockdown cells, showed a marked decrease in lung metastasis and inflammation of the blood vessels. The cultured lung tissue showed a significant decrease in cell growth in mice implanted with RhoC-depleted cell lines as compared with shRNA-scrambled sequence control lines. Microscopic studies of CD31 expression revealed substantial quantitative and qualitative differences in the primary tumor microvessel density as compared with parental and shRNA-scrambled controls. This study is the first of its kind to establish the involvement of RhoC specifically in head and neck metastasis. These findings suggest that RhoC warrants further investigation to delineate its robustness as a novel potentially therapeutic target.