ARHGAP24 inhibits cell cycle progression, induces apoptosis and suppresses invasion in renal cell carcinoma

Exosome-transmitted circular RNA circ-LMO7 facilitates the progression of osteosarcoma by regulating miR-21-5p/ARHGAP24 axis

The potential function and mechanism of circRNAs in regulating malignant performances of Osteosarcoma (OS) cells have not been well investigated. The expression level of CircLMO7, miR-21-5p and ARHGAP24 were detected by RT-qPCR. The relationship between miR-21-5p and circ-LMO7, as well as between miR-21-5p and ARHGAP24, was predicted and examined through bioinformatics analysis and luciferase reporter gene experiments. Moreover, OS cell growth, invasion, migration, and apoptosis were detected using the cell counting kit-8 (CCK-8), transwell and flow cytometry assays, respectively. ARHGAP24 protein level was measured using western blotting. In present study, we choose to investigate the role and mechanism of circ-LOM7 on OS cell proliferation, migration and invasion. circ-LOM7 was found to be down-regulated in OS tissues and cell lines. Enforced expression of circ-LOM7 suppressed the growth, invasion, and migration of OS cells. In contrast, decreasing circ-LMO7 expression had opposite effects. Furthermore, miR-21-5p was predicted to be sponged by circ-LMO7, and had an opposite role of circ-LMO7 in OS. Moreover, ARHGAP24 served as miR-21-5p's downstream target. Mechanistically, circ-LMO7 was packed in exosomes and acted as a cancer-suppresser on OS by sponging miR-21-5p and upregulating the expression of ARHGAP24. The exosomal circ-LMO7 expression was significantly decreased in OS cell exosomes, and co-culture experiments showed that exosomal circ-LMO7 suppressed the proliferation ability of OS cells. Circ-LMO7 exerts as a tumor suppressor in OS, and the circ-LMO7/miR-21-5P/ARHGAP24 axis is involved in OS progression.

Knockdown of ARHGAP24 reduces intimal hyperplasia through inhibiting the proliferation and phenotypic switching of smooth muscle cells possibly by inactivating both AKT and ERK1/2 signaling pathways

Intimal hyperplasia is one of the common pathophysiological foundations of vascular remodeling including restenosis and atherosclerosis. The Rho GTPase activating protein 24 (ARHGAP24) has been reported as a tumor suppressor in multiple cancers. Nevertheless, the role of ARHGAP24 in intimal hyperplasia is unclear. Interestingly, our results showed that ARHGAP24 was significantly up-regulated in dedifferentiated VSMC in vitro and vivo, which suggested that ARHGAP24 could promote VSMC dedifferentiation and proliferation. Knockdown of ARHGAP24 effectively inhibited VSMC dedifferentiation and proliferation in the absence and present of PDGF-BB, which might inactivate both ATK and ERK1/2 signaling pathways. Moreover, AAV9-mediated silencing of Arhgap24 also alleviates VSMC dedifferentiation and proliferation in the wire-injured mouse femoral arteries, contributing to reducing neointima formation. AAV9-mediated overexpression of Arhgap24 exacerbates intimal hyperplasia. We demonstrate that decreased ARHGAP24 expression restrained VSMC proliferation and dedifferentiation possibly by inactivating both AKT and ERK1/2 signaling pathways, which may provide a potential therapeutic strategy for diseases associated with intimal hyperplasia including restenosis and atherosclerosis.

HAGLR, A Long Non-coding RNA of Potential Tumor Suppressive Function in Clear Cell Renal Cell Carcinoma: Diagnostic and Prognostic Implications

Research works suggested the role of long non-coding RNAs (lncRNAs) in pathogenesis of clear cell renal cell carcinoma (ccRCC). lncRNA HAGLR is studied in several malignancies, but not in ccRCC. From The Cancer Genome Atlas Kidney Renal Clear Cell Carcinoma (TCGA-KIRC) dataset, we analyzed molecular alterations of HAGLR and constructed a competitive endogenous RNA (ceRNA) network with related miRNAs and mRNAs. Gene Ontology analysis was done to identify important pathways enriched with HAGLR recovered mRNAs. Clinical importance of HAGLR and related mRNAs was assessed and, the impact of selected mRNA-encoding genes on tumor immune infiltration was studied using TIMER. HAGLR expression was reduced in ccRCC than in normal kidneys, and correlated significantly with gene promoter methylation. Low HAGLR level in tumors showed diagnostic potency, and was associated with clinicopathological parameters (stage/grade/metastasis) and poor patient survival. The HAGLR-associated ceRNA network constituted 13 miRNAs and 23 mRNAs differentially expressed in the TCGA-KIRC dataset. From HAGLR recovered mRNA-encoding genes, we developed a 5-gene (PAQR5, ARHGAP24, HABP4, PDLIM5, and RPS6KA2) prognostic signature in the training dataset and validated it in testing as well as entire datasets. The expression level of signature genes showed negative correlation with tumor infiltration of immune cells having adverse impact on ccRCC prognosis and also with tumor derived chemokines facilitating the infiltration. In conclusion, HAGLR seemed to play a tumor suppressive role in ccRCC. HAGLR and associated gene signature may have implementation in improving existing prognostic measure and developing effective immunotherapeutic strategies for ccRCC.

