Girdin protein: a new potential distant metastasis predictor of breast cancer

Heterotrimeric G protein signaling without GPCRs: The Gα-binding-and-activating (GBA) motif

Heterotrimeric G proteins (Gαβγ) are molecular switches that relay signals from 7-transmembrane receptors located at the cell surface to the cytoplasm. The function of these receptors is so intimately linked to heterotrimeric G proteins that they are named G protein-coupled receptors (GPCRs), showcasing the interdependent nature of this archetypical receptor-transducer axis of transmembrane signaling in eukaryotes. It is generally assumed that activation of heterotrimeric G protein signaling occurs exclusively by the action of GPCRs, but this idea has been challenged by the discovery of alternative mechanisms by which G proteins can propagate signals in the cell. This review will focus on a general principle of G protein signaling that operates without the direct involvement of GPCRs. The mechanism of G protein signaling reviewed here is mediated by a class of G protein regulators defined by containing an evolutionarily conserved sequence named the Gα-binding-and-activating (GBA) motif. Using the best characterized proteins with a GBA motif as examples, Gα-interacting vesicle-associated protein (GIV)/Girdin and dishevelled-associating protein with a high frequency of leucine residues (DAPLE), this review will cover (i) the mechanisms by which extracellular cues not relayed by GPCRs promote the coupling of GBA motif-containing regulators with G proteins, (ii) the structural and molecular basis for how GBA motifs interact with Gα subunits to facilitate signaling, (iii) the relevance of this mechanism in different cellular and pathological processes, including cancer and birth defects, and (iv) strategies to manipulate GBA-G protein coupling for experimental therapeutics purposes, including the development of rationally engineered proteins and chemical probes.

Girdin correlated with autophagy in invasive ductal breast carcinomas

Aims and background

Increasing evidence claims that autophagy is essential for breast cancer progression. Girdin was found highly expressed in breast cancers. It has been reported that Girdin attenuates autophagy in HeLa cells. We explored the relationship between Girdin expression and autophagic patterns in breast cancer.

Methods and study design

In the study, Girdin expression and autophagic activity were investigated in a series of 99 invasive ductal breast carcinomas after immunohistochemical staining for the autophagy-associated proteins LC3-II and Girdin.

Results

The level of Girdin expression negatively correlated with LC3-II level, which represents autophagic activity (r = −0.289), and positively correlated with lymph node metastasis (r = 0.472). Girdin level was found no different in the “diffuse cytoplasmic” and “stone-like” patterns of LC3-II.

Conclusions

Up-regulated autophagy was negatively associated with Girdin level. There was a significant correlation between Girdin expression and lymph nodes metastasis in invasive ductal breast carcinoma.

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.

The Gαi-GIV binding interface is a druggable protein-protein interaction

Heterotrimeric G proteins are usually activated by the guanine-nucleotide exchange factor (GEF) activity of GPCRs. However, some non-receptor proteins are also GEFs. GIV (a.k.a Girdin) was the first non-receptor protein for which the GEF activity was ascribed to a well-defined protein sequence that directly binds Gαi. GIV expression promotes metastasis and disruption of its binding to Gαi blunts the pro-metastatic behavior of cancer cells. Although this suggests that inhibition of the Gαi-GIV interaction is a promising therapeutic strategy, protein-protein interactions (PPIs) are considered poorly "druggable" targets requiring case-by-case validation. Here, we set out to investigate whether Gαi-GIV is a druggable PPI. We tested a collection of >1,000 compounds on the Gαi-GIV PPI by in silico ligand screening and separately by a chemical high-throughput screening (HTS) assay. Two hits, ATA and NF023, obtained in both screens were confirmed in secondary HTS and low-throughput assays. The binding site of NF023, identified by NMR spectroscopy and biochemical assays, overlaps with the Gαi-GIV interface. Importantly, NF023 did not disrupt Gαi-Gβγ binding, indicating its specificity toward Gαi-GIV. This work establishes the Gαi-GIV PPI as a druggable target and sets the conceptual and technical framework for the discovery of novel inhibitors of this PPI.

