Girdin, an actin-binding protein, is critical for migration, adhesion, and invasion of human glioblastoma cells

An orchestra of machine learning methods reveals landmarks in single-cell data exemplified with aging fibroblasts

In this work, a Python framework for characteristic feature extraction is developed and applied to gene expression data of human fibroblasts. Unlabeled feature selection objectively determines groups and minimal gene sets separating groups. ML explainability methods transform the features correlating with phenotypic differences into causal reasoning, supported by further pipeline and visualization tools, allowing user knowledge to boost causal reasoning. The purpose of the framework is to identify characteristic features that are causally related to phenotypic differences of single cells. The pipeline consists of several data science methods enriched with purposeful visualization of the intermediate results in order to check them systematically and infuse the domain knowledge about the investigated process. A specific focus is to extract a small but meaningful set of genes to facilitate causal reasoning for the phenotypic differences. One application could be drug target identification. For this purpose, the framework follows different steps: feature reduction (PFA), low dimensional embedding (UMAP), clustering ((H)DBSCAN), feature correlation (chi-square, mutual information), ML validation and explainability (SHAP, tree explainer). The pipeline is validated by identifying and correctly separating signature genes associated with aging in fibroblasts from single-cell gene expression measurements: PLK3, polo-like protein kinase 3; CCDC88A, Coiled-Coil Domain Containing 88A; STAT3, signal transducer and activator of transcription-3; ZNF7, Zinc Finger Protein 7; SLC24A2, solute carrier family 24 member 2 and lncRNA RP11-372K14.2. The code for the preprocessing step can be found in the GitHub repository https://github.com/AC-PHD/NoLabelPFA, along with the characteristic feature extraction https://github.com/LauritzR/characteristic-feature-extraction.

Girdin regulates both migration and angiogenesis in pancreatic cancer cell lines

Girdin, an actin‑binding protein, is reportedly involved in the invasion and angiogenesis of various cancers. It has been suggested that the flavonoid Scutellarin (SCU) inhibits Girdin signaling. In the present study, the function and therapeutic applications of Girdin in pancreatic cancer (PaCa) were investigated. Immunohistochemical staining of Girdin in resected PaCa specimens from the Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Science showed that high Girdin expression was associated with poor overall survival and relapse‑free survival, as well as with T factor, indicating invasion into the surrounding tissues. On the other hand, Girdin was highly expressed in almost all PaCa cell lines, and the migration ability of Girdin‑knockdown cell lines was decreased even under epidermal growth factor (EGF) stimulation. In addition, SCU suppressed PaCa cell migration by inhibiting the phosphorylation of Girdin. The expression and production of vascular endothelial growth factor A (VEGF‑A) was significantly decreased in Girdin‑knockdown cell lines. Furthermore, in Matrigel tube formation assays performed using culture supernatant, the lumen‑forming ability of vascular endothelial cells was also decreased in Girdin‑knockdown cell lines. However, SCU treatment did not significantly alter the expression or production of VEGF‑A. These results suggested that Girdin is involved in EGF signaling‑mediated migration of PaCa cells, that SCU inhibits PaCa invasion by suppressing Girdin activity, and that Girdin is also involved in angiogenesis via an activation pathway different from the action site of SCU. Girdin may be a prognostic biomarker, and the development of a novel molecular‑targeted drugs for Girdin may improve the prognosis of PaCa in the future.

hsa-miR-199b-3p suppresses osteosarcoma progression by targeting CCDC88A, inhibiting epithelial-to-mesenchymal transition, and Wnt/beta-catenin signaling pathway

The present study investigated microRNA (miR)-199b-3p expression in osteosarcoma (OS) and aimed to identify its potential mechanism of action contributing to the development of this disease. Firstly, miR-199b-3p and coiled-coil domain containing 88A (CCDC88A) expression data were evaluated from Gene Expression Profiling Interactive Analysis and Kaplan Meier plotter was used to assess the survival data. By analyzing the GSE65071 dataset from gene expression omnibus, it was found that miR-199b-3p was expressed at a low level. By using reverse transcription-quantitative PCR analysis in OS cells and tissues, CCDC88A was found to be expressed at a high level. Moreover, TargetScan predicted CCDC88A to be a downstream target of miR-199b-3p. Luciferase reporter assays were used to verify this prediction. In vitro overexpression of miR-199b-3p decreased the invasive and proliferative activity of OS cells. Mechanistic studies indicated that decreased miR-199b-3p resulted in increased expression of CCDC88A. Concomitantly, it impeded the Wnt/beta-catenin pathway and the epithelial-to-mesenchymal transition process. Overall, the results of the present study emphasized the pivotal role of the miR-199b-3p in the formation and progression of OS, suggesting that it could be used as a potential tumor biomarker.