ARHGAP11A Is a Novel Prognostic and Predictive Biomarker Correlated with Immunosuppressive Microenvironment in Clear Cell Renal Cell Carcinoma

Clear cell renal cell carcinoma (ccRCC) is a highly immunogenic tumor and immune dysfunction is associated with ccRCC poor prognosis. The RhoGTPase-activating proteins (RhoGAPs) family was reported to affect ccRCC development, but its role in immunity and prognosis prediction for ccRCC remain unknown. In the current study, we found ARHGAP11A was the only independent risk factor among 33 RhoGAPs (hazard ratio [HR] 1.949, 95% confidence interval [CI] 1.364-2.785). High ARHGAP11A level was associated with shorter overall survival (OS, HR 2.040, 95% CI 1.646-3.417) and ARHGAP11A is a prognostic biomarker for ccRCC. ARHGAP11A knockdown suppressed renal cell carcinoma (RCC) cell proliferation, colony formation, and migration, suggesting the promoting role of ARHGAP11A on RCC development. Mechanistically, ARHGAP11A might contribute to the suppressive tumor immune microenvironment (TIME). High ARHGAP11A level was correlated with infiltration of immunosuppressive cells (including T helper 2 (Th2) cells, regulatory T (Treg) cells, myeloid derived suppressor cells (MDSC), and M2 macrophage cells), activation of immunosuppressive pathways (IL6-JAK-STAT3 signaling and IFNγ response), and expression of inhibitory immune checkpoints (ICs). ARHGAP11A could promote T cell exhaustion and induce immune escape. ccRCC patients with low ARHGAP11A level were more suitable for immune checkpoint inhibitors (ICIs) therapy, while those with high ARHGAP11A level might benefit from a combination of ARHGAP11A blockade and ICIs. In all, ARHGAP11A might serve as a novel prognostic marker, therapeutic target, and predictor in the clinical response to ICIs therapy for ccRCC.

Ras superfamily GTPase activating proteins in cancer: Potential therapeutic targets?

To search more therapeutic strategies for Ras-mutant tumors, regulators of the Ras superfamily involved in the GTP/GDP (guanosine triphosphate/guanosine diphosphate) cycle have been well concerned for their anti-tumor potentials. GTPase activating proteins (GAPs) provide the catalytic group necessary for the hydrolysis of GTPs, which accelerate the switch by cycling between GTP-bound active and GDP-bound inactive forms. Inactivated GAPs lose their function in activating GTPase, leading to the continuous activation of downstream signaling pathways, uncontrolled cell proliferation, and eventually carcinogenesis. A growing number of evidence has shown the close link between GAPs and human tumors, and as a result, GAPs are believed as potential anti-tumor targets. The present review mainly summarizes the critically important role of GAPs in human tumors by introducing the classification, function and regulatory mechanism. Moreover, we comprehensively describe the relationship between dysregulated GAPs and the certain type of tumor. Finally, the current status, research progress, and clinical value of GAPs as therapeutic targets are also discussed, as well as the challenges and future direction in the cancer therapy.

RELA-induced MiR-21 Exerts Oncogenic Effects on PDAC via Targeting of ARHGAP24

Inflammation is one of the inducing factors of pancreatic ductal adenocarcinoma (PDAC), and microRNAs have been confirmed to be involved in the occurrence and development of PDAC. However, whether RELA, an inflammatory regulator, is involved in the regulation of PDAC by miRNA remains to be further studied. In the present study miR-21 was characterized and its upstream regulatory mechanism was investigated, as well as its functional effects and target genes in pancreatic ductal adenocarcinoma (PDAC). In situ hybridization analysis confirmed increased miR-21 expression levels in PDAC tissues. The results of the chromatin immunoprecipitation and dual-luciferase reporter assays demonstrated that transcription factor RELA modulated miR-21 transcription in the PDAC, PANC-1 and MIA PaCa-2 cell lines. Subsequently, a cell viability assay, EdU staining assay and flow cytometry analysis, demonstrated that miR-21 promoted cell proliferation and cell cycle progression, but inhibited cell apoptosis in vitro. Furthermore, a xenograft assay demonstrated that miR-21 accelerated tumor growth in vivo. Mechanistically, miR-21 directly regulated the expression of Rho GTPase activating protein 24 (ARHGAP24), which was indicated to be a tumor suppressor gene. Moreover, both miR-21 and ARHGAP24 were strongly associated with clinical features and may therefore serve as valuable biomarkers in PDAC prognosis.

miR-21-5p serves as a promoter in renal cell carcinoma progression through ARHGAP24 downregulation

Renal cell carcinoma (RCC) is a highly recurrent aggressive tumor. This study works for the regulation of miR-21-5p on RCC cell functions and novel ideas for therapies of RCC. Isoform expression quantification data were offered by The Cancer Genome Atlas Kidney Renal Clear Cell Carcinoma (TCGA-KIRC) to investigate differentially expressed miRNAs. The way miR-21-5p works on biological functions of RCC was examined with MTT and Transwell assays. The downstream targets of miR-21-5p were predicted using bioinformatics analysis. The binding of two researched objects was verified by the dual-luciferase method. TCGA data manifested a considerably high level of miR-21-5p in RCC tissue, while ARHGAP24 was significantly lowly expressed. miR-21-5p bound ARHGAP24 and stimulated RCC cell functions, whereas ARHGAP24 mimic could reverse such promotion. This work observed miR-21-5p, a stimulator in RCC, and it deteriorated this cancer via repressing its downstream target gene ARHGAP24 expression.

E6/E7 from Beta-2-HPVs 122, 38b, and 107 possess transforming properties in a fibroblast model in vitro

Beta-2 Human papillomaviruses 38b, 107, and 122 have been frequently found in cervical cancer samples in western Mexico. Because their E6/E7 genes functions are not fully elucidated, we deepen into their transformation capabilities. To achieve this goal, primary human fibroblasts (FB) were transduced with E6/E7 genotype-specific viral particles. Additionally, E6/E7 from HPVs 16 and 18 were included as controls. All E6/E7-cell models increased their lifespan; however, it is important to highlight that FB-E6/E7-122 showed growth as accelerated as FB-E6/E7-16 and 18. Furthermore, both FB-E6/E7-38b and 122 exhibited abilities to migrate, and FB-E6/E7-122 presented high invasive capacity. On the other hand, ΔNp73 expression was found in all cell models, except for FB-pLVX (empty-vector). Finally, RNAseq found differentially expressed genes enriched in signaling pathways related to cell cycle, epithelial-mesenchymal transition, and cancer, among others. This study shows for the first time, the great transformative potential that genotypes of the Beta-2 also possess, especially HPV122. These Beta-2 HPVs can modulate some of the genes that are well known to be regulated by Alpha-HPVs, however, they also possess alternative strategies to modulate diverse signaling pathways. These data support the idea that Beta-2 HPVs should play an important role in co-infections with Alpha-HPV during carcinogenesis.

