RhoE is frequently down-regulated in hepatocellular carcinoma (HCC) and suppresses HCC invasion through antagonizing the Rho/Rho-kinase/myosin phosphatase target pathway

Loss of RND3/RHOE controls entosis through LAMP1 expression in hepatocellular carcinoma

Entosis is a process that leads to the formation of cell-in-cell structures commonly found in cancers. Here, we identified entosis in hepatocellular carcinoma and the loss of Rnd3 (also known as RhoE) as an efficient inducer of this mechanism. We characterized the different stages and the molecular regulators of entosis induced after Rnd3 silencing. We demonstrated that this process depends on the RhoA/ROCK pathway, but not on E-cadherin. The proteomic profiling of entotic cells allowed us to identify LAMP1 as a protein upregulated by Rnd3 silencing and implicated not only in the degradation final stage of entosis, but also in the full mechanism. Moreover, we found a positive correlation between the presence of entotic cells and the metastatic potential of tumors in human patient samples. Altogether, these data suggest the involvement of entosis in liver tumor progression and highlight a new perspective for entosis analysis in medicine research as a novel therapeutic target.

Silencing of RND3/RHOE inhibits the growth of human hepatocellular carcinoma and is associated with reversible senescence

Rnd3/RhoE is an atypical Rho GTPase family member, known to be deregulated in many types of cancer. Previously, we showed that RND3 expression is downregulated in hepatocellular carcinoma (HCC) cell lines and tissues. In cancer cells, Rnd3 is involved in the regulation of cell proliferation and cell invasion. The implication of Rnd3 in HCC invasion was importantly studied whereas its role in cell growth needs further investigation. Thus, in this work, we aimed to better understand the impact of Rnd3 on tumor hepatocyte proliferation. Our results indicate that the silencing of RND3 induces a cell growth arrest both in vitro in 2D and 3D culture conditions and in vivo in tumor xenografts. The growth alteration after RND3 silencing in HCC cells is not due to an increase of cell death but to the induction of senescence. This RND3 knockdown-mediated phenomenon is dependent on the decrease of hTERT expression. Interestingly, after re-expression of RND3, these cells are able to bypass senescence and regain the ability to proliferate, with a re-expression of hTERT. Given that a low expression of Rnd3 is linked to the presence of satellite nodules in HCC, the transient senescence state observed might play a role in cancer progression.

miRNA-148b and its role in various cancers

miRNA-148b belongs to the family miR-148/-152, with significant differences in nonseed sequences, which can target diverse mRNA molecules. Reportedly, it may undergo deregulation in lung and ovarian cancers and downregulation in gastric, pancreatic and colon cancers. However, there is a need for further studies to better characterize its mechanism of action and in different types of cancer. In this review, we focus on the aberrant expression of miR-148b in different cancer types and highlight its main target genes and signaling pathways, as well as its pathophysiologic role and relevance to tumorigenesis in several types of cancer.

Effect of RhoE expression on the migration and invasion of tongue squamous cell carcinoma

OBJECTIVES

This study aims to investigate the effect of RhoE expression on the migration and invasion of tongue squamous cell carcinoma (TSCC).

METHODS

Forty-eight TSCC cases were selected from the Maxillofacial Surgery Center of Qingdao Municipal Hospital from 2017 to 2019. The expression of RhoE in the specimens (TSCC and adjacent tissues) was detected by immunohistochemistry, and RhoE mRNA and protein were extracted to further detect the expression of RhoE. SCC-4 and CAL-27 cells were selected for in vitro experiments. Transient transfection was used to overexpress RhoE. Real-time fluorescence quantitative PCR (qRT-PCR) and Western blot analyses were conducted to detect the overexpression efficiency. Scratch test and Transwell cell invasion tests were used to detect the migration and invasion ability of TSCC, respectively. The expression levels of Rho-associated coiled-coil-containing protein kinase 1 (ROCK1), matrix metalloproteinase-2 (MMP-2), and matrix metalloproteinase-9 (MMP-9) were detected by Western blot. Experimental data were analyzed by Graphpad prism 8.2.1 software.

RESULTS

The expression level of RhoE in TSCC was significantly lower than that in adjacent tissues (P<0.05). The migration and invasion abilities of TSCC were significantly lower than those in the control group (P<0.05). The Western blot showed significantly lower expression levels of ROCK1, MMP-2, and MMP-9 in the experimental group than in the control group (P<0.05).

CONCLUSIONS

RhoE expression is low in TSCC. Over expression RhoE in TSCC can significantly decrease its migration and invasion abilities. Hence, RhoE may play an important role in regulating the metastasis and invasion of TSCC and provide a new target for gene therapy.

Hedgehog Signaling: Implications in Cancers and Viral Infections

The hedgehog (SHH) signaling pathway is primarily involved in embryonic gut development, smooth muscle differentiation, cell proliferation, adult tissue homeostasis, tissue repair following injury, and tissue polarity during the development of vertebrate and invertebrate organisms. GLIoma-associated oncogene homolog (GLI) family of zinc-finger transcription factors and smoothened (SMO) are the signal transducers of the SHH pathway. Both SHH ligand-dependent and independent mechanisms activate GLI proteins. Various transcriptional mechanisms, posttranslational modifications (phosphorylation, ubiquitination, proteolytic processing, SUMOylation, and acetylation), and nuclear-cytoplasmic shuttling control the activity of SHH signaling pathway proteins. The dysregulated SHH pathway is associated with bone and soft tissue sarcomas, GLIomas, medulloblastomas, leukemias, and tumors of breast, lung, skin, prostate, brain, gastric, and pancreas. While extensively studied in development and sarcomas, GLI family proteins play an essential role in many host-pathogen interactions, including bacterial and viral infections and their associated cancers. Viruses hijack host GLI family transcription factors and their downstream signaling cascades to enhance the viral gene transcription required for replication and pathogenesis. In this review, we discuss a distinct role(s) of GLI proteins in the process of tumorigenesis and host-pathogen interactions in the context of viral infection-associated malignancies and cancers due to other causes. Here, we emphasize the potential of the Hedgehog (HH) pathway targeting as a potential anti-cancer therapeutic approach, which in the future could also be tested in infection-associated fatalities.

