RhoGDI2 as a therapeutic target in cancer

PLK1 phosphorylates RhoGDI1 and promotes cancer cell migration and invasion

BACKGROUND

Rho guanine nucleotide dissociation inhibitor 1 (RhoGDI1) plays an important role in diverse cellular processes by regulating Rho guanosine triphosphate (GTP)ases activity. RhoGDI1 phosphorylation regulates the spatiotemporal activation of Rho GTPases during cell migration. In this study, we identified polo-like kinase 1 (PLK1) as a novel kinase of RhoGDI1 and investigated the molecular mechanism by which the interaction between RhoGDI1 and PLK1 regulates cancer cell migration.

METHODS

Immunoprecipitation, GST pull-down assay, and proximity ligation assay (PLA) were performed to analyze the interaction between RhoGDI1 and PLK1. In vitro kinase assay and immunoprecipitation were performed with Phospho-(Ser/Thr) antibody. We evaluated RhoA activation using RhoGTPases activity assay. Cell migration and invasion were analyzed by transwell assays.

RESULTS

GST pull-down assays and PLA showed that PLK1 directly interacted with RhoGDI1 in vitro and in vivo. Truncation mutagenesis revealed that aa 90-111 of RhoGDI1 are critical for interacting with PLK1. We also showed that PLK1 phosphorylated RhoGDI1 at Thr7 and Thr91, which induces cell motility. Overexpression of the GFP-tagged RhoGDI1 truncated mutant (aa 90-111) inhibited the interaction of PLK1 with RhoGDI1 and attenuated RhoA activation by PLK1. Furthermore, the overexpression of the RhoGDI1 truncated mutant reduced cancer cell migration and invasion in vitro and suppressed lung metastasis in vivo.

CONCLUSIONS

Collectively, we demonstrate that the phosphorylation of RhoGDI1 by PLK1 promotes cancer cell migration and invasion through RhoA activation. This study connects the interaction between PLK1 and RhoGDI1 to the promotion of cancer cell behavior associated with malignant progression, thereby providing opportunities for cancer therapeutic interventions.

RhoGDI1 interacts with PHLDA2, suppresses the proliferation, migration, and invasion of trophoblast cells, and participates in the pathogenesis of preeclampsia

Preeclampsia (PE) is a pregnancy-associated disease, which is the major cause of mortality on maternity and perinatal infants. It is hypothesized that PE is a consequence of the dysfunction of the trophoblast cells. Pleckstrin homology-like domain, family A, member 2 (PHLDA2) was shown to inhibit the proliferation, migration, and invasion of trophoblast cells in our previous studies. However, the mechanism by which PHLDA2 affects trophoblast cell function has not been clarified. In the current study, co-immunoprecipitation (Co-IP) with mass spectroscopy analysis was used to explore the proteins that interacted with PHLDA2. A total of 291 candidate proteins were found to be associated with PHLDA2. The interaction between PHLDA2 and Rho guanine nucleotide dissociation inhibitor (RhoGDI) 1 was identified by Co-IP and immunofluorescence staining. Western blot analysis indicated that overexpression of PHLDA2 resulted in upregulation of the RhoGDI1 protein levels, which were stabilized in the presence of cycloheximide. Similarly, overexpression of RhoGDI1 promoted PHLDA2 expression and its stability. Furthermore, pull-down and Co-IP results indicated that PHLDA2 repressed the activity of Rho guanosine triphosphate hydrolase family proteins by regulating RhoGDI1 expression. In addition, RhoGDI1 expression was upregulated in the placental tissues of patients with PE. The effects of the suppression of PHLDA2 expression on proliferation, migration, and invasion of trophoblast cells were partly abrogated following knockdown of RhoGDI1. Taken together, the data indicated that RhoGDI1 mediated regulation of PHLDA2 on the biological behavior of trophoblast cells and may participate in the pathophysiology of PE.

RhoGDI2 induced malignant phenotypes of pancreatic cancer cells via regulating Snail expression

BACKGROUND

Rho GDP dissociation inhibitor 2 (RhoGDI2) has been shown to contribute to the aggressive phenotypes of human cancers, such as tumor metastasis and chemoresistance.

OBJECTIVE

This study aimed to assess the effects of RhoGDI2 on tumor progression and chemoresistance in pancreatic cancer cells.

METHODS

The expression of RhoGDI2 in pancreatic cancer cells was detected by Western blot analysis. Gain-of-function and loss-of-function approaches were done to examine the malignant phenotypes of the RhoGDI2-expressing or RhoGDI2-depleting cells. The correlation between RhoGDI2 and Snail was also analyzed.

RESULTS

Differential expression of RhoGDI2 protein in pancreatic cancer cell lines was identified. Gain-of-function and loss-of-function experiments showed that RhoGDI2 induced the malignant phenotypes of pancreatic cancer cells, including proliferation, migration, invasion, and gemcitabine (GEM) chemoresistance. The upregulation of RhoGDI2 stimulated the expression of Snail, resulting in the altered expression of epithelial marker E-cadherin and mesenchymal marker Vimentin, which were characteristics of the tumorigenic activity of epithelial-mesenchymal transition. The expression of RhoGDI2 and Snail was upregulated in clinical tumor samples, and higher expression of RhoGDI2 or Snail was significantly associated with poor patient survival in pancreatic ductal adenocarcinoma (PDAC).

CONCLUSION

The findings indicated that RhoGDI2 promoted GEM resistance and tumor progression in pancreatic cancer and that RhoGDI2 might be a potential therapeutic target in patients with PDAC.

Underappreciated roles for Rho GDP dissociation inhibitors (RhoGDIs) in cell function: Lessons learned from the pancreatic islet β-cell

Rho subfamily of G proteins (e.g., Rac1) have been implicated in glucose-stimulated insulin secretion from the pancreatic β-cell. Interestingly, metabolic stress (e.g., chronic exposure to high glucose) results in sustained activation of Rac1 leading to increased oxidative stress, impaired insulin secretion and β-cell dysfunction. Activation-deactivation of Rho G proteins is mediated by three classes of regulatory proteins, namely the guanine nucleotide exchange factors (GEFs), which facilitate the conversion of inactive G proteins to their active conformations; the GTPase-activating proteins (GAPs), which convert the active G proteins to their inactive forms); and the GDP-dissociation inhibitors (GDIs), which prevent the dissociation of GDP from G proteins. Contrary to a large number of GEFs (82 members) and GAPs (69 members), only three members of RhoGDIs (RhoGDIα, RhoGDIβ and RhoGDIγ) are expressed in mammalian cells.Even though relatively smaller in number, the GDIs appear to play essential roles in G protein function (e.g., subcellular targeting) for effector activation and cell regulation. Emerging evidence also suggests that the GDIs are functionally regulated via post-translational modification (e.g., phosphorylation) and by lipid second messengers, lipid kinases and lipid phosphatases. We highlight the underappreciated regulatory roles of RhoGDI-Rho G protein signalome in islet β-cell function in health and metabolic stress. Potential knowledge gaps in the field, and directions for future research for the identification of novel therapeutic targets to loss of functional β-cell mass under the duress of metabolic stress are highlighted.

