Vav3 oncogene activates estrogen receptor and its overexpression may be involved in human breast cancer

Hub metastatic gene signature and risk score of breast cancer patients with small tumor sizes using WGCNA

BACKGROUND

Breast cancer (BC) is the most common cancer in women and accounts for approximately 15% of all cancer deaths among women globally. The underlying mechanism of BC patients with small tumor size and developing distant metastasis (DM) remains elusive in clinical practices.

METHODS

We integrated the gene expression of BCs from ten RNAseq datasets from Gene Expression Omnibus (GEO) database to create a genetic prediction model for distant metastasis-free survival (DMFS) in BC patients with small tumor sizes (≤ 2 cm) using weighted gene co-expression network (WGCNA) analysis and LASSO cox regression.

RESULTS

ABHD11, DDX39A, G3BP2, GOLM1, IL1R1, MMP11, PIK3R1, SNRPB2, and VAV3 were hub metastatic genes identified by WGCNA and used to create a risk score using multivariable Cox regression. At the cut-point value of the median risk score, the high-risk score (≥ median risk score) group had a higher risk of DM than the low-risk score group in the training cohort [hazard ratio (HR) 4.51, p < 0.0001] and in the validation cohort (HR 5.48, p = 0.003). The nomogram prediction model of 3-, 5-, and 7-year DMFS shows good prediction results with C-indices of 0.72-0.76. The enriched pathways were immune regulation and cell-cell signaling. EGFR serves as the hub gene for the protein-protein interaction network of PIK3R1, IL1R1, MMP11, GOLM1, and VAV3.

CONCLUSION

Prognostic gene signature was predictive of DMFS for BCs with small tumor sizes. The protein-protein interaction network of PIK3R1, IL1R1, MMP11, GOLM1, and VAV3 connected by EGFR merits further experiments for elucidating the underlying mechanisms.

Prognostic Significance of VAV3 Gene Variants and Expression in Renal Cell Carcinoma

Renal cell carcinoma (RCC) is characterized by high mortality and morbidity rates. Vav guanine nucleotide exchange factors (VAVs), crucial for signal transduction between cell membrane receptors and intracellular mediators, have been implicated in carcinogenesis. However, their potential prognostic value in RCC remains unclear. The impact of 150 common VAV polymorphisms on RCC risk and survival was investigated in a cohort of 630 individuals. Publicly available gene expression datasets were utilized to analyze VAV gene expression in relation to patient outcomes. The VAV3 rs17019888 polymorphism was significantly associated with RCC risk and overall survival after adjusting for false discovery rates. Expression quantitative trait loci analysis revealed that the risk allele of rs17019888 is linked to reduced VAV3 expression. Analysis of 19 kidney cancer gene expression datasets revealed lower VAV3 expression in RCC tissues compared to normal tissues, with higher expression correlating with better prognosis. Gene set enrichment analysis demonstrated that VAV3 negatively regulates the ubiquitin-proteasome system, extracellular matrix and membrane receptors, inflammatory responses, matrix metalloproteinases, and cell cycle pathways. Furthermore, elevated VAV3 expression was associated with increased infiltration of B cells, macrophages, and neutrophils into the RCC tumor microenvironment. Our findings suggest that VAV3 gene variants influence RCC risk and survival, contributing to a favorable prognosis in RCC.

Bioinformatic analysis and experimental validation of six cuproptosis-associated genes as a prognostic signature of breast cancer

Background

Breast carcinoma (BRCA) is a life-threatening malignancy in women and shows a poor prognosis. Cuproptosis is a novel mode of cell death but its relationship with BRCA is unclear. This study attempted to develop a cuproptosis-relevant prognostic gene signature for BRCA.

Methods

Cuproptosis-relevant subtypes of BRCA were obtained by consensus clustering. Differential expression analysis was implemented using the 'limma' package. Univariate Cox and multivariate Cox analyses were performed to determine a cuproptosis-relevant prognostic gene signature. The signature was constructed and validated in distinct datasets. Gene set variation analysis (GSVA) and gene set enrichment analysis (GSEA) were also conducted using the prognostic signature to uncover the underlying molecular mechanisms. ESTIMATE and CIBERSORT algorithms were applied to probe the linkage between the gene signature and tumor microenvironment (TME). Immunotherapy responsiveness was assessed using the Tumor Immune Dysfunction and Exclusion (TIDE) web tool. Real-time quantitative PCR (RT-qPCR) was performed to detect the expressions of cuproptosis-relevant prognostic genes in breast cancer cell lines.

Results

Thirty-eight cuproptosis-associated differentially expressed genes (DEGs) in BRCA were mined by consensus clustering and differential expression analysis. Based on univariate Cox and multivariate Cox analyses, six cuproptosis-relevant prognostic genes, namely SAA1, KRT17, VAV3, IGHG1, TFF1, and CLEC3A, were mined to establish a corresponding signature. The signature was validated using external validation sets. GSVA and GSEA showed that multiple cell cycle-linked and immune-related pathways along with biological processes were associated with the signature. The results ESTIMATE and CIBERSORT analyses revealed significantly different TMEs between the two Cusig score subgroups. Finally, RT-qPCR analysis of cell lines further confirmed the expressional trends of SAA1, KRT17, IGHG1, and CLEC3A.

Conclusion

Taken together, we constructed a signature for projecting the overall survival of BRCA patients and our findings authenticated the cuproptosis-relevant prognostic genes, which are expected to provide a basis for developing prognostic molecular biomarkers and an in-depth understanding of the relationship between cuproptosis and BRCA.

Key mRNAs and lncRNAs of pituitary that affect the reproduction of FecB + + small tail han sheep

BACKGROUND

The pituitary directly regulates the reproductive process through follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Transcriptomic research on the pituitaries of ewes with different FecB (fecundity Booroola) genotypes has shown that some key genes and lncRNAs play an important role in pituitary function and sheep fecundity. Our previous study found that ewes with FecB + + genotypes (without FecB mutation) still had individuals with more than one offspring per birth. It is hoped to analyze this phenomenon from the perspective of the pituitary transcriptome.

RESULTS

The 12 Small Tail Han Sheep were equally divided into polytocous sheep in the follicular phase (PF), polytocous sheep in the luteal phase (PL), monotocous sheep in the follicular phase (MF), and monotocous sheep in the luteal phase (ML). Pituitary tissues were collected after estrus synchronous treatment for transcriptomic analysis. A total of 384 differentially expressed genes (DEGs) (182 in PF vs. MF and 202 in PL vs. ML) and 844 differentially expressed lncRNAs (DELs) (427 in PF vs. MF and 417 in PL vs. ML) were obtained from the polytocous-monotocous comparison groups in the two phases. Functional enrichment analysis showed that the DEGs in the two phases were enriched in signaling pathways known to play an important role in sheep fecundity, such as calcium ion binding and cAMP signaling pathways. A total of 1322 target relationship pairs (551 pairs in PF vs. MF and 771 pairs in PL vs. ML) were obtained for the target genes prediction of DELs, of which 29 DEL-DEG target relationship pairs (nine pairs in PF vs. MF and twenty pairs in PL vs. ML). In addition, the competing endogenous RNA (ceRNA) networks were constructed to explore the regulatory relationships of DEGs, and some important regulatory relationship pairs were obtained.