Pathophysiological functions of Rnd proteins

Rnd proteins constitute a subfamily of Rho GTPases represented in mammals by Rnd1, Rnd2 and Rnd3. Despite their GTPase structure, their specific feature is the inability to hydrolyse GTP-bound nucleotide. This aspect makes them atypical among Rho GTPases. Rnds are regulated for their expression at the transcriptional or post-transcriptional levels and they are activated through post-translational modifications and interactions with other proteins. Rnd proteins are mainly involved in the regulation of the actin cytoskeleton and cell proliferation. Whereas Rnd3 is ubiquitously expressed, Rnd1 and 2 are tissue-specific. Increasing data has described their important role during development and diseases. Herein, we describe their involvement in physiological and pathological conditions with a focus on the neuronal and vascular systems, and summarize their implications in tumorigenesis.

Targeting ROCK signaling in health, malignant and non-malignant diseases

A Rho-associated coiled-coil kinase (ROCK) is identified as a critical downstream effector of GTPase RhoA which contains two isoforms, ROCK1 (also known as p160ROCK and ROKβ) and ROCK2 (also known as Rho-kinase and ROKα), the gene of which is placed on chromosomes 18 (18q11.1) and 2 (2p24), respectively. ROCKs have a principal function in the generation of actin-myosin contractility and regulation of actin cytoskeleton dynamics. They represent a chief role in regulating various cellular functions, such as apoptosis, growth, migration, and metabolism through modulation of cytoskeletal actin synthesis, and cellular contraction through phosphorylation of numerous downstream targets. Emerging evidence has indicated that ROCKs present a significant function in cardiac physiology. Of note, dysregulation of ROCKs involves in several cardiac pathological processes like cardiac hypertrophy, cardiac fibrosis, systemic blood pressure disorder, and pulmonary hypertension. Moreover, ROCKs, in addition to their role in regulating renal arteriolar contraction, glomerular blood flow, and filtration, can also play a role in controlling podocytes, tubular cells, and mesangial cell structure and function. Hyperactivity disorder and over-gene expression of Rho/ROCK have been indicated in different cancers. Furthermore, it seems that increasing the expression of mRNA or ROCK protein has an undesirable effect on patient survival and has a positive impact on the progression and worsening of disease prognosis. This review focuses on the physiological and pathological functions of ROCKs with a particular view on its possible value of ROCK inhibitors as a new therapy in cancers and non-cancer diseases.

Knockdown of RhoE Expression Enhances TGF-β-Induced EMT (epithelial-to-mesenchymal transition) in Cervical Cancer HeLa Cells

Cervical cancer with early metastasis of the primary tumor is associated with poor prognosis and poor therapeutic outcomes. Since epithelial-to-mesenchymal transition (EMT) plays a role in acquisition of the ability to invade the pelvic lymph nodes and surrounding tissue, it is important to clarify the molecular mechanism underlying EMT in cervical cancer. RhoE, also known as Rnd3, is a member of the Rnd subfamily of Rho GTPases. While previous reports have suggested that RhoE may act as either a positive or a negative regulator of cancer metastasis and EMT, the role of RhoE during EMT in cervical cancer cells remains unclear. The present study revealed that RhoE expression was upregulated during transforming growth factor-β (TGF-β)-mediated EMT in human cervical cancer HeLa cells. Furthermore, reduced RhoE expression enhanced TGF-β-mediated EMT and migration of HeLa cells. In addition, we demonstrated that RhoE knockdown elevated RhoA activity and a ROCK inhibitor partially suppressed the acceleration of TGF-β-mediated EMT by RhoE knockdown. These results indicate that RhoE suppresses TGF-β-mediated EMT, partially via RhoA/ROCK signaling in cervical cancer HeLa cells.

NCKAP1 improves patient outcome and inhibits cell growth by enhancing Rb1/p53 activation in hepatocellular carcinoma

In our previous report, we identified miR-34c-3p as an independent factor contributing to the carcinogenesis of hepatocellular carcinoma (HCC) by targeting NCK Associated Protein 1 (NCKAP1). NCKAP1 has been known to promote the malignancy of cancer cells by disrupting the structural stability of WAS protein family member 1 (WASF1) and is correlated with poor prognosis of patients in several cancer types. Our results, however, show that NCKAP1 is correlated with a favorable outcome in HCC patients. The underlying mechanism of this contradictory phenomenon is unknown. The current study was designed to explore the mechanism of NCKAP1 in HCC. As a result, clinicopathological correlations and results from in vivo and in vitro models indicated that NCKAP1 was a tumor suppressor gene. Cell cycle analysis suggested that NCKAP1 inhibit cells from entering G2/M phase. Western blot analysis showed that WASF1 was barely expressed in HCC cell lines compared to that of breast cancer cell lines, which serve as positive controls. Furthermore, Rb1 and p53 expression was upregulated in cell lines overexpressing NCKAP1. Expression of several cell cycle regulating proteins also varied in the HCC cell lines. In conclusion, although previous studies have identified NCKAP1 as a cell invasion promoter by binding to WASF1, we found that NCKAP1 is a tumor suppress gene that modulates the cell cycle of HCC cell lines by targeting Rb1/p53 regulation.

