Gene Summary

Gene:RHOB; ras homolog family member B
Aliases: ARH6, ARHB, RHOH6, MST081, MSTP081
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:rho-related GTP-binding protein RhoB
Source:NCBIAccessed: 01 September, 2019


What does this gene/protein do?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 01 September 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

Tag cloud generated 01 September, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: RHOB (cancer-related)

Ma Q, Gao Y, Xu P, et al.
Atorvastatin Inhibits Breast Cancer Cells by Downregulating PTEN/AKT Pathway via Promoting Ras Homolog Family Member B (RhoB).
Biomed Res Int. 2019; 2019:3235021 [PubMed] Free Access to Full Article Related Publications
Background: Breast cancer (BC) is one of the most common malignant tumors in women around the world. Atorvastatin (ATO) was found to be associated with a decreased risk of recurrence and mortality in cancer. But the exact mechanism of its carcinostatic effects is unclear. The expression level of Ras homolog family member B (RhoB) in breast cancer cells was found to be upregulated after being treated with ATO. Thus, we conjecture that altered expression of RhoB induced by ATO may be decisive for the migration and progression of breast cancer.
Methods: The effects of ATO on breast tumor cells
Results: ATO inhibits proliferation, invasion, EMT, and PTEN/AKT pathway and promotes apoptosis in breast tumor cells. In addition, ATO inhibits the volume and weight of breast tumor in tumor-bearing mice and upregulated RhoB in tumor tissues. The expression of RhoB in mRNA and protein level was upregulated in statin-treated breast cancer cells and downregulated in cancer tissues. Low expression of RhoB links with poor prognosis in patients with breast cancer (HR = 0.74[0.66-0.83],
Conclusions: The exact mechanism of ATO's carcinostatic effects in breast cancer is related to downregulating PTEN/AKT pathway via promoting RhoB. Our study also demonstrates the potential applicability of RhoB as a therapeutic target for breast cancer.

Keller M, Dubois F, Teulier S, et al.
NDR2 kinase contributes to cell invasion and cytokinesis defects induced by the inactivation of RASSF1A tumor-suppressor gene in lung cancer cells.
J Exp Clin Cancer Res. 2019; 38(1):158 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: RASSF1A, a tumor suppressor gene, is frequently inactivated in lung cancer leading to a YAP-dependent epithelial-mesenchymal transition (EMT). Such effects are partly due to the inactivation of the anti-migratory RhoB GTPase via the inhibitory phosphorylation of GEF-H1, the GDP/GTP exchange factor for RhoB. However, the kinase responsible for RhoB/GEF-H1 inactivation in RASSF1A-depleted cells remained unknown.
METHODS: NDR1/2 inactivation by siRNA or shRNA effects on epithelial-mesenchymal transition, invasion, xenograft formation and growth in SCID-/- Beige mice, apoptosis, proliferation, cytokinesis, YAP/TAZ activation were investigated upon RASSF1A loss in human bronchial epithelial cells (HBEC).
RESULTS: We demonstrate here that depletion of the YAP-kinases NDR1/2 reverts migration and metastatic properties upon RASSF1A loss in HBEC. We show that NDR2 interacts directly with GEF-H1 (which contains the NDR phosphorylation consensus motif HXRXXS/T), leading to GEF-H1 phosphorylation. We further report that the RASSF1A/NDR2/GEF-H1/RhoB/YAP axis is involved in proper cytokinesis in human bronchial cells, since chromosome proper segregation are NDR-dependent upon RASSF1A or GEF-H1 loss in HBEC.
CONCLUSION: To summarize, our data support a model in which, upon RASSF1A silencing, NDR2 gets activated, phosphorylates and inactivates GEF-H1, leading to RhoB inactivation. This cascade induced by RASSF1A loss in bronchial cells is responsible for metastasis properties, YAP activation and cytokinesis defects.

Wudu M, Ren H, Hui L, et al.
DRAM2 acts as an oncogene in non-small cell lung cancer and suppresses the expression of p53.
J Exp Clin Cancer Res. 2019; 38(1):72 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Damage-regulated autophagy modulator 2(DRAM2) is associated with autophagy processes. However, the role of DRAM2 in the progression of human neoplasms is still unknown. Here, we show that DRAM2 may act as an oncogenic regulator in non-small cell lung cancer (NSCLC).
METHODS: Tumor specimens from 259 NSCLC patients were collected and analyzed. Transwell migration, cell cycle analysis, MTT and colony formation assays were performed to determine the effect of DRAM2 overexpression and knockdown on NSCLC-cell migration and proliferation. Western blotting confirmed the expression of DRAM2, p53, and the other involved proteins.
RESULTS: DRAM2 was preferentially upregulated in NSCLC tissues and higher expression of DRAM2 in NSCLC correlated with tumor node metastases stage and lymph node metastasis. Additionally, DRAM2 overexpression promoted cell metastasis and proliferation in vitro, while knockdown of DRAM2 expression yielded opposite result. Furthermore, DRAM2 overexpression increased the expression of proteins RAC1, RHOA, RHOC, ROCK1, and decreased RHOB expression, all of which are cell migration factors. DRAM2 overexpression also increased proteins CDK4, CyclinD3, and decreased p27 expression, all of which are cell cycle-related factors. Consistently knocked down DRAM2 had the opposite effect. We also found that DRAM2 expression was negatively correlated to p53 expression. Knockdown of DRAM2 caused an increase of p53 and p21 expression, and overexpression of p53 caused a decrease of DRAM2 expression. Finally, absence of p53 did not influence the function of DRAM2 in NSCLC, but overexpression of p53 repressed its function.
CONCLUSIONS: DRAM2 plays an oncogenic role in NSCLC via regulating p53 expression. Therefore, DRAM2 may act as an oncogene in NSCLC and could serve as a prognostic factor and potential target for NSCLC treatment.