Girdin protein expression is associated with poor prognosis in patients with invasive breast cancer

Girdin is an actin-binding Akt substrate that is an integral component of the PI3K/Akt signalling pathway. However, the clinicopathological significance of Girdin expression in breast cancer has not been clarified. The purpose of this study was to characterise the clinicopathological implication of Girdin expression in breast cancer. Immunohistochemistry-based protein expression analyses of 892 human breast cancer tissues showed that Girdin was expressed in 289 (32.4%) cases. Girdin expression was significantly associated with larger tumour size, frequent lymph node invasion, advanced cancer stage, and expression of oestrogen and progesterone receptors. Patients who had breast cancer with Girdin expression experienced significantly poorer overall survival (OS) (p=0.021) and disease-free survival (DFS) (p=0.002) than those without Girdin expression. In subtype analyses, Girdin expression was significantly correlated with poorer OS and DFS in HER2 subtype (p=0.004 and p=0.034, respectively). In triple negative breast cancer (TNBC) subtype, Girdin expression was significantly correlated with poorer DFS (p=0.035), and there was a trend toward poorer OS (p=0.060) in TNBC patients with Girdin expression. Multivariate analysis revealed that Girdin expression was an independent prognostic factor for OS (p=0.022) and DFS (p=0.030) in patients with breast cancer. In HER2 subtype under multivariate analysis, Girdin expression retained its role as an independent prognostic predictor for worse OS (p=0.023), and there was a trend toward poorer DFS (p=0.086) in patients with HER2 subtype expressing Girdin. Girdin expression may serve as a useful prognostic factor for invasive breast cancer, especially for the HER2 subtype.

Membrane Recruitment of the Non-receptor Protein GIV/Girdin (Gα-interacting, Vesicle-associated Protein/Girdin) Is Sufficient for Activating Heterotrimeric G Protein Signaling

GIV (aka Girdin) is a guanine nucleotide exchange factor that activates heterotrimeric G protein signaling downstream of RTKs and integrins, thereby serving as a platform for signaling cascade cross-talk. GIV is recruited to the cytoplasmic tail of receptors upon stimulation, but the mechanism of activation of its G protein regulatory function is not well understood. Here we used assays in humanized yeast models and G protein activity biosensors in mammalian cells to investigate the role of GIV subcellular compartmentalization in regulating its ability to promote G protein signaling. We found that in unstimulated cells GIV does not co-fractionate with its substrate G protein Gα_i3 on cell membranes and that constitutive membrane anchoring of GIV in yeast cells or rapid membrane translocation in mammalian cells via chemically induced dimerization leads to robust G protein activation. We show that membrane recruitment of the GIV "Gα binding and activating" motif alone is sufficient for G protein activation and that it does not require phosphomodification. Furthermore, we engineered a synthetic protein to show that recruitment of the GIV "Gα binding and activating" motif to membranes via association with active RTKs, instead of via chemically induced dimerization, is also sufficient for G protein activation. These results reveal that recruitment of GIV to membranes in close proximity to its substrate G protein is a major mechanism responsible for the activation of its G protein regulatory function.

Prognostic impact of total and tyrosine phosphorylated GIV/Girdin in breast cancers