RhoGDI2-Mediated Rac1 Recruitment to Filamin A Enhances Rac1 Activity and Promotes Invasive Abilities of Gastric Cancer Cells

Simple Summary

Rho GDP dissociation inhibitor 2 (RhoGDI2), a regulator of Rho family GTPase, has been known to promote tumor growth and malignant progression by activating Rac1 in gastric cancer. However, the precise molecular mechanism by which RhoGDI2 activates Rac1 in gastric cancer cells remains unclear. In this study, we found that interaction between RhoGDI2 and Rac1 is a prerequisite for the recruitment of Rac1 to Filamin A. Moreover, we found that Filamin A acts as a scaffold protein that mediates Rac1 activation. Furthermore, we found that Trio, a Rac1-specific GEF, is critical for Rac1 activation in gastric cancer cells. Conclusively, RhoGDI2 increases Rac1 activity by recruiting Rac1 to Filamin A and enhancing the interaction between Rac1 and Trio, which is critical for invasive ability of gastric cancer cells. Our findings suggest that RhoGDI2 might be a potential therapeutic target for reducing gastric cancer cell metastasis.

Abstract

Rho GDP dissociation inhibitor 2 (RhoGDI2), a regulator of Rho family GTPase, has been known to promote tumor growth and malignant progression in gastric cancer. We previously showed that RhoGDI2 positively regulates Rac1 activity and Rac1 activation is critical for RhoGDI2-induced gastric cancer cell invasion. In this study, to identify the precise molecular mechanism by which RhoGDI2 activates Rac1 activity, we performed two-hybrid screenings using yeast and found that RhoGDI2 plays an important role in the interaction between Rac1, Filamin A and Rac1 activation in gastric cancer cells. Moreover, we found that Filamin A is required for Rac1 activation and the invasive ability of gastric cancer cells. Depletion of Filamin A expression markedly reduced Rac1 activity in RhoGDI2-expressing gastric cancer cells. The migration and invasion ability of RhoGDI2-expressing gastric cancer cells also substantially decreased when Filamin A expression was depleted. Furthermore, we found that Trio, a Rac1-specific guanine nucleotide exchange factor (GEF), is critical for Rac1 activation and the invasive ability of gastric cancer cells. Therefore, we conclude that RhoGDI2 increases Rac1 activity by recruiting Rac1 to Filamin A and enhancing the interaction between Rac1 and Trio, which is critical for the invasive ability of gastric cancer cells.

CRIF1 deficiency suppresses endothelial cell migration via upregulation of RhoGDI2

Rho GDP-dissociation inhibitor (RhoGDI), a downregulator of Rho family GTPases, prevents nucleotide exchange and membrane association. It is responsible for the activation of Rho GTPases, which regulate a variety of cellular processes, such as migration. Although RhoGDI2 has been identified as a tumor suppressor gene involved in cellular migration and invasion, little is known about its role in vascular endothelial cell (EC) migration. CR6-interacting factor 1 (CRIF1) is a CR6/GADD45-interacting protein with important mitochondrial functions and regulation of cell growth. We examined the expression of RhoGDI2 in CRIF1-deficient human umbilical vein endothelial cells (HUVECs) and its role in cell migration. Expression of RhoGDI2 was found to be considerably higher in CRIF1-deficient HUVECs along with suppression of cell migration. Moreover, the phosphorylation levels of Akt and CREB were decreased in CRIF1-silenced cells. The Akt-CREB signaling pathway was implicated in the changes in endothelial cell migration caused by CRIF1 downregulation. In addition to RhoGDI2, we identified another factor that promotes migration and invasion of ECs. Adrenomedullin2 (ADM2) is an autocrine/paracrine factor that regulates vascular tone and other vascular functions. Endogenous ADM2 levels were elevated in CRIF1-silenced HUVECs with no effect on cell migration. However, siRNA-mediated depletion of RhoGDI2 or exogenous ADM2 administration significantly restored cell migration via the Akt-CREB signaling pathway. In conclusion, RhoGDI2 and ADM2 play important roles in the migration of CRIF1-deficient endothelial cells.

A Complete Survey of RhoGDI Targets Reveals Novel Interactions with Atypical Small GTPases

There are three RhoGDIs in mammalian cells, which were initially defined as negative regulators of Rho family small GTPases. However, it is now accepted that RhoGDIs not only maintain small GTPases in their inactive GDP-bound form but also act as chaperones for small GTPases, targeting them to specific intracellular membranes and protecting them from degradation. Studies to date with RhoGDIs have usually focused on the interactions between the "typical" or "classical" small GTPases, such as the Rho, Rac, and Cdc42 subfamily members, and either the widely expressed RhoGDI-1 or the hematopoietic-specific RhoGDI-2. Less is known about the third member of the family, RhoGDI-3 and its interacting partners. RhoGDI-3 has a unique N-terminal extension and is found to localize in both the cytoplasm and the Golgi. RhoGDI-3 has been shown to target RhoB and RhoG to endomembranes. In order to facilitate a more thorough understanding of RhoGDI function, we undertook a systematic study to determine all possible Rho family small GTPases that interact with the RhoGDIs. RhoGDI-1 and RhoGDI-2 were found to have relatively restricted activity, mainly binding members of the Rho and Rac subfamilies. RhoGDI-3 displayed wider specificity, interacting with the members of Rho, Rac, and Cdc42 subfamilies but also forming complexes with "atypical" small Rho GTPases such as Wrch2/RhoV, Rnd2, Miro2, and RhoH. Levels of RhoA, RhoB, RhoC, Rac1, RhoH, and Wrch2/RhoV bound to GTP were found to decrease following coexpression with RhoGDI-3, confirming its role as a negative regulator of these small Rho GTPases.