The emerging roles of srGAPs in cancer

GTPase activating proteins (GAPs) were initially considered as the inhibitors of cell signaling pathways because of their nature to activate the intrinsic GTPase activity of the RhoGTPases. But recent studies of dysregulated GAPs in many cancers such as glioblastoma, colorectal cancer, breast cancer, and renal cancer have elucidated the important roles of GAPs in carcinogenesis and GAPs have been shown to perform multiple nonconventional functions in different contexts. We have discussed the recent developments in the roles played by different types of srGAPs (SLIT-ROBO Rho GTPase-activating proteins) in cancer.

CdGAP promotes prostate cancer metastasis by regulating epithelial-to-mesenchymal transition, cell cycle progression, and apoptosis

High mortality of prostate cancer patients is primarily due to metastasis. Understanding the mechanisms controlling metastatic processes remains essential to develop novel therapies designed to prevent the progression from localized disease to metastasis. CdGAP plays important roles in the control of cell adhesion, migration, and proliferation, which are central to cancer progression. Here we show that elevated CdGAP expression is associated with early biochemical recurrence and bone metastasis in prostate cancer patients. Knockdown of CdGAP in metastatic castration-resistant prostate cancer (CRPC) PC-3 and 22Rv1 cells reduces cell motility, invasion, and proliferation while inducing apoptosis in CdGAP-depleted PC-3 cells. Conversely, overexpression of CdGAP in DU-145, 22Rv1, and LNCaP cells increases cell migration and invasion. Using global gene expression approaches, we found that CdGAP regulates the expression of genes involved in epithelial-to-mesenchymal transition, apoptosis and cell cycle progression. Subcutaneous injection of CdGAP-depleted PC-3 cells into mice shows a delayed tumor initiation and attenuated tumor growth. Orthotopic injection of CdGAP-depleted PC-3 cells reduces distant metastasic burden. Collectively, these findings support a pro-oncogenic role of CdGAP in prostate tumorigenesis and unveil CdGAP as a potential biomarker and target for prostate cancer treatments.

Mehra et al. investigate the role of CdGAP in early biochemical recurrence and bone metastasis in prostate cancer. The authors find that knocking down CdGAP leads to reduced cell motility, invasion and proliferation in PC-3 and 22Rv1 cells while orthotopic injection of CdGAP-depleted PC-3 cells reduces distant metastatic burden.

miR-21-5p Regulates the Proliferation and Differentiation of Skeletal Muscle Satellite Cells by Targeting KLF3 in Chicken

The proliferation and differentiation of skeletal muscle satellite cells (SMSCs) play an important role in the development of skeletal muscle. Our previous sequencing data showed that miR-21-5p is one of the most abundant miRNAs in chicken skeletal muscle. Therefore, in this study, the spatiotemporal expression of miR-21-5p and its effects on skeletal muscle development of chickens were explored using in vitro cultured SMSCs as a model. The results in this study showed that miR-21-5p was highly expressed in the skeletal muscle of chickens. The overexpression of miR-21-5p promoted the proliferation of SMSCs as evidenced by increased cell viability, increased cell number in the proliferative phase, and increased mRNA and protein expression of proliferation markers including PCNA, CDK2, and CCND1. Moreover, it was revealed that miR-21-5p promotes the formation of myotubes by modulating the expression of myogenic markers including MyoG, MyoD, and MyHC, whereas knockdown of miR-21-5p showed the opposite result. Gene prediction and dual fluorescence analysis confirmed that KLF3 was one of the direct target genes of miR-21-5p. We confirmed that, contrary to the function of miR-21-5p, KLF3 plays a negative role in the proliferation and differentiation of SMSCs. Si-KLF3 promotes cell number and proliferation activity, as well as the cell differentiation processes. Our results demonstrated that miR-21-5p promotes the proliferation and differentiation of SMSCs by targeting KLF3. Collectively, the results obtained in this study laid a foundation for exploring the mechanism through which miR-21-5p regulates SMSCs.

ARHGAP25 Inhibits Pancreatic Adenocarcinoma Growth by Suppressing Glycolysis via AKT/mTOR Pathway

Increasing evidence reveals that the Rho GTPase-activating protein is a crucial negative regulator of Rho family GTPase involved in tumorigenesis. The Rho GTPase-activating protein 25 (ARHGAP25) has been shown to specifically inactivate the Rho family GTPase Rac1, which plays an important role in pancreatic adenocarcinoma (PAAD) progression. Therefore, here we aimed to clarify the expression and functional role of ARHGAP25 in PAAD. The ARHGAP25 expression was lower in PAAD tissues than that in normal pancreatic tissues based on bioinformatics analysis and immunohistochemistry staining. Overexpression of ARHGAP25 inhibited cell growth of AsPC-1 human pancreatic cancer cells in vitro, while opposite results were observed in BxPC-3 human pancreatic cancer cells with ARHGAP25 knockdown. Consistently, in vivo tumorigenicity assays also confirmed that ARHGAP25 overexpression suppressed tumor growth. Mechanically, overexpression of ARHGAP25 inactivated AKT/mTOR signaling pathway by regulating Rac1/PAK1 signaling, which was in line with the results from the Gene set enrichment analysis on The Cancer Genome Atlas dataset. Furthermore, we found that ARHGAP25 reduced HIF-1α-mediated glycolysis in PAAD cells. Treatment with PF-04691502, a dual PI3K/mTOR inhibitor, hampered the increased cell growth and glycolysis due to ARHGAP25 knockdown in PAAD cells. Altogether, these results conclude that ARHGAP25 acts as a tumor suppressor by inhibiting the AKT/mTOR signaling pathway, which might provide a therapeutic target for PAAD.