Gα-interacting vesicle-associated protein (GIV, aka Girdin) is a guanine exchange factor (GEF) for the trimeric G protein Gαi and a bona fide metastasis-related gene that serves as a platform for amplification of tyrosine-based signals via G-protein intermediates. Here we present the first exploratory biomarker study conducted on a cohort of 187 patients with breast cancer to evaluate the prognostic role of total GIV (tGIV) and tyrosine phosphorylated GIV (pYGIV) across the various molecular subtypes. A Kaplan-Meier analysis of recurrence-free survival showed that the presence of tGIV, either cytoplasmic or nuclear, carried poor prognosis, but that nuclear tGIV had a greater prognostic impact (P = 0.007 in early and P = 0.0048 in late clinical stages). Activated pYGIV in the cytoplasm had the greatest prognostic impact in late clinical stages (P = 0.006). Furthermore, we found that the prognostic impacts of cytoplasmic pYGIV and nuclear tGIV were additive (hazard ratio 19.0548; P = 0.0002). Surprisingly, this additive effect of nuclear tGIV/cytoplasmic pYGIV was observed in human epidermal growth factor receptor 2-positive tumors (hazard ratio 16.918; P = 0.0005) but not in triple-negative breast cancers. In triple-negative breast cancers, tGIV and cytoplasmic pYGIV had no prognostic impact; however, membrane-association of pYGIV carried a poor prognosis (P = 0.026). Both tGIV and pYGIV showed no correlation with clinical stage, tumor size, pathologic type, lymph node involvement, and BRCA1/2 status. We conclude that immunocytochemical detection of pYGIV and tGIV can serve as an effective prognosticator. On the basis of the differential prognostic impact of tGIV/pYGIV within each molecular subtype, we propose a diagnostic algorithm. Further studies on larger cohorts are essential to rigorously assess the effectiveness and robustness of this algorithm in prognosticating outcome among patients with breast cancer.-Dunkel, Y., Diao, K., Aznar, N., Swanson, L., Liu, L., Zhu, W., Mi, X.-Y., Ghosh, P. Prognostic impact of total and tyrosine phosphorylated GIV/Girdin in breast cancers.

Girdin expression in cervical carcinoma and its role in the malignant properties of HeLa cells

Cervical cancer is a major cause of mortality in females worldwide, with the majority of cases reported in developing countries. The molecular mechanisms of this disease are unclear. However, increasing evidence indicates that the expression or overexpression of Girdin is associated with a poor prognosis in a variety of cancer types. Therefore, the aim of the current study was to evaluate the potential association between Girdin expression, and malignant properties of cervical cancer lesions and HeLa cells. Girdin protein expression was examined in 87 samples of cervical squamous cell lesions, including intraepithelial neoplasia (grades I and III) and invasive carcinoma, using immunohistochemical (IHC) staining. A short-hairpin RNA (shRNA) approach was employed to specifically suppress the expression of Girdin mRNA in HeLa cells in vitro, allowing the role of Girdin in a number of malignant properties to be evaluated. Girdin protein was observed in the cytoplasm of 79/87 (90.8%) cervical cancer lesion specimens. However, no positive Girdin signals were identified in healthy cervical squamous epithelium samples. Furthermore, a significant correlation between Girdin expression and lesion grade was identified (Spearman's correlation coefficient, 0.566; P<0.001). When Girdin was suppressed by Girdin shRNA, the rate of HeLa cell growth was significantly reduced in vitro (P<0.05). Additional analysis determined that Girdin was associated with serum-deprived induced HeLa apoptosis. Thus, patients with high-grade cervical cancer tumors exhibited a strong expression for Girdin, and Girdin appears to key in HeLa cell proliferation and serum-deprived induced apoptosis, supporting the hypothesis that Girdin may be important in the process of cervical carcinogenesis.

GIV/Girdin (Gα-interacting, Vesicle-associated Protein/Girdin) Creates a Positive Feedback Loop That Potentiates Outside-in Integrin Signaling in Cancer Cells