KDM6A-ARHGDIB axis blocks metastasis of bladder cancer by inhibiting Rac1

Background

KDM6A, a histone demethylase, is frequently mutated in bladder cancer (BCa). However, the role and detailed molecular mechanism of KDM6A involved in bladder cancer progression remains unknown.

Methods

Tissue specimens were used to determine the expression levels and prognostic values of KDM6A and ARHGDIB. The MTT, colony formation, wound healing and Transwell migration and invasion assays were employed to detect the BCa cell proliferation, migration and invasion, respectively. Chemotaxis of macrophages was used to evaluate the ability of KDM6A to recruit macrophages. A subcutaneous tumour model and tail vein tumour injection in nude mice were used to assess the role of KDM6A in vivo. RNA sequencing, qPCR, Western blot, ChIP and phalloidin staining assay were performed to investigate the molecular functions of KDM6A. Dual-luciferase reporter assay was used to determine the effects of KDM6A and FOXA1 on the promoters of the ARHGDIB and KDM6A.

Results

We showed that the KDM6A inhibited the motility and invasiveness of the BCa cells. Mechanistically, KDM6A promotes the transcription of ARHGDIB by demethylating histone H3 lysine di/trimethylation (H3K27me2/3) and consequently leads to inhibition of Rac1. EZH2, which catalyses the methylation of H3K27, functions to silence ARHGDIB expression, and an EZH2 inhibitor can neutralize the metastatic effect caused by KDM6A deficiency. Furthermore, we demonstrated that FOXA1 directly binds to the KDM6A promoter and thus transactivates KDM6A, leading to diminished metastatic potential.

Conclusion

Our findings establish the critical role of the FOXA1-KDM6A-ARHGDIB axis in restraining the malignancy of BCa and identify KDM6A and EZH2 as potential therapeutic targets in the management of BCa.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-021-01369-9.

Knockdown of RhoGDI2 represses human gastric cancer cell proliferation, invasion and drug resistance via the Rac1/Pak1/LIMK1 pathway

Gastric cancer (GC) is the fifth most common primary malignancy in humans. Rho GDP dissociation inhibitor 2 (RhoGDI2) is overexpressed in multiple cancer types, but the role of RhoGDI2 in GC has not been elucidated. This study aims to determine the level of RhoGDI2 in GC and to confirm the effect of its inhibition or overexpression on GC cell migration, invasion and chemosensitivity. RhoGDI2 level is significantly enhanced in human GC tissue samples in comparison with normal gastric epithelium and corresponding para-cancerous samples. The expression of RhoGDI2 is correlated with clinicopathological parameters and prognosis. Transfection in combination with miRNA targeting of RhoGDI2 in GC cell lines remarkably downregulates GC cell migration and invasion and reduces the mRNA levels of Rac1, Pak1 and LIMK1. The inhibition of RhoGDI2 downregulates GC cell migration and invasion by attenuating the EMT cascade via the Rac1/Pak1/LIMK1 pathway. Knockdown of RhoGDI2 is a potential therapeutic strategy for GC.

Identification of hub genes associated with RNAi-induced silencing of XIAP through targeted proteomics approach in MCF7 cells

Background

The X-linked inhibitor of apoptosis protein (XIAP) is the most potent caspase inhibitor of the IAP family in apoptosis pathway. This study aims to identify the molecular targets of XIAP in human breast cancer cells exposed to XIAP siRNA by proteomics screening. The expression of XIAP was reduced in MCF-7 breast cancer cells by siRNA. Cell viability and the mRNA expression level of this gene were evaluated by MTS and quantitative real-time PCR procedures, respectively. Subsequently, the XIAP protein level was visualized by Western blotting and analyzed by two-dimensional (2D) electrophoresis and LC–ESI–MS/MS.

Results

Following XIAP silencing, cell proliferation was reduced in XIAP siRNA transfected cells. The mRNA transcription and protein expression of XIAP were decreased in cells exposed to XIAP siRNA than si-NEG. We identified 30 proteins that were regulated by XIAP, of which 27 down-regulated and 3 up-regulated. The most down-regulated proteins belonged to the Heat Shock Proteins family. They participate in cancer related processes including apoptosis and MAPK signaling pathway. Reduced expression of HSP90B1 was associated with apoptosis induction by androgen receptor and prostate specific antigen. Suppression of XIAP resulted in the enhancement of GDIB, ENO1, and CH60 proteins expression. The network analysis of XIAP-regulated proteins identified HSPA8, HSP90AA1, ENO1, and HSPA9 as key nodes in terms of degree and betweenness centrality methods.

Conclusions

These results suggested that XIAP may have a number of biological functions in a diverse set of non-apoptotic signaling pathways and may provide an insight into the biomedical significance of XIAP over-expression in MCF-7 cells.

Dysregulation of Rho GTPases in Human Cancers

Rho GTPases play central roles in numerous cellular processes, including cell motility, cell polarity, and cell cycle progression, by regulating actin cytoskeletal dynamics and cell adhesion. Dysregulation of Rho GTPase signaling is observed in a broad range of human cancers, and is associated with cancer development and malignant phenotypes, including metastasis and chemoresistance. Rho GTPase activity is precisely controlled by guanine nucleotide exchange factors, GTPase-activating proteins, and guanine nucleotide dissociation inhibitors. Recent evidence demonstrates that it is also regulated by post-translational modifications, such as phosphorylation, ubiquitination, and sumoylation. Here, we review the current knowledge on the role of Rho GTPases, and the precise mechanisms controlling their activity in the regulation of cancer progression. In addition, we discuss targeting strategies for the development of new drugs to improve cancer therapy.

Antibodies against ARHGDIB are associated with long-term kidney graft loss

The clinical significance of non-HLA antibodies on renal allograft survival is a matter of debate, due to differences in reported results and lack of large-scale studies incorporating analysis of multiple non-HLA antibodies simultaneously. We developed a multiplex non-HLA antibody assay against 14 proteins highly expressed in the kidney. In this study, the presence of pretransplant non-HLA antibodies was correlated to renal allograft survival in a nationwide cohort of 4770 recipients transplanted between 1995 and 2006. Autoantibodies against Rho GDP-dissociation inhibitor 2 (ARHGDIB) were significantly associated with graft loss in recipients transplanted with a deceased-donor kidney (N = 3276) but not in recipients of a living-donor kidney (N = 1496). At 10 years after deceased-donor transplantation, recipients with anti-ARHGDIB antibodies (94/3276 = 2.9%) had a 13% lower death-censored covariate-adjusted graft survival compared to the anti-ARHGDIB-negative (3182/3276 = 97.1%) population (hazard ratio 1.82; 95% confidence interval, 1.32-2.53; P = .0003). These antibodies occur independently from donor-specific anti-HLA antibodies (DSA) or other non-HLA antibodies investigated. No significant relations with graft loss were found for the other 13 non-HLA antibodies. We suggest that pretransplant risk assessment can be improved by measuring anti-ARHGDIB antibodies in all patients awaiting deceased-donor transplantation.