Zacharopoulou N, Tsapara A, Kallergi G, et al.
The Epigenetic Factor KDM2B Regulates EMT and Small GTPases in Colon Tumor Cells.
Cell Physiol Biochem. 2018; 47(1):368-377 [PubMed] Related Publications
BACKGROUND/AIMS: The epigenetic factor KDM2B is a histone demethylase expressed in various tumors. Recently, we have shown that KDM2B regulates actin cytoskeleton organization, small Rho GTPases signaling, cell-cell adhesion and migration of prostate tumor cells. In the present study, we addressed its role in regulating EMT and small GTPases expression in colon tumor cells.
METHODS: We used RT-PCR for the transcriptional analysis of various genes, Western blotting for the assessment of protein expression and immunofluorescence microscopy for visualization of fluorescently labeled proteins.
RESULTS: We report here that KDM2B regulates EZH2 and BMI1 in HCT116 colon tumor cells. Knockdown of this epigenetic factor induced potent up-regulation of the protein levels of the epithelial markers E-cadherin and ZO-1, while the mesenchymal marker N-cadherin was downregulated. On the other hand, KDM2B overexpression downregulated the levels of both epithelial markers and upregulated the mesenchymal marker, suggesting control of EMT by KDM2B. In addition, RhoA, RhoB and RhoC protein levels diminished upon KDM2B-knockdown, while all three small GTPases became upregulated in KDM2B-overexpressing HCT116 cell clones. Interestingly, Rac1 GTPase level increased upon KDM2B-knockdown and diminished in KDM2B-overexpressing HCT116 colon tumor- and DU-145 prostate cancer cells.
CONCLUSIONS: These results establish a clear functional role of the epigenetic factor KDM2B in the regulation of EMT and small-GTPases expression in colon tumor cells and further support the recently postulated oncogenic role of this histone demethylase in various tumors.

Zou Q, Xiao X, Liang Y, et al.
miR-19a-mediated downregulation of RhoB inhibits the dephosphorylation of AKT1 and induces osteosarcoma cell metastasis.
Cancer Lett. 2018; 428:147-159 [PubMed] Related Publications
Osteosarcoma is a primary malignancy that develops in bone, along with serious recurrence and metastasis. As an isoform of Rho family GTPases, RhoB could suppress cell proliferation, invasion, and anti-angiogenesis. But it is not clear how RhoB involves in tumor metastasis. Here we found that expression of RhoB was decreased in osteosarcoma primary samples and cell lines. Ectopic expression of RhoB restrains the migration of osteosarcoma cells in vitro and in vivo, and induces osteosarcoma cell apopotsis. Further study showed that overexpression of RhoB could increase the proportion of B55 in PP2A complex and enhance the dephosphorylation of AKT1 by interacting with B55. Moreover, we demonstrated that miR-19a, which exhibits abnormal expression in highly metastatic osteosarcoma cell lines, could inhibit the expression of RhoB and promote the lung metastasis of osteosarcoma cells in vivo. Our results indicate that miR-19a-mediated RhoB is a critical regulator for the dephosphorylation of AKT1 in osteosarcoma cells. It may have a possible strategy on suppressing osteosarcoma metastasis by miR-19a inhibitory oligonucleotides. The miR-19a/RhoB/AKT1 network may help us to better understand the mechanism of osteosarcoma metastasis.

Wei LJ, Li JA, Bai DM, Song Y
miR-223-RhoB signaling pathway regulates the proliferation and apoptosis of colon adenocarcinoma.
Chem Biol Interact. 2018; 289:9-14 [PubMed] Related Publications
MicroRNAs (miRNAs) can function as tumor suppressor or oncogenic genes. The putative targets of miR-223 include tumor suppressor gene, RhoB. Here we sought to investigate the role of miR-223-RhoB signaling pathway in proliferation of colon cancer. We used Western blot, immunofluorescence staining, or RT-PCR to detect expression levels of miR-223 and RhoB in colon adenocarcinoma and adjacent non-cancerous tissue samples, or in human colon adenocarcinoma cell lines. MTT assay was used to determine proliferation and apoptosis in cell lines. We further used Western blot to determine levels of cell cycle regulators CDK1 and Cyclin B1 with anti-miR-223 or apoptosis with overexpression of RhoB. The expression level of miR-223 was significantly upregulated in clinical samples and cell lines of colon adenocarcinoma, in contrast to down-regulation of RhoB. In addition, we showed that inhibition of miR-223 led to upregulation of RhoB and in turn suppression of proliferation of colon adenocarcinoma. Moreover, inhibition of miR-223 or overexpression of RhoB induced cell arrest or apoptosis in colon adenocarcinoma. These results suggest that miR-223-RhoB signaling pathway plays an important role in modulation of proliferation, cell arrest, and apoptosis in colon cancer.

Luo J, Shi K, Yin SY, et al.
Clinical value of miR-182-5p in lung squamous cell carcinoma: a study combining data from TCGA, GEO, and RT-qPCR validation.
World J Surg Oncol. 2018; 16(1):76 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: MiR-182-5p, as a member of miRNA family, can be detected in lung cancer and plays an important role in lung cancer. To explore the clinical value of miR-182-5p in lung squamous cell carcinoma (LUSC) and to unveil the molecular mechanism of LUSC.
METHODS: The clinical value of miR-182-5p in LUSC was investigated by collecting and calculating data from The Cancer Genome Atlas (TCGA) database, the Gene Expression Omnibus (GEO) database, and real-time quantitative polymerase chain reaction (RT-qPCR). Twelve prediction platforms were used to predict the target genes of miR-182-5p. Protein-protein interaction (PPI) networks and gene ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used to explore the molecular mechanism of LUSC.
RESULTS: The expression of miR-182-5p was significantly over-expressed in LUSC than in non-cancerous tissues, as evidenced by various approaches, including the TCGA database, GEO microarrays, RT-qPCR, and a comprehensive meta-analysis of 501 LUSC cases and 148 non-cancerous cases. Furthermore, a total of 81 potential target genes were chosen from the union of predicted genes and the TCGA database. GO and KEGG analyses demonstrated that the target genes are involved in pathways related to biological processes. PPIs revealed the relationships between these genes, with EPAS1, PRKCE, NR3C1, and RHOB being located in the center of the PPI network.
CONCLUSIONS: MiR-182-5p upregulation greatly contributes to LUSC and may serve as a biomarker in LUSC.

