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

Bioinformatic analysis of the expression profile and identification of RhoGDI2 as a biomarker in imatinib-resistant K562 cells

OBJECTIVES

Chronic myeloid leukemia (CML) is an aggressive malignancy originating from hematopoietic stem cells. Imatinib (IM), the first-generation tyrosine kinase inhibitor, has greatly improved theliving quality of CML patients. However, owing to the recurrence and treatment failure coming from tyrosine kinase inhibitor (TKIs) resistance, some CML patients still bear poor prognosis. Therefore, we aimed to seek potential signaling pathways and specific biomarkers for imatinib resistance.

METHODS

We performed mRNA and miRNA expression profiling in imatinib-sensitive K562 cells (IS-K562) and imatinib-resistant K562 cells (IR-K562). Differentially expressed genes (DEGs) were identified and pathway enrichment analyses were performed to explore the potential mechanism. The protein-protein interaction (PPI) network and miRNA-mRNA regulatory network were constructed to explore potential relationships among these genes. RT-qPCR, western blot and CCK8 were used for further experiments.

RESULTS

A total of 623 DEGs and 61 differentially expressed miRNAs were identified. GO revealed that DEGs were mainly involved in cell adhesion, cell migration, differentiation, and inflammatory response. KEGG revealed that DEGs were typically enriched in the Rap1 signaling pathway, focal adhesion, proteoglycans and transcriptional misregulation in cancer, signaling pathways regulating pluripotency of stem cells and some immune-related pathways. The protein-protein interaction (PPI) network and miRNA-mRNA regulatory network revealed a web of diverse connections among genes. Finally, we proved that RHoGDI2 played a critical role in imatinib resistance.

CONCLUSION

The dynamic interplay between genes and signaling pathways is associated with TKIs resistance and RHoGDI2 is identified as a biomarker in IR-K562.

Differential functions of RhoGDIβ in malignant transformation and progression of urothelial cell following N-butyl-N-(4-hydmoxybutyl) nitrosamine exposure

BACKGROUND

Functional role of Rho GDP-dissociation inhibitor beta (RhoGDIβ) in tumor biology appears to be contradictory across various studies. Thus, the exploration of the molecular mechanisms underlying the differential functions of this protein in urinary bladder carcinogenesis is highly significant in the field. Here, RhoGDIβ expression patterns, biological functions, and mechanisms leading to transformation and progression of human urothelial cells (UROtsa cells) were evaluated following varying lengths of exposure to the bladder carcinogen N-butyl-N-(4-hydmoxybutyl) nitrosamine (BBN).

RESULTS

It was seen that compared to expression in vehicle-treated control cells, RhoGDIβ protein expression was downregulated after 2-month of BBN exposure, but upregulated after 6-month of exposure. Assessments of cell function showed that RhoGDIβ inhibited UROtsa cell growth in cells with BBN for 2-month exposure, whereas it promoted the invasion of cells treated with BBN for 6 months. Mechanistic studies revealed that 2-month of BBN exposure markedly attenuated DNMT3a abundance, and this led to reduced miR-219a promoter methylation, increased miR-219a binding to the RhoGDIβ mRNA 3'UTR, and reduced RhoGDIβ protein translation. While after 6-mo of BBN treatment, the cells showed increased PP2A/JNK/C-Jun axis phosphorylation and this in turn mediated overall RhoGDIβ mRNA transcription and protein expression as well as invasion.

CONCLUSIONS

These findings indicate that RhoGDIβ is likely to inhibit the transformation of human urothelial cells during the early phase of BBN exposure, whereas it promotes invasion of the transformed/progressed urothelial cells in the late stage of BBN exposure. The studies also suggest that RhoGDIβ may be a useful biomarker for evaluating the progression of human bladder cancers.