Integrative analysis of a novel 5 methylated snoRNA genes prognostic signature in patients with glioma

Aim: To explore the prognostic value of methylated snoRNA genes in glioma and construct a prognostic risk signature. Materials & methods: We retrieved clinical information and 450K methylation data from The Cancer Genome Atlas and obtained five methylated snoRNA genes. Then we established a risk signature and verified the effect of SNORA71B on glioma cells with functional assays. Results: A risk signature containing five methylated snoRNA genes was constructed and demonstrated to be an independent predictor of glioma prognosis. Silencing SNORA71B restrained the proliferation, migration and invasion of glioma cells and reduced the expression of mesenchymal and cell cycle marker proteins. Conclusion: This study constructed a methylated snoRNA gene risk signature, which may provide a reference for glioma patients' prognosis assessment.

Knockdown of Girdin Induced Apoptosis of Glioblastoma Cells via the Mitochondrion Signaling Pathway

Glioblastoma is the most common primary brain tumor with poor survival rate and without effective treatment strategy. However, the influence of Girdin on human glioblastoma and the underlying molecular mechanisms have yet to be uncovered. We mainly investigated the role of Girdin in glioblastoma cells apoptosis. First, we examined Girdin expression in 90 glioma patients by using immunohistochemistry (IHC) and analyzed its association with patients' prognosis. The results showed that the expression of Girdin was positively associated with the histological grade of glioma, and glioma patients with high Girdin expression had a poor prognosis. Next, proliferation assay, Colony formation assay and Cell Counting Kit-8 (CCK-8) results showed that knockdown of Girdin suppressed proliferation and reduced cell survival rate. Flow cytometry and DAPI staining results showed that knockdown of Girdin induced apoptosis in LN229 cells. Western blot results suggested that reduction of Gridin increased the level of Cytochrome C (Cyt-C) and Bad while decreased the expression of Bcl-2 and p-AKT. Moreover, subcutaneous mouse xenograft model was used to validate the role of Girdin in glioblastoma apoptosis. Consistently, in vivo assays showed that knockdown of Girdin inhibited the growth of the grafted tumor and increased the level of Cyt-C and Bad. These findings demonstrated that knockdown of Girdin may induce Bad expression and reduce Bcl-2 expression by inhibiting the activation of AKT, leading to the release of Cyt-C from mitochondria, thereby promoting glioblastoma cells apoptosis.

Girdin Knockdown Increases Gemcitabine Chemosensitivity to Pancreatic Cancer by Modulating Autophagy

Chemotherapy is crucial for the treatment of pancreatic cancer (PC). Gemcitabine (GEM) as the first-line chemotherapy drug has a high resistance rate. Increasing the sensitivity of gemcitabine is currently the objectives and challenges of this study. Our previous study showed Girdin was closely related to the progression and prognosis of PC, indicating that Girdin may be associated with chemosensitivity. In the current study, we use recombinant adenovirus to specifically knockdown Girdin in PC cell lines to determine the effect of Girdin in the process of gemcitabine chemosensitivity. Autophagy is one of the pathways affecting the gemcitabine chemosensitivity in PC. Further research validated that Girdin may activate autophagy by interacting with autophagy protein p62/SQSTM1, which could enhance chemotherapy resistance to gemcitabine in PC. Down-regulation of Girdin may therefore increase gemcitabine chemosensitivity in PC. Our results reveal that Girdin acted as a negative regulator of gemcitabine chemosensitivity in PC. Increased autophagy activity caused by abnormally high Girdin expression may be one of the main factors for the reduction in chemosensitivity, which may provide new perspectives on understanding chemosensitization in PC.