Activation of the tyrosine kinase focal adhesion kinase (FAK) upon cell stimulation by the extracellular matrix initiates integrin outside-in signaling. FAK is directly recruited to active integrins, which enhances its kinase activity and triggers downstream signaling like activation of PI3K. We recently described that Gα-interacting, vesicle-associated protein (GIV), a protein up-regulated in metastatic cancers, is also required for outside-in integrin signaling. More specifically, we found that GIV is a non-receptor guanine nucleotide exchange factor that activates trimeric G proteins in response to integrin stimulation to enhance PI3K signaling and tumor cell migration. In contrast, previous reports have established that GIV is involved in phosphotyrosine (Tyr(P))-based signaling in response to growth factor stimulation;i.e.GIV phosphorylation at Tyr-1764 and Tyr-1798 recruits and activates PI3K. Here we show that phosphorylation of GIV at Tyr-1764/Tyr-1798 is also required to enhance PI3K-Akt signaling and tumor cell migration in response to integrin stimulation, indicating that GIV functions in Tyr(P)-dependent integrin signaling. Unexpectedly, we found that activation of FAK, an upstream component of the integrin Tyr(P) signaling cascade, was diminished in GIV-depleted cells, suggesting that GIV is required to establish a positive feedback loop that enhances integrin-FAK signaling. Mechanistically, we demonstrate that this feedback activation of FAK depends on both guanine nucleotide exchange factor and Tyr(P) GIV signaling as well as on their convergence point, PI3K. Taken together, our results provide novel mechanistic insights into how GIV promotes proinvasive cancer cell behavior by working as a signal-amplifying platform at the crossroads of trimeric G protein and Tyr(P) signaling.

Constitutive activation of STAT3 in breast cancer cells: A review

Signal transducer and activator of transcription 3 (STAT3) is constitutively activated in numerous cancer types, including more than 40% of breast cancers. In contrast to tight regulation of STAT3 as a latent transcription factor in normal cells, its signaling in breast cancer oncogenesis is multifaceted. Signaling through the IL-6/JAK/STAT3 pathway initiated by the binding of IL-6 family of cytokines (i.e., IL-6 and IL-11) to their receptors have been implicated in breast cancer development. Receptors with intrinsic kinase activity such as EGFR and VEGFR directly or indirectly induce STAT3 activation in various breast cancer types. Aberrant STAT3 signaling promotes breast tumor progression through deregulation of the expression of downstream target genes which control proliferation (Bcl-2, Bcl-xL, Survivin, Cyclin D1, c-Myc and Mcl-1), angiogenesis (Hif1α and VEGF) and epithelial-mesenchymal transition (Vimentin, TWIST, MMP-9 and MMP-7). These multiple modes of STAT3 regulation therefore make it a central linking point for a multitude of signaling processes. Extensive efforts to target STAT3 activation in breast cancer had no remarkable success in the past because the highly interconnected nature of STAT3 signaling introduces lack of selectivity in pathway identification for STAT3 targeted molecular therapies or because its role in tumorigenesis may not be as critical as it was thought. This review provides a full spectrum of STAT3's involvement in breast cancer by consolidating the knowledge about its role in breast cancer development at multiple levels: its differential regulation by different receptor signaling pathways, its downstream target genes, and modification of its transcriptional activity by its coregulatory transcription factors.

Interleukin-17 promotes angiogenesis by stimulating VEGF production of cancer cells via the STAT3/GIV signaling pathway in non-small-cell lung cancer

The presence of IL-17-positive cells is observed in a variety of inflammatory associated cancers and IL-17 has been found to be involved in angiogenesis. However, it remains unclear how IL-17 might contribute to tumor angiogenesis. In our study, IL-17 enhanced the formation of vessel-like tubes in HUVECs both directly (when HUVECs were incubated with IL-17) and indirectly (when HUVECs were incubated in conditioned cell media (CCM) from IL-17-treated cancer cells). Our results from experiments using siRNA-mediated knockdowns of STAT3 and GIV suggest that the effects of IL-17 were mediated by activating STAT3/GIV signaling in NSCLC cells and subsequently up-regulating its downstream target VEGF. Consistent with these findings, immunostaining experiments on human NSCLC tissues indicated that IL-17 and GIV expression were significantly and positively associated with increased tumor vascularity. The clinical significance of IL-17 was authenticated by our finding that the combination of intratumoral IL-17 + cells and GIV expression served as a better prognosticator for survival than either marker alone. Therefore, our finding highlights a novel aspect of STAT3/GIV pathway in the IL-17 promotes tumor angiogenesis of NSCLC.