FilGAP, a GAP protein for Rac, regulates front-rear polarity and tumor cell migration through the ECM

Migrating tumor cells are characterized by a sustained front-rear asymmetry, with a front enriched in filamentous actin, which is induced by Rho small GTPase Rac. Regulation of Rac activity by its regulators should be required for effective motility. Here, we show that FilGAP, a GTPase-activating protein (GAP) for Rac, controls front-rear polarity and contributes to maintain effective tumor cell migration through the extracellular matrix (ECM). Overexpression of FilGAP in breast cancer cells induced polarized morphology and led to increased migration speed in collagen matrices, while depletion of FilGAP impaired the cell polarity and migration. FilGAP localizes to the cell front through its pleckstrin-homology (PH) domain in a phosphatidylinositol 3,4,5-trisphosphate (PIP3)-dependent manner and appears to inactivate Rac at its site. We found that the affinity of PH domain to PIP3 is critically involved in the maintenance of cell polarity. Moreover, small GTPase ADP-ribosylation factor 6 (Arf6), which binds to the FilGAP PH domain, also regulates FilGAP-mediated cell polarity and migration of breast cancer cells. We propose that FilGAP regulates front-rear polarity through its PIP3 and Arf6 binding in tumor cell migration through the ECM.

ARHGAP24 ameliorates inflammatory response through inactivating Rac1/Akt/NF-κB pathway in acute pneumonia model of rat

Background

ARHGAP24 might play a protective effect in the development of acute pneumonia, but the underlying mechanism remained a mystery. We aimed to investigate the effect of ARHGAP24 and explore the protective mechanism based on the acute pneumonia model of rats.

Methods

Western blotting analysis was conducted to measure the expression of ARHGAP24 in the rat model of bacillus pyocyaneus-induced acute pneumonia after 12, 24, 36, and 48 h modeling. In the acute pneumonia model of rat, lung histopathological change, lung edema, and levels of inflammatory cytokines in the broncho alveolar lavage fluid (BALF) were respectively measured to comprehensively evaluate the beneficial effect of overexpression of ARHGAP24 mediated by adenovirus. The western blotting analysis was conducted to evaluate Rac1/Akt/NF-κB pathway-related protein expression change with ARHGAP24 overexpression.

Results

We found that ARHGAP24 expression tended to be lower in the acute pneumonia model of the rat after bacillus pyocyaneus treated 12, 24, 36, and 48 h. High expression of ARHGAP24 and a substantial ARHGAP24 positive area was found in the western blotting analysis and immunohistochemical staining in rats transfected with ARHGAP24. In the meantime, overexpression of ARHGAP24 suppressed the development of acute pneumonia through alleviating lung histopathological deterioration, lung edema, and levels of inflammatory cytokines in the BALF of the lung. What is more critical, ARHGAP24 overexpression inhibits the activation of Rac1, Akt, and NF-κB.

Conclusions

Thus, we conclude that ARHGAP24 ameliorated the inflammatory response in the acute pneumonia model of the rat through inactivating the Rac1/Akt/NF-κB pathway.

ARHGAP24 inhibits cell proliferation and cell cycle progression and induces apoptosis of lung cancer via a STAT6-WWP2-p27 axis

Rho GTPase-activating proteins (RhoGAPs) have been reported to be of great importance in the initiation and development of many different cancers. However, their biological roles and regulatory mechanisms in lung cancer development and progression are poorly defined. Real-time PCR or western blotting analysis was used to detect Rho GTPase-activating protein 24 (ARHGAP24), WWP2, p27, p-STAT6 and STAT6 expression levels as well as the activity of RhoA and Rac1 in lung cancer. Cell proliferation, apoptosis and cell cycle were measured by CCK-8 and flow cytometry analysis. Tumor growth of lung cancer cells was measured using a nude mouse xenograft experiment model in vivo. The correlation between WWP2 and p27 was measured by co-immunoprecipitation and ubiquitination analysis. We found that ARHGAP24 expression was lower in lung cancer tissues collected from the The Cancer Genome Atlas and independent hospital database. Overexpression of ARHGAP24 significantly suppressed cell proliferation and the activity of RhoA and Rac1, induced cell apoptosis and arrested cell cycle at the G₀–G₁ phase. ARHGAP24 overexpression also inhibited tumor growth in nude mice, whereas knockdown of ARHGAP24 significantly promoted cell proliferation and WWP2 expression and inhibited cell cycle arrest at G₁ phase through activating STAT6 signaling. ARHGAP24 overexpression inhibited WWP2 overexpression-induced cell proliferation, cell cycle progression and the decreased p27 expression. Moreover, WWP2 was found interacted with p27, and WWP2 overexpression promoted the ubiquitination of p27. In conclusion, our findings suggest that ARHGAP24 inhibits cell proliferation and cell cycle progression and induces cell apoptosis of lung cancer via a STAT6-WWP2-p27 axis.

HOTAIRM1 suppresses cell proliferation and invasion in ovarian cancer through facilitating ARHGAP24 expression by sponging miR-106a-5p

AIMS

Ovarian cancer (OC) is the most lethal gynecologic malignant tumors all over the world. HOX antisense intergenic RNA myeloid 1 (HOTAIRM1) has been reported as an important regulator in multiple tumors. However, the functions of HOTAIRM1 in OC and its possible molecular mechanisms remain unclear.