The role of interferon-gamma and its receptors in gastrointestinal cancers

Gastrointestinal malignancies are the most prevalent type of cancer around the world. Even though numerous studies have evaluated gastrointestinal malignancies, the actual underlying mechanism is still unknown. These tumors have a poor prognosis and are frequently discovered at an advanced stage. Globally, there is an increase in the incidence and mortality of gastrointestinal malignancies, including those of the stomach, esophagus, colon, liver, and pancreas. Growth factors and cytokines are signaling molecules that are part of the tumor microenvironment and play a significant role in the development and spread of malignancies. IFN-γ induce its effects by activation of intracellular molecular networks. The main pathway involved in IFN-γ signaling is the JAK/STAT pathway, which regulates the transcription of hundreds of genes and mediates various biological responses. IFN-γ receptor is composed of two IFN-γR1 chains and two IFN-γR2 chains. Binding to IFN-γ, causes the intracellular domains of IFN-γR2 to oligomerize and transphosphorylate with IFN-γR1 which activates downstream signaling components: JAK1 and JAK2. These activated JAKs phosphorylate the receptor, creating binding sites for STAT1. STAT1 is then phosphorylated by JAK, resulting in the formation of STAT1 homodimers (gamma activated factors or GAFs) that translocate to the nucleus and regulate gene expression. The balance between positive and negative regulation of this pathway is crucial for immune responses and tumorigenesis. In this paper, we evaluate the dynamic roles of IFN- γ and its receptors in gastrointestinal cancers and present evidence that inhibiting IFN- γ signaling may be an effective treatment strategy.

The Dual Function of RhoGDI2 in Immunity and Cancer

RhoGDI2 is a guanine nucleotide dissociation inhibitor (GDI) specific for the Rho family of small GTPases. It is highly expressed in hematopoietic cells but is also present in a large array of other cell types. RhoGDI2 has been implicated in multiple human cancers and immunity regulation, where it can display a dual role. Despite its involvement in various biological processes, we still do not have a clear understanding of its mechanistic functions. This review sheds a light on the dual opposite role of RhoGDI2 in cancer, highlights its underappreciated role in immunity and proposes ways to explain its intricate regulatory functions.

2-O-Octadecylascorbic acid represses RhoGDIβ expression and ameliorates DNA damage-induced abnormal spindle orientations

The appropriate regulation of spindle orientation maintains proper tissue homeostasis and avoids aberrant tissue repair or regeneration. Spindle misorientation due to imbalance or improper functioning leads to a loss of tissue integrity and aberrant growth, such as tissue loss or overgrowth. Pharmacological manipulation to prevent spindle misorientation will enable a better understanding of how spindle orientation is involved in physiological and pathological conditions and will provide therapeutic possibilities to treat patients associated with abnormal tissue function caused by spindle misorientation. N-terminal-deleted Rho guanine nucleotide dissociation inhibitor β (RhoGDIβ/RhoGDI2/LyGDI) produced by caspase-3 activation perturbs spindle orientation in surviving cells following exposure to either ionizing radiation or UVC. Thus, presumably, RhoGDIβ cleaved by caspase-3 activation acts as a determinant of radiation-induced spindle misorientation that promote aberrant tissue repair due to deregulation of directional organization of cell population and therefore becomes a potential target of drugs to prevent such response. The objective of this study was to screen and identify chemicals that suppress RhoGDIβ expression. We focused our attention on ascorbic acid (AA) derivatives because of their impact on the maintenance of skin tissue homeostasis. Here, we screened for AA derivatives that suppress RhoGDIβ expression in HeLa cells and identified a lipophilic derivative, 2-O-octadecylascorbic acid (2-OctadecylAA), as a novel RhoGDIβ inhibitor that ameliorated ionizing radiation-induced abnormal spindle orientations. Among all examined AA derivatives, which were also antioxidative, the inhibition activity was specific to 2-OctadecylAA. Therefore, this activity was not due to simple antioxidant properties. 2-OctadecylAA was previously shown to prevent hepatocellular carcinoma development. Our findings suggest that the anticarcinogenic effects of 2-OctadecylAA are partly due to RhoGDIβ inhibition mechanisms by which spindle orientation perturbations are attenuated. Thus, the molecular targeting features of RhoGDIβ warrant its further development for the treatment or control of spindle orientation abnormalities that affect epithelial homeostasis.

Systematic investigation of biomarker-like role of ARHGDIB in breast cancer

BACKGROUND

ARHGDIB, a Rho GDP dissociation inhibitor protein, has been reported playing critical roles in regulation of multiple biological responses. However, whether ARHGDIB serves as a valuable biomarker in cancer is little known so far, especially in breast cancer.