Nomikou E, Livitsanou M, Stournaras C, Kardassis D
Transcriptional and post-transcriptional regulation of the genes encoding the small GTPases RhoA, RhoB, and RhoC: implications for the pathogenesis of human diseases.
Cell Mol Life Sci. 2018; 75(12):2111-2124 [PubMed] Related Publications
Rho GTPases are highly conserved proteins that play critical roles in many cellular processes including actin dynamics, vesicular trafficking, gene transcription, cell-cycle progression, and cell adhesion. The main mode of regulation of Rho GTPases is through guanine nucleotide binding (cycling between an active GTP-bound form and an inactive GDP-bound form), but transcriptional, post-transcriptional, and post-translational modes of Rho regulation have also been described. In the present review, we summarize recent progress on the mechanisms that control the expression of the three members of the Rho-like subfamily (RhoA, RhoB, and RhoC) at the level of gene transcription as well as their post-transcriptional regulation by microRNAs. We also discuss the progress made in deciphering the mechanisms of cross-talk between Rho proteins and the transforming growth factor β signaling pathway and their implications for the pathogenesis of human diseases such as cancer metastasis and fibrosis.

Niu S, Ma X, Zhang Y, et al.
MicroRNA-19a and microRNA-19b promote the malignancy of clear cell renal cell carcinoma through targeting the tumor suppressor RhoB.
PLoS One. 2018; 13(2):e0192790 [PubMed] Free Access to Full Article Related Publications
Clear cell renal cell carcinoma (ccRCC) is the most common subtype of renal cell carcinoma, which shows high aggressiveness and lacks biomarkers. RhoB acts as a tumor suppressor that inhibits the progression of ccRCC. In the present study, we examined the effects of oncogenic microRNAs, miR-19a and miR-19b, on RhoB expression in ccRCC cells. The results showed that both miR-19a and miR-19b could directly target the 3'untranslated region (3'UTR) of RhoB, resulting in the reduced expression of RhoB. With RT-PCR analysis, we detected the increased expression of miR-19a and miR-19b in ccRCC tissues compared to adjacent non-tumor renal tissues. These data also demonstrated an exclusive negative correlation between miR-19a/19b and RhoB expression in ccRCC specimens and cell lines. In addition, the knockdown of RhoB or overexpression of miR-19a and miR-19b in ccRCC cells could promote cell proliferation, migration and invasion. These data demonstrate the direct roles of miR-19a and miR-19b on the repression of RhoB and its consequences on tumorigenesis, cancer cell proliferation and invasiveness. These results suggest the potential clinical impact of miR-19a and miR-19b as molecular targets for ccRCC.

Zampini M, Tregnago C, Bisio V, et al.
Epigenetic heterogeneity affects the risk of relapse in children with t(8;21)RUNX1-RUNX1T1-rearranged AML.
Leukemia. 2018; 32(5):1124-1134 [PubMed] Related Publications
The somatic translocation t(8;21)(q22;q22)/RUNX1-RUNX1T1 is one of the most frequent rearrangements found in children with standard-risk acute myeloid leukemia (AML). Despite the favorable prognostic role of this aberration, we recently observed a higher than expected frequency of relapse. Here, we employed an integrated high-throughput approach aimed at identifying new biological features predicting relapse among 34 t(8;21)-rearranged patients. We found that the DNA methylation status of patients who suffered from relapse was peculiarly different from that of children maintaining complete remission. The epigenetic signature, made up of 337 differentially methylated regions, was then integrated with gene and protein expression profiles, leading to a network, where cell-to-cell adhesion and cell-motility pathways were found to be aberrantly activated in relapsed patients. We identified most of these factors as RUNX1-RUNX1T1 targets, with Ras Homolog Family Member (RHOB) overexpression being the core of this network. We documented how RHOB re-organized the actin cytoskeleton through its downstream ROCK-LIMK-COFILIN axis: this increases blast adhesion by stress fiber formation, and reduces mitochondrial apoptotic cell death after chemotherapy treatment. Altogether, our data show an epigenetic heterogeneity within t(8;21)-rearranged AML patients at diagnosis able to influence the program of the chimeric transcript, promoting blast re-emergence and progression to relapse.

Zacharopoulou N, Tsapara A, Kallergi G, et al.
The epigenetic factor KDM2B regulates cell adhesion, small rho GTPases, actin cytoskeleton and migration in prostate cancer cells.
Biochim Biophys Acta Mol Cell Res. 2018; 1865(4):587-597 [PubMed] Related Publications
The histone demethylase KDM2B is an epigenetic factor with oncogenic properties that is regulated by the basic fibroblasts growth factor (FGF-2). It has recently been shown that KDM2B co-operates with Polycomb Group proteins to promote cell migration and angiogenesis in tumors. In the present study we addressed the role of KDM2B in regulating actin cytoskeleton signaling, cell-cell adhesion and migration of prostate tumor cells. We report here that KDM2B is functionally expressed in DU-145 prostate cancer cells, activated by FGF-2 and regulates EZH2. KDM2B knockdown induced potent up-regulation of gene transcription and protein expression of the epithelial markers E-cadherin and ZO-1, while KDM2B overexpression down-regulated the levels of both markers, suggesting control of cell adhesion by KDM2B. RhoA and RhoB protein expression and activity were diminished upon KDM2B-knockdown and upregulated in KDM2B-overexpressing cell clones. In accordance, actin reorganization with formation of stress fibers became evident in KDM2B-overexpressing cells and abolished in the presence of the Rho inhibitor C3 transferase. DU-145 cell migration was significantly enhanced in KDM2B overexpressing cells and abolished in C3-pretreated cells. Conversely, the retardation of cell migration observed in KDM2B knockdown cells was enhanced in C3-pretreated cells. These results establish a clear functional link between the epigenetic factor KDM2B and the regulation of cell adhesion and Rho-GTPases signaling that controls actin reorganization and cell migration.