MAIN METHODS

qRT-PCR analysis was performed to detect the expression levels of HOTAIRM1, miR-106a-5p and ARHGAP24 mRNA in OC tissues and cells. The functional effects of HOTAIRM1, miR-106a-5p and ARHGAP24 on OC cells were determined by MTT, colony formation, flow cytometry and Transwell assays. Luciferase reporter, RIP and RNA pull-down assays were used to examine the interaction between miR-106a-5p and HOTAIRM1 or ARHGAP24. Tumor xenografts were constructed in nude mice to confirm the roles of HOTAIRM1 in OC in vivo.

KEY FINDINGS

HOTAIRM1 expression was lowered in OC tumor tissues and cells. Decreased HOTAIRM1 expression was associated with advanced FIGO stages and lymphatic metastasis. Up-regulation of HOTAIRM1 suppressed OC cell proliferation and invasion, and promoted apoptosis. Also, HOTAIRM1 slowed OC tumor growth in vivo. Moreover, HOTAIRM1 could serve as a competing endogenous RNA (ceRNA) of miR-106a-5p to derepress ARHGAP24 expression. HOTAIRM1-mediated inhibitory effect on OC progression was partly reversed following the restoration of miR-106a-5p expression. Furthermore, ARHGAP24 overexpression repressed OC progression in vitro.

SIGNIFICANCE

In conclusion, our study showed that HOTAIRM1 suppressed OC progression through derepression of ARHGAP24 by sponging miR-106a-5p. This finding provides novel insights into the mechanisms of HOTAIRM1 in OC and highlights a potential therapeutic strategy for the treatment of OC.

ARHGAP4 mediates the Warburg effect in pancreatic cancer through the mTOR and HIF-1α signaling pathways

Objective

The phenomenon that cancer cells avidly exhibit glycolysis with lactate secretion and decrease in mitochondrial activity under aerobic conditions is known historically as the Warburg effect. Rho GTPase-activating protein 4 (ARHGAP4) is an important negative regulator of the Rho signaling pathway that was associated with the tumorigenesis. Our study aims to determine the function of ARHGAP4 in controlling the glycolytic process of pancreatic cancer in vitro and possible molecular mechanism involved.

Methods

ARHGAP4 and PKM2 expressions in pancreatic cancer tissues were measured by immunohistochemistry. Human pancreatic cancer cells transfected with ARHGAP4 expressing lentivirus or siRNA were treated with either mTOR inhibitor (Rapamycin) or HIF-1α inhibitor (YC-1), and the effects were analyzed on cell viability, glucose uptake, lactate release, and the levels of ARHGAP4, p-mTOR, mTOR, PKM2, and HIF-1α expression.

Results

Our findings showed that ARHGAP4 and PKM2 expressions were, respectively, down-regulated and up-regulated in pancreatic cancer tissues. Overexpression of ARHGAP4 significantly inhibited cell viability, glucose uptake, lactate release, PKM2 expression, and activation of mTOR and HIF-1α signaling pathways in pancreatic cancer cells while ARHGAP4 silencing and treatment of Rapamycin or YC-1 showed inverse effects. Additionally, ARHGAP4 downregulation induced cell morphology of pancreatic cancer was inhibited by Rapamycin or YC-1 treatment.

Conclusion

These findings suggest that mTOR and HIF-1α signaling pathways can regulate the ARHGAP4-mediated glycolytic process of pancreatic cancer.

NDNF inhibits the migration and invasion of human renal cancer cells through epithelial-mesenchymal transition

Neuron-derived neurotrophic factor (NDNF) is a glycosylated, disulfide-bonded secretory protein that contains a fibronectin type III domain. NDNF has been identified as a neurotrophic factor; however, its role in carcinogenesis has not yet been identified. To investigate the expression and role of NDNF in carcinogenesis, the expression of NDNF in human Renal cell carcinoma (RCC) cell lines and tissues was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis. Cell proliferation was investigated using CCK-8 and colony formation assays, and the cell invasion and immigration capacity was evaluated using the transwell assay. The results demonstrated that NDNF expression was downregulated in RCC cell lines and RCC tissues. Restoring NDNF expression significantly inhibited the proliferation, migration and invasion of RCC cells. The study also demonstrated that the inhibitory effect of NDNF on invasive ability was mediated by suppressing the epithelial-mesenchymal transition (EMT) in RCC cells. NDNF may therefore be considered an important regulator of EMT in RCC progression and may represent a novel promising target for antimetastatic therapy.

Rho GTPase Activating Protein 24 (ARHGAP24) Silencing Promotes Lung Cancer Cell Migration and Invasion by Activating β-Catenin Signaling

BACKGROUND Rho GTPase activating protein (RhoGAPs) is an important negative regulator of the Rho signaling pathway that is involved in tumorigenesis in liver, colon, and renal cancer. However, the mechanism by which Rho GTPase activating protein 24 (ARHGAP24) regulates cell invasion and migration of lung cancer has not been fully explained. MATERIAL AND METHODS In this study, ARHGAP24 expression in lung cancer tissues and cell lines was measured by immunohistochemical and Western blot analysis. Transwell or wound healing analysis was performed to detect the cell migration and invasion of ARHGAP24 modulated A549 and NCI-H1975 cells with β-catenin inhibitor XAV-939 (10 µM) treatment, and the expression of MMP9, VEGF, and β-catenin protein was measured by Western blotting. RESULTS Our results showed that ARHGAP24 expression was downregulated in lung cancer tissues and cell lines. pLVX-Puro-ARHGAP24 transfection in A549 cells significantly inhibited cell invasion and migration, along with increased E-cadherin and decreased MMP9, VEGF, Vimentin, and β-catenin protein expression. pLKO.1-ARHGAP24-shRNA transfection in NCI-H1975 cells significantly promoted cell invasion and migration, accompanied with decreased E-cadherin and increased MMP9, VEGF, and β-catenin protein expression. Moreover, NCI-H1975 cells with XAV-939 treatment showed decreased cell invasion and migration when compared with pLKO.1-ARHGAP24-shRNA transfection. ARHGAP24 silencing promoted the transcriptional activity of β-catenin in NCI-H1975 cells. CONCLUSIONS Our findings indicate that ARHGAP24 silencing promotes lung cancer cell migration and invasion through activating β-catenin signaling.