Aquaporin 1 promotes sensitivity of anthracycline chemotherapy in breast cancer by inhibiting β-catenin degradation to enhance TopoIIα activity

Anthracyclines are a class of conventional and commonly used frontline chemotherapy drugs to treat breast cancer. However, the anthracycline-based regimens can only reduce breast cancer mortality by 20–30%. Furthermore, there is no appropriate biomarker for predicting responses to this kind of chemotherapy currently. Here we report our findings that may fill this gap by showing the AQP1 (Aquaporin1) protein as a potential response predictor in the anthracycline chemotherapy. We showed that breast cancer patients with a high level of AQP1 expression who underwent the anthracycline treatment had a better clinical outcome relative to those with a low level of AQP1 expression. In the exploration of the underlying mechanisms, we found that the AQP1 and glycogen synthase kinase-3β (GSK3β) competitively interacted with the 12 armadillo repeats of β-catenin, followed by the inhibition of the β-catenin degradation that led to β-catenin’s accumulation in the cytoplasm and nuclear translocation. The nuclear β-catenin interacted with TopoIIα and enhanced TopoIIα’s activity, which resulted in a high sensitivity of breast cancer cells to anthracyclines. We also found, the miR-320a-3p can attenuate the anthracycline’s chemosensitivity by inhibiting the AQP1 expression. Taken together, our findings suggest the efficacy of AQP1 as a response predictor in the anthracycline chemotherapy. The application of our study includes, but is not limited to, facilitating screening of the most appropriate breast cancer patients (who have a high AQP1 expression) for better anthracycline chemotherapy and improved prognosis purposes.

The DISC1-Girdin complex - a missing link in signaling to the T cell cytoskeleton

In this study, using Jurkat cells, we show that DISC1 (disrupted in schizophrenia 1) and Girdin (girders of actin filament) are essential for typical actin accumulation at the immunological synapse. Furthermore, DISC1, Girdin and dynein are bound in a complex. Although this complex initially forms as a central patch at the synapse, it relocates to a peripheral ring corresponding to the peripheral supramolecular activation cluster (pSMAC). In the absence of DISC1, the classic actin ring does not form, cell spreading is blocked, and the dynein complex fails to relocate to the pSMAC. A similar effect is seen when Girdin is deleted. When cells are treated with inhibitors of actin polymerization, the dynein-NDE1 complex is lost from the synapse and the microtubule-organizing center fails to translocate, suggesting that actin and dynein might be linked. Upon stimulation of T cell receptors, DISC1 becomes associated with talin, which likely explains why the dynein complex colocalizes with the pSMAC. These results show that the DISC1-Girdin complex regulates actin accumulation, cell spreading and distribution of the dynein complex at the synapse.This article has an associated First Person interview with the first author of the paper.

Collective Locomotion of Human Cells, Wound Healing and Their Control by Extracts and Isolated Compounds from Marine Invertebrates

The collective migration of cells is a complex integrated process that represents a common theme joining morphogenesis, tissue regeneration, and tumor biology. It is known that a remarkable amount of secondary metabolites produced by aquatic invertebrates displays active pharmacological properties against a variety of diseases. The aim of this review is to pick up selected studies that report the extraction and identification of crude extracts or isolated compounds that exert a modulatory effect on collective cell locomotion and/or skin tissue reconstitution and recapitulate the molecular, biochemical, and/or physiological aspects, where available, which are associated to the substances under examination, grouping the producing species according to their taxonomic hierarchy. Taken all of the collected data into account, marine invertebrates emerge as a still poorly-exploited valuable resource of natural products that may significantly improve the process of skin regeneration and restrain tumor cell migration, as documented by in vitro and in vivo studies. Therefore, the identification of the most promising invertebrate-derived extracts/molecules for the utilization as new targets for biomedical translation merits further and more detailed investigations.