Adenosine Inhibits Ovarian Cancer Growth Through Regulating RhoGDI2 Protein Expression

Objective

This study aimed to investigate the effect of adenosine (Ado) on the growth of ovarian cancer and to explore the related mechanisms.

Methods

The effect of Ado on the proliferation of A2780 human ovarian cancer cells was examined according to the MTT method. Moreover, the nude mouse model of subcutaneous A2780 xenograft was constructed, and then, Ado and cisplatin were administered intraperitoneally to investigate the effect of Ado on tumor growth in vivo. Immunohistochemistry (IHC) was carried out to study the effect of Ado on the expression of Rho-specific guanine nucleotide dissociation inhibitor 2 (RhoGDI2) in the subcutaneous xenografts. Afterwards, the commercially constructed RhoGDI2 siRNA plasmid was transfected into A2780 cells, and tube formation assay was conducted to determine the effect of down-regulating RhoGDI2 expression on the regulation of angiogenesis in ovarian cancer by Ado. Besides, Western blotting was performed to detect the effect of RhoGDI2 down-regulation on the regulation of matrix metalloproteinase 2 (MMP-2), MMP-9, vascular endothelial growth factor (VEGF), transforming growth factor beta (TGF-β), tumor necrosis factor (TNF-α), and platelet endothelial cell adhesion molecule-1 (PECAM-1 or CD31) expression in ovarian cancer cells by Ado.

Results

The relative viability of cells subsequent to Ado treatment proved to be both concentration- and time dependent. IHC results showed that Ado evidently enhanced the RhoGDI2 protein expression. In addition, interference with RhoGDI2 outstandingly attenuated the ability of Ado to suppress tumor cell invasion and induce angiogenesis in vitro. Furthermore, molecular mechanism studies indicated that Ado remarkably inhibited the expression of MMP-2, MMP-9, VEGF, TGF-β, TNF-α, and CD31, while interference with RhoGDI2 restored the expression of the above-mentioned angiogenic factors.

Conclusion

Ado inhibits the growth of A2780 human ovarian cancer cells through inhibiting tumor cell invasion and angiogenesis in a RhoGDI2-dependent manner.

Regulation of Rho GTPases by RhoGDIs in Human Cancers

Rho GDP dissociation inhibitors (RhoGDIs) play important roles in various cellular processes, including cell migration, adhesion, and proliferation, by regulating the functions of the Rho GTPase family. Dissociation of Rho GTPases from RhoGDIs is necessary for their spatiotemporal activation and is dynamically regulated by several mechanisms, such as phosphorylation, sumoylation, and protein interaction. The expression of RhoGDIs has changed in many human cancers and become associated with the malignant phenotype, including migration, invasion, metastasis, and resistance to anticancer agents. Here, we review how RhoGDIs control the function of Rho GTPases by regulating their spatiotemporal activity and describe the regulatory mechanisms of the dissociation of Rho GTPases from RhoGDIs. We also discuss the role of RhoGDIs in cancer progression and their potential uses for therapeutic intervention.

[Proteomic analysis and verification of protein expression after upregulation of human CD99 in Hodgkin lymphoma cell line L428]

Objective: To investigate the proteins expression difference after upregulation of human CD99 in Hodgkin Lymphoma cell line, L428 cell, and verify the function of differential proteins. Methods: The differential proteins were detected by two-dimensional fluorescence difference gel electrophoresis and mass spectrometry analysis, cluster analysis was done by GOfact. Results: There were 38 proteins screened out, of which 21 proteins were positively associated with CD99, while 17 proteins were negative. Among the 38 proteins, 32 proteins participated in biological process, and 35 proteins were involved in the composition and construction. And 28 proteins participated in multifaceted biological activities including antioxidation, protein binding, catalytic activity, regulation of enzyme, signal transduction, molecular structure, regulation of translation and ion transport. Conclusions: The changes of the differential proteins, correlated with cytoskeleton, cell differentiation, signal pathway and regulating gene expression, are closely relevant to the translation between Hodgkin/Reed-Sternberg and B lymphocyte cell.

XIAP overexpression promotes bladder cancer invasion in vitro and lung metastasis in vivo via enhancing nucleolin-mediated Rho-GDIβ mRNA stability

Our recent studies demonstrate that X-linked inhibitor of apoptosis protein (XIAP) is essential for regulating colorectal cancer invasion. Here, we discovered that RhoGDIβ was a key XIAP downstream effector mediating bladder cancer (BC) invasion in vitro and in vivo. We found that both XIAP and RhoGDIβ expressions were consistently elevated in BCs of N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN)-treated mice in comparison to bladder tissues from vehicle-treated mice and human BCs in comparison to the paired adjacent normal bladder tissues. Knockdown of XIAP attenuated RhoGDIβ expression and reduced cancer cell invasion, whereas RhoGDIβ expression was attenuated in BBN-treated urothelium of RING-deletion knockin mice. Mechanistically, XIAP stabilized RhoGDIβ mRNA by its positively regulating nucleolin mRNA stability via Erks-dependent manner. Moreover, ectopic expression of GFP-RhoGDIβ in T24T(shXIAP) cells restored its lung metastasis in nude mice. Our results demonstrate that XIAP-regulated Erks/nucleolin/RhoGDIβ axis promoted BC invasion and lung metastasis.

Over forty years of bladder cancer glycobiology: Where do glycans stand facing precision oncology?

The high molecular heterogeneity of bladder tumours is responsible for significant variations in disease course, as well as elevated recurrence and progression rates, thereby hampering the introduction of more effective targeted therapeutics. The implementation of precision oncology settings supported by robust molecular models for individualization of patient management is warranted. This effort requires a comprehensive integration of large sets of panomics data that is yet to be fully achieved. Contributing to this goal, over 40 years of bladder cancer glycobiology have disclosed a plethora of cancer-specific glycans and glycoconjugates (glycoproteins, glycolipids, proteoglycans) accompanying disease progressions and dissemination. This review comprehensively addresses the main structural findings in the field and consequent biological and clinical implications. Given the cell surface and secreted nature of these molecules, we further discuss their potential for non-invasive detection and therapeutic development. Moreover, we highlight novel mass-spectrometry-based high-throughput analytical and bioinformatics tools to interrogate the glycome in the postgenomic era. Ultimately, we outline a roadmap to guide future developments in glycomics envisaging clinical implementation.