Blockade of ARHGAP11A reverses malignant progress via inactivating Rac1B in hepatocellular carcinoma

Background

The molecular signaling events involving in high malignancy and poor prognosis of hepatocellular carcinoma (HCC) are extremely complicated. Blockade of currently known targets has not yet led to successful clinical outcome. More understanding about the regulatory mechanisms in HCC is necessary for developing new effective therapeutic strategies for HCC patients.

Methods

The expression of Rho GTPase-activating protein 11A (ARHGAP11A) was examined in human normal liver and HCC tissues. The correlations between ARHGAP11A expression and clinicopathological stage or prognosis in HCC patients were analyzed. ARHGAP11A was downregulated to determine its role in the proliferation, invasion, migration, epithelial-to-mesenchymal transition (EMT) development, and regulatory signaling of HCC cells in vitro and in vivo.

Results

ARHGAP11A exhibited high expression in HCC, and was significantly correlated with clinicopathological stage and prognosis in HCC patients. Moreover, ARHGAP11A facilitated Hep3B and MHCC97-H cell proliferation, invasion, migration and EMT development in vitro. ARHGAP11A knockdown significantly inhibited the in vivo growth and metastasis of HCC cells. Furthermore, ARHGAP11A directly interacted with Rac1B independent of Rho GTPase- activating activity. Rac1B blockade effectively interrupted ARHGAP11A-elicited HCC malignant phenotype. Meanwhile, upregulation of Rac1B reversed ARHGAP11A knockdown mediated mesenchymal-to-epithelial transition (MET) development in HCC cells.

Conclusion

ARHGAP11A facilitates malignant progression in HCC patients via ARHGAP11A-Rac1B interaction. The ARHGAP11A/Rac1B signaling could be a potential therapeutic target in the clinical treatment of HCC.

Electronic supplementary material

The online version of this article (10.1186/s12964-018-0312-4) contains supplementary material, which is available to authorized users.

Rho GTPase Activating Protein 24 (ARHGAP24) Regulates the Anti-Cancer Activity of Sorafenib Against Breast Cancer MDA-MB-231 Cells via the Signal Transducer and Activator of Transcription 3 (STAT3) Signaling Pathway

BACKGROUND STAT3 has emerged as a novel potential target for sorafenib, a multikinase inhibitor, in the context of cancer therapy. ARHGAP24 is a Rac-specific Rho GTPase-activating protein (Rho GAP), which can convert Rho GTPases to an inactive state. It has been proved to be an oncosuppressor protein in renal cancer. In the present study, we investigated its anti-cancer effect in breast cancer (BC). MATERIAL AND METHODS Quantitative real-time PCR (qRT-PCR) and Western blot analysis were performed to detect the expression of ARHGAP24 in clinical tissue samples. Then, BC MDA-MB-231 cells were virally transduced with ARHGAP24 silencing or overexpression lentiviral vectors in the absence or presence of sorafenib. Cell viability and metastatic ability were evaluated by using the Cell Counting Kit-8 (CCK-8) and Transwell assays. Proteins belonging to the STAT3 pathway were detected by Western blot. RESULTS ARHGAP24 decreased in BC tissues compared with the adjacent normal tissues. Forced expression of ARHGAP24 and sorafenib treatment significantly suppressed the viability, migration, and invasion of MDA-MB-231 cells. Conversely, elimination of the endogenous ARHGAP24 with shRNA promoted cell viability, migration, and invasion. The phosphorylation of STAT3 and the expression of MMP-2 and MMP-9 were attenuated by ARHGAP24 ectopic expression and sorafenib treatment. Furthermore, forced expression of ARHGAP24 significantly enhanced sorafenib-induced decrease of cell viability, migration, and invasion of MDA-MB-231 cells, while elimination of the endogenous ARHGAP24 with shRNA inhibited it. CONCLUSIONS ARHGAP24 can suppress the development of MDA-MB-231 cells via the STAT3 signaling pathway, and sorafenib inhibits cell viability, migration, invasion, and STAT3 activation in MDA-MB-231 cells through ARHGAP24.

Ginsenoside Rg3 inhibits the migration and invasion of liver cancer cells by increasing the protein expression of ARHGAP9

Ginsenoside Rg3, a naturally occurring phytochemical, serves an important role in the prevention and treatment of cancer. In the present study, with the aim to reveal the molecular mechanism of Rg3 in liver cancer cell metastasis, the anti-migration and anti-invasion effects of Rg3 on liver cancer cells were investigated. It was demonstrated that Rg3 caused marked inhibition of cell migration and invasion of human liver cancer cells, HepG2 and MHCC-97L, in vitro, and the growth of HepG2 and MHCC-97L tumors in BABL/c nude mice. The protein expression of Rho GTPase activating protein 9 (ARHGAP9) was increased both in HepG2 and MHCC-97L cells. Following ARHGAP9 knockdown, the results of Transwell and tumorigenesis assays revealed that the anti-migration, anti-invasion and anti-tumor growth effects of Rg3 were impaired significantly. The increased expression of ARHGAP9 protein induced by Rg3 was remarkably suppressed. All results suggested that ARHGAP9 protein may be a vital regulator in the anti-metastatic role of Rg3. To the best of our knowledge, the present study is the first to report that Rg3 effectively suppressed the migration and invasion of liver cancer cells by upregulating the protein expression of ARHGAP9, indicating a novel natural therapeutic agent and a therapeutic target for the treatment of liver cancer.