CONCLUSION

According to the analysis results, we hypothesized that the pituitary first receives steroid hormone signals from the ovary and uterus and that VAV3 (Vav Guanine Nucleotide Exchange Factor 3), GABRG1 (Gamma-Aminobutyric Acid A Receptor, Gamma 1), and FNDC1 (Fibronectin Type III Domain Containing 1) played an important role in this process. Subsequently, the reproductive process was regulated by gonadotropins, and IGFBP1 (Insulin-like Growth Factor Binding Protein 1) was directly involved in this process, ultimately affecting litter size. In addition, TGIF1 (Transforming Growth Factor-Beta-Induced Factor 1) and TMEFF2 (Transmembrane Protein With EGF Like And Two Follistatin Like Domains 2) compensated for the effect of the FecB mutation and function by acting on TGF-β/SMAD signaling pathway, an important pathway for sheep reproduction. These results provided a reference for understanding the mechanism of multiple births in Small Tail Han Sheep without FecB mutation.

The role of Vav3 expression for inflammation and cell death during experimental myocardial infarction

OBJECTIVES

Myocardial Infarction (MI) is the leading cause of chronic heart failure. Previous studies have suggested that Vav3, a receptor protein tyrosine kinase signal transducer, is associated with a variety of cellular signaling processes such as cell morphology regulation and cell transformation with oncogenic activity. However, the mechanism of Vav3-mediated MI development requires further investigation.

METHOD

Here, The authors established an MI rat model by ligating the anterior descending branch of the left coronary artery, and an MI cell model by treating cardiomyocytes with H2O2. Microarray analysis was conducted to identify genes with differential expression in heart tissues relevant to MI occurrence and development. Vav3 was thus selected for further investigation.

RESULTS

Vav3 downregulation was observed in MI heart tissue and H2O2-treated cardiomyocytes. Administration of Lentiviral Vav3 (LV-VAV3) in MI rats upregulated Vav3 expression in MI heart tissue. Restoration of Vav3 expression reduced infarct area and ameliorated cardiac function in MI rats. Cardiac inflammation, apoptosis, and upregulation of NFκB signal in heart tissue of MI animals were assessed using ELISA, TUNEL staining, real-time PCR, and WB. Vav3 overexpression reduced cardiac inflammation and apoptosis and inhibited NFκB expression and activation. Betulinic Acid (BA) was then used to re-activate NFκB in Vav3-overexpressed and H2O2-induced cardiomyocytes. The expression of P50 and P65, as well as nuclear P65, was significantly increased by BA exposure.

CONCLUSIONS

Vav3 might serve as a target to reduce ischemia damage by suppressing the inflammation and apoptosis of cardiomyocytes.

VAV3 in human cancers: Mechanism and clinical implication

Guanine nucleotide exchange factors (GEFs) are primarily involved in signal transmission between cell membrane receptors and intracellular mediators. Upon replacing GDP with GTP, GEFs can alter their conformation, resulting in their binding to downstream effectors, such as GTPases like Ras homologous (Rho). VAV GEF family are versatile proteins working as an adaptor mediator and GEF for Rho GTPase. They act as a phosphorylation-dependent molecular switcher, fluctuating between active (tyrosine phosphorylated) and inactive (non-phosphorylated) conformation in cell signaling. Accumulating data showed that VAV3 is implicated in cancer progression. The higher levels of VAV3 in human cancers proposed that it may have an oncogenic role in cancer progression. Available studies demonstrated that VAV3 promoted cell proliferation, epithelial-mesenchymal transition (EMT), colony formation, cell cycle, survival, migration and invasion, and suppressed cell apoptosis. In addition, other studies indicated that VAV3 may have a prognostic value in cancer as well as it may act as a mediator in cancer chemoresistance. Here, we aimed to investigate the underlying molecular mechanism of VAV3 in cancer progression as well as to review its value as a prognostic biomarker and chemoresistance mediator in human cancers.

The scaffold RhoGAP protein ARHGAP8/BPGAP1 synchronizes Rac and Rho signaling to facilitate cell migration

Rho GTPases regulate cell morphogenesis and motility under the tight control of guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). However, the underlying mechanism(s) that coordinate their spatiotemporal activities, whether separately or together, remain unclear. We show that a prometastatic RhoGAP, ARHGAP8/BPGAP1, binds to inactive Rac1 and localizes to lamellipodia. BPGAP1 recruits the RacGEF Vav1 under epidermal growth factor (EGF) stimulation and activates Rac1, leading to polarized cell motility, spreading, invadopodium formation, and cell extravasation and promotes cancer cell migration. Importantly, BPGAP1 down-regulates local RhoA activity, which influences Rac1 binding to BPGAP1 and its subsequent activation by Vav1. Our results highlight the importance of BPGAP1 in recruiting Vav1 and Rac1 to promote Rac1 activation for cell motility. BPGAP1 also serves to control the timing of Rac1 activation with RhoA inactivation via its RhoGAP activity. BPGAP1, therefore, acts as a dual-function scaffold that recruits Vav1 to activate Rac1 while inactivating RhoA to synchronize both Rho and Rac signaling in cell motility. As epidermal growth factor receptor (EGFR), Vav1, RhoA, Rac1, and BPGAP1 are all associated with cancer metastasis, BPGAP1 could provide a crucial checkpoint for the EGFR-BPGAP1-Vav1-Rac1-RhoA signaling axis for cancer intervention.

Targeting HuR-Vav3 mRNA interaction prevents Pseudomonas aeruginosa adhesion to the cystic fibrosis airway epithelium

Cystic fibrosis (CF) is characterized by chronic bacterial infections leading to progressive bronchiectasis and respiratory failure. Pseudomonas aeruginosa (Pa) is the predominant opportunistic pathogen infecting the CF airways. The guanine nucleotide exchange factor Vav3 plays a critical role in Pa adhesion to the CF airways by inducing luminal fibronectin deposition that favors bacteria trapping. Here we report that Vav3 overexpression in CF is caused by upregulation of the mRNA-stabilizing protein HuR. We found that HuR accumulates in the cytoplasm of CF airway epithelial cells and that it binds to and stabilizes Vav3 mRNA. Interestingly, disruption of the HuR-Vav3 mRNA interaction improved the CF epithelial integrity, inhibited the formation of the fibronectin-made bacterial docking platforms, and prevented Pa adhesion to the CF airway epithelium. These findings indicate that targeting HuR represents a promising antiadhesive approach in CF that can prevent initial stages of Pa infection in a context of emergence of multidrug-resistant pathogens.