APOBEC3B promotes hepatocarcinogenesis and metastasis through novel deaminase-independent activity

Cytidine deaminase APOBEC3B (A3B) is known to play important roles in creating de novo genomic C-to-T mutations in cancers and contribute to induction of genomic instability. Our study evaluated the roles of A3B in the progression and metastasis of human hepatocellular carcinoma (HCC). Using whole-transcriptome and whole-exome sequencing, and quantitative PCR, we found that A3B was overexpressed in human HCCs and A3B expression was significantly correlated with the proportion of genomic C-to-A and G-to-T mutations. Upon clinicopathological correlation, higher A3B expression was associated with more aggressive tumor behavior. Wild-type A3B (wt-A3B) overexpression in HCC cells promoted cell proliferation, and cell migratory and invasive abilities in vitro, and tumorigenicity and metastasis in vivo. On the other hand, knockdown of A3B suppressed cell proliferation, migratory, and invasive abilities of HCC cells with high endogenous A3B level. However, to our surprise, overexpression of A3B deaminase-dead double mutant (E68A/E255Q) led to similar results as wt-A3B in HCC. Furthermore, overexpression of wt-A3B and mutant A3B both enhanced cell cycle progression in HCC cells. Altogether, our data demonstrated a novel deaminase-independent role of A3B in contributing to HCC tumorigenesis and metastasis.

Analysis of expression profile data identifies key genes and pathways in hepatocellular carcinoma

The aims of the present study were to identify key genes and pathways associated with hepatocellular carcinoma (HCC) progression and predict compounds potentially associated with this type of carcinogenesis. The gene expression profile data of the GSE49515 dataset was obtained from the Gene Expression Omnibus database. The limma software package was used to identify the differentially expressed genes (DEGs). Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were performed using the Biological Networks Gene Ontology tool and the Database for Annotation, Visualization and Integrated Discovery, respectively. The Michigan Molecular Interactions database plugin within the Cytoscape software platform was used to perform protein-protein interaction (PPI) network analysis. Chemical-gene interaction data for HCC were obtained from the Comparative Toxicogenomics Database to evaluate the associations between drugs and specific genes. A total of 302 DEGs, including 231 downregulated and 71 upregulated, were identified. Cytokine-cytokine receptor interaction and chemokine signaling were the significantly enriched pathways. Additionally, PPI network analysis indicated a total of 13 highest degree hub nodes, including FBJ murine osteosarcoma viral oncogene homolog (FOS) and DNA damage-inducible transcript 3 protein (DDIT3). Chemical-gene interaction analysis revealed that FUN and FOS were targeted by >500 compounds, while >200 genes were targeted by 2,3,7,8-tetrachlorodibenzodioxin and benzo(α)pyrene. In conclusion, the present study demonstrated that FOS, DDIT3, the cytokine-cytokine receptor interaction pathway and the chemokine signaling pathway may be key genes and pathways associated with the development of HCC. Furthermore, exposure to 2,3,7,8-tetrachlorodibenzodioxin or benzo(α)pyrene may lead to hepatocarcinogenesis.

RhoE/ROCK2 regulates chemoresistance through NF-κB/IL-6/ STAT3 signaling in hepatocellular carcinoma

Small Rho GTPase (Rho) and its immediate effector Rho kinase (ROCK) are reported to regulate cell survival, but the detailed molecular mechanism remains largely unknown. We had previously shown that Rho/ROCK signaling was highly activated in hepatocellular carcinoma (HCC). In this study, we further demonstrated that downregulation of RhoE, a RhoA antagonist, and upregulation of ROCK enhanced resistance to chemotherapy in HCC in both in vitro cell and in vivo murine xenograft models, whereas a ROCK inhibitor was able to profoundly sensitize HCC tumors to cisplatin treatment. Specifically, the ROCK2 isoform but not ROCK1 maintained the chemoresistance in HCC cells. Mechanistically, we demonstrated that activation of ROCK2 enhanced the phosphorylation of JAK2 and STAT3 through increased expression of IL-6 and the IL-6 receptor complex. We also identified IKKβ as the direct downstream target of Rho/ROCK, and activation of ROCK2 significantly augmented NF-κB transcription activity and induced IL-6 expression. These data indicate that Rho/ROCK signaling activates a positive feedback loop of IKKβ/NF-κB/IL-6/STAT3 which confers chemoresistance to HCC cells and is a potential molecular target for HCC therapy.

Retracted Article: MiR-182-5p and miR-96-5p increased hepatocellular carcinoma cell mobility, proliferation and cisplatin resistance partially by targeting RND3

We investigated whether miR-182-5p or miR-96-5p could increase hepatocellular carcinoma (HCC) development by targeting Rho Family GTPase 3 (RND3) gene expression. The expression levels of miR-182-5p, miR-96-5p and mRNA/protein of RND3 in non-HCC liver tissue, HCC tissue and adjacent tissue specimens were evaluated by RT-qPCR and western blot. Patient-derived HCC cell culture was established, and miR-182-5p or miR-96-5p agomir or antagomir treatment was performed to mimic the overexpression or knockdown of the two miRNAs. HCC cell mobility in vitro was monitored by trans-well migration and invasion assay, while HCC cell growth in vitro was evaluated by cell viability, proliferation and apoptosis assay. HCC cell apoptosis was further investigated by caspase-3/-8/-9 activity assay. MiR-182-5p and miR-96-5p were significantly upregulated in HCC tissue specimens compared with non-HCC or adjacent tissue specimens, inversely correlating to RND3 mRNA expression level. Treatment with miR-182-5p or miR-96-5p agomir significantly reduced RND3 mRNA/protein expression level in HCC cells. MiR-182-5p- or miR-96-5p-targeting RND3 mRNA was verified by luciferase reporter assay and AGO2-RNA immunoprecipitation assay. MiR-182-5p or miR-96-5p agomir treatment significantly rescued HCC cell migration and invasion in vitro that were repressed by RND3 overexpression, during which ROCK1 and ROCK2 inhibition were involved. MiR-182-5p or miR-96-5p agomir treatment also increased HCC cell proliferation and cisplatin resistance in vitro, which could be antagonized by RND3 overexpression or ROCK inhibition. Thus, miR-182-5p and miR-96-5p increased HCC cell mobility, proliferation and cisplatin resistance in vitro partially by targeting RND3.