OBJECTIVE

In this study, we aimed to investigate the importance of ARHGDIB in breast cancer, including but not limited to biomarker-like role, as well as potential mechanisms.

METHODS

Total 100 breast cancer samples and 100 benign breast disease samples were enrolled and underwent detailed pathological assessment and IHC analysis. Human breast cancer cell lines and epithelial cell line were subjected to siRNA-mediated knock-down, RT-qPCR, western blot, MTT staining, cell cycle assay, transwell analysis respectively.

RESULTS

We observed the expression of ARHGDIB is significantly higher in human breast cancer tissues compared with the benign tissues. ARHGDIB expression was positively correlated with tumor size, lymph node metastasis and TNM stage in breast cancer patients. Moreover, ARHGDIB depletion decreased proliferation, migration and invasion of breast cancer cells. Furthermore, we found ARHGDIB mediated epithelial-mesenchymal transition, and MMP2 is the key downstream effector of ARHGDIB.

CONCLUSIONS

Hence, our results suggested the significance and predictive role of ARHGDIB in breast cancer. High expression of ARHGDIB indicated the poor prognosis for breast cancer patients.

A Review on the Function and Regulation of ARHGDIB/RhoGDI2 Expression Including the Hypothetical Role of ARHGDIB/RhoGDI2 Autoantibodies in Kidney Transplantation

Challenging and still unsolved problems in kidney transplantation are risk stratification and the treatment of humoral rejection. Antibody-mediated rejection is an important cause of early and chronic rejection. The impact of donor-specific HLA antibodies on antibody-mediated rejection–causing graft damage is well known, but the clinical relevance of non-HLA antibodies remains unclear. Recently, in 2 independent studies, a new correlation was found between the presence of non-HLA anti-Rho guanosine diphosphate dissociation inhibitor 2 (ARHGDIB) antibodies and increased graft failure. RhoGDI2, another name for ARHGDIB, is a negative regulator of the Rho guanosine triphosphate (RhoGTP)ases RhoA, Rac1m, and Cdc42, whose main function is regulating the actin network in a variety of cells. RhoGDI2 is mainly expressed intracellularly, and some expression is observed on the cell surface. Currently, there is no mechanism known to explain this correlation. Additionally, the reason why the antibodies are produced is unknown. In this review, we will address these questions, provide an overview of other diseases in which these antibodies are prevalent, and describe the physiological role of RhoGDI2 itself. If the mechanism and impact of RhoGDI2 antibodies in kidney graft failure are known, improved risk stratification can be provided to decrease the rate of donor kidney graft failure.

Comparative RNA-seq analysis reveals dys-regulation of major canonical pathways in ERG-inducible LNCaP cell progression model of prostate cancer

Prostate Cancer (CaP) is the second leading cause of cancer related death in USA. In human CaP, gene fusion between androgen responsive regulatory elements at the 5'-untranslated region of TMPRSS2 and ETS-related genes (ERG) is present in at least 50% of prostate tumors. Here we have investigated the unique cellular transcriptome associated with over-expression of ERG in ERG-inducible LNCaP cell model system of human CaP. Comprehensive transcriptome analyses reveal a distinct signature that distinguishes ERG dependent and independent CaP in LNCaP cells. Our data highlight a significant heterogeneity among the transcripts. Out of the 526 statistically significant differentially expressed genes, 232 genes are up-regulated and 294 genes are down-regulated in response to ERG. These ERG-associated genes are linked to several major cellular pathways, cell cycle regulation being the most significant. Consistently our data indicate that ERG plays a key role in modulating the expression of genes required for G1 to S phase transition, particularly those that affect cell cycle arrest at G1 phase. Moreover, cell cycle arrest in response to ERG appears to be promoted by induction of p21 in a p53 independent manner. These findings may provide new insights into mechanisms that promote growth and progression of CaP.