LncRNA RP11-138J23.1 Contributes to Gastric Cancer Progression by Interacting With RNA-Binding Protein HuR

In spite of improvements in diagnostics and treatment of gastric cancer (GC), it remains the most common malignancy of human digestive system. It is now widely appreciated that long noncoding RNAs (lncRNAs) exert extensive regulatory effects on a spectrum of fundamental biological processes through diverse mechanisms. In this study, we explored the expression level and functional role of lncRNA RP11-138J23.1 in GC. Through bioinformatics analyses and in situ hybridization (ISH), we identified that RP11-138J23.1 was upregulated in GC tissue. Further study showed that RP11-138J23.1 knockdown significantly inhibited cell proliferation and metastatic ability. Whereas, RP11-138J23.1 overexpression could promote tumor cell growth and metastasis in vitro. Additionally, loss-of-function assays were used to confirm the role of RP11-138J23.1 in vivo. Mechanistically, RP11-138J23.1 exerted its oncogenic functions by binding to HuR protein and increasing stability of VAV3 mRNA. Overall, our study highlights the essential role of RP11-138J23.1 in GC, suggesting that RP11-138J23.1 might be a potent therapeutic target for patients with GC.

Vav Proteins in Development of the Brain: A Potential Relationship to the Pathogenesis of Congenital Zika Syndrome?

Zika virus (ZIKV) infection during pregnancy can result in a significant impact on the brain and eye of the developing fetus, termed congenital zika syndrome (CZS). At a morphological level, the main serious presentations of CZS are microcephaly and retinal scarring. At a cellular level, many cell types of the brain may be involved, but primarily neuronal progenitor cells (NPC) and developing neurons. Vav proteins have guanine exchange activity in converting GDP to GTP on proteins such as Rac1, Cdc42 and RhoA to stimulate intracellular signaling pathways. These signaling pathways are known to play important roles in maintaining the polarity and self-renewal of NPC pools by coordinating the formation of adherens junctions with cytoskeletal rearrangements. In developing neurons, these same pathways are adopted to control the formation and growth of neurites and mediate axonal guidance and targeting in the brain and retina. This review describes the role of Vavs in these processes and highlights the points of potential ZIKV interaction, such as (i) the binding and entry of ZIKV in cells via TAM receptors, which may activate Vav/Rac/RhoA signaling; (ii) the functional convergence of ZIKV NS2A with Vav in modulating adherens junctions; (iii) ZIKV NS4A/4B protein effects on PI3K/AKT in a regulatory loop via PPI3 to influence Vav/Rac1 signaling in neurite outgrowth; and (iv) the induction of SOCS1 and USP9X following ZIKV infection to regulate Vav protein degradation or activation, respectively, and impact Vav/Rac/RhoA signaling in NPC and neurons. Experiments to define these interactions will further our understanding of the molecular basis of CZS and potentially other developmental disorders stemming from in utero infections. Additionally, Vav/Rac/RhoA signaling pathways may present tractable targets for therapeutic intervention or molecular rationale for disease severity in CZS.

Differential gene expression in liver of colored broiler chicken divergently selected for residual feed intake

Feed constitutes about 60-70% of the total cost of poultry production. So maximizing the feed efficiency will reduce production cost. The rapid growth in the juvenile period is essential to achieve higher body weight. Therefore, identifying the genes and pathways involved in rapid growth at an early age with a lesser requirement of feed is of utmost importance to further economize the broiler production. The efficiency of feed utilization was measured using RFI (residual feed intake). The present study aimed to estimate the RFI (0-5 week) in a population of indigenously developed colored broiler sire line chicken as well as identifying the differentially expressed genes influencing RFI in high and low RFI groups. The liver samples of high and low RFI broiler chicken aged 35 days were used for microarray analysis. A total of 2798 differentially expressed genes (DEGs) were identified, out of which 913 genes were downregulated and 1885 were upregulated. The fold change varied from - 475.17 to 552.94. A subset of genes was confirmed by qRT-PCR, and outcomes were matched well with microarray data. In the functional annotation study of DEGs, the highest significant GO (Gene Ontology) terms in the biological process included protein transport, protein localization, regulation of apoptosis, and mitochondrial transport. Gene network analysis of these DEGs plays an important role to understand the interaction among genes. Study of the important genes which were differentially expressed and the related molecular pathways in this population may hold the potential for future breeding strategies for augmenting feed efficiency.

The guanine nucleotide exchange factor VAV3 participates in ERBB4-mediated cancer cell migration

ERBB4 is a member of the epidermal growth factor receptor (EGFR)/ERBB subfamily of receptor tyrosine kinases that regulates cellular processes including proliferation, migration, and survival. ERBB4 signaling is involved in embryogenesis and homeostasis of healthy adult tissues, but also in human pathologies such as cancer, neurological disorders, and cardiovascular diseases. Here, an MS-based analysis revealed the Vav guanine nucleotide exchange factor 3 (VAV3), an activator of Rho family GTPases, as a critical ERBB4-interacting protein in breast cancer cells. We confirmed the ERBB4-VAV3 interaction by targeted MS and coimmunoprecipitation experiments and further defined it by demonstrating that kinase activity and Tyr-1022 and Tyr-1162 of ERBB4, as well as the intact phosphotyrosine-interacting SH2 domain of VAV3, are necessary for this interaction. We found that ERBB4 stimulates tyrosine phosphorylation of the VAV3 activation domain, known to be required for guanine nucleotide exchange factor (GEF) activity of VAV proteins. In addition to VAV3, the other members of the VAV family, VAV1 and VAV2, also coprecipitated with ERBB4. Analyses of the effects of overexpression of dominant-negative VAV3 constructs or shRNA-mediated down-regulation of VAV3 expression in breast cancer cells indicated that active VAV3 is involved in ERBB4-stimulated cell migration. These results define the VAV GEFs as effectors of ERBB4 activity in a signaling pathway relevant for cancer cell migration.

QuaDMutNetEx: a method for detecting cancer driver genes with low mutation frequency

BACKGROUND

Cancer is caused by genetic mutations, but not all somatic mutations in human DNA drive the emergence or growth of cancers. While many frequently-mutated cancer driver genes have already been identified and are being utilized for diagnostic, prognostic, or therapeutic purposes, identifying driver genes that harbor mutations occurring with low frequency in human cancers is an ongoing endeavor. Typically, mutations that do not confer growth advantage to tumors - passenger mutations - dominate the mutation landscape of tumor cell genome, making identification of low-frequency driver mutations a challenge. The leading approach for discovering new putative driver genes involves analyzing patterns of mutations in large cohorts of patients and using statistical methods to discriminate driver from passenger mutations.

RESULTS

We propose a novel cancer driver gene detection method, QuaDMutNetEx. QuaDMutNetEx discovers cancer drivers with low mutation frequency by giving preference to genes encoding proteins that are connected in human protein-protein interaction networks, and that at the same time show low deviation from the mutual exclusivity pattern that characterizes driver mutations occurring in the same pathway or functional gene group across a cohort of cancer samples.