Kasorn A, Loison F, Kangsamaksin T, et al.
Terrein inhibits migration of human breast cancer cells via inhibition of the Rho and Rac signaling pathways.
Oncol Rep. 2018; 39(3):1378-1386 [PubMed] Related Publications
Breast cancer is the most common cancer in women worldwide. Progression and aggressiveness of breast cancer is usually associated with its migration and invasion abilities. Recently, natural products with potential anticancer activity have become attractive candidates for alternative treatment of cancer. A fungal metabolite, terrein, isolated from the Aspergillus terreus has been revealed to exhibit selective anticancer activity; although this molecule has a variety of biological activities. The inhibitory effect on cell proliferation in hepatoma, keratinocytes, and lung cancer cells was due to cell cycle arrest without induction of apoptosis. In contrast, its effects on cervical and breast cancer cells were mediated through activation of the apoptotic process. However, the effect of terrein on cell migration and invasion has not been explored. In the present study we analyzed the molecular effects of terrein on cell adhesion, cell migration, and cell invasion using two breast cancer cell lines, MCF-7 and MDA-MB-231, which exhibit different levels of invasiveness. Terrein induced apoptosis in both breast cancer cell lines in a dose-dependent manner. In addition, at a non-toxic concentration terrein exhibited a weak inhibition of cell adhesion, using either fibronectin or type IV collagen as substrates. Notably, terrein significantly inhibited both the migration and invasion abilities of MDA-MB-231 cells at the same non-toxic concentration. A marked decrease in MMP-2 and MMP-9 transcripts, as evaluated by real-time PCR, confirmed the anti-invasion effect of terrein at the transcriptional level. Western blot analyses revealed that terrein treatment suppressed RhoB expression and reduced Rac1 phosphorylation, leading to Rho GTPase inhibition. In addition, terrein-treated MCF-7 and MDA-MB-231 cells both displayed a scattered pattern of migration, suggesting that the suppression of RhoB and Rac1 disturbed the collective migration processes of breast cancer cells.

Hurst CD, Alder O, Platt FM, et al.
Genomic Subtypes of Non-invasive Bladder Cancer with Distinct Metabolic Profile and Female Gender Bias in KDM6A Mutation Frequency.
Cancer Cell. 2017; 32(5):701-715.e7 [PubMed] Free Access to Full Article Related Publications
Bladder cancer incurs a higher lifetime treatment cost than other cancers due to frequent recurrence of non-invasive disease. Improved prognostic biomarkers and localized therapy are needed for this large patient group. We defined two major genomic subtypes of primary stage Ta tumors. One of these was characterized by loss of 9q including TSC1, increased KI67 labeling index, upregulated glycolysis, DNA repair, mTORC1 signaling, features of the unfolded protein response, and altered cholesterol homeostasis. Comparison with muscle-invasive bladder cancer mutation profiles revealed lower overall mutation rates and more frequent mutations in RHOB and chromatin modifier genes. More mutations in the histone lysine demethylase KDM6A were present in non-invasive tumors from females than males.

Arsic N, Ho-Pun-Cheung A, Lopez-Crapez E, et al.
The p53 isoform delta133p53ß regulates cancer cell apoptosis in a RhoB-dependent manner.
PLoS One. 2017; 12(2):e0172125 [PubMed] Free Access to Full Article Related Publications
The TP53 gene plays essential roles in cancer. Conventionally, wild type (WT) p53 is thought to prevent cancer development and metastasis formation, while mutant p53 has transforming abilities. However, clinical studies failed to establish p53 mutation status as an unequivocal predictive or prognostic factor of cancer progression. The recent discovery of p53 isoforms that can differentially regulate cell cycle arrest and apoptosis suggests that their expression, rather than p53 mutations, could be a more clinically relevant biomarker in patients with cancer. In this study, we show that the p53 isoform delta133p53ß is involved in regulating the apoptotic response in colorectal cancer cell lines. We first demonstrate delta133p53ß association with the small GTPase RhoB, a well-described anti-apoptotic protein. We then show that, by inhibiting RhoB activity, delta133p53ß protects cells from camptothecin-induced apoptosis. Moreover, we found that high delta133p53 mRNA expression levels are correlated with higher risk of recurrence in a series of patients with locally advanced rectal cancer (n = 36). Our findings describe how a WT TP53 isoform can act as an oncogene and add a new layer to the already complex p53 signaling network.

Sun M, Nie FQ, Zang C, et al.
The Pseudogene DUXAP8 Promotes Non-small-cell Lung Cancer Cell Proliferation and Invasion by Epigenetically Silencing EGR1 and RHOB.
Mol Ther. 2017; 25(3):739-751 [PubMed] Free Access to Full Article Related Publications
Recently, the non-protein-coding functional elements in the human genome have been identified as key regulators in postgenomic biology, and a large number of pseudogenes as well as long non-coding RNAs (lncRNAs) have been found to be transcribed in multiple human cancers. However, only a small proportion of these pseudogenes has been functionally characterized. In this study, we screened for pseudogenes associated with human non-small-cell lung cancer (NSCLC) by comparative analysis of several independent datasets from the GEO. We identified a transcribed pseudogene named DUXAP8 that is upregulated in tumor tissues. Patients with higher DUXAP8 expression exhibited shorter survival, suggesting DUXAP8 as a new candidate prognostic marker for NSCLC patients. Knockdown of DUXAP8 impairs cell growth, migration, and invasion, and induces apoptosis both in vitro and in vivo. Mechanistically, DUXAP8 represses the tumor suppressors EGR1 and RHOB by recruiting histone demethylase LSD1 and histone methyltransferase EZH2, thereby promoting cell proliferation, migration, and invasion. These findings indicate that the pseudogene DUXAP8 may act as an oncogene in NSCLC by silencing EGR1 and RHOB transcription by binding with EZH2 and LSD1, which may offer a novel therapeutic target for this disease.