Integrins activate trimeric G proteins via the nonreceptor protein GIV/Girdin

Signal transduction via integrins and G protein-coupled receptors is critical to control cell behavior. These two receptor classes have been traditionally believed to trigger distinct and independent signaling cascades in response to extracellular cues. Here, we report a novel mechanism of integrin signaling that requires activation of the trimeric G protein Gαi by the nonreceptor guanine nucleotide exchange factor (GEF) GIV (also known as Girdin), a metastasis-associated protein. We demonstrate that GIV enhances integrin-dependent cell responses upon extracellular matrix stimulation and makes tumor cells more invasive. These responses include remodeling of the actin cytoskeleton and PI3K-dependent signaling, resulting in enhanced haptotaxis and invasion. We show that both GIV and its substrate Gαi3 are recruited to active integrin complexes and that tumor cells engineered to express GEF-deficient GIV fail to transduce integrin signals into proinvasive responses via a Gβγ-PI3K axis. Our discoveries delineate a novel mechanism by which integrin signaling is rewired during metastasis to result in increased tumor invasiveness.

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.

GIV/Girdin transmits signals from multiple receptors by triggering trimeric G protein activation

Activation of trimeric G proteins has been traditionally viewed as the exclusive job of G protein-coupled receptors (GPCRs). This view has been challenged by the discovery of non-receptor activators of trimeric G proteins. Among them, GIV (a.k.a. Girdin) is the first for which a guanine nucleotide exchange factor (GEF) activity has been unequivocally associated with a well defined motif. Here we discuss how GIV assembles alternative signaling pathways by sensing cues from various classes of surface receptors and relaying them via G protein activation. We also describe the dysregulation of this mechanism in disease and how its targeting holds promise for novel therapeutics.

Expression of tumor necrosis factor receptor-assicated factor 4 correlates with expression of Girdin and promotes nuclear translocation of Girdin in breast cancer

Overexpression of tumor necrosis factor receptor‑associated factor 4 (TRAF4) has been reported in several human malignancies; however its association with Girdin in breast cancer is unclear. The aim of the present study was to analyze the correlation, expression and nuclear and cytoplasmic localizations of TRAF4 and Girdin in breast cancer tissues. Tissue samples from 38 patients with breast cancer, the MCF‑10A normal mammary epithelial cell line, the MCF‑7 estrogen‑receptor (ER)‑positive and MDA‑MB‑231 ER‑negative breast cancer cell lines were used in the present study. The results demonstrated that cytoplasmic expression of TRAF4 was positively correlated with cytoplasmic expression of Girdin. Furthermore, coexpression of TRAF4 and Girdin was highest in tissue samples from patients with lymph node metastases. Girdin was observed to be predominantly expressed in the cytoplasm of breast cancer cells; however TRAF4 promoted its translocation to the nucleus. These findings suggest that cytoplasmic expression of TRAF4 may be a novel potential marker for cell migration in breast cancer.

Talen-mediated girdin knockout downregulates cell proliferation, migration and invasion in human esophageal carcinoma ECA109 cells

Girdin is an actin-binding Akt substrate that is involved in the regulation of cell migration. Accumulating evidence has revealed that girdin has regulatory effects on invasion and metastasis in several types of cancer. However, the role of girdin in esophageal squamous cell carcinomas (ESCCs) is yet to be investigated. In the present study, tissue microarray data revealed that among 95 cases of ESCC, 27 cases (28.7%) exhibited a low expression of girdin, while 67 cases (71.3%) had an enhanced expression of girdin. However, among 78 cases of adjacent tissues, 64 cases (82.1%) did not express girdin and 14 cases (17.9%) exhibited a low expression of girdin. Furthermore, the expression of girdin was significantly associated with the tumor stage, lymph node metastasis stage, and tumor, lymph node and metastasis stage. Of note, the mean survival time of girdin-positive cases was only 30.62±2.99 months, while it was 53.37±5.02 months in girdin-negative cases, indicating that girdin protein expression is an independent prognostic factor of poor survival. Talen-mediated girdin knockout (KO) significantly suppressed cellular proliferation, migration and invasion in ESCC ECA109 cells. In conclusion, the present study suggested that girdin protein expression was significantly correlated with cancer progression and poor prognosis in ESCCs, and that girdin had a positive role in the regulation of cell proliferation, migration and invasion in ESCC cells. Therefore, girdin may be a potential candidate for the development of novel prognostic tools and therapeutic strategies for ESCCs.