CONCLUSIONS

Evaluation of QuaDMutNetEx on four different tumor sample datasets show that the proposed method finds biologically-connected sets of low-frequency driver genes, including many genes that are not found if the network connectivity information is not considered. Improved quality and interpretability of the discovered putative driver gene sets compared to existing methods shows that QuaDMutNetEx is a valuable new tool for detecting driver genes. QuaDMutNetEx is available for download from https://github.com/bokhariy/QuaDMutNetExunder the GNU GPLv3 license.

Evaluation of Vav3.1 as prognostic marker in endometrial cancer

PURPOSE

Vav3 is a guanine nucleotide exchange factor that regulates the activity of Rho/Rac family GTPases. In a study on ovarian cancer, we recently demonstrated pronounced prognostic and predictive value of Vav3.1, a specific truncation variant of the parental Vav3 gene. Here, we sought to investigate the role of Vav3.1 in the most prevalent gynecological tumor entity, endometrial cancer.

METHODS

Vav3.1 transcript levels were determined in a large cohort of endometrial cancer patients using variant-specific PCR (n = 239), and non-malignant endometrial tissue served as control (n = 26). Expression levels of Vav3.1 were stratified according to established clinicopathological characteristics and correlated to long-term patient survival (average follow-up of > 7.5 years). Type 1 and type 2 cancers were separately investigated.

RESULTS

While Vav3.1 was markedly overexpressed in endometrial cancer tissue, we could not detect associations with clinical parameters related to prognosis, such as FIGO stage and tumor grade. Kaplan-Meier estimators of different measures of survival failed to show prognostic significance of Vav3.1 in endometrial cancer. Lack of prognostic value was observed for both type 1 and type 2 cancers.

CONCLUSIONS

Our study shows that Vav3.1 is not suited as a marker of cancer progression and/or treatment response in endometrial cancer. Feasibility and potential benefit of targeting Vav3.1 in endometrial cancer needs to be evaluated in future studies, proceeding from its clear, roughly ten-fold, induction in the malignant endometrium.

Characterization of FGD5 Expression in Primary Breast Cancers and Lymph Node Metastases

Faciogenital dysplasia 5 ( FGD5) amplification drives tumor cell proliferation, and is present in 9.5% of breast cancers. We describe FGD5 expression, assess associations between FGD5 amplification and FGD5 expression, and assess FGD5 expression in relation to proliferation and prognosis. FGD5 immunohistochemistry was done on primary tumors ( n=829) and lymph node metastases ( n=231) from a cohort of Norwegian patients. We explored associations between FGD5 amplification, FGD5 expression, and proliferation, and analyzed the prognostic value of FGD5 expression by estimating cumulative risks of death and hazard ratios (HRs). We identified nuclear and cytoplasmic expression in 64% and 73% of primary tumors, respectively, and found an association between gene amplification and nuclear expression ( p=0.02). The proportion of cases with FGD5 expression was higher in lymph node metastases, compared with primary tumors ( p=0.004 for nuclear and p=0.001 for cytoplasmic staining). Neither proliferation nor prognosis was associated with FGD5 expression (age-adjusted HR 1.12 [95% confidence interval = 0.89-1.41] for nuclear expression; and 0.88 [95% CI = 0.70-1.12] for cytoplasmic expression). FGD5 is expressed in a high proportion of breast cancers and lymph node metastases. There was a correlation between FGD5 amplification and nuclear expression, but no association between FGD5 expression and proliferation or prognosis.

Therapeutic sensitivity to Rac GTPase inhibition requires consequential suppression of mTORC1, AKT, and MEK signaling in breast cancer

Rac GTPases have oncogenic roles in cell growth, survival, and migration. We tested response to the Rac inhibitor EHT1864 in a panel of breast cancer cell lines. EHT1864-induced growth inhibition was associated with dual inhibition of the PI3K/AKT/mTORC1 and MEK/ERK pathways. Breast cancer cells harboring PIK3CA mutations or HER2 overexpression were most sensitive to Rac inhibition, suggesting that such oncogenic alterations link Rac activation with PI3K/AKT/mTORC1 and MEK/ERK signaling. Interestingly, EHT1864 decreased activation of the mTORC1 substrate p70S6K earlier than AKT inhibition, suggesting that Rac may activate mTORC1/p70S6K independently of AKT. Comparison of the growth-inhibitory profile of EHT1864 to 137 other anti-cancer drugs across 656 cancer cell lines revealed significant correlation with the p70S6K inhibitor PF-4708671. We confirmed that Rac complexes contain MEK1/2 and ERK1/2, but also contain p70S6K; these interactions were disrupted by EHT1864. Pharmacokinetic profiles revealed that EHT1864 was present in mouse plasma at concentrations effective in vitro for approximately 1 h after intraperitoneal administration. EHT1864 suppressed growth of HER2+ tumors, and enhanced response to anti-estrogen treatment in ER+ tumors. Further therapeutic development of Rac inhibitors for HER2+ and PIK3CA-mutant cancers is warranted.

Widespread alternative exon usage in clinically distinct subtypes of Invasive Ductal Carcinoma

Cancer cells can have different patterns of exon usage of individual genes when compared to normal tissue, suggesting that alternative splicing may play a role in shaping the tumor phenotype. The discovery and identification of gene variants has increased dramatically with the introduction of RNA-sequencing technology, which enables whole transcriptome analysis of known, as well as novel isoforms. Here we report alternative splicing and transcriptional events among subtypes of invasive ductal carcinoma in The Cancer Genome Atlas (TCGA) Breast Invasive Carcinoma (BRCA) cohort. Alternative exon usage was widespread, and although common events were shared among three subtypes, ER+ HER2−, ER− HER2−, and HER2+, many events on the exon level were subtype specific. Additional RNA-seq analysis was carried out in an independent cohort of 43 ER+ HER2− and ER− HER2− primary breast tumors, confirming many of the exon events identified in the TCGA cohort. Alternative splicing and transcriptional events detected in five genes, MYO6, EPB41L1, TPD52, IQCG, and ACOX2 were validated by qRT-PCR in a third cohort of 40 ER+ HER2− and ER− HER2− patients, showing that these events were truly subtype specific.

Expression of Vav3 protein and its prognostic value in patients with gastric cancer

Vav3 is associated with tumor growth, apoptosis, invasion, metastasis and angiogenesis. In this study, we detected the expression of Vav3 in gastric cancer tissues, and explored its role in invasion, metastasis and prognosis of gastric cancer. Vav3, MMP-2, MMP-9, TIMP-1 and TIMP-2 in primary lesion and pericarcinous tissues were tested with Immunohistochemistry and Western blot. Results showed a higher expression of Vav3 in primary lesion than in pericarcinous tissue, and the expression of Vav3 was significantly correlated with MMP-2, MMP-9 and TIMP-1 in gastric cancer tissues. Overexpression of Vav3 was associated with poorer differentiation, advanced clinical stage, more significant infiltration depth, lymphatic metastasis, and perineural invasion. Results of Kaplan-Meier verified that overexpression of Vav3 was related to poorer prognosis and shorter survival time. Moreover, Cox proportional hazard model revealed that overexpression of Vav3 was an independent risk factor of prognosis for patients with gastric cancer. In all, we conclude that overexpression of Vav3 is an independent risk factor for prognosis of gastric cancer, and can be used as a prognostic indicator. This may be because that Vav3 could regulate genes which associated with the invasion and metastasis.