Interferon Gamma Inhibits CXCL8-Induced Proliferation and Migration of Pancreatic Cancer BxPC-3 Cell Line via a RhoGDI2/Rac1/NF-κB Signaling Pathway

Interferon gamma (IFN-γ) is a dimeric soluble cytokine and the only type II interferon. Accumulated evidence suggests that IFN-γ inhibits tumor progression. This study investigated the effects of IFN-γ on the proliferation and migration of pancreatic cancer (PC) cells and the underlying mechanism. IFN-γ treatment decreased the expression and secretion of CXCL8 in BxPC-3 PC cells, suppressed the proliferation and migration of these cells, and enhanced their apoptosis, as determined by increased levels of cleaved Caspase-8 and Bax together with reduced expression of Bcl-2. These effects were abolished by overexpression of CXCL8. Moreover, IFN-γ treatment downregulated RhoGDI2 expression. Depletion of RhoGDI2 and Rac1 by using small interfering RNAs and inhibition of NF-κB by BMS-345541 (an IκB kinase [IKK] inhibitor) suppressed expression of CXCL8. Our results indicate that IFN-γ inhibits the proliferation and migration of PC cells by suppressing CXCL8 expression via a RhoGDI2/Rac1/NF-κB signaling pathway.

Increased dermal collagen bundle alignment in systemic sclerosis is associated with a cell migration signature and role of Arhgdib in directed fibroblast migration on aligned ECMs

Systemic sclerosis (SSc) is a devastating disease affecting the skin and internal organs. Dermal fibrosis manifests early and Modified Rodnan Skin Scores (MRSS) correlate with disease progression. Transcriptomics of SSc skin biopsies suggest the role of the in vivo microenvironment in maintaining the pathological myofibroblasts. Therefore, defining the structural changes in dermal collagen in SSc patients could inform our understanding of fibrosis pathogenesis. Here, we report a method for quantitative whole-slide image analysis of dermal collagen from SSc patients, and our findings of more aligned dermal collagen bundles in diffuse cutaneous SSc (dcSSc) patients. Using the bleomycin-induced mouse model of SSc, we identified a distinct high dermal collagen bundle alignment gene signature, characterized by a concerted upregulation in cell migration, adhesion, and guidance pathways, and downregulation of spindle, replication, and cytokinesis pathways. Furthermore, increased bundle alignment induced a cell migration gene signature in fibroblasts in vitro, and these cells demonstrated increased directed migration on aligned ECM fibers that is dependent on expression of Arhgdib (Rho GDP-dissociation inhibitor 2). Our results indicate that increased cell migration is a cellular response to the increased collagen bundle alignment featured in fibrotic skin. Moreover, many of the cell migration genes identified in our study are shared with human SSc skin and may be new targets for therapeutic intervention.

Immunological and Functional Characterization of RhoGDI3 and Its Molecular Targets RhoG and RhoB in Human Pancreatic Cancerous and Normal Cells

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.

Screening and identification of five serum proteins as novel potential biomarkers for cured pulmonary tuberculosis

Rapid and efficient methods for the determination of cured tuberculosis (TB) are lacking. A total of 85 differentially expressed serum proteins were identified by iTRAQ labeling coupled with two-dimensional liquid chromatography-tandem mass spectrometry (2D LC-MS/MS) analysis (fold change >1.50 or <0.60, P < 0.05). We validated albumin (ALB), Rho GDP-dissociation inhibitor 2 (ARHGDIB), complement 3 (C3), ficolin-2 (FCN2), and apolipoprotein (a) (LPA) using the enzyme-linked immunosorbent assay (ELISA) method. Significantly increased ALB and LPA levels (P = 0.036 and P = 0.012, respectively) and significantly reduced ARHGDIB, C3, and FCN2 levels (P < 0.001, P = 0.035, and P = 0.018, respectively) were observed in cured TB patients compared with untreated TB patients. In addition, changes in ALB and FCN2 levels occurred after 2 months of treatment (P < 0.001 and P = 0.030, respectively). We established a cured TB model with 87.10% sensitivity, 79.49% specificity, and an area under the curve (AUC) of 0.876. The results indicated that ALB, ARHGDIB, C3, FCN2, and LPA levels might serve as potential biomarkers for cured TB. Our study provides experimental data for establishing objective indicators of cured TB and also proposes potential markers for evaluating the efficacy of anti-TB drugs.

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.