EphrinB1 promotes cancer cell migration and invasion through the interaction with RhoGDI1

Eph receptors and their corresponding ephrin ligands have been associated with regulating cell–cell adhesion and motility, and thus have a critical role in various biological processes including tissue morphogenesis and homeostasis, as well as pathogenesis of several diseases. Aberrant regulation of Eph/ephrin signaling pathways is implicated in tumor progression of various human cancers. Here, we show that a Rho family GTPase regulator, Rho guanine nucleotide dissociation inhibitor 1 (RhoGDI1), can interact with ephrinB1, and this interaction is enhanced upon binding the extracellular domain of the cognate EphB2 receptor. Deletion mutagenesis revealed that amino acids 327–334 of the ephrinB1 intracellular domain are critical for the interaction with RhoGDI1. Stimulation with an EphB2 extracellular domain-Fc fusion protein (EphB2-Fc) induces RhoA activation and enhances the motility as well as invasiveness of wild-type ephrinB1-expressing cells. These Eph-Fc-induced effects were markedly diminished in cells expressing the mutant ephrinB1 construct (Δ327–334) that is ineffective at interacting with RhoGDI1. Furthermore, ephrinB1 depletion by siRNA suppresses EphB2-Fc-induced RhoA activation, and reduces motility and invasiveness of the SW480 and Hs578T human cancer cell lines. Our study connects the interaction between RhoGDI1 and ephrinB1 to the promotion of cancer cell behavior associated with tumor progression. This interaction may represent a therapeutic target in cancers that express ephrinB1.

The molecular effect of metastasis suppressors on Src signaling and tumorigenesis: new therapeutic targets

A major problem for cancer patients is the metastasis of cancer cells from the primary tumor. This involves: (1) migration through the basement membrane; (2) dissemination via the circulatory system; and (3) invasion into a secondary site. Metastasis suppressors, by definition, inhibit metastasis at any step of the metastatic cascade. Notably, Src is a non-receptor, cytoplasmic, tyrosine kinase, which becomes aberrantly activated in many cancer-types following stimulation of plasma membrane receptors (e.g., receptor tyrosine kinases and integrins). There is evidence of a prominent role of Src in tumor progression-related events such as the epithelial–mesenchymal transition (EMT) and the development of metastasis. However, the precise molecular interactions of Src with metastasis suppressors remain unclear. Herein, we review known metastasis suppressors and summarize recent advances in understanding the mechanisms of how these proteins inhibit metastasis through modulation of Src. Particular emphasis is bestowed on the potent metastasis suppressor, N-myc downstream regulated gene 1 (NDRG1) and its interactions with the Src signaling cascade. Recent studies demonstrated a novel mechanism through which NDRG1 plays a significant role in regulating cancer cell migration by inhibiting Src activity. Moreover, we discuss the rationale for targeting metastasis suppressor genes as a sound therapeutic modality, and we review several examples from the literature where such strategies show promise. Collectively, this review summarizes the essential interactions of metastasis suppressors with Src and their effects on progression of cancer metastasis. Moreover, interesting unresolved issues regarding these proteins as well as their potential as therapeutic targets are also discussed.

Overexpression of RhoGDI2 correlates with the progression and prognosis of pancreatic carcinoma

Rho GDP dissociation inhibitor 2 (RhoGDI2) has been found to be a regulator of tumor metastasis. However, the expression of RhoGDI2 and its clinicopathological significance as well as the pathway of RhoGDI2 in tumor metastasis have yet to be investigated. To investigate the role of RhoGDI2 in the progression and prognosis of pancreatic carcinoma (PC), the expression of RhoGDI2 in human PC tissues was examined and compared with the clinicopathological characteristics and prognosis. Moreover, the relationship between RhoGDI2 and E-cadherin was examined. The results indicated that RhoGDI2 was overexpressed in PC tissues and associated with clinicopathological characteristics, including clinical stage and lymph node metastasis. Patients with a RhoGDI2‑negative expression had a significantly longer survival time than those with a RhoGDI2‑positive expression. Additionally, the expression of RhoGDI2 was negatively correlated with the expression of E-cadherin in PC tissues. Taken together, the findings suggest that RhoGDI2 is important in the progression and prognosis of PC, and may be used as a potential prognostic biomarker and a therapeutic target for PC.

RhoGDI2 promotes epithelial-mesenchymal transition via induction of Snail in gastric cancer cells

Rho GDP dissociation inhibitor 2 (RhoGDI2) expression correlates with tumor growth, metastasis, and chemoresistance in gastric cancer. Here, we show that RhoGDI2 functions in the epithelial-mesenchymal transition (EMT), which is responsible for invasiveness during tumor progression. This tumorigenic activity is associated with repression of E-cadherin by RhoGDI2 via upregulation of Snail. Overexpression of RhoGDI2 induced phenotypic changes consistent with EMT in gastric cancer cells, including abnormal epithelial cell morphology, fibroblast-like properties, and reduced intercellular adhesion. RhoGDI2 overexpression also resulted in decreased expression of the epithelial markers E-cadherin and β-catenin and increased expression of the mesenchymal markers vimentin and fibronectin. Importantly, RhoGDI2 overexpression also stimulated the expression of Snail, a repressor of E-cadherin and inducer of EMT, but not other family members such as Slug or Twist. RNA interference-mediated knockdown of Snail expression suppressed RhoGDI2-induced EMT and invasion, confirming that the effect was Snail-specific. These results indicate that RhoGDI2 plays a critical role in tumor progression in gastric cancer through induction of EMT. Targeting RhoGDI2 may thus be a useful strategy to inhibit gastric cancer cell invasion and metastasis.