We investigated whether miR-182-5p or miR-96-5p could increase hepatocellular carcinoma (HCC) development by targeting Rho Family GTPase 3 (RND3) gene expression.

Genetic deletion of Rnd3 in neural stem cells promotes proliferation via upregulation of Notch signaling

Rnd3, a Rho GTPase, is involved in the inhibition of actin cytoskeleton dynamics through the Rho kinase-dependent signaling pathway. We previously demonstrated that mice with genetic deletion of Rnd3 developed a markedly larger brain compared with wild-type mice. Here, we demonstrate that Rnd3 knockout mice developed an enlarged subventricular zone, and we identify a novel role for Rnd3 as an inhibitor of Notch signaling in neural stem cells. Rnd3 deficiency, both in vivo and in vitro, resulted in increased levels of Notch intracellular domain protein. This led to enhanced Notch signaling and promotion of aberrant neural stem cell growth, thereby resulting in a larger subventricular zone and a markedly larger brain. Inhibition of Notch activity abrogated this aberrant neural stem cell growth.

miR-149 represses metastasis of hepatocellular carcinoma by targeting actin-regulatory proteins PPM1F

microRNAs have been implicated in hepatocellular carcinoma (HCC) metastasis, which is predominant cause of high mortality in these patients. Although an increasing body of evidence indicates that miR-149 plays an important role in the growth and metastasis of multiple types of cancers, its role in the progression of HCC remains unknown. Here, we demonstrated that miR-149 was significantly down-regulated in HCC, which was correlated with distant metastasis and TNM stage with statistical significance. A survival analysis showed that decreased miR-149 expression was correlated with a poor prognosis of HCC as well. We found that over-expression of miR-149 suppressed migration and invasion of HCC cells in vitro. In addition, we identified PPM1F (protein phosphatase, Mg(2+)/Mn(2+)-dependent, 1F) as a direct target of miR-149 whose expression was negatively correlated with the expression of miR-149 in HCC tissues. The re-expression of PPM1F rescued the miR-149-mediated inhibition of cell migration and invasion. miR-149 regulated formation of stress fibers to inhibit migration, and re-expression of PPM1F reverted the miR-149-mediated loss of stress fibers. Moreover, we demonstrated that over-expression of miR-149 reduced pMLC2, a downstream effector of PPM1F, in MHCC-97H cells. In vivo studies confirm inhibition of HCC metastasis by miR-149. Taken together, our findings indicates that miR-149 is a potential prognostic biomarker of HCC and that the miR-149/PPM1F regulatory axis represents a novel therapeutic target for HCC treatment.

Rnd3 in Cancer: A Review of the Evidence for Tumor Promoter or Suppressor

Rho-GTPases are members of the Ras superfamily of small GTPases and are general modulators of important cellular processes in tumor biology such as migration and proliferation. Among these proteins, Rnd3/RhoE, an atypical Rho-GTPase devoid of GTP hydrolytic activity, has recently been studied for its putative role in tumorigenesis. Indeed, Rnd3 is implicated in processes, such as proliferation and migration, whose deregulation is linked to cancer development and metastasis. The aim of this review is to provide an overview of the data surrounding Rnd3 deregulation in cancers, its origin, and consequences. Presented here is a comprehensive account of the expression status and biological output obtained in prostate, liver, stomach, colon, lung, and brain cancers as well as in melanoma and squamous cell carcinoma. Although there appears to be no general consensus about Rnd3 expression in cancers as this protein is differently altered according to the tumor context, these alterations overwhelmingly favor a protumorigenic role. Thus, depending on the tumor type, it may behave either as a tumor suppressor or as a tumor promoter. Importantly, the deregulation of Rnd3, in most cases, is linked to patient poor outcome.

IMPLICATIONS

Rnd3 has prognostic marker potential as exemplified in lung cancers and Rnd3 or Rnd3-associated signaling pathways may represent a new putative therapeutic target. Mol Cancer Res; 14(11); 1033-44. ©2016 AACR.

Down-regulation of TIMP2 by HIF-1α/miR-210/HIF-3α regulatory feedback circuit enhances cancer metastasis in hepatocellular carcinoma

Cancer metastasis is a multistep process that involves a series of tumor-stromal interaction, including extracellular matrix (ECM) remodeling, which requires a concerted action of multiple proteolytic enzymes and their endogenous inhibitors. This study investigated the role of tissue inhibitor of metalloproteinases (TIMP) 2 in the context of hepatocellular carcinoma (HCC) metastasis. We found that TIMP2 was the most significantly down-regulated member among the TIMP family in human HCCs. Moreover, TIMP2 underexpression was frequent (41.8%; 23 of 55) in human HCCs and was significantly associated with liver invasion and poorer survival outcomes of HCC patients. Furthermore, stable silencing of TIMP2 in HCC cell lines enhanced cell invasive ability and ECM degradation associated with formation of invadopodia-like feature, suggesting that TIMP2 is a negative regulator of HCC metastasis. Using an orthotopic tumor xenograft model, we demonstrated that ectopic expression of TIMP2 open reading frame in the highly metastatic HCC cell line, MHCC-97L, significantly reduced HCC progression as well as pulmonary metastasis. Mechanistically, TIMP2 suppression, in a hypoxic environment, was induced through a regulatory feedback circuit consisting of hypoxia-inducible factor (HIF) 1 alpha, microRNA-210 (miR-210), and HIF-3α.

CONCLUSION

TIMP2 is frequently down-regulated in human HCCs and its down-regulation is associated with aggressive tumor behavior and poorer patient outcome. Its suppression is under the regulation of a novel feedback circuit consisting of HIF-1α/miR-210/HIF-3α. TIMP2 is an important regulator of ECM degradation and HCC metastasis. (Hepatology 2016;64:473-487).