Astragaloside IV inhibits breast cancer cell invasion by suppressing Vav3 mediated Rac1/MAPK signaling

BACKGROUND

Astragaloside IV (AS-IV), the major active triterpenoid in Radix Astragali, has shown anti-tumorigenic properties in certain cancers; however, its role in breast cancer remains unclear. The present study investigated the effects of AS-IV on breast cancer in vitro and in vivo and examined the underlying mechanisms.

METHODS

The effects of AS-IV on MDA-MB-231 cell proliferation, migration, invasion and metastasis were investigated by MTT and Transwell assays, and western blotting. In addition, an orthotopic mouse tumor model was established for in vivo experiments.

RESULTS

AS-IV inhibited the viability and invasive potential of MDA-MB-231 breast cancer cells, suppressed the activation of the mitogen activated protein kinase (MAPK) family members ERK1/2 and JNK, and downregulated matrix metalloproteases (MMP)-2 and -9. The effects of AS-IV were mediated by the downregulation of Vav3, a guanine nucleotide exchange factor, leading to decreased levels of activated Rac1, a Rho family GTPase. Vav3 overexpression promoted cell proliferation and invasion in vitro, whereas Vav3 silencing had the opposite effects. AS-IV suppressed orthotopic breast tumor growth and metastasis to the lungs, whereas ectopic expression of Vav3 reversed the inhibitory effect of AS-IV on cell viability, invasiveness, MAPK signaling and MMP expression.

CONCLUSION

The present results provide a mechanistic explanation for the antitumor effects of AS-IV and suggest its potential in the treatment of metastatic breast cancer.

Vav3 is linked to poor prognosis of pancreatic cancers and promotes the motility and invasiveness of pancreatic cancer cells

BACKGROUND/OBJECTIVES

The aim of this study was to investigate the role of the guanine nucleotide exchange factor Vav3 in the motility and invasiveness of pancreatic ductal adenocarcinoma (PDAC) cells.

METHODS

Immunohistochemistry was used to determine whether high Vav3 expression in human PDAC tissues is correlated with poor prognosis. Immunocytochemistry was used to determine the association and intracellular distribution of Vav3, Rac1 and Akt in PDAC cells. Phosphoprotein array analysis was performed to determine the Vav3-associated intracellular signaling pathways. Immunocytochemistry and Matrigel invasion assays were used to examine the effects of Vav3 on the formation of cell protrusions and PDAC cell invasion.

RESULTS

Expression of Vav3 in PDAC tissue was significantly correlated with overall survival. Vav3 was localized in cell protrusions of migrating PDAC cells. Knockdown of Vav3 inhibited the motility and invasiveness of PDAC cells through a decrease in cell protrusions. The levels of active Rac1 or active Akt were not associated with the concentration of Vav3 in cell protrusions. The Vav3-dependent promotion of motility and invasiveness was not modulated by Rac1 or Akt. Additionally, knockdown of Vav3 increased phosphorylated WNK1 in PDAC cells, and knockdown of WNK1 inhibited the motility and invasiveness. This study suggests that Vav3 can be a useful marker for predicting the outcome of patients with PDAC and that Vav3 can promote PDAC cell motility and invasion through association with dephosphorylation of WNK1.

CONCLUSIONS

Vav3 was accumulated in cell protrusions, contributed to the formation of membrane protrusions, and thereby increased the motility and invasiveness of PDAC cells.

Overexpression of miR-499-5p inhibits non-small cell lung cancer proliferation and metastasis by targeting VAV3

Dysregulation of miRNAs is reported to be involved in the invasion and metastasis of lung cancer. Previous studies showed that low serum miR-499 expression was associated with advanced TNM stage and poor prognosis. The present study is carried out to evaluate the biological functions of miR-499-5p in lung cancer. We demonstrated that miR-499-5p was significantly reduced in NSCLC tissues and correlated with poor clinical outcomes. Overexpression of miR-499-5p inhibited cell proliferation and induced apoptosis in vitro and in vivo. Furthermore, miR-499-5p overexpression also inhibited NSCLC metastasis in vitro and in vivo. Using bioinformatics tools, we identified VAV3 as a candidate target of miR-499-5p, and demonstrated that restoration of miR-499-5p expression in NSCLC cells downregulated VAV3 expression while inhibition of miR-499-5p upregulated VAV3 expression. Luciferase reporter assays showed that miR-499-5p targeted 3′-UTR of VAV3. Moreover, cancer growth, proliferation and metastasis were decreased and apoptosis was increased after VAV3 blockage induced by miR-499-5p overexpression. We conclude that miR-499-5p functions as a tumor suppressor by targeting VAV3. This finding may provide a therapeutic approach for future treatment of NSCLC.

Inhibition of Vav3 gene can promote apoptosis of human gastric cancer cell line MGC803 by regulating ERK pathway

Previous studies proved that Vav3 gene was overexpressed in cancers. However, the molecular mechanism of Vav3 in apoptosis still keeps unclear; therefore, the relationship between Vav3 gene and apoptosis of gastric cancer (GC) was explored in the present study. Vav3-siRNA was transfected into MGC803 cells, and then cell activity and apoptosis rate were tested with MTT and FCM; apoptosis-related genes and proteins in MAPK signaling pathway were also tested. Results showed that Vav3 was overexpressed in GC than in adjacent normal tissues (all P < 0.05), and expression of Vav3 was related to degree of histological differentiation, cancer invasion depth, and lymphatic metastasis (Χ (2)  = 7.185, P = 0.007; Χ (2)  = 18.654, P < 0.001; Χ (2)  = 5.058, P = 0.025). Vav3 silencing inhibited activity of MGC803 cells, and apoptosis rate of cells was affected. Vav3-siRNA transfection led to changes of apoptosis-related genes such as Survivin, xIAP, Bcl-2, caspase-3, and Bax (all P < 0.01). After transfection, ratio of phosphorylation of ERK significantly reduced. We concluded that Vav3 inhibition can suppress cell activity and promote apoptosis by regulating the apoptosis-related genes through the ERK pathway.

PH motifs in PAR1&2 endow breast cancer growth

Although emerging roles of protease-activated receptor_1&2 (PAR_1&2) in cancer are recognized, their underlying signalling events are poorly understood. Here we show signal-binding motifs in PAR_1&2 that are critical for breast cancer growth. This occurs via the association of the pleckstrin homology (PH) domain with Akt/PKB as a key signalling event of PARs. Other PH-domain signal-proteins such as Etk/Bmx and Vav₃ also associate with PAR₁ and PAR₂ through their PH domains. PAR₁ and PAR₂ bind with priority to Etk/Bmx. A point mutation in PAR₂, H349A, but not in R352A, abrogates PH-protein association and is sufficient to markedly reduce PAR₂-instigated breast tumour growth in vivo and placental extravillous trophoblast (EVT) invasion in vitro. Similarly, the PAR₁ mutant hPar1-7A, which is unable to bind the PH domain, reduces mammary tumours and EVT invasion, endowing these motifs with physiological significance and underscoring the importance of these previously unknown PAR₁ and PAR₂ PH-domain-binding motifs in both pathological and physiological invasion processes.