Validation of Osteogenic Properties of Cytochalasin D by High-Resolution RNA-Sequencing in Mesenchymal Stem Cells Derived from Bone Marrow and Adipose Tissues

Differentiation of mesenchymal stromal/stem cells (MSCs) involves a series of molecular signals and gene transcription events required for attaining cell lineage commitment. Modulation of the actin cytoskeleton using cytochalasin D (CytoD) drives osteogenesis at early timepoints in bone marrow-derived MSCs and also initiates a robust osteogenic differentiation program in adipose tissue-derived MSCs. To understand the molecular basis for these pronounced effects on osteogenic differentiation, we investigated global changes in gene expression in CytoD-treated murine and human MSCs by high-resolution RNA-sequencing (RNA-seq) analysis. A three-way bioinformatic comparison between human adipose tissue-derived MSCs (hAMSCs), human bone marrow-derived MSCs (hBMSCs), and mouse bone marrow-derived MSCs (mBMSCs) revealed significant upregulation of genes linked to extracellular matrix organization, cell adhesion and bone metabolism. As anticipated, the activation of these differentiation-related genes is accompanied by a downregulation of nuclear and cell cycle-related genes presumably reflecting cytostatic effects of CytoD. We also identified eight novel CytoD activated genes-VGLL4, ARHGAP24, KLHL24, RCBTB2, BDH2, SCARF2, ACAD10, HEPH-which are commonly upregulated across the two species and tissue sources of our MSC samples. We selected the Hippo pathway-related VGLL4 gene, which encodes the transcriptional co-factor Vestigial-like 4, for further study because this pathway is linked to osteogenesis. VGLL4 small interfering RNA depletion reduces mineralization of hAMSCs during CytoD-induced osteogenic differentiation. Together, our RNA-seq analyses suggest that while the stimulatory effects of CytoD on osteogenesis are pleiotropic and depend on the biological state of the cell type, a small group of genes including VGLL4 may contribute to MSC commitment toward the bone lineage.

ARHGAP24 regulates cell ability and apoptosis of colorectal cancer cells via the regulation of P53

Colorectal cancer is a human malignancy ranked the third highest of the global incidence of malignant tumors. Rho GTPase-activating proteins (RHOGAPs) were identified functional in several processes of tumors. In the present study, through reverse transcription-quantitative PCR (RT-qPCR) and western blot analysis, expression of Rho GTPase-activating protein 24 (ARHGAP24) and p53 was measured in colorectal cancer tissues, which was lower than that in adjacent normal tissues, revealing that ARHGAP24 may be implicated in the progress of colorectal cancer and in vitro, overexpression of ARHGAP24 in LoVo and HCT116 cells inhibited the cell ability and enhanced cell apoptosis, and accompanied with high protein expression of p53, p21 and Bax. Further, addition of p53 inhibitor PFT-α had an antagonistic effect on cell proliferation and apoptosis of LoVo and HCT116 cells induced by ARHGAP24 overexpression. In addition, the expression of p21 and Bax was positively correlated with p53 expression. All of the above data demonstrated that ARHGAP24 was likely to be a tumor suppressor in colorectal cancer and may function closely related to p53, p21 and Bax. We inferred that ARHGAP24 may be a novel target for in-depth study of colorectal cancer.

MicroRNA-590-5p regulates cell viability, apoptosis, migration and invasion of renal cell carcinoma cell lines through targeting ARHGAP24

Renal cell carcinoma (RCC) is the leading cause of death in renal malignancies. MicroRNA-590-5p (miR-590-5p) is of great importance in the processes of many cancers regarding regulation of cancer cell invasion and proliferation. In our study, alternation of miR-590-5p expression in RCC cell lines through transfection with pre-miR-590-5p (up-regulation) or anti-miR-590-5p (down-regulation) was performed. Apoptosis and viability of RCC cell lines were measured by flow cytometry and CCK-8 analysis, respectively. Cell invasion and migration were estimated by Transwell assay. The association of miR-590-5p with ARHGAP24 expression was evaluated using luciferase assays, real-time PCR and western blot assay. The expressions of apoptosis and migration-related protein were also measured by western blotting. We found that pre-miR-590-5p transfection in Caki-2 and 786-O cells showed significant increases in cell viability, invasion and migration, which were accompanied by decreased cell apoptosis, while anti-miR-590-5p transfection obviously inhibited the cell viability, migration and invasion of Caki-2 and 786-O cells as well as induced apoptosis, compared with the negative control group. Furthermore, bioinformatics combined with luciferase reporter assays indicated that ARHGAP24 is directly targeted by miR-590-5p. ARHGAP24 overexpression in 786-O and Caki-2 cells phenocopied the effects of anti-miR-590-5p transfection along with enhanced expression of active Caspase-3 and Bax/Bcl-2 ratio as well as decreased expression of MMP-2 and MMP-9. These findings suggested that miR-590-5p/ARHGAP24 seems to function as a potentially beneficial target for RCC treatment.