Expression and clinical significance of girdin in gastric cancer

Gastric cancer is one of the most common malignant tumors and the second leading cause of cancer-related mortality. Elucidating the molecular mechanism underlying the development of gastric cancer is crucial in identifying gastric cancer-susceptible populations, screening for tumor markers and in the application of gene therapy. This study was conducted to investigate girdin expression in gastric cancer and para-cancer tissues and to elucidate the role of girdin in the development of gastric cancer. Tissue micro-array and streptavidin-peroxidase immunohistochemical staining were used to detect girdin expression in 105 gastric cancer and 72 para-cancer tissue samples. Analyses of the patients' clinical and pathological data were also performed. The expression ratio of girdin was 40.0% in gastric cancer and 11.1% in the para-cancer tissues and the difference was statistically significant (P<0.05). Girdin expression was found to be positively correlated (P<0.05) with tumor invasion depth and lymph node metastasis, while no significant associations were found between girdin expression and gender, age, tumor size, pathological grade and clinical stage (P>0.05). In conclusion, the upregulation of girdin expression in gastric cancer may contribute to tumor metastasis and cancer development, suggesting that girdin may be a novel indicator for evaluating lymph node metastasis and gastric cancer outcome.

Clinical significance of Girdin expression detected by immunohistochemistry in non-small cell lung cancer

Girdin protein has been implicated in cell migration and proliferation control. Previous evidence has confirmed that Girdin is a pivotal protein during cancer progression. To date, no evidence has been identified for the clinical significance of Girdin expression in non-small cell lung cancer (NSCLC). The current study aimed to investigate the expression and clinical significance of Girdin protein in NSCLC. In total, 36 tumor samples were obtained from patients undergoing surgery for NSCLC at The 309th Hospital of Chinese People’s Liberation Army (Beijing, China). The protein expression of Girdin was determined by immunohistochemistry analysis and the levels of Girdin protein were significantly higher in tumor samples than in distal normal lung tissue. A significant correlation was identified between Girdin overexpression and blood vessel infiltration of the tumor (P=0.013). Furthermore, analysis found that the Girdin-high phenotype was not associated with higher Ki-67 score. Girdin protein was frequently overexpressed in NSCLC and expression of Girdin was associated with blood vessel infiltration. The results of the present study suggest that Girdin should be considered as a potential marker for the prognosis of NSCLC; however, future studies are required to confirm theses results.

Activators of G protein signaling exhibit broad functionality and define a distinct core signaling triad

Activators of G protein signaling (AGS), initially discovered in the search for receptor-independent activators of G protein signaling, define a broad panel of biologic regulators that influence signal transfer from receptor to G-protein, guanine nucleotide binding and hydrolysis, G protein subunit interactions, and/or serve as alternative binding partners for Gα and Gβγ independently of the classic heterotrimeric Gαβγ. AGS proteins generally fall into three groups based upon their interaction with and regulation of G protein subunits: group I, guanine nucleotide exchange factors (GEF); group II, guanine nucleotide dissociation inhibitors; and group III, entities that bind to Gβγ. Group I AGS proteins can engage all subclasses of G proteins, whereas group II AGS proteins primarily engage the Gi/Go/transducin family of G proteins. A fourth group of AGS proteins with selectivity for Gα16 may be defined by the Mitf-Tfe family of transcription factors. Groups I-III may act in concert, generating a core signaling triad analogous to the core triad for heterotrimeric G proteins (GEF + G proteins + effector). These two core triads may function independently of each other or actually cross-integrate for additional signal processing. AGS proteins have broad functional roles, and their discovery has advanced new concepts in signal processing, cell and tissue biology, receptor pharmacology, and system adaptation, providing unexpected platforms for therapeutic and diagnostic development.