Girdin interaction with vimentin induces EMT and promotes the growth and metastasis of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant cancer of the digestive tract that has a high potential for metastasis and a poor prognosis. Girdin was first reported in 2005 as an actin-binding protein and was designated as Akt-phosphorylation enhancer (APE); thus, Girdin has been revealed to have an important role in regulating cancer development. There is additional evidence indicating that Girdin is associated with cell proliferation, migration, invasion and survival in certain cancers. However, the potential mechanisms involving Girdin and mobility in pancreatic cancer have not been elucidated. In the present study, it was revealed that Girdin was highly expressed in pancreatic cancer tissue and was associated with tumor grade. The present study, to the best of our knowledge, is the first aimed at investigating the unknown role of Girdin in PDAC metastasis. A short hairpin RNA for Girdin (sh-Girdin) was successfully constructed with recombinant adenoviral vectors to suppress the expression of Girdin in pancreatic cancer cell lines (PANC-1 and BXPC-3). The silencing efficiency of the Girdin shRNA was determined by RT-qPCR and western blot analysis, and decreased Girdin expression in the cytoplasm was revealed by immunofluorescence detection. Then, sulforhodamine B (SRB) and colony formation assays were used to confirm that the knockdown of Girdin inhibited proliferation in vitro, and Transwell assays were used to examine the influence of Girdin knockdown on cellular mobility. Animal experiments also confirmed that silencing the expression of Girdin in pancreatic cancer cells inhibited the growth and metastasis of pancreatic cancer in vivo. Transforming growth factor-β (TGF-β) is a common inducer of epithelial-mesenchymal transition (EMT) and can effectively induce EMT in PDAC. Notably, TGF-β-treated cells exhibited changes in the classic biological markers of EMT. The expression of E-cadherin, a marker of the epithelial phenotype, increased, and the expression of N-cadherin and vimentin, markers of the interstitial phenotype, decreased in response to sh-Girdin. According to these experiments, Girdin may affect pancreatic cancer progression and development by interacting with vimentin. Therefore, there is evidence indicating that Girdin could be designated as a prognostic biological indicator and a candidate therapeutic target for pancreatic cancer.

Anti-Invasion and Antiangiogenic Effects of Stellettin B through Inhibition of the Akt/Girdin Signaling Pathway and VEGF in Glioblastoma Cells

Angiogenesis and invasion are highly related with tumor metastatic potential and recurrence prediction in the most aggressive brain cancer, glioblastoma multiforme (GBM). For the first time, this study reveals that marine-sponge-derived stellettin B reduces angiogenesis and invasion. We discovered that stellettin B reduces migration of glioblastoma cells by scratch wound healing assay and invasion via chamber transwell assay. Further, stellettin B downregulates Akt/Mammalian Target of Rapamycin (Akt/mTOR) and Signal transducer and activator of transcription 3 (Stat3) signaling pathways, which are essential for invasion and angiogenesis in glioblastoma. This study further demonstrates that stellettin B affects filamentous actin (F-actin) rearrangement by decreasing the cross-linkage of phosphor-Girdin (p-Girdin), which attenuates glioblastoma cell invasion. Moreover, stellettin B blocks the expression and secretion of a major proangiogenic factor, vascular endothelial growth factor (VEGF), in glioblastoma cells. Stellettin B also reduces angiogenic tubule formation in human umbilical vein endothelial cells (HUVECs). In vivo, we observed that stellettin B decreased blood vesicle formation in developmental zebrafish and suppressed angiogenesis in Matrigel plug transplant assay in mice. Decreased VEGF transcriptional expression was also found in stellettin B⁻treated zebrafish embryos. Overall, we conclude that stellettin B might be a potential antiangiogenic and anti-invasion agent for future development of therapeutic agents for cancer therapy.

Long noncoding RNA MEG3 prevents vascular endothelial cell senescence by impairing miR-128-dependent Girdin downregulation

Long noncoding RNAs (lncRNAs) are commonly associated with various biological functions, in which the function of lncRNA maternally expressed gene 3 (MEG3) has been identified in various cancers. Strikingly, an association between MEG3 with microRNAs (miRNAs), mRNAs, and proteins has been reported. This study investigates the role of MEG3 in vascular endothelial cell (VEC) senescence. Expression of Girdin and miR-128 was monitored in the blood vessel samples of young and old mice/healthy volunteers, along with the measurement of human umbilical vein endothelial cells (HUVECs). The relationship between MEG3/Girdin and miR-128 was determined and verified. Loss- and gain-of-function approaches were applied to analyze the regulatory effects of MEG3 on platelet phagocytosis and lipoprotein oxidation of HUVEC membrane. In addition, the effect of MEG3 on HUVEC senescence was evaluated by detection of the reactive oxygen species, telomerase activity, and telomere length. To further analyze the MEG3-mediated regulatory mechanism, miR-128 upregulation and inhibition were introduced into the HUVECs. Downregulated Girdin and upregulated miR-128 were found in the blood vessels of old individuals and old mice, as well as in senescent HUVECs. MEG3 downregulation was found to be capable of inhibiting Girdin but enhancing miR-128 expression. It was also indicated to inhibit platelet phagocytosis and reduce telomerase activity and telomere length, while enhancing lipoprotein oxidation and reactive oxygen species production, which ultimately contributed in preventing and protecting HUEVCs from senescence. These findings provide evidence supporting that MEG3 leads to miR-128 downregulation and Girdin upregulation, which promotes platelet phagocytosis, thus protecting VECs from senescence.