The RhoE/ROCK/ARHGAP25 signaling pathway controls cell invasion by inhibition of Rac activity

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma of skeletal muscle origin in children and adolescents. Among RMS subtypes, alveolar rhabdomyosarcoma (ARMS), which is characterized by the presence of the PAX3-FOXO1A or PAX7-FOXO1A chimeric oncogenic transcription factor, is associated with poor prognosis and a strong risk of metastasis compared with the embryonal subtype (ERMS). To identify molecular pathways involved in ARMS aggressiveness, we first characterized the migratory behavior of cell lines derived from ARMS and ERMS biopsies using a three-dimensional spheroid cell invasion assay. ARMS cells were more invasive than ERMS cells and adopted an ellipsoidal morphology to efficiently invade the extracellular matrix. Moreover, the invasive potential of ARMS cells depended on ROCK activity, which is regulated by the GTPase RhoE. Specifically, RhoE expression was low in ARMS biopsies, and its overexpression in ARMS cells reduced their invasion potential. Conversely, ARHGAP25, a GTPase-activating protein for Rac, was up-regulated in ARMS biopsies. Moreover, we found that ARHGAP25 inhibits Rac activity downstream of ROCKII and is required for ARMS cell invasion. Our results indicate that the RhoE/ROCK/ARHGAP25 signaling pathway promotes ARMS invasive potential and identify these proteins as potential therapeutic targets for ARMS treatment.

Knock-Down of Endogenous Bornavirus-Like Nucleoprotein 1 Inhibits Cell Growth and Induces Apoptosis in Human Oligodendroglia Cells

Endogenous bornavirus-like nucleoprotein elements (EBLNs) have been discovered in the genomes of various animals including humans, whose functions have been seldom studied. To explore the biological functions of human EBLNs, we constructed a lentiviral vector expressing a short-hairpin RNA against human EBLN1, which successfully inhibited EBLN1 expression by above 80% in infected human oligodendroglia cells (OL cells). We found that EBLN1 silencing suppressed cell proliferation, induced G2/M phase arrest, and promoted apoptosis in OL cells. Gene expression profiling demonstrated that 1067 genes were up-regulated, and 2004 were down-regulated after EBLN1 silencing. The top 10 most upregulated genes were PI3, RND3, BLZF1, SOD2, EPGN, SBSN, INSIG1, OSMR, CREB3L2, and MSMO1, and the top 10 most-downregulated genes were KRTAP2-4, FLRT2, DIDO1, FAT4, ESCO2, ZNF804A, SUV420H1, ZC3H4, YAE1D1, and NCOA5. Pathway analysis revealed that these differentially expressed genes were mainly involved in pathways related to the cell cycle, the mitogen-activated protein kinase pathway, p53 signaling, and apoptosis. The gene expression profiles were validated by using quantitative reverse transcription polymerase chain reaction (RT-PCR) for detecting these 20 most-changed genes. Three genes closely related to glioma, RND3, OSMR, and CREB3L2, were significantly upregulated and might be the key factors in EBLN1 regulating the proliferation and apoptosis of OL cells. This study provides evidence that EBLN1 plays a key role in regulating cell life and death, thereby opening several avenues of investigation regarding EBLN1 in the future.

Rh2E2, a novel metabolic suppressor, specifically inhibits energy-based metabolism of tumor cells

Energy metabolism in cancer cells is often increased to meet their higher proliferative rate and biosynthesis demands. Suppressing cancer cell metabolism using agents like metformin has become an attractive strategy for treating cancer patients. We showed that a novel ginsenoside derivative, Rh2E2, is as effective as aspirin in preventing the development of AOM/DSS-induced colorectal cancer and suppresses tumor growth and metastasis in a LLC-1 xenograft. A sub-chronic and acute toxicity LD50 test of Rh2E2 showed no harmful reactions at the maximum oral dosage of 5000 mg/kg body weight in mice. Proteomic profiling revealed that Rh2E2 specifically inhibited ATP production in cancer cells via down-regulation of metabolic enzymes involving glycolysis, fatty acid β-oxidation and the tricarboxylic acid cycle, leading to specific cytotoxicity and S-phase cell cycle arrest in cancer cells. Those findings suggest that Rh2E2 possesses a novel and safe anti-metabolic agent for cancer patients by specific reduction of energy-based metabolism in cancer cells.

Novel Insights into the Roles of Rho Kinase in Cancer

Rho-associated coiled-coil kinase (ROCK) is a major downstream effector of the small GTPase RhoA. The ROCK family, consisting of ROCK1 and ROCK2, plays a central role in the organization of the actin cytoskeleton, and is involved in a wide range of fundamental cellular functions such as contraction, adhesion, migration, proliferation, and apoptosis. Since the discovery of effective inhibitors such as fasudil and Y27632, the biological roles of ROCK have been extensively explored in numerous diseases, including cancer. Accumulating evidence supports the concept that ROCK plays important roles in tumor development and progression through regulating many key cellular functions associated with malignancy, including tumorigenicity, tumor growth, metastasis, angiogenesis, tumor cell apoptosis/survival and chemoresistance as well. This review focuses on the new advances of the most recent 5 years from the studies on the roles of ROCK in cancer development and progression; the discussion is mainly focused on the potential value of ROCK inhibitors in cancer therapy.

Pathophysiological Functions of Rnd3/RhoE

Rnd3, also known as RhoE, belongs to the Rnd subclass of the Rho family of small guanosine triphosphate (GTP)-binding proteins. Rnd proteins are unique due to their inability to switch from a GTP-bound to GDP-bound conformation. Even though studies of the biological function of Rnd3 are far from being concluded, information is available regarding its expression pattern, cellular localization, and its activity, which can be altered depending on the conditions. The compiled data from these studies implies that Rnd3 may not be a traditional small GTPase. The basic role of Rnd3 is to report as an endogenous antagonist of RhoA signaling-mediated actin cytoskeleton dynamics, which specifically contributes to cell migration and neuron polarity. In addition, Rnd3 also plays a critical role in arresting cell cycle distribution, inhibiting cell growth, and inducing apoptosis and differentiation. Increasing data have shown that aberrant Rnd3 expression may be the leading cause of some systemic diseases; particularly highlighted in apoptotic cardiomyopathy, developmental arrhythmogenesis and heart failure, hydrocephalus, as well as tumor metastasis and chemotherapy resistance. Therefore, a better understanding of the function of Rnd3 under different physiological and pathological conditions, through the use of suitable models, would provide a novel insight into the origin and treatment of multiple human diseases.