Jin L, Liu WR, Tian MX, et al.
CCL24 contributes to HCC malignancy via RhoB- VEGFA-VEGFR2 angiogenesis pathway and indicates poor prognosis.
Oncotarget. 2017; 8(3):5135-5148 [PubMed] Free Access to Full Article Related Publications
CCL24 is one chemotactic factor extensively studied in airway inflammation and colorectal cancer but less studied in hepatocellular carcinoma (HCC) retrospectively. So HCC tissue microarray (TMA) was used to estimate relationship between CCL24 and prognosis, cell experiments were conducted to study its influence for HCC cell biological behavior. CCL24 was injected to nude mice to monitor tumor formation and pulmonary metastasis; qRT-PCR, western blot and Immunohistochemistry were used to explore potential mechanism. CCL24 plays roles in target cells via its downstream CCR3, or it is regulated by Type 2 helper T cells (Th2 cell) factors, so immune related experiments were conducted. Meanwhile, Rho GTPase family have close relation not only with T cell priming, but with neovascularization; CCL24 contributes to neovascularization in age-related macular degeneration via CCR3, so Rho GTPase family, Th2 cell factors, Human Umbilical Vein Endothelial Cells were used to uncover their trafficking. Ultimate validation was confirmed by small interfering RNA. Results showed CCL24 expression was higher in caner tissues than adjacent normal tissues, it could contribute to proliferation, migration, and invasion in HCCs, could accelerate pulmonary metastasis, promote HUVECs tube formation. Th2 cell factors were irrelevant with CCL24 in HCCs; and RhoB, VEGFA, and VEGFR2 correlated with CCL24 in both mRNA and protein level. Downstream RhoB-VEGFA signaling pathway was validated by siRhoB and siVEGFA inhibition. In a word, CCL24 contributes to HCC malignancy via RhoB-VEGFA-VEGFR2 angiogenesis pathway and indicates poor prognosis, which urges us to study further CCL24 effects on diagnosis and potential therapy for HCC.

Vega FM, Ridley AJ
The RhoB small GTPase in physiology and disease.
Small GTPases. 2018; 9(5):384-393 [PubMed] Free Access to Full Article Related Publications
RhoB is a Rho family GTPase that is highly similar to RhoA and RhoC, yet has distinct functions in cells. Its unique C-terminal region is subject to specific post-translational modifications that confer different localization and functions to RhoB. Apart from the common role with RhoA and RhoC in actin organization and cell migration, RhoB is also implicated in a variety of other cellular processes including membrane trafficking, cell proliferation, DNA-repair and apoptosis. RhoB is not an essential gene in mice, but it is implicated in several physiological and pathological processes. Its multiple roles will be discussed in this review.

de León-Bautista MP, Cardenas-Aguayo MD, Casique-Aguirre D, et al.
Immunological and Functional Characterization of RhoGDI3 and Its Molecular Targets RhoG and RhoB in Human Pancreatic Cancerous and Normal Cells.
PLoS One. 2016; 11(11):e0166370 [PubMed] Free Access to Full Article Related Publications
RhoGDI proteins have been implicated in several human cancers; changes in their expression levels have shown pro- or anti-tumorigenic effects. Pancreatic Ductal Adenocarcinoma (PDAC) is a complex pathology, with poor prognosis, and most patients die shortly after diagnosis. Efforts have been focused on understanding the role of RhoGDI's in PDAC, specially, RhoGDI1 and RhoGDI2. However, the role of RhoGDI3 has not been studied in relation to cancer or to PDAC. Here, we characterized the expression and functionality of RhoGDI3 and its target GTPases, RhoG and RhoB in pancreatic cell lines from both normal pancreatic tissue and tissue in late stages of PDAC, and compared them to human biopsies. Through immunofluorescences, pulldown assays and subcellular fractionation, we found a reduction in RhoGDI3 expression in the late stages of PDAC, and this reduction correlates with tumor progression and aggressiveness. Despite the reduction in the expression of RhoGDI3 in PDAC, we found that RhoB was underexpressed while RhoG was overexpressed, suggesting that cancerous cells preserve their capacity to activate this pathway, thus these cells may be more eager to response to the stimuli needed to proliferate and become invasive unlike normal cells. Surprisingly, we found nuclear localization of RhoGDI3 in non-cancerous pancreatic cell line and normal pancreatic tissue biopsies, which could open the possibility of novel nuclear functions for this protein, impacting gene expression regulation and cellular homeostasis.

Ansari SS, Akgün N, Berger MR
Erufosine increases RhoB expression in oral squamous carcinoma cells independent of its tumor suppressive mode of action - a short report.
Cell Oncol (Dordr). 2017; 40(1):89-96 [PubMed] Related Publications
PURPOSE: Recently, we found that erufosine (erucylphospho-N,N,N trimethylpropylammonium) can induce up-regulation of RhoB expression in oral squamous carcinoma (OSCC) cells, thereby hinting at a tumor suppressive role. Therefore, we aimed to evaluate the role of RhoB in the tumor suppressive mode of action of erufosine on OSCC cells.
METHODS: Anti-proliferative effects of erufosine were determined in HN-5 and FaDu OSCC-derived cells using a MTT assay. RhoB up-regulation was detected using microarray and qRT-PCR-based expression assays at IC
RESULTS: We found that after erufosine treatment of HN-5 and FaDu cells for 24, 48 and 72 h the IC
CONCLUSIONS: Our data show that erufosine can cause up-regulation of RhoB expression in OSCC cells. Combining erufosine treatment with siRNA-mediated RhoB knockdown did, however, not reveal a role of RhoB in its tumor suppressive mode of action.