The impact of Girdin expression on recurrence-free survival in patients with luminal-type breast cancer

BACKGROUND

In patients with luminal-type breast cancer (positive for ER and/or PgR), a complete consensus on the threshold indication for a combination of chemotherapy and endocrine therapy has not been achieved, especially for patients with HER2-negative luminal type (HNLT). Girdin, an actin-binding Akt substrate, plays a crucial role in the migration of cancer cells. This study examined the expression of Girdin in relation to clinicopathological features and other immunohistochemical markers (HER2, Ki-67), especially in patients with HNLT breast cancer.

METHODS

One hundred one breast cancer patients who underwent surgery were evaluated. Immunohistochemical staining was performed for Girdin and other biomarkers, such as ER, PgR, HER2, and Ki-67.

RESULTS

Positive expression of Girdin was observed in 26 patients. The expression of Girdin was significantly associated with the incidence of lymph node metastases (p = 0.001). Among the other examined biomarkers, positive expression of Ki-67 also showed a significant association with the incidence of lymph node metastases (p = 0.04). In the HNLT breast cancer patients (n = 73), the 5-year recurrence-free survival rate was significantly lower (57 %) in patients with positive expression of both Girdin and Ki-67 than the rate in other patients (92 %) (p = 0.002).

CONCLUSION

This study demonstrated that the expression of Girdin in invasive breast cancer is strongly associated with lymph node metastasis. The expression status of Girdin and Ki-67 can be a useful biomarker in stratifying patients with HNLT breast cancer into those with high risk of recurrence and the need for additional chemotherapy.

Clinical implications of Girdin and PI3K protein expression in breast cancer

The aim of this study was to investigate the correlation between Girdin and PI3K in breast cancer stem cells and the clinical implications of the co-expression of these two proteins in breast cancer patients. CD44⁺/CD24⁻ tumor cells from the MD-231 cell line were sorted by flow cytometry. The expression status of Girdin and PI3K proteins was detected using western blotting and immunohistochemical staining. The relationship between Girdin and PI3K proteins and clinicopathological parameters was analyzed in 820 breast cancer patients. Girdin and PI3K proteins were more highly expressed in CD44⁺/CD24⁻ tumor stem cells compared to the control group and Girdin and PI3K proteins were co-immunoprecipitated in the MD-231 cell line. Of the 820 enrolled breast cancer patients, Girdin and PI3K proteins were expressed in 295 (35.98%) and 492 (60.00%) cases, respectively. There were 162 (19.76%) cases which co-expressed Girdin and PI3K proteins. Univariate and multivariate analyses indicated that the co-expression of Girdin and PI3K proteins correlated with histological type, metastatic nodes and distant metastasis (P=0.01, 0.001 and 0.001, respectively). After analyzing survival rates, cases with Girdin and PI3K co-expression were shown to attain a significantly increased distant metastasis rate and poorer postoperative, disease-specific survival compared to those with Girdin and PI3K co-expression (P=0.001). In the Cox regression test, Girdin and PI3K co-expression was detected as an independent prognostic factor (P=0.001). Girdin may regulate the biological behavior of breast cancer via the PI3K/Akt/mTOR pathway, and thus, serve as a potential new target for breast cancer treatment.

Expression of girdin in human colorectal cancer and its association with tumor progression

BACKGROUND

Girdin is crucial for cellular motility in cancer cell lines and for metastasis in a mouse model. Its expression has been demonstrated in a range of cancers by a few studies and was a prognostic factor in a subset of patients.

OBJECTIVE

The aim of this study was to investigate the relationship of Girdin expression to clinicopathologic factors in terms of the progression of colorectal cancers and patient survival.

DESIGN

This study is a retrospective review of immunohistochemical and clinicopathologic data.