RNA interference-mediated knockdown of RhoGDI2 induces the migration and invasion of human lung cancer A549 cells via activating the PI3K/Akt pathway

Rho GDP dissociation inhibitor 2 (RhoGDI2) has been identified as a tumor suppressor gene for cellular migration and invasion. However, the underlying mechanism and effector targets of RhoGDI2 in lung cancer are still not fully understood. In this study, a vector-expressed small hairpin RNA (shRNA) of RhoGDI2 was transfected into the human lung cancer cell line A549. After the successful transfection, the down-regulation of RhoGDI2 promoted the proliferation, migration, and invasion of lung cancer cells in vitro through the increasing expression and activities of the matrix metallopeptidase 9 (MMP-9) and PI3K/Akt pathways. Transiently transfecting the small interfering RNA (siRNA) of MMP-9 into the RhoGDI2 shRNA cells reduced the MMP-9 expression. Both transfecting the siRNA and adding the MMP-9 antibody into the RhoGDI2 shRNA cells led to a decrease in the invasion and migration of the lung cancer cells. The blockade of the PI3K/Akt pathway by LY294002 resulted in abolishment of the effects of RhoGDI2 shRNA in Akt phosphorylation and MMP-9 expression. This result suggests that the down-regulated RhoGDI2 contributed to the migration and invasion of the lung cancer cell line via activating the PI3K/Akt pathway and the ensuing increase in the expression and activity of MMP-9. In conclusion, we report that the shRNA-mediated knockdown of RhoGDI2 induces the invasion and migration of lung cancer due to cross-talk with the PI3K/Akt pathway and MMP-9. Verifying the role and molecular mechanism of the participation of RhoGDI2 in the migration and invasion of lung cancer may provide a target for better treatment.

14-3-3σ attenuates RhoGDI2-induced cisplatin resistance through activation of Erk and p38 in gastric cancer cells

Rho GDP dissociation inhibitor 2 (RhoGDI2) promotes tumor growth and malignant progression and enhances chemoresistance of gastric cancer. Recently, we noted an inverse correlation between RhoGDI2 and 14-3-3σ expression, which suggests that 14-3-3σ is a target of gastric cancer metastasis and the chemoresistance-promoting effect of RhoGDI2. Herein, we evaluated whether 14-3-3σ is regulated by RhoGDI2 and is functionally important for the RhoGDI2-induced cisplatin resistance of gastric cancer cells. We used highly metastatic and cisplatin-resistant RhoGDI2-overexpressing SNU-484 cells and observed decreased 14-3-3σ mRNA and protein expression. Depletion of 14-3-3σ in SNU-484 control cells enhanced cisplatin resistance, whereas restoration of 14-3-3σ in RhoGDI2-overexpressing SNU-484 cells impaired cisplatin resistance in vitro and in vivo. We also found that the phosphorylation levels of Erk and p38 kinases significantly decreased in RhoGDI2-overexpressing SNU-484 cells and recovered after 14-3-3σ expression, and that decreased activities of these kinases were critical for RhoGDI2-induced cisplatin resistance. In conclusion, 14-3-3σ is a RhoGDI2-regulated gene that appears to be important for suppressing the chemoresistance of gastric cancer cells.

Rho GDP dissociation inhibitor beta promotes cell proliferation and invasion by modulating the AKT pathway in hepatocellular carcinoma

Rho GDP dissociation inhibitor (GDI) beta, (RhoGDI2), has been identified as a proto-oncogene that is upregulated in human cancers, but the role of RhoGDI2 in hepatocellular carcinoma (HCC) remains unclear. In the present study, we investigated the RhoGDI2 expression level in HCC tissues and the function of RhoGDI2 in HCC cell growth and metastasis. We examined the RhoGDI2 mRNA expression level in 64 sets of HCC tissue and their adjacent nontumor tissue counterparts using quantitative real-time polymerase chain reaction. In vitro proliferation and invasion assays were conducted to determine the effect of RhoGDI2 on the ability of HCC cells to proliferate and invade, respectively. Western blot analysis was conducted to examine expression levels of RhoGDI2p-AKT, MMP-2, and MMP-9 in HCC cells. RhoGDI2 mRNA was significantly overexpressed in the HCC specimens compared with the nonneoplastic liver specimens, and the RhoGDI2 mRNA and protein levels were higher in the HCC cell lines, especially the highly metastatic cell lines 97L and 97H. To further investigate the role that RhoGDI2 plays in HCC, we overexpressed RhoGDI2 using a lentivirus-mediated overexpression technique in two HCC cell lines (Huh7 and 7721) that endogenously express a low level of RhoGDI2. Stable cells overexpressing RhoGDI2 demonstrated a significant increase in cell proliferation and invasion. Furthermore, our additional findings indicated that RhoGDI2-mediated cellular invasion requires the PI3K/Akt signaling-dependent expression of matrix metalloproteinases (MMPs). Our findings suggest that RhoGDI2 plays an important role in HCC growth and invasion and should be considered a novel HCC therapeutic target candidate.

Depletion of RhoGDI2 expression inhibits the ability of invasion and migration in pancreatic carcinoma

Rho GDP dissociation inhibitor 2 (RhoGDI2) has been identified as a regulator of tumor metastasis, although its role in tumor progression remains controversial. In this study, we examined the expression of RhoGDI2 in PC tissues and cell lines. To investigate the function of RhoGDI2 in PC cells, RhoGDI2 expression was depleted in PANC-1 and Patu8988 cells by small interfering RNA (siRNA). RhoGDI2 was found to be overexpressed in pancreatic carcinoma (PC) tissues and PC cell lines. Additionally, the results showed that depletion of RhoGDI2 significantly inhibited cell motility and invasion in vitro, but did not affect cell proliferation. The clinical study together with the experimental data confirmed that RhoGDI2 modulated the expression of matrix metalloproteinase 2 (MMP2). Taken together, findings of the present study indicated that RhoGDI2 is involved in pancreatic tumor malignancy and metastasis. Thus, RhoGDI2 is a potential target for the gene therapy of PC.

VEGF-C mediates RhoGDI2-induced gastric cancer cell metastasis and cisplatin resistance

Rho GDP dissociation inhibitor 2 (RhoGDI2) expression is correlated with tumor growth, metastasis and chemoresistance in gastric cancer. However, the mechanisms by which RhoGDI2 promotes tumor cell survival and metastasis remain unclear. In this study, we clearly demonstrate that RhoGDI2 upregulates VEGF-C expression and RhoGDI2 expression is positively correlated with VEGF-C expression in human gastric tumor tissues as well as parental gastric cancer cell lines. VEGF-C depletion suppressed RhoGDI2-induced gastric cancer metastasis and sensitized RhoGDI2-overexpressing cells to cisplatin-induced apoptosis in vitro and in vivo. Secreted VEGF-C enhanced gastric cancer cell invasion and conferred cisplatin resistance to RhoGDI2-overexpressing cells. We also show that RhoGDI2 positively regulates Rac1 activity in gastric cancer cells. Inhibition of Rac1 expression suppressed RhoGDI2-induced VEGF-C expression, and this inhibition was associated with decreased invasiveness and increased sensitivity to cisplatin in RhoGDI2-overexpressing cells. Our results indicate that RhoGDI2 might be a potential therapeutic target for simultaneously reducing metastasis risk and enhancing chemotherapy efficacy in gastric cancer.