Chang HR, Nam S, Lee J, et al.
Systematic approach identifies RHOA as a potential biomarker therapeutic target for Asian gastric cancer.
Oncotarget. 2016; 7(49):81435-81451 [PubMed] Free Access to Full Article Related Publications
Gastric cancer (GC) is a highly heterogeneous disease, in dire need of specific, biomarker-driven cancer therapies. While the accumulation of cancer "Big Data" has propelled the search for novel molecular targets for GC, its specific subpathway and cellular functions vary from patient to patient. In particular, mutations in the small GTPase gene RHOA have been identified in recent genome-wide sequencing of GC tumors. Moreover, protein overexpression of RHOA was reported in Chinese populations, while RHOA mutations were found in Caucasian GC tumors. To develop evidence-based precision medicine for heterogeneous cancers, we established a systematic approach to integrate transcriptomic and genomic data. Predicted signaling subpathways were then laboratory-validated both in vitro and in vivo, resulting in the identification of new candidate therapeutic targets. Here, we show: i) differences in RHOA expression patterns, and its pathway activity, between Asian and Caucasian GC tumors; ii) in vitro and in vivo perturbed RHOA expression inhibits GC cell growth in high RHOA-expressing cell lines; iii) inverse correlation between RHOA and RHOB expression; and iv) an innovative small molecule design strategy for RHOA inhibitors. In summary, RHOA, and its oncogenic signaling pathway, represent a strong biomarker-driven therapeutic target for Asian GC. This comprehensive strategy represents a promising approach for the development of "hit" compounds.

Calvayrac O, Pradines A, Favre G
RHOB expression controls the activity of serine/threonine protein phosphatase PP2A to modulate mesenchymal phenotype and invasion in non-small cell lung cancers.
Small GTPases. 2018; 9(4):339-344 [PubMed] Free Access to Full Article Related Publications
Metastatic dissemination is the cause of death in the vast majority of cancers, including lung cancers. In order to metastasize, tumor cells must undergo a well-known series of changes, however the molecular details of how they manage to overcome the barriers at each stage remain incomplete. One critical step is acquiring the ability to migrate through the extracellular matrix. Loss of expression of the RAS-related small GTPase RHOB is a common feature of lung cancer progression, and we recently reported that this induces an epithelial-to-mesenchymal transition (EMT) that is dependent on SLUG overexpression and E-Cadherin inhibition and is characterized by 3-dimensional cell shape reorganization and the increased invasiveness of bronchial cells. RHOB loss was found to induce AKT1 activation, which in turn activates RAC1 through its GEF TRIO. Further investigation of this pathway revealed that RHOB interacts with and positively regulates PP2A, one of the major cellular serine-threonine phosphatases, by recruiting its regulatory subunit B55. Here we discuss the role of this newly discovered RHOB/PP2A/AKT1/RAC1 pathway in relation to mesenchymal migration and invasion in lung cancer.

Peruzzo P, Comelli M, Di Giorgio E, et al.
Transformation by different oncogenes relies on specific metabolic adaptations.
Cell Cycle. 2016; 15(19):2656-2668 [PubMed] Free Access to Full Article Related Publications
Metabolic adaptations are emerging as common traits of cancer cells and tumor progression. In vitro transformation of NIH 3T3 cells allows the analysis of the metabolic changes triggered by a single oncogene. In this work, we have compared the metabolic changes induced by H-RAS and by the nuclear resident mutant of histone deacetylase 4 (HDAC4). RAS-transformed cells exhibit a dominant aerobic glycolytic phenotype characterized by up-regulation of glycolytic enzymes, reduced oxygen consumption and a defect in complex I activity. In this model of transformation, glycolysis is strictly required for sustaining the ATP levels and the robust cellular proliferation. By contrast, in HDAC4/TM transformed cells, glycolysis is only modestly up-regulated, lactate secretion is not augmented and, instead, mitochondrial oxygen consumption is increased. Our results demonstrate that cellular transformation can be accomplished through different metabolic adaptations and HDAC4/TM cells can represent a useful model to investigate oncogene-driven metabolic changes besides the Warburg effect.

Chen W, Niu S, Ma X, et al.
RhoB Acts as a Tumor Suppressor That Inhibits Malignancy of Clear Cell Renal Cell Carcinoma.
PLoS One. 2016; 11(7):e0157599 [PubMed] Free Access to Full Article Related Publications
This study aims to investigate the biological role of RhoB in clear cell renal cell carcinoma (ccRCC). The expression of RhoB was examined in specimens of patients and cell lines by Western blot and Immunohistochemistry. The correlation between RhoB expression and clinicopathologic variables was also analyzed. The effects of RhoB on cell proliferation, cell cycle, cell apoptosis, and invasion/migration were detected by over-expression and knockdown of RhoB level in ccRCC cells via plasmids and RNAi. The results showed that RhoB was low-expressed in ccRCC surgical specimens and cell lines compared with adjacent normal renal tissues and normal human renal proximal tubular epithelial cell lines (HKC), and its protein expression level was significantly associated with the tumor pathologic parameter embracing tumor size(P = 0.0157), pT stage(P = 0.0035), TNM stage(P = 0.0024) and Fuhrman tumor grade(P = 0.0008). Further, over-expression of RhoB remarkably inhibited the cancer cell proliferation, colony formation and promoted cancer cell apoptosis, and aslo reduced the invasion and migration ability of ccRCC cells. Interestingly, up-regulation of RhoB could induce cell cycle arrest in G2/M phase and led to cell cycle regulators(CyclineB1,CDK1) and pro-apoptotic protein(casp3,casp9) aberrant expression. Moreover, knockdown of RhoB in HKC cells promoted cell proliferation and migration. Taken together, our study indicates that RhoB expression is decreased in ccRCC carcinogenesis and progression. Up-regulation of RhoB significantly inhibits ccRCC cell malignant phenotype. These findings show that RhoB may play a tumor suppressive role in ccRCC cells, raising its potential value in futural therapeutic target for the patients of ccRCC.