Girdin regulates the proliferation and apoptosis of pancreatic cancer cells via the PI3K/Akt signalling pathway

Girdin functions as an Akt phosphorylation enhancer (APE), which expedites the proliferation and survival of many types of tumours. However, the influence of Girdin on pancreatic cancer and the underlying molecular mechanisms have yet to be uncovered. Hence, in the present study, we sought to elucidate the function of Girdin in pancreatic cancer malignancy, particularly its role in pancreatic cancer cell proliferation, migration and apoptosis. Immunohistochemistry (IHC) was used to evaluate Girdin expression in pancreatic cancer tissues and to analyse its correlation with pathological grade. Girdin expression was further validated in pancreatic cancer cell lines (AsPC-1, BxPC-3 and PANC-1), and human pancreatic ductal epithelial (HPNE) cells were used as a control. Recombinant adenovirus vectors containing Girdin-siRNA were constructed to inhibit Girdin expression and were used in subsequent experiments to determine the effects of Girdin silencing on pancreatic cancer cells. Girdin silencing suppressed pancreatic cancer cell proliferation and induced pancreatic cancer cell apoptosis in vitro and in vivo. According to the results of further mechanistic investigations, Girdin may regulate cell processes through the phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) signalling pathway to exert additive effects on pancreatic cancer.

Disrupted in schizophrenia 1 (DISC1) inhibits glioblastoma development by regulating mitochondria dynamics

Glioblastoma(GBM) is one of the most common and aggressive malignant primary tumors of the central nervous system and mitochondria have been proposed to participate in GBM tumorigenesis. Previous studies have identified a potential role of Disrupted in Schizophrenia 1 (DISC1), a multi-compartmentalized protein, in mitochondria. But whether DISC1 could regulate GBM tumorigenesis via mitochondria is still unknown. We determined the expression level of DISC1 by both bioinformatics analysis and tissue analysis, and found that DISC1 was highly expressed in GBM. Knocking down of DISC1 by shRNA in GBM cells significantly inhibited cell proliferation both in vitro and in vivo. In addition, down-regulation of DISC1 decreased cell migration and invasion of GBM and self renewal capacity of glioblastoma stem-like cells. Furthermore, multiple independent rings or spheres could be observed in mitochondria in GBM depleted of DISC1, while normal filamentous morphology was observed in control cells, demonstrating that DISC1 affected the mitochondrial dynamic. Dynamin-related protein 1 (Drp1) was reported to contribute to mitochondrial dynamic regulation and influence glioma cells proliferation and invasion by RHOA/ ROCK1 pathway. Our data showed a significant decrease of Drp1 both in mRNA and protein level in GBM lack of DISC1, indicating that DISC1 maybe affect the mitochondrial dynamic by regulating Drp1. Taken together, our findings reveal that DISC1 affects glioblastoma cell development via mitochondria dynamics partly by down regulation of Drp1.

Girdin protein: A potential metastasis predictor associated with prognosis in lung cancer

The present study explored the relationship between Girdin protein expression and the survival rate of patients with lung carcinoma. A total of 334 lung cancer specimens, 20 benign lung disease tissue sections and 24 fresh tissues from patients with lung carcinoma were analyzed by immunohistochemistry and western blotting. Girdin protein was expressed in 130/334 (38.93%) of the cases examined. Girdin protein expression was correlated with tumor/node/metastasis stage (P<0.001), lymph node metastasis (P=0.001), distant metastasis (P<0.001) and specimen sites (P=0.034). Girdin expression was also correlated with signal transducer and activator of transcription 3 (STAT3) expression (P<0.001). Patients with high Girdin and STAT3 expression had a significantly poorer prognosis compared with those with low/high, high/low or low/low expression (P<0.001). In summary, Girdin may be a prognostic marker of lung cancer and serve as a biomarker for metastasis.