Brief Overview of a Decade of Genome-Wide Association Studies on Primary Hypertension

Primary hypertension is widely believed to be a complex polygenic disorder with the manifestation influenced by the interactions of genomic and environmental factors making identification of susceptibility genes a major challenge. With major advancement in high-throughput genotyping technology, genome-wide association study (GWAS) has become a powerful tool for researchers studying genetically complex diseases. GWASs work through revealing links between DNA sequence variation and a disease or trait with biomedical importance. The human genome is a very long DNA sequence which consists of billions of nucleotides arranged in a unique way. A single base-pair change in the DNA sequence is known as a single nucleotide polymorphism (SNP). With the help of modern genotyping techniques such as chip-based genotyping arrays, thousands of SNPs can be genotyped easily. Large-scale GWASs, in which more than half a million of common SNPs are genotyped and analyzed for disease association in hundreds of thousands of cases and controls, have been broadly successful in identifying SNPs associated with heart diseases, diabetes, autoimmune diseases, and psychiatric disorders. It is however still debatable whether GWAS is the best approach for hypertension. The following is a brief overview on the outcomes of a decade of GWASs on primary hypertension.

Gene expression profiling of brain metastatic cell from triple negative breast cancer: Understanding the molecular events

Brain metastatic triple negative breast cancer (BM-TNBC) is afflicted with unfavorable prognosis. However, the molecular events underlying BM-TNBC remain largely unknown. In the present study, we conducted gene expression microarray analysis using the triple negative breast cancer cell line MDA-MB-231 and its brain metastatic derivative (MDA-MB-231Brm). Results of microarray analysis showed that a total of 4296 genes were differentially expressed, of which 2433 genes were up-regulated and 1863 genes were down-regulated. Gene Ontology (GO), KEGG pathway and protein-protein interaction (PPI) analyses indicated differentially expressed genes functionally categorized as genes of signal transduction, multicellular organismal development, ion transport, nervous system development, plasma membrane, extracellular region, calcium ion binding, GTP binding neuroactive ligand-receptor interaction. The validity of the microarray results was verified by quantitative real-time PCR analysis of twelve representative genes. The present findings revealed molecular basis and events associated with brain metastasis in TNBC, which will potentially contribute to the understanding of underlying mechanism and develop therapeutic targets.

The Rac GTPase in Cancer: From Old Concepts to New Paradigms

Rho family GTPases are critical regulators of cellular functions that play important roles in cancer progression. Aberrant activity of Rho small G-proteins, particularly Rac1 and their regulators, is a hallmark of cancer and contributes to the tumorigenic and metastatic phenotypes of cancer cells. This review examines the multiple mechanisms leading to Rac1 hyperactivation, particularly focusing on emerging paradigms that involve gain-of-function mutations in Rac and guanine nucleotide exchange factors, defects in Rac1 degradation, and mislocalization of Rac signaling components. The unexpected pro-oncogenic functions of Rac GTPase-activating proteins also challenged the dogma that these negative Rac regulators solely act as tumor suppressors. The potential contribution of Rac hyperactivation to resistance to anticancer agents, including targeted therapies, as well as to the suppression of antitumor immune response, highlights the critical need to develop therapeutic strategies to target the Rac pathway in a clinical setting. Cancer Res; 77(20); 5445-51. ©2017 AACR.

Multiple pro-tumorigenic functions of the human minor Histocompatibility Antigen-1 (HA-1) in melanoma progression

BACKGROUND

Remodeling of cytoskeleton plays an important role in development of multiple cancers, including melanoma. As a group of F-actin regulators, the Ras homology (Rho) GTPase-activating proteins (ARHGAPs) were reported by accumulating studies as a set of significant mediators in cell morphology, proliferation, migration and invasion.

OBJECTIVE

To investigate the function of HMHA1 and its encode protein HA-1 in melanoma.

METHODS

The mRNA microarray was performed to screen the expression of ARHGAP family genes between melanoma tissues and nevi tissues. QRT-PCR and Western Blot were used to detect the expression of mRNA of HMHA1 and its relevant protein HA-1 respectively. Small interfering RNA was used to knock down the expression of HMHA1. Cell-count kit 8 assays and colony formation assays were used to evaluate the cell proliferative viability of melanoma cells. Flow cytometry was employed to analyze cell apoptosis. Transwell assay and the observation of cell morphology were used to evaluate the invasive and migrating activity of melanoma cells.

RESULTS

In previous study, we first found that both the mRNA level of HMHA1and the expression of HA-1 were up-regulated in melanoma tissues and cell lines compared with nevi tissues and normal human melanocytes respectively. Blocking HMHA1 expression in melanoma cell lines WM35 and A375 suppressed their proliferation and function of colony forming. Moreover, silencing HMHA1 not only significantly increased cell apoptosis but also suppressed cell migration and invasion.

CONCLUSION

Our results demonstrate that HMHA1 significantly promotes melanoma cells proliferation, invasion and migration, and prevents cell apoptosis. Additionally, it can be considered as a new diagnostic marker and drug target of melanoma.

IQGAP1 Mediates Hcp1-Promoted Escherichia coli Meningitis by Stimulating the MAPK Pathway

Escherichia coli-induced meningitis remains a life-threatening disease despite recent advances in the field of antibiotics-based therapeutics, necessitating continued research on its pathogenesis. The current study aims to elucidate the mechanism through which hemolysin-coregulated protein 1 (Hcp1) induces the apoptosis of human brain microvascular endothelial cells (HBMEC). Co-immunoprecipitation coupled with mass spectrometric (MS) characterization led to the identification of IQ motif containing GTPase activating protein 1 (IQGAP1) as a downstream target of Hcp1. IQGAP1 was found to be up-regulated by Hcp1 treatment and mediate the stimulation of HBMEC apoptosis. It was shown that Hcp1 could compete against Smurf1 for binding to IQGAP1, thereby rescuing the latter from ubiquitin-dependent degradation. Subsequent study suggested that IQGAP1 could stimulate the MAPK signaling pathway by promoting the phosphorylation of ERK1/2, an effect that was blocked by U0126, an MAPK inhibitor. Furthermore, U0126 also demonstrated therapeutic potential against E. coli meningitis in a mouse model. Taken together, our results suggested the feasibility of targeting the MAPK pathway as a putative therapeutic strategy against bacterial meningitis.