Chen Q, Guo W, Zhang Y, et al.
MiR-19a promotes cell proliferation and invasion by targeting RhoB in human glioma cells.
Neurosci Lett. 2016; 628:161-6 [PubMed] Related Publications
MicroRNA-19a (miR-19a) is upregulated in different types of cancers, including gliomas, but its specific role and function in gliomas have yet to be fully elucidated. In this study, we found that miR-19a was significantly upregulated in human glioma tissues and cell lines. Overexpression of miR-19a by a miR-19a mimic promoted glioma cell proliferation and invasion. In contrast, miR-19a inhibitor suppressed cell proliferation and invasion. Furthermore, by a dual-luciferase reporter assay and expression analysis, we determined that Ras homolog family member B was a direct target of miR-19a. Knockdown of Ras homolog family member B could block cell proliferation and invasion induced by the miR-19a mimic. In conclusion, our study demonstrated that miR-19a upregulation is common in gliomas and that suppression of miR-19a expression inhibits cell proliferation and invasion, which indicates that miR-19a may act as an oncogene in gliomas.

Taverna S, Fontana S, Monteleone F, et al.
Curcumin modulates chronic myelogenous leukemia exosomes composition and affects angiogenic phenotype via exosomal miR-21.
Oncotarget. 2016; 7(21):30420-39 [PubMed] Free Access to Full Article Related Publications
Tumor derived exosomes are vesicles which contain proteins and microRNAs that mediate cell-cell communication and are involved in angiogenesis and tumor progression. Curcumin derived from the plant Curcuma longa, shows anticancer effects. Exosomes released by CML cells treated with Curcumin contain a high amount of miR-21 that is shuttled into the endothelial cells in a biologically active form. The treatment of HUVECs with CML Curcu-exosomes reduced RhoB expression and negatively modulated endothelial cells motility. We showed that the addition of CML control exosomes to HUVECs caused an increase in IL8 and VCAM1 levels, but Curcu-exosomes reversed these effects thus attenuating their angiogenic properties. This antiangiogenic effect was confirmed with in vitro and in vivo vascular network formation assays. SWATH analysis of the proteomic profile of Curcu-exosomes revealed that Curcumin treatment deeply changes their molecular properties, in particular, Curcumin induces a release of exosomes depleted in pro-angiogenic proteins and enriched in proteins endowed with anti-angiogenic activity. Among the proteins differential expressed we focused on MARCKS, since it was the most modulated protein and a target of miR-21. Taken together our data indicated that also Curcumin attenuates the exosome's ability to promote the angiogenic phenotype and to modulate the endothelial barrier organization.

Dubois F, Keller M, Calvayrac O, et al.
RASSF1A Suppresses the Invasion and Metastatic Potential of Human Non-Small Cell Lung Cancer Cells by Inhibiting YAP Activation through the GEF-H1/RhoB Pathway.
Cancer Res. 2016; 76(6):1627-40 [PubMed] Related Publications
Inactivation of the tumor suppressor gene RASSF1A by promoter hypermethylation represents a key event underlying the initiation and progression of lung cancer. RASSF1A inactivation is also associated with poor prognosis and may promote metastatic spread. In this study, we investigated how RASSF1A inactivation conferred invasive phenotypes to human bronchial cells. RNAi-mediated silencing of RASSF1A induced epithelial-to-mesenchymal transition (EMT), fomenting a motile and invasive cellular phenotype in vitro and increased metastatic prowess in vivo. Mechanistic investigations revealed that RASSF1A blocked tumor growth by stimulating cofilin/PP2A-mediated dephosphorylation of the guanine nucleotide exchange factor GEF-H1, thereby stimulating its ability to activate the antimetastatic small GTPase RhoB. Furthermore, RASSF1A reduced nuclear accumulation of the Hippo pathway transcriptional cofactor Yes-associated protein (YAP), which was reinforced by RhoB activation. Collectively, our results indicated that RASSF1 acts to restrict EMT and invasion by indirectly controlling YAP nuclear shuttling and activation through a RhoB-regulated cytoskeletal remodeling process, with potential implications to delay the progression of RASSF1-hypermethylated lung tumors.

Tseliou M, Al-Qahtani A, Alarifi S, et al.
The Role of RhoA, RhoB and RhoC GTPases in Cell Morphology, Proliferation and Migration in Human Cytomegalovirus (HCMV) Infected Glioblastoma Cells.
Cell Physiol Biochem. 2016; 38(1):94-109 [PubMed] Related Publications
BACKGROUND/AIMS: Rho GTPases are crucial regulators of the actin cytoskeleton, membrane trafficking and cell signaling and their importance in cell migration and invasion is well- established. The human cytomegalovirus (HCMV) is a widespread pathogen responsible for generally asymptomatic and persistent infections in healthy people. Recent evidence indicates that HCMV gene products are expressed in over 90% of malignant type glioblastomas (GBM). In addition, the HCMV Immediate Early-1 protein (IE1) is expressed in >90% of tumors analyzed.
METHODS: RhoA, RhoB and RhoC were individually depleted in U373MG glioblastoma cells as well as U373MG cells stably expressing the HCMV IE1 protein (named U373MG-IE1 cells) shRNA lentivirus vectors. Cell proliferation assays, migration as well as wound-healing assays were performed in uninfected and HCMV-infected cells.
RESULTS: The depletion of RhoA, RhoB and RhoC protein resulted in significant alterations in the morphology of the uninfected cells, which were further enhanced by the cytopathic effect caused by HCMV. Furthermore, in the absence or presence of HCMV, the knockdown of RhoB and RhoC proteins decreased the proliferation rate of the parental and the IE1-expressing glioblastoma cells, whereas the knockdown of RhoA protein in the HCMV infected cell lines restored their proliferation rate. In addition, wound healing assays in U373MG cells revealed that depletion of RhoA, RhoB and RhoC differentially reduced their migration rate, even in the presence or the absence of HCMV.
CONCLUSION: Collectively, these data show for the first time a differential implication of Rho GTPases in morphology, proliferation rate and motility of human glioblastoma cells during HCMV infection, further supporting an oncomodulatory role of HCMV depending on the Rho isoforms' state.