Protease-activated-receptor 1 and 2 (PAR1 and PAR2) are key players in tumor growth. In this study, the authors identify PAR1 and PAR2 domains that bind oncogenic signalling proteins driving breast cancer progression in vivo and placental extravillous trophoblast invasion in vitro.

Genome-wide association study of susceptibility loci for breast cancer in Sardinian population

BACKGROUND

Despite progress in identifying genes associated with breast cancer, many more risk loci exist. Genome-wide association analyses in genetically-homogeneous populations, such as that of Sardinia (Italy), could represent an additional approach to detect low penetrance alleles.

METHODS

We performed a genome-wide association study comparing 1431 Sardinian patients with non-familial, BRCA1/2-mutation-negative breast cancer to 2171 healthy Sardinian blood donors. DNA was genotyped using GeneChip Human Mapping 500 K Arrays or Genome-Wide Human SNP Arrays 6.0. To increase genomic coverage, genotypes of additional SNPs were imputed using data from HapMap Phase II. After quality control filtering of genotype data, 1367 cases (9 men) and 1658 controls (1156 men) were analyzed on a total of 2,067,645 SNPs.

RESULTS

Overall, 33 genomic regions (67 candidate SNPs) were associated with breast cancer risk at the p <  0(-6) level. Twenty of these regions contained defined genes, including one already associated with breast cancer risk: TOX3. With a lower threshold for preliminary significance to p < 10(-5), we identified 11 additional SNPs in FGFR2, a well-established breast cancer-associated gene. Ten candidate SNPs were selected, excluding those already associated with breast cancer, for technical validation as well as replication in 1668 samples from the same population. Only SNP rs345299, located in intron 1 of VAV3, remained suggestively associated (p-value, 1.16 x 10(-5)), but it did not associate with breast cancer risk in pooled data from two large, mixed-population cohorts.

CONCLUSIONS

This study indicated the role of TOX3 and FGFR2 as breast cancer susceptibility genes in BRCA1/2-wild-type breast cancer patients from Sardinian population.

High nuclear level of Vav1 is a positive prognostic factor in early invasive breast tumors: a role in modulating genes related to the efficiency of metastatic process

Vav1 is one of the signalling proteins normally restricted to hematopoietic cells that results ectopically expressed in solid tumors, including breast cancer. By immunohistochemical analysis on TMAs containing invasive breast tumor from patients without lymph node involvement, we have found that Vav1 is expressed in almost all investigated cancers and shows a peculiar localization inside the nucleus of tumor cells. High amounts of nuclear Vav1 are positively correlated with low incidence of relapse, regardless phenotype and molecular subtype of breast neoplasia. In particular, Kaplan-Meier plots showed an elevated risk of distant metastasis in patients with low Vav1 expression compared with patients with high Vav1 expression in their tumors. Experiments performed with breast tumor-derived cells indicated that Vav1 negatively modulates their invasiveness in vitro and their metastatic efficiency in vivo, possibly by affecting the expression of genes involved in invasion and/or metastasis of breast tumors. Since the high heterogeneity of breast tumors makes difficult to predict the evolution of early breast neoplasias, the evaluation of nuclear Vav1 levels may help in the characterization and management of early breast cancer patients. In particular, Vav1 may serve as a prognostic biomarker and a target for new therapies aimed to prevent breast cancer progression.

VAV3 Overexpressed in Cancer Stem Cells Is a Poor Prognostic Indicator in Ovarian Cancer Patients

Ovarian carcinoma is a highly lethal malignancy due to frequent relapse and drug resistance. Cancer stem cells (CSCs) are thought to contribute significantly to disease relapse and drug resistance. In this study, a subpopulation of CSCs of ovarian carcinoma was isolated and the genes differentially expressed in these cells were identified to characterize CSCs and to find candidate biomarkers. Ovarian carcinoma cells from patients were primarily cultured, and spheroid-forming cells (SFCs) were isolated. The characteristic genes of SFCs were identified through cDNA microarray and validation by quantitative real-time polymerase chain reaction and immunohistochemistry, and the association of their expression with clinicopathologic parameters was analyzed. GSC (4.26-fold), VAV3 (7.05-fold), FOXA2 (12.06-fold), LEF1 (17.26-fold), COMP (21.33-fold), GRIN2A (9.36-fold), CD86 (23.14-fold), PYY (4.18-fold), NKX3-2 (10.35-fold), and PDK4 (74.26-fold) were significantly upregulated in SFCs compared with parental cancer cells. With validation for human ovarian carcinomas, LEF1, PYY, NKX3-2, and WNT3A were significantly upregulated in chemoresistant cancers compared with chemosensitive cancers. Overexpression of LEF1, VAV3, and NKX3-2 was significantly associated with distant metastasis by immunohistochemistry. VAV3 overexpression was an independent poor survival indicator (hazard ratio=15.27, P<0.05) by multivariate Cox analysis. The further functional assay revealed that VAV3 knockdown regulated CSC activation and ovarian cancer cell proliferation and sensitized paclitaxel (PTX)-resistant cancer cells to PTX treatment. Taken together, we identified by high-throughput analysis of CSCs that VAV3 overexpression is a novel biomarker for poor prognosis and survival in ovarian carcinoma.

VAV3 oncogene expression in colorectal cancer: clinical aspects and functional characterization

Although colorectal cancer (CRC) is one of the most common malignancies worldwide, the current therapeutic approaches for advanced CRC are ineffective. In this study, we investigated the involvement of the VAV3 oncogene in tumor progression and in the prognosis of human CRC. The two patient cohorts in this study comprised 354 CRC cases from 1998 to 2005 with documented pathologic and clinical factors and clinical outcomes. VAV3 protein levels were significantly correlated with the depth of invasion (P = 0.0259), the nodal status (P < 0.0001), distant metastasis (P = 0.0354), the stage (P < 0.0001), and poor disease-free survival (P = 0.003). Multivariate Cox regression analysis showed that VAV3 overexpression is an independent prognostic marker for CRC (P = 0.041). In vitro experiments indicated that VAV3 knockdown inhibited CRC cell growth, spread, and xenograft proliferation. Mechanistic studies further revealed that VAV3 overexpression could dysregulate the expression of cell cycle control- and metastasis-related molecules by activating the PI3K-AKT signaling pathway in both CRC cells and xenografts. This study suggests that VAV3 overexpression could be a useful marker for predicting the outcomes of CRC patients and that VAV3 targeting represents a potential modality for treating CRC.