Combination of cytoplasmic and nuclear girdin expression is an independent prognosis factor of breast cancer

Girdin is an actin-binding protein playing key roles in the development of various carcinomas. Although online tools have predicted nuclear localization of girdin with a high probability, convincing proof has rarely been provided until now. The purpose of this study was to discover girdin's precise subcellular distribution and the potential prognostic value corresponding to its localization. The subcellular distribution of girdin was detected in a human breast cancer cell line and in >800 samples of human breast tissue by clinical pathologic analysis. In this study, we discovered for the first time that girdin could attach to chromatin and interact with topoisomerase-IIα in nucleus. Cytoplasmic and nuclear girdin exhibited different roles in prognosis of breast cancer: cytoplasmic girdin expression was an independent prognostic factor for progression-free survival (PFS), whereas nuclear girdin expression was an independent prognostic factor for overall survival (OS). More important, combination cytoplasmic and nuclear girdin was an independent prognosis factor of both OS and PFS. In conclusion, our research results strongly recommend combination analysis of cytoplasmic and nuclear girdin for a precise prognostic prediction in breast cancer.-Zhang, H., Yu, F., Qin, F., Shao, Y., Chong, W., Guo, Z., Liu, X., Fu, L., Gu, F., Ma, Y. Combination of cytoplasmic and nuclear girdin expression is an independent prognosis factor of breast cancer.

Cell Migration in Microfabricated 3D Collagen Microtracks is Mediated through the Prometastatic Protein Girdin

Introduction

In vivo, cancer cells can utilize tube-like microtracks formed within the extracellular matrix (ECM) of the stroma as 'highways' to escape the primary tumor, however very little is known about the molecular mechanisms that govern cell migration through these microtracks. Cell polarization and actin organization are both essential for efficient cell migration and cells are known to migrate very unidirectionally in confined spaces. In this study, we focused on understanding the role of Girdin during unidirectional migration. Girdin is a prometastatic protein known to be involved in cell polarity by directly interacting with the cell polarity protein Par-3 (Partitioning defective-3) and also known as an actin binding protein.

Methods

We utilized a microfabricated platform to recreate these microtracks in vitro using collagen and used siRNA to knockdown Girdin in MDA-MB-231 cells.

Results

Our data indicate that knockdown of Girdin results in decreased cell speed during 3D collagen microtrack migration. Loss of Girdin also results in altered cell morphology and cell orientation. Moreover, Girdin-depletion impairs actin organization and stress fiber formation, which can be restored by upregulating the GTPase RhoA. Activation of RhoA induces actin stress fiber formation, restores elongated migratory cell shape and partial cell migration in 3D collagen microtracks in the absence of Girdin.

Conclusions

Our data suggest that Girdin helps directional migration in collagen microtracks by promoting actin cytoskeletal organization and maintaining morphological cell polarity.

Scutellarin suppresses migration and invasion of human hepatocellular carcinoma by inhibiting the STAT3/Girdin/Akt activity

Scutellarin is an active flavone from Erigeron breviscapine (vant) Hand Mass. This study aimed to investigate the potential role of scutellarin in migration and invasion of human hepatocellular carcinoma (HCC) cells and its possible mechanism. In comparison with the vehicle-treated controls, treatment with scutellarin (50 mg/kg/day) for 35 days significantly mitigated the lung and intrahepatic metastasis of HCC tumors in vivo. Scutellarin treatment significantly reduced HepG2 cell viability in a dose-dependent manner, and inhibited migration and invasion of HCC cells in vitro. Scutellarin treatment significantly reduced STAT3 and Girders of actin filaments (Girdin) expression, STAT3 and Akt phosphorylation in HCC cells. Introduction of STAT3 overexpression restored the scutellarin-downregulated Girdin expression, Akt activation, migration and invasion of HCC cells. Furthermore, induction of Girdin overexpression completely abrogated the inhibition of scutellarin on the Akt phosphorylation, migration and invasion of HCC cells. Scutellarin can inhibit HCC cell metastasis in vivo, and migration and invasion in vitro by down-regulating the STAT3/Girdin/Akt signaling.

Biochemical, Biophysical and Cellular Techniques to Study the Guanine Nucleotide Exchange Factor, GIV/Girdin

Canonical signal transduction via heterotrimeric G proteins is spatiotemporally restricted, i.e., triggered exclusively at the plasma membrane, only by agonist activation of G protein-coupled receptors via a finite process that is terminated within a few hundred milliseconds. Recently, a rapidly emerging paradigm has revealed a noncanonical pathway for activation of heterotrimeric G proteins via the nonreceptor guanidine-nucleotide exchange factor, GIV/Girdin. Biochemical, biophysical, and functional studies evaluating this pathway have unraveled its unique properties and distinctive spatiotemporal features. As in the case of any new pathway/paradigm, these studies first required an in-depth optimization of tools/techniques and protocols, governed by rationale and fundamentals unique to the pathway, and more specifically to the large multimodular GIV protein. Here we provide the most up-to-date overview of protocols that have generated most of what we know today about noncanonical G protein activation by GIV and its relevance in health and disease. © 2016 by John Wiley & Sons, Inc.