Ferreira AC, de-Freitas-Junior JC, Morgado-Díaz JA, et al.
Dual inhibition of histone deacetylases and phosphoinositide 3-kinases: effects on Burkitt lymphoma cell growth and migration.
J Leukoc Biol. 2016; 99(4):569-78 [PubMed] Related Publications
Burkitt lymphoma is a highly aggressive non-Hodgkin lymphoma that is characterized by MYC deregulation. Recently, the PI3K pathway has emerged as a cooperative prosurvival mechanism in Burkitt lymphoma. Despite the highly successful results of treatment that use high-dose chemotherapy regimens in pediatric Burkitt lymphoma patients, the survival rate of pediatric patients with progressive or recurrent disease is low. PI3Ks are also known to regulate cell migration, and abnormal cell migration may contribute to cancer progression and dissemination in Burkitt lymphoma. Little is known about Burkitt lymphoma cell migration, but the cooperation between MYC and PI3K in Burkitt lymphoma pathogenesis suggests that a drug combination could be used to target the different steps involved in Burkitt lymphoma cell dissemination and disease progression. The aim of this study was to investigate the effects of the histone deacetylase inhibitor suberoylanilide hydroxamic acid combined with the PI3K inhibitor LY294002 on Burkitt lymphoma cell growth and migration. The combination enhanced the cell growth inhibition and cell-cycle arrest induced by the PI3K inhibitor or histone deacetylase inhibitor individually. Moreover, histone deacetylase inhibitor/PI3K inhibitor cotreatment suppressed Burkitt lymphoma cell migration and decreased cell polarization, Akt and ERK1/2 phosphorylation, and leads to RhoB induction. In summary, the histone deacetylase inhibitor/PI3Ki combination inhibits cell proliferation and migration via alterations in PI3K signaling and histone deacetylase activity, which is involved in the acetylation of α-tubulin and the regulation of RhoB expression.

Bhullar KS, Jha A, Rupasinghe HP
Novel carbocyclic curcumin analog CUR3d modulates genes involved in multiple apoptosis pathways in human hepatocellular carcinoma cells.
Chem Biol Interact. 2015; 242:107-22 [PubMed] Related Publications
Anticancer activity of a novel curcumin analog (E)-2-(4-hydroxy-3-methoxybenzylidene)-5-((E)-3-(4-hydroxy-3-methoxyphenyl)acryloyl)cyclopentanone (CUR3d) was studied using a human hepatocellular carcinoma cell line (HepG2). The results showed that CUR3d completely inhibits the tumor cell proliferation in a dose- and time-dependent manner. CUR3d at 100 μmol/L activated the pro-apoptotic caspase-3 along with downregulation of anti-apoptotic BIRC5 and Bcl2. CUR3d treatment controlled the cancer cell growth by downregulating the expression of PI3K/Akt (Akt1, Akt2) pathway along with NF-κB. CUR3d down-regulated the members of epidermal growth receptor family (EGFR, ERBB3, ERBB2) and insulin like growth receptors (IGF1, IGF-1R, IGF2). This correlated with the downregulation of G-protein (RHOA, RHOB) and RAS (ATF2, HRAS, KRAS, NRAS) pathway signaling. CUR3d also arrested cell cycle via inhibition of CDK2, CDK4, CDK5, CDK9, MDM2, MDM4 and TERT genes. Cell cycle essential aurora kinases (AURKα, AURKβ) and polo-like kinases (PLK1, PLK2, PLK3) were also modulated by CUR3d. Topoisomerases (TOP2α, TOP2β), important factors in cancer cell immortality, as well as HIF-1α were downregulated following CUR3d treatment. The expression of protein kinase-C family (PRKC-A, PRKC-D, PRKC-E) was also attenuated by CUR3d. The downregulation of histone deacetylases (Class I, II, IV) and PARP I further strengthened the anticancer efficacy of CUR3d. Downregulation of carcinogenic cathepsins (CTSB, CTSD) and heat shock proteins exhibited CUR3d's potency as a potential immunological adjuvant. Finally, the non-toxic manifestation of CUR3d in healthy liver and lung cells along with downregulation of drug resistant gene ABCC1 further warrant need for advance investigations.

Pon JR, Wong J, Saberi S, et al.
MEF2B mutations in non-Hodgkin lymphoma dysregulate cell migration by decreasing MEF2B target gene activation.
Nat Commun. 2015; 6:7953 [PubMed] Free Access to Full Article Related Publications
Myocyte enhancer factor 2B (MEF2B) is a transcription factor with mutation hotspots at K4, Y69 and D83 in diffuse large B-cell lymphoma (DLBCL). To provide insight into the regulatory network of MEF2B, in this study, we analyse global gene expression and DNA-binding patterns. We find that candidate MEF2B direct target genes include RHOB, RHOD, CDH13, ITGA5 and CAV1, and that indirect target genes of MEF2B include MYC, TGFB1, CARD11, MEF2C, NDRG1 and FN1. MEF2B overexpression increases HEK293A cell migration and epithelial-mesenchymal transition, and decreases DLBCL cell chemotaxis. K4E, Y69H and D83V MEF2B mutations decrease the capacity of MEF2B to activate transcription and decrease its' effects on cell migration. The K4E and D83V mutations decrease MEF2B DNA binding. In conclusion, our map of the MEF2B regulome connects MEF2B to drivers of oncogenesis.

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