Proteomic analysis reveals the deregulation of inflammation-related proteins in acupuncture-treated rats with asthma onset

Although the beneficial effects of acupuncture in asthma treatment have been well documented, little is known regarding the biological basis of this treatment. Changes in the lung proteome of acupuncture-treated rats with asthma onset were comparatively analyzed using a two-dimensional gel electrophoresis (2DE) and mass-spectrometry- (MS-) based proteomic approach. Acupuncture on specific acupuncture points appeared to improve respiratory function and reduce the total number of leukocytes and eosinophils in bronchoalveolar lavage fluid in OVA-induced asthma onset. Image analysis of 2DE gels revealed 32 differentially expressed acupuncture-specific protein spots in asthma onset; 30 of which were successfully identified as 28 unique proteins using LC-MS/MS. Bioinformatic analyses indicated that these altered proteins are most likely involved in inflammation-related biological functions, and the functional associations of these proteins result in an inflammation signaling pathway. Acupuncture regulates the pathway at different levels by regulating several key nodal proteins, including downregulating of proinflammatory proteins (e.g., S100A8, RAGE, and S100A11) and upregulating of anti-inflammatory proteins (e.g., CC10, ANXA5, and sRAGE). These deregulated inflammation-related proteins may mediate, at least in part, the antiasthmatic effect of acupuncture. Further functional investigation of these acupuncture-specific effector proteins could identify new drug candidates for the prophylaxis and treatment of asthma.

Differential proteomic analysis of HL60 cells treated with secalonic acid F reveals caspase 3-induced cleavage of Rho GDP dissociation inhibitor 2

Secalonic acid F (SAF) has been previously identified, however, little is known about its cytotoxic activity and related cytotoxic mechanism. The aim of this study was to evaluate the cytotoxic activity of SAF isolated from a deep sea originated fungus Penicillium sp. F11 in HL60 cells and to analyze the differences in protein expression of HL60 cells treated with SAF. The CCK-8 assay and Annexin V-FLUOS/PI assay indicated that SAF displayed dose- and time-dependent inhibition of HL60 cell proliferation and induced apoptosis. Two-dimensional gel electrophoresis (2-DE) analysis of HL60 cells treated with SAF (4 µg/ml) revealed 10 differentially expressed protein spots (P<0.05), 5 upregulated and 5 downregulated. Three spots (1 downregulated and 2 upregulated) were identified as Rho GDP dissociation inhibitor 2 (RhoGDI 2) proteins by MALDI-TOF MS. Western blotting further demonstrated the decreased abundance of full-length RhoGDI 2 together with the increased abundance of caspase 3-cleaved product of RhoGDI 2. The caspase 3 inhibitor Ac-DEVD-CHO could suppress the cytotoxic effect of SAF and significantly block the cleavage of RhoGDI 2. RhoGDI 2 is a cytosolic regulator of Rho GTPase and the caspase 3-cleaved product of RhoGDI 2 can advance progression of the apoptotic process. Our data showed that SAF may modulate RhoGDI 2 levels in HL60 cells, thereby potentially disrupting cell signaling pathways important for HL60 cell function.

Regulation of neural stem cell differentiation by transcription factors HNF4-1 and MAZ-1

Neural stem cells (NSCs) are promising candidates for a variety of neurological diseases due to their ability to differentiate into neurons, astrocytes, and oligodentrocytes. During this process, Rho GTPases are heavily involved in neuritogenesis, axon formation and dendritic development, due to their effects on the cytoskeleton through downstream effectors. The activities of Rho GTPases are controlled by Rho-GDP dissociation inhibitors (Rho-GDIs). As shown in our previous study, these are also involved in the differentiation of NSCs; however, little is known about the underlying regulatory mechanism. Here, we describe how the transcription factors hepatic nuclear factor (HNF4-1) and myc-associated zinc finger protein (MAZ-1) regulate the expression of Rho-GDIγ in the stimulation of NSC differentiation. Using a transfection of cis-element double-stranded oligodeoxynucleotides (ODNs) strategy, referred to as "decoy" ODNs, we examined the effects of HNF4-1 and MAZ-1 on NSC differentiation in the NSC line C17.2. Our results show that HNF4-1 and MAZ-1 decoy ODNs significantly knock down Rho-GDIγ gene transcription, leading to NSC differentiation towards neurons. We observed that HNF4-1 and MAZ-1 decoy ODNs are able enter to the cell nucleolus and specifically bind to their target transcription factors. Furthermore, the expression of Rho-GDIγ-mediated genes was identified, suggesting that the regulatory mechanism for the differentiation of NSCs is triggered by the transcription factors MAZ-1 and HNF4-1. These findings indicate that HNF4-1 and MAZ-1 regulate the expression of Rho-GDIγ and contribute to the differentiation of NSCs. Our findings provide a new perspective within regulatory mechanism research during differentiation of NSCs, especially the clinical application of transcription factor decoys in vivo, suggesting potential therapeutic strategies for neurodegenerative disease.

PLCγ is required for RhoGDI2-mediated cisplatin resistance in gastric cancer

Rho GDP dissociation inhibitor 2 (RhoGDI2) is a regulator of the Rho family GTPases. Recent work from our laboratory suggests that RhoGDI2 expression potentially enhances resistance to cisplatin as well as promotes tumor growth and malignant progression in gastric cancer. In this study, we demonstrate that phospholipase C-gamma (PLCγ) is required for RhoGDI2-mediated cisplatin resistance and cancer cell invasion in gastric cancer. The levels of phosphorylated PLCγ are markedly enhanced in RhoGDI2-overexpressing SNU-484 cells and, by contrast, repressed in RhoGDI2-depleted MKN-28 cells. Depletion of PLCγ expression or inhibition of its activity not only significantly increases cisplatin-induced apoptosis but also suppresses the invasive ability of RhoGDI2-overexpressing SNU-484 cells. Taken together, our results suggest that PLCγ plays a key role in RhoGDI2-mediated cisplatin resistance and cell invasion in gastric cancer cells.