TMEM140 is associated with the prognosis of glioma by promoting cell viability and invasion

Background

Gliomas are the most common types of primary brain tumors in the adult central nervous system. TMEM140 is identified as an amplified gene in the human gastric cancer genome. However, the function of TMEM140 in gliomas has not been thoroughly elucidated. The aim of the current study was to determine the clinical significance of TMEM140 expression in patients with gliomas and its effect on tumor cell malignant phenotypes.

Methods

Immunohistochemical analysis and real-time reverse transcription PCR were performed to detect the expression levels of TMEM140 in 70 glioma brain tissue samples. Next, the correlation between the TMEM140 expression levels and the clinical characteristics and outcomes of glioma patients was statistically analyzed. TMEM140 expression was inhibited in two glioma cell lines (i.e., U87 and U373) using a knockdown method with small interfering RNA. Cell Counting Kit-8 and Transwell assays were used to investigate TMEM140 function during cell proliferation, invasion, and migration, respectively. Using flow cytometry and Western blot analysis, we subsequently determined the cell cycle and apoptosis profile of the TMEM140-silenced cells.

Results

TMEM140 protein expression was significantly higher in gliomas than in normal brain tissues (p < 0.0001). TMEM140 overexpression was strongly correlated with tumor size, histologic grade, and overall survival time (P < 0.05). TMEM140 decreased cell viability in vitro and dramatically decreased tumor volume in vivo. This phenomenon might be caused by G1 phase cell cycle arrest and cell apoptosis. TMEM140 silencing could suppress the viability, migration, and invasion of glioma cells.

Conclusions

Our results suggest that TMEM140 expression is a prognostic factor that might play an important role in the viability, migration, and invasion of glioma cells. This study highlights the importance of TMEM140 as a novel prognostic marker and as an attractive therapeutic target for gliomas.

Girdin regulates the migration and invasion of glioma cells via the PI3K-Akt signaling pathway

Girdin, an actin‑binding protein, is associated with cell migration and is expressed at high levels in glioma cells. However, the association between girdin and the development of glioma remains to be elucidated. In the present study, short‑hairpin RNA technology was used to silence the gene expression of girdin. The effects of girdin silencing on glioma cell proliferation, migration and invasion were then assessed using a cell viability assay, wound‑healing assay, transwell invasion assay, reverse transcription‑quantitative polymerase chain reaction, western blot analysis and gelatin zymography. The results suggested that girdin silencing inhibited the proliferation, migration and invasion of glioma cells. In addition, the expression levels and activity of matrix metalloproteinase (MMP)‑2 and MMP‑9 were also affected by girdin silencing. Further mechanistic investigation indicated that girdin may regulate glioma cell migration and invasion through the phosphatidylinositol‑3‑kinase/protein kinase B (PI3K‑Akt) signaling pathway. Therefore, the results of the present study provide a theoretical foundation for the development of anticancer drugs.

Heterotrimeric G proteins as emerging targets for network based therapy in cancer: End of a long futile campaign striking heads of a Hydra

Most common diseases, e.g., cancer are driven by not one, but multiple cell surface receptors that trigger and sustain a pathologic signaling network. The largest fraction of therapeutic agents that target individual receptors/pathways eventually fail due to the emergence of compensatory mechanisms that reestablish the pathologic network. Recently, a rapidly emerging paradigm has revealed GIV/Girdin as a central platform for receptor cross-talk which integrates signals downstream of a myriad of cell surface receptors, and modulates several key pathways within downstream signaling network, all via non-canonical activation of trimeric G proteins. Unlike canonical signal transduction via G proteins, which is spatially and temporally restricted, the temporal and spatial features of non-canonical activation of G protein via GIV is unusually unrestricted. Consequently, the GIV●G protein interface serves as a central hub allowing for control over several pathways within the pathologic signaling network, all at once. The relevance of this new paradigm in cancer and other disease states and the pros and cons of targeting the GIV●G protein interface are discussed.