Minireview: Tipping the balance: ligand-independent activation of steroid receptors

Steroid receptors are prototypical ligand-dependent transcription factors and a textbook example for allosteric regulation. According to this canonical model, binding of cognate steroid is an absolute requirement for transcriptional activation. Remarkably, the simple one ligand-one receptor model could not be farther from the truth. Steroid receptors, notably the sex steroid receptors, can receive multiple inputs. Activation of steroid receptors by other signals, working through their own signaling pathways, in the absence of the cognate steroids, represents the most extreme form of signaling cross talk. Compared with cognate steroids, ligand-independent activation pathways produce similar but not identical outputs. Here we review the phenomena and discuss what is known about the underlying molecular mechanisms and the biological significance. We hypothesize that steroid receptors may have evolved to be trigger happy. In addition to their cognate steroids, many posttranslational modifications and interactors, modulated by other signals, may be able to tip the balance.

Inhibition of Vav3 could reverse the drug resistance of gastric cancer cells by downregulating JNK signaling pathway

This study aims to investigate the effect and mechanism of Vav3 on the multidrug resistance of gastric cancer. Fluorescence quantitative RT-PCR and western blot assay were used to detect Vav3 and drug resistance genes in gastric cancer tissues as well as gastric cell lines such as SGC7901, SGC7901/adriamycin (ADR) and GES-1. Besides, Vav3-specific small interfering RNA (Vav3-siRNA) was applied to inhibit Vav3 in SGC7901/ADR, and SRB assay was used to determine chemosensitivity. After that, drug resistance genes and proteins in MAPK and PI3K/AKT signaling pathway were detected after Vav3-siRNA transfection. The results showed that overexpressed Vav3 was found in gastric cancer tissues and SGC7901 and SGC7901/ADR cells. Activity of SGC7901/ADR cells transfected with Vav3-siRNA combined with 5-fluorouracil/oxaliplatin was much lower than that of control groups, and MDR1/P-gp, GST-π and Bcl-2, Bax genes were significantly downregulated in Vav3-siRNA transfection group. AKT, ERK and p38 total protein and their phosphorylation levels showed no significant change in Vav3-siRNA-transfected SGC7901/ADR cells, whereas the ratio of C-Jun phosphorylation levels to total C-Jun protein was significantly downregulated. The results suggested that Vav3 may play a role in drug resistance of gastric cancer by inhibiting drug resistance genes MDR1/P-gp, GST-π and Bcl-2 through regulating the JNK signaling pathway.

SPARC and Vav3 Expression in Meningioma: Factors Related to Prognosis

Background:

Meningiomas account for approximately 24-30% of primary intracranial neoplasms. Histopathologic grade and degree of resection are two major prognostic factors. The aim of this study was to determine the factors associated with the prognosis of meningioma.

Methods:

We used immunohistochemistry to analyze the expression levels of Vav3, SPARC, p-Akt, cyclin D1, and Ki-67 in 287 meningiomas of all grades.

Results:

The expression of Vav3, SPARC, p-Akt, cyclin D1, and Ki- 67 significantly increased with meningioma grade (p<0.01), and was higher in brain-invasive meningiomas compared to non-invasive meningiomas (WHO grade I) (p<0.05). Furthermore, the expression of Vav3, p-Akt, and Ki-67 was higher in recurrent meningiomas compared to non-recurrent meningiomas (WHO grade I) (p<0.05).

Conclusion:

The expression of Vav3, SPARC, p-Akt, cyclin D1, and Ki-67 in meningiomas appears to correlate with meningioma invasiveness, aggressiveness, and recurrence.

VAV3 mediates resistance to breast cancer endocrine therapy

Introduction

Endocrine therapies targeting cell proliferation and survival mediated by estrogen receptor α (ERα) are among the most effective systemic treatments for ERα-positive breast cancer. However, most tumors initially responsive to these therapies acquire resistance through mechanisms that involve ERα transcriptional regulatory plasticity. Herein we identify VAV3 as a critical component in this process.

Methods

A cell-based chemical compound screen was carried out to identify therapeutic strategies against resistance to endocrine therapy. Binding to ERα was evaluated by molecular docking analyses, an agonist fluoligand assay and short hairpin (sh)RNA–mediated protein depletion. Microarray analyses were performed to identify altered gene expression. Western blot analysis of signaling and proliferation markers, and shRNA-mediated protein depletion in viability and clonogenic assays, were performed to delineate the role of VAV3. Genetic variation in VAV3 was assessed for association with the response to tamoxifen. Immunohistochemical analyses of VAV3 were carried out to determine its association with therapeutic response and different tumor markers. An analysis of gene expression association with drug sensitivity was carried out to identify a potential therapeutic approach based on differential VAV3 expression.

Results

The compound YC-1 was found to comparatively reduce the viability of cell models of acquired resistance. This effect was probably not due to activation of its canonical target (soluble guanylyl cyclase), but instead was likely a result of binding to ERα. VAV3 was selectively reduced upon exposure to YC-1 or ERα depletion, and, accordingly, VAV3 depletion comparatively reduced the viability of cell models of acquired resistance. In the clinical scenario, germline variation in VAV3 was associated with the response to tamoxifen in Japanese breast cancer patients (rs10494071 combined P value = 8.4 × 10⁻⁴). The allele association combined with gene expression analyses indicated that low VAV3 expression predicts better clinical outcome. Conversely, high nuclear VAV3 expression in tumor cells was associated with poorer endocrine therapy response. Based on VAV3 expression levels and the response to erlotinib in cancer cell lines, targeting EGFR signaling may be a promising therapeutic strategy.

Conclusions

This study proposes VAV3 as a biomarker and a rationale for its use as a signaling target to prevent and/or overcome resistance to endocrine therapy in breast cancer.

Inhibition of gastric cancer cell growth and invasion through siRNA-mediated knockdown of guanine nucleotide exchange factor Vav3

Vav3, a Rho GTPase guanine nucleotide exchange factor, is associated with tumor growth, apoptosis, invasion and metastasis, and angiogenesis. However, the role of Vav3 in gastric cancer remains unclear. In this study, Vav3 expression was blocked by specific siRNA in gastric cancer cell line MGC803. MTT was used to assay cell proliferation activity; wound healing assay and transwell assay were applied to detect cell migration and invasion ability; and qRT-PCR and Western blot were employed to detect expression levels of Vav3 as well as proliferation, migration, and invasion-related genes. The results showed that Vav3 expression in gastric cancer tissues and cell lines was significantly upregulated and was higher than that in adjacent tissues of cancer and normal gastric mucosal cell lines. Vav3 knockdown inhibited proliferation, migration, and invasion of MGC803 gastric cancer cells. The expression of P21, P27, TIMP-1, and TIMP-2 was upregulated, while proliferating cell nuclear antigen, cyclin E1, matrix metalloproteinase (MMP)-2, and MMP-7 were downregulated by Vav3 knockdown in MGC803 gastric cells. In conclusion, Vav3 is involved in the proliferation, migration, and invasion of gastric cancer cell as a tumor oncogene.