SETTING

This study was conducted at a tertiary care hospital/referral center in South Korea.

PATIENTS

Tissue microarrays were made from surgical biopsies of 298 patients with colorectal cancer diagnosed between November 1996 and August 2007. Patients were included in the study if their survival time was known and if well-preserved surgical biopsy specimens were available.

MAIN OUTCOME MEASURES

The primary outcomes measured were Girdin expression and its association in tumor progression and patient survival.

RESULTS

Positive staining for Girdin was observed in samples from 66 of 242 patients (27.3%). Expression of Girdin was significantly associated with tumor-node-metastasis stage (p = 0.036), liver metastasis (p = 0.025), and metastases involving the liver and other organs (p = 0.009). However, Girdin expression did not correlate significantly with the overall survival of patients and was not a significant negative prognostic factor for survival by univariate or multivariate analyses.

LIMITATIONS

The number of investigated patients and the number of cases with positive staining for Girdin were rather small for the multivariate analysis. The inclusion time frame is long and includes other surgical and medical improvements, which influence a patient's survival.

CONCLUSION

The expression of Girdin is related to tumor metastasis but not to survival in human colorectal cancers.

STAT3 protein up-regulates Gα-interacting vesicle-associated protein (GIV)/Girdin expression, and GIV enhances STAT3 activation in a positive feedback loop during wound healing and tumor invasion/metastasis

Gα-interacting vesicle-associated protein (GIV) is a guanine nucleotide exchange factor that modulates key signaling pathways during a diverse set of biological processes, e.g. wound healing, macrophage chemotaxis, tumor angiogenesis, vascular repair, and cancer invasion/metastasis. We recently demonstrated that GIV is a metastasis-related protein, which serves both as a therapeutic target and as a biomarker for prognostication in cancer patients. Here we report the discovery that GIV is a direct target of the transcription factor signal transducer and activator of transcription-3 (STAT3), which is commonly known as a central regulator of tumor metastasis. We identified a single STAT3-binding site on the GIV promoter that was necessary and sufficient for transcriptional activation of GIV during wound healing and cancer invasion. Immunohistochemical analysis of breast carcinomas showed significant correlation between STAT3 activation and elevated GIV expression. Furthermore, we provide evidence that GIV positively autoregulates its own transcription by enhancing STAT3 activation via its guanine nucleotide exchange factor activity. Our findings provide mechanistic insights into how STAT3 activation is directly integrated with the receptor tyrosine kinase-GIV-G protein signaling axis. The forward feedback regulation we describe here between GIV and STAT3 may have profound therapeutic implications for cancer and epithelial regeneration/repair and could help invent novel approaches in treating and prognosticating cancer.

Stem cell gene Girdin: a potential early liver metastasis predictor of colorectal cancer

The objective of this study is to investigate the liver's metastasis-related genes and the relationship between Girdin protein expression and clinical and pathological characteristics and prognosis in colorectal cancer. The differential expression of genes between tumor cells from cases with liver metastasis and those from cases without liver metastasis were detected using an RT(2) Profiler™ PCR Array. The expression of the stem cell gene Girdin was analyzed using immunohistochemistry staining. Subsequently, the relationship between Girdin and clinicopathological parameters of colorectal cancer was determined. The Girdin protein was verified as a gene related to liver metastasis and was expressed positively in 161 (37.01 %) of the 435 cases examined. The expression of Girdin protein was related to histological grade and distant metastasis (P = 0.007 and 0.007, respectively). After analyzing survival rates, cases with highly expressed Girdin protein were shown to attain a significantly higher rate of liver metastasis and poorer postoperative, disease-specific survival than those with no or low expressed Girdin protein (P = 0.001). In the Cox regression test, the depth of tumor invasion, histological grade, duke's stage, distant metastasis, and the Girdin protein were detected as an independent prognostic factor (0.020, 0.032, 0.001, 0.001, and 0.010, respectively). The Girdin protein may be a potential new early liver metastasis biomarker of colorectal cancer.