MiR-145 suppresses cell proliferation and motility by inhibiting ROCK1 in hepatocellular carcinoma

MicroRNAs (miRNAs) play key roles in cancer development and progression. In the present study, we investigated the role of miR-145 in the progression of hepatocellular carcinoma (HCC). Ten HCC cell lines and samples from 96 patients with HCC were analyzed for the expression of miR-145 by quantitative real-time polymerase chain reaction (qRT-PCR). Overexpression of miR-145 was established by transfecting mimics into HepG2 and QGY-7703 cells. Cell proliferation and cell migration were assessed by cell viability assay and transwell assay. Western blot was to verify ROCK1 as a novel target gene of miR-145. Our results showed that miR-145 was frequently downregulated in HCC tumors and cell lines. Overexpression of miR-145 in HCC cell lines significantly inhibited cell proliferation, migration, and invasion in vitro. ROCK1 was identified as a target of miR-145, and ectopic expression of miR-145 downregulated ROCK1. Together, these findings indicate that miR-145 acts as a tumor suppressor and its downregulation in tumor tissues may contribute to the progression and metastasis of HCC through a mechanism involving ROCK1, suggesting miR-145 as a potential new diagnostic and therapeutic target for the treatment of HCC.

miR-128 regulates the apoptosis and proliferation of glioma cells by targeting RhoE

In this study, we investigate whether miR-128 is capable of regulating the apoptosis and proliferation of human U251 glioma cells by downregulating RhoE. The expression of miR-128 was assessed by quantitative polymerase chain reaction in normal brain tissue and glioma samples. A significant downregulation of the expression of miR-128 was detected in glioma in contrast to normal brain tissue. Following the transfection of pre-miR-128 and anti-miR-128 into U251 cells, the high expression of miR-128 could inhibit proliferation and induce apoptosis in U251 cells, and those effects could be restored by miR-128 knockdown. To analyze the regulation mechanism of miR-128, TargetScan, miRanda and PicTar were used to ascertain whether RhoE was a potential target gene. Next, luciferase activity assay and western blot analysis confirmed that RhoE was a direct and specific target gene of miR-128. The advanced effects of pre-miR-128 on the apoptosis and proliferation of U251 cells were reversed by the upregulation of RhoE expression. In summary, aberrantly expressed miR-128 regulates apoptosis and proliferation in human glioma U251 cells partly by directly targeting RhoE. This finding may offer a new potential therapeutic strategy for the treatment of glioma.

MicroRNA-148b targets Rho-associated protein kinase 1 to inhibit cell proliferation, migration and invasion in hepatocellular carcinoma

microRNA(miR)-148b has been found to be downregulated in various human malignancies, including hepatocellular carcinoma (HCC) as well as gastric, pancreatic, colon and oral cancer. However, the function of miR‑148b in HCC has remained elusive. The present study examined the effects of miR‑148b on the proliferation, migration and invasion of HCC cells in vitro. After transfection of the HepG2 and SMMC‑7721 HCC cell lines with miR‑148b, an MTT assay, a Transwell migration and invasion assay as well as western blot analysis were performed. miR-148b was shown to inhibit cell proliferation, migration and invasion in the two cell lines. Using a luciferase reporter assay, the present study also provided the first evidence that miR‑148b directly targets Rho‑associated protein kinase 1 in HCC. These results suggested that miR-148 may represent a novel molecular marker and a potential molecular therapeutic for inhibiting metastasis of HCC.

Rnd3 regulates lung cancer cell proliferation through notch signaling

Rnd3/RhoE is a small Rho GTPase involved in the regulation of different cell behaviors. Dysregulation of Rnd3 has been linked to tumorigenesis and metastasis. Lung cancers are the leading cause of cancer-related death in the West and around the world. The expression of Rnd3 and its ectopic role in non-small cell lung cancer (NSCLC) remain to be explored. Here, we reported that Rnd3 was down-regulated in three NSCLC cell lines: H358, H520 and A549. The down-regulation of Rnd3 led to hyper-activation of Rho Kinase and Notch signaling. The reintroduction of Rnd3 or selective inhibition of Notch signaling, but not Rho Kinase signaling, blocked the proliferation of H358 and H520 cells. Mechanistically, Notch intracellular domain (NICD) protein abundance in H358 cells was regulated by Rnd3-mediated NICD proteasome degradation. Rnd3 regulated H358 and H520 cell proliferation through a Notch1/NICD/Hes1 signaling axis independent of Rho Kinase.

Effects of microRNA-30a on migration, invasion and prognosis of hepatocellular carcinoma

The role of microRNA-30a (miR-30a) deregulation in tumor progression and its downstream signaling pathways remain unknown. Here we confirmed significant downregulation of miR-30a in hepatocellular carcinoma (HCC) tissues and cell lines compared with non-tumor counterparts. MiR-30a downregulation was significantly associated with worse disease-free survival (DFS) of HCC patients. Gain- and loss-of-function studies revealed that downregulation of miR-30a facilitated tumor cell migration, invasion and epithelial-mesenchymal transition (EMT). We identified SNAI1 as a direct target of miR-30a and demonstrated miR-30a as a novel regulator of EMT by targeting SNAI1, indicating its potential therapeutic value for reducing invasion and metastasis of HCC.