Overexpression of RhoGDI2 correlates with tumor progression and poor prognosis in colorectal carcinoma

BACKGROUND

RhoGDI2 has been identified as a regulator of tumor metastasis but its role in cancer remains controversial. The aims of this study were to analyze the function of RhoGDI2 in colorectal carcinoma (CRC), and to determine its possible signaling pathway in CRC.

METHODS

The expression of RhoGDI2 was detected in CRC cell lines, and 20 matched pairs of fresh CRC tissues, and 120 cases of clinical paraffin-embedded CRC tissues by real-time RT-PCR, Western blot, RT-PCR, or immunohistochemistry. The levels of activations of p-PI3K, p-Akt, p-MAPK, and p-MEK were then examined in RhoGDI2-overexpressing cells by Western blot. A series of assays were finally performed to evaluate the effect of RhoGDI2 on CRC cell behaviors in vitro.

RESULTS

RhoGDI2 expression was higher in highly metastatic CRC cell lines than in lowly metastatic ones. RhoGDI2 expression was up-regulated in CRC or lymphatic metastatic tissues relative to normal mucosa (P < 0.05). RhoGDI2 expression was correlated strongly with tumor size, differentiation, and Duke's stage (P < 0.05). Patients with lower RhoGDI2 expression had better overall survival (P = 0.012), and RhoGDI2 could predict prognosis only in patients with early-stage disease. High levels of activations of p-PI3K and p-Akt were observed in RhoGDI2-overexpressing cells. LY294002 inhibitor could abrogate the activation of PI3K/Akt pathway in those cells. Over-expression of RhoGDI2 enhanced CRC cell proliferation, motility, and invasion in vitro.

CONCLUSIONS

Over-expression of RhoGDI2 is associated with poor overall survival in CRC patients, especially those presenting in early-stage. RhoGDI2 contributes to cell proliferation, motility, and invasion of CRC, at least in part, by activating the PI3K/Akt pathway.

RhoGDI2 antagonizes ovarian carcinoma growth, invasion and metastasis

Previous studies described functional roles for Rho GDP dissociation inhibitor 2 (RhoGDI2) in bladder, gastric and breast cancers. However, only limited expression and no functional analyses have been done for RhoGDI2 in ovarian cancer. We determined RhoGDI2 protein expression and function in ovarian cancer. First, protein gel blot analysis was performed to determine the expression levels of RhoGDI2 in ovarian cells lines. RhoGDI2 but not RhoGDI1 protein expression levels varied widely in ovarian carcinoma cell lines, with elevated levels seen in Ras-transformed ovarian epithelial cells. Next, immunohistochemistry was performed to detect RhoGDI2 expression in patient samples of ovarian cysts and ovarian cancer with known histological subtype, stage, grade and outcome. RhoGDI2 protein was significantly overexpressed in high-grade compared with low-grade ovarian cancers, correlated with histological subtype, and did not correlate with stage of ovarian cancer nor between carcinomas and benign cysts. Unexpectedly, stable suppression of RhoGDI2 protein expression in HeyA8 ovarian cancer cells increased anchorage-independent growth and Matrigel invasion in vitro and in tail-vein lung colony metastatic growth in vivo. Finally, we found that RhoGDI2 stably-associated preferentially with Rac1 and suppression of RhoGDI2 expression resulted in decreased Rac1 activity and Rac-associated JNK and p38 mitogenactivated protein kinase signaling. RhoGDI2 antagonizes the invasive and metastatic phenotype of HeyA8 ovarian cancer cells. In summary, our results suggest significant cell context differences in RhoGDI2 function in cancer cell growth.

RhoGDI2 confers gastric cancer cells resistance against cisplatin-induced apoptosis by upregulation of Bcl-2 expression

Rho GDP dissociation inhibitor (RhoGDI)2 has been identified as a regulator of Rho family GTPase. Recently, we suggested that RhoGDI2 could promote tumor growth and malignant progression in gastric cancer. In this study, we demonstrate that RhoGDI2 contributes to another important feature of aggressive cancers, i.e., resistance to chemotherapeutic agents such as cisplatin. Forced expression of RhoGDI2 attenuated cisplatin-induced apoptosis, whereas RhoGDI2 depletion showed opposite effects in vitro. Moreover, the increased anti-apoptotic effect of RhoGDI2 on cisplatin was further validated in RhoGDI2-overexpressing SNU-484 xenograft model in nude mice. Furthermore, we identified Bcl-2 as a major determinant of RhoGDI2-mediated cisplatin resistance in gastric cancer cells. Depletion of Bcl-2 expression significantly increased cisplatin-induced apoptosis in RhoGDI2-overexpressing gastric cancer cells, whereas overexpression of Bcl-2 blocked cisplatin-induced apoptosis in RhoGDI2-depleted gastric cancer cells. Overall, these findings establish RhoGDI2 as an important therapeutic target for simultaneously enhancing chemotherapy efficacy and reducing metastasis risk in gastric cancer.

Significance of RhoC mRNA expression in esophageal squamous cell carcinoma

AIM: To investigate the expression of RhoC mRNA in esophageal squamous cell carcinoma (ESCC) and to explore its correlation with the development and progression of ESCC.

METHODS: Semi-quantitative RT-PCR was used to detect the relative expression levels of RhoC mRNA in 62 ESCC specimens, 31 tumor-adjacent atypical hyperplastic epithelial specimens and 62 normal esophageal epithelial specimens. The distribution of RhoC transcripts in ESCC was determined by in situ hybridization.

RESULTS: The mRNA expression of RhoC was closely correlated with tumor grade, infiltration and lymph node metastasis in ESCC (all P < 0.05). The expression intensity of RhoC mRNA in carcinoma, adjacent atypical hyperplasia epithelium and normal esophageal epithelium were 0.902 ± 0.119, 0. 731 ± 0.065 and 0.653 ± 0.069, respectively, with a significant difference among the three groups (P < 0.01). In situ hybridization analysis demonstrated that RhoC transcripts were detected in the cytoplasm of cells. The positive rates of RhoC mRNA expression in carcinoma, tumor-adjacent atypical hyperplasia epithelium and normal esophageal epithelium were 80.6% (50/62), 32.3% (10/31) and 21.0% (13/62), respectively, with a significant difference among the three groups (P < 0.01). RT-PCR results were consistent with those obtained by in situ hybridization.

CONCLUSION: The mRNA expression of RhoC in ESCC increases significantly and is closely correlated with tumor biological behavior, which suggests that RhoC overexpression is closed associated with the pathogenesis of ESCC. RhoC may be a new auxiliary parameter for early diagnosis and prognostic prediction for ESCC.