Rnd3 haploinsufficient mice are predisposed to hemodynamic stress and develop apoptotic cardiomyopathy with heart failure

Rho family guanosine triphosphatase (GTPase) 3 (Rnd3), a member of the small Rho GTPase family, has been suggested to regulate cell actin cytoskeleton dynamics, cell migration, and apoptosis through the Rho kinase-dependent signaling pathway. The biological function of Rnd3 in the heart is unknown. The downregulation of small GTPase Rnd3 transcripts was found in patients with end-stage heart failure. The pathological significance of Rnd3 loss in the transition to heart failure remains unexplored. To investigate the functional consequence of Rnd3 downregulation and the associated molecular mechanism, we generated Rnd3^+/− haploinsufficient mice to mimic the downregulation of Rnd3 observed in the failing human heart. Rnd3^+/− mice were viable; however, the mice developed heart failure after pressure overload by transverse aortic constriction (TAC). Remarkable apoptosis, increased caspase-3 activity, and elevated Rho kinase activity were detected in the Rnd3^+/− haploinsufficient animal hearts. Pharmacological inhibition of Rho kinase by fasudil treatment partially improved Rnd3^+/− mouse cardiac functions and attenuated myocardial apoptosis. To determine if Rho-associated coiled-coil kinase 1 (ROCK1) was responsible for Rnd3 deficiency-mediated apoptotic cardiomyopathy, we established a double-knockout mouse line, the Rnd3 haploinsufficient mice with ROCK1-null background (Rnd3^{+/−/ROCK1−/−}). Again, genetic deletion of ROCK1 partially but not completely rescued Rnd3 deficiency-mediated heart failure phenotype. These data suggest that downregulation of Rnd3 correlates with cardiac loss of function as in heart failure patients. Animals with Rnd3 haploinsufficiency are predisposed to hemodynamic stress. Hyperactivation of Rho kinase activity is responsible in part for the apoptotic cardiomyopathy development. Further investigation of ROCK1-independent mechanisms in Rnd3-mediated cardiac remodeling should be the focus for future study.

CCL5 secreted from bone marrow stromal cells stimulates the migration and invasion of Huh7 hepatocellular carcinoma cells via the PI3K-Akt pathway

Bone metastases from hepatocellular carcinoma (HCC) seem to be increasing. Previous studies showed that soluble factors secreted by host cells and direct cell-to-cell interactions contributed to the preferential metastasis and growth of cancer cells in bone, while the underlying mechanism(s) of the metastasis of HCC in the bone are poorly understood. Here, we determined the effect of HS-5 cells on Huh7 cell proliferation, and investigated the role of CCL5 from HS-5 cells on the development of Huh7 cells. In addition, the underlying mechanisms on the influence in Huh7 cells were investigated. Our results showed that HS-5 cells could promote the proliferation, migration and invasion of Huh7 cells, and inhibited apoptosis. CCL5 downregulation was able to inhibit the effects of HS-5 cells on Huh7 cell migration and invasion via the PI3K-Akt signaling pathway and reduce MMP-2 expression. Therefore, these findings suggest that CCL5 secreted from MSCs can promote the migration and invasion of Huh7 cells and could be an important factor in HCC related to occurrence of bone metastases.

Rho'ing in and out of cells: viral interactions with Rho GTPase signaling

Rho GTPases are key regulators of actin and microtubule dynamics and organization. Increasing evidence shows that many viruses have evolved diverse interactions with Rho GTPase signaling and manipulate them for their own benefit. In this review, we discuss how Rho GTPase signaling interferes with many steps in the viral replication cycle, especially entry, replication, and spread. Seen the diversity between viruses, it is not surprising that there is considerable variability in viral interactions with Rho GTPase signaling. However, several largely common effects on Rho GTPases and actin architecture and microtubule dynamics have been reported. For some of these processes, the molecular signaling and biological consequences are well documented while for others we just begin to understand them. A better knowledge and identification of common threads in the different viral interactions with Rho GTPase signaling and their ultimate consequences for virus and host may pave the way toward the development of new antiviral drugs that may target different viruses.

Rho GTPases and cancer

Rho GTPases are a family of small GTPases, which play an important role in the regulation of the actin cytoskeleton. Not surprisingly, Rho GTPases are crucial for cell migration and therefore highly important for cancer cell invasion and the formation of metastases. In addition, Rho GTPases are involved in growth and survival of tumor cells, in the interaction of tumor cells with their environment, and they are vital for the cancer supporting functions of the tumor stroma. Recent research has significantly improved our understanding of the regulation of Rho GTPase activity, the specificity of Rho GTPases, and their function in tumor stem cells and tumor stroma. This review summarizes these novel findings and tries to define challenging questions for future research.

The Rho GTPase RhoE is a p53-regulated candidate tumor suppressor in cancer cells

Previous studies have shown that RhoE, an atypical member of the Rho GTPase family, may play an opposite role to RhoA in regulating cell proliferation and invasion. To explore the relationship between RhoE and the malignant phenotypes of human cancer, we have determined the expression patterns of RhoE in varying grade of human cancer tissues and tested the effects of RhoE expression in several RhoE underexpressing cancer cell lines. Systemic immunocytochemistry analyses of gastric, colorectal, lung and breast carcinomas, respectively, showed that RhoE protein expression was significantly decreased in most cancer cases compared with that of adjacent normal tissues. Enhanced RhoE expression could markedly inhibit proliferation, migration and invasion and induce apoptosis of the cancer cells which have relatively low levels of endogenous RhoE expression. Wild-type p53 (wt-p53) could strongly increase RhoE expression in p53-transfected cells. Furthermore, the luciferase assays indicated that wt-p53 significantly enhanced the activities of RhoE promoter compared with mutant p53 (mt-p53) in PC3 cells (p53 null). Collectively, data are presented showing that RhoE may participate in human cancer progression and act as a candidate target of p53, and these findings also strongly suggest that RhoE may be a new candidate tumor suppressor and could serve as a potential target in the gene therapy of cancer.

RhoE promotes metastasis in gastric cancer through a mechanism dependent on enhanced expression of CXCR4

RhoE, a novel member of the Rho protein family, is a key regulator of the cytoskeleton and cell migration. Our group has previously shown that RhoE as a direct target for HIF-1α and mediates hypoxia-induced epithelial to mesenchymal transition in gastric cancer cells. Therefore, we assumed that RhoE might play an important role in gastric cancer metastasis. In the present study, we have explored the role of RhoE expression in gastric cancer, cell invasion and metastasis, and the influence of RhoE on regulating the potential expression of down-stream genes. RhoE expression was elevated in gastric cancer tissues as compared with normal gastric tissues. We also found a close correlation between the histological grade and the diagnosis of the patient. Up-regulation of RhoE significantly enhanced the migratory and invasive abilities of gastric cancer cells both in vitro and in vivo. Moreover, down-regulation of RhoE diminished the metastatic potential of cancer cells. PCR array and subsequent transwell assay showed that the regulation of gastric cancer metastasis by RhoE was partially mediated by CXCR4. This observation suggested that CXCR4 might be a downstream effector for RhoE. In summary, our study identified RhoE as a novel prognostic biomarker and metastatic-promoting gene of gastric cancer.

Musashi2 predicts poor prognosis and invasion in hepatocellular carcinoma by driving epithelial-mesenchymal transition

The high incidence of recurrence and the poor prognosis of hepatocellular carcinoma (HCC) necessitate the discovery of new predictive markers of HCC invasion and prognosis. In this study, we evaluated the expression pattern of two members of a novel oncogene family, Musashi1 (MSI1) and Musashi2 (MSI2) in 40 normal hepatic tissue specimens, 149 HCC specimens and their adjacent non-tumourous tissues. We observed that MSI1 and MSI2 were significantly up-regulated in HCC tissues. High expression levels of MSI1 and MSI2 were detectable in 37.6% (56/149) and 49.0% (73/149) of the HCC specimens, respectively, but were rarely detected in adjacent non-tumourous tissues and were never detected in normal hepatic tissue specimens. Nevertheless, only high expression of MSI2 correlated with poor prognosis. In addition, MSI2 up-regulation correlated with clinicopathological parameters representative of highly invasive HCC. Further study indicated that MSI2 might enhance invasion of HCC by inducing epithelial–mesenchymal transition (EMT). Knockdown of MSI2 significantly decreased the invasion of HCC cells and changed the expression pattern of EMT markers. Moreover, immunohistochemistry assays of 149 HCC tissue specimens further confirmed this correlation. Taken together, the results of our study demonstrated that MSI2 correlates with EMT and has the potential to be a new predictive biomarker of HCC prognosis and invasion to help guide diagnosis and treatment of post-operative HCC patients.

Hepatitis B virus X protein disrupts stress fiber formation and triggers apoptosis

Cytoskeletal proteins are key participants in the cellular progression to apoptosis. In a previous study we injected nude mice with CCL13-HBx cells and identified in contrast to non-HBx transfected cells a differentially phosphorylated myosin light chain (p-MLC) by two-dimensional PAGE and mass spectrometry of the tumor material. To investigate the role of HBx in myosin light chain kinase (MLCK) signaling pathways, we analyzed the key molecules, p-MLC and MLCK, by western blotting. Immunofluorescence staining analysis showed that HBx disrupted stress fiber formation and that focal adhesion kinase (FAK) and integrin-linked kinase (ILK) were regulated by HBx-mediated phosphatase and tensin homolog (PTEN). We also used pharmacological inhibitors to explore the correlation between cytoskeletal rearrangements and HBx-mediated cell apoptosis via an MLCK and a PTEN-dependent pathway. The results showed that both ML9 and bvp restored the effects caused by HBx induction. Our findings suggest that HBx disrupts stress fiber formation and triggers apoptosis via an MLCK and a PTEN-dependent pathway.

Metastasin leads to poor prognosis of hepatocellular carcinoma through partly inducing EMT

Hepatocellular carcinoma (HCC) is a common malignant cancer worldwide characterized by high metastatic potential and poor prognosis following radical resection. Metastasin is a Ca(2+)-binding protein associated with tumor metastasis. However, the expression and function of metastasin remain unknown. In the present study, we found that the expression of metastasin was upregulated in HCC tissues and positively correlated with poor prognosis following radical resection. Ectopic expression of metastasin in vitro induced typical epithelial-mesenchymal transition (EMT) in Hep3B cells including higher capacity of both migration and invasion, increased expression of both Vimentin and N-cadherin and decreased expression of E-cadherin. Knockdown of metastasin produced the opposite results in MHCC97H cells, which indicates that metastasin promotes HCC progression via induction of EMT. SNAI1 expression was upregulated by enforced expression of metastasin and, consequently, suppressing upregulation of SNAI1 secondary to metastasin overexpression abolished EMT. Collectively, the present results suggest that metastasin leads to HCC EMT partly through upregulating SNAI1 and contributes to poor prognosis following radical liver resection.

Regulation of ROCK activity in cancer

Cancer-associated changes in cellular behavior, such as modified cell-cell contact, increased migratory potential, and generation of cellular force, all require alteration of the cytoskeleton. Two homologous mammalian serine/threonine kinases, Rho-associated protein kinases (ROCK I and II), are key regulators of the actin cytoskeleton acting downstream of the small GTPase Rho. ROCK is associated with cancer progression, and ROCK protein expression is elevated in several types of cancer. ROCKs exist in a closed, inactive conformation under quiescent conditions, which is changed to an open, active conformation by the direct binding of guanosine triphosphate (GTP)–loaded Rho. In recent years, a number of ROCK isoform-specific binding partners have been found to modulate the kinase activity through direct interactions with the catalytic domain or via altered cellular localization of the kinases. Thus, these findings demonstrate additional modes to regulate ROCK activity. This review describes the molecular mechanisms of ROCK activity regulation in cancer, with emphasis on ROCK isoform-specific regulation and interaction partners, and discusses the potential of ROCKs as therapeutic targets in cancer.