How integrins control breast biology

This article explores new ideas about how the ECM-integrin axis controls normal and malignant breast biology. We discuss the role of integrins in mammary stem cells, and how cell-matrix interactions regulate ductal and alveolar development and function. We also examine the contribution of integrins to tissue disorganisation and metastasis, and how an altered stromal and ECM tumour microenvironment affects the cancer cell niche both within primary tumours and at distant sites. Finally, we mention novel strategies for integrin-directed breast cancer treatment.

Targeted estrogen delivery reverses the metabolic syndrome

We report the development of a new combinatorial approach that allows for peptide-mediated selective tissue targeting of nuclear hormone pharmacology while eliminating adverse effects in other tissues. Specifically, we report the development of a glucagon-like peptide-1 (GLP-1)-estrogen conjugate that has superior sex-independent efficacy over either of the individual hormones alone to correct obesity, hyperglycemia and dyslipidemia in mice. The therapeutic benefits are driven by pleiotropic dual hormone action to improve energy, glucose and lipid metabolism, as shown by loss-of-function models and genetic action profiling. Notably, the peptide-based targeting strategy also prevents hallmark side effects of estrogen in male and female mice, such as reproductive endocrine toxicity and oncogenicity. Collectively, selective activation of estrogen receptors in GLP-1-targeted tissues produces unprecedented efficacy to enhance the metabolic benefits of GLP-1 agonism. This example of targeting the metabolic syndrome represents the discovery of a new class of therapeutics that enables synergistic co-agonism through peptide-based selective delivery of small molecules. Although our observations with the GLP-1-estrogen conjugate justify translational studies for diabetes and obesity, the multitude of other possible combinations of peptides and small molecules may offer equal promise for other diseases.

PCA3 noncoding RNA is involved in the control of prostate-cancer cell survival and modulates androgen receptor signaling

BACKGROUND

PCA3 is a non-coding RNA (ncRNA) that is highly expressed in prostate cancer (PCa) cells, but its functional role is unknown. To investigate its putative function in PCa biology, we used gene expression knockdown by small interference RNA, and also analyzed its involvement in androgen receptor (AR) signaling.

METHODS

LNCaP and PC3 cells were used as in vitro models for these functional assays, and three different siRNA sequences were specifically designed to target PCA3 exon 4. Transfected cells were analyzed by real-time qRT-PCR and cell growth, viability, and apoptosis assays. Associations between PCA3 and the androgen-receptor (AR) signaling pathway were investigated by treating LNCaP cells with 100 nM dihydrotestosterone (DHT) and with its antagonist (flutamide), and analyzing the expression of some AR-modulated genes (TMPRSS2, NDRG1, GREB1, PSA, AR, FGF8, CdK1, CdK2 and PMEPA1). PCA3 expression levels were investigated in different cell compartments by using differential centrifugation and qRT-PCR.

RESULTS

LNCaP siPCA3-transfected cells significantly inhibited cell growth and viability, and increased the proportion of cells in the sub G0/G1 phase of the cell cycle and the percentage of pyknotic nuclei, compared to those transfected with scramble siRNA (siSCr)-transfected cells. DHT-treated LNCaP cells induced a significant upregulation of PCA3 expression, which was reversed by flutamide. In siPCA3/LNCaP-transfected cells, the expression of AR target genes was downregulated compared to siSCr-transfected cells. The siPCA3 transfection also counteracted DHT stimulatory effects on the AR signaling cascade, significantly downregulating expression of the AR target gene. Analysis of PCA3 expression in different cell compartments provided evidence that the main functional roles of PCA3 occur in the nuclei and microsomal cell fractions.

CONCLUSIONS

Our findings suggest that the ncRNA PCA3 is involved in the control of PCa cell survival, in part through modulating AR signaling, which may raise new possibilities of using PCA3 knockdown as an additional therapeutic strategy for PCa control.

Rho GEFs and cancer: linking gene expression and metastatic dissemination

Guanine nucleotide exchange factors (GEFs) that promote GTP loading onto the guanosine triphosphatases (GTPases) Rho and Rac are prominent players in cancer progression. Recent studies have highlighted the relevance of several GEFs, including the phosphatidylinositol 3,4,5-trisphosphate Rac exchangers P-Rex1 and P-Rex2a, in breast tumorigenesis. New evidence suggests that the exchange factors Vav2 and Vav3 play synergistic roles in breast cancer by sustaining tumor growth, neoangiogenesis, and metastasis. The identification of a Vav-regulated transcriptome and Vav-related genes that control specific steps of metastatic dissemination of breast cancer cells to the lungs highlights the complexities of the signaling networks regulated by Rho/Rac GTPases and may lead to novel therapeutic targets.

Gankyrin promotes breast cancer cell metastasis by regulating Rac1 activity

Tumor metastasis is responsible for most cancer patients' deaths. Understanding the mechanism of metastasis is crucial for improving the cure rate for cancer. Here, we report that Gankyrin, a chaperone of ubiquitin-proteasome, has an essential role in breast cancer metastasis. We find that Gankyrin is highly overexpressed in human breast cancers and the expression correlates strongly with lymph node metastasis. Knocking down Gankyrin expression in highly metastatic human breast cancer cells significantly decreases cancer cell migration and invasion. Furthermore, we demonstrate that depletion of Gankyrin inhibits intrinsic Rac1 activity and induces large focal adhesions. Overexpression of Gankyrin accelerates focal adhesion turnover and increases cell migration. Notably, reduction of Gankyrin expression in mouse mammary tumor cell significantly decreases tumor metastasis to lung in animal models. Therefore, our findings suggest that Gankyrin is crucial for breast cancer metastasis and highlight the potential of Gankyrin as a therapeutic target for tumor metastasis.

Expression of VAV1 in the tumour microenvironment of glioblastoma multiforme

Even though much progress has been made towards understanding the molecular nature of glioma, the survival rates of patients affected by this tumour have not changed significantly over recent years. Better knowledge of this malignancy is still needed in order to predict its outcome and improve patient treatment. VAV1 is an GDP/GTP exchange factor for Rho/Rac proteins with oncogenic potential that is involved in the regulation of cytoskeletal dynamics and cell migration. Here we report its overexpression in 59 patients diagnosed with high-grade glioma, and the associated upregulation of a number of genes coding for proteins also involved in cell invasion- and migration-related processes. Unexpectedly, immunohistochemical experiments revealed that VAV1 is not expressed in glioma cells. Instead, VAV1 is found in non-tumoural astrocyte-like cells that are located either peritumouraly or perivascularly. We propose that the expression of VAV1 is linked to synergistic signalling cross-talk between cancer and infiltrating cells. Interestingly, we show that the pattern of expression of VAV1 could have a role in the neoplastic process in glioblastoma tumours.

Clinical significance of increased guanine nucleotide exchange factor Vav3 expression in human gastric cancer

Although gastric cancer is one of the most common malignancies worldwide, little is known on the molecular process of its development and progression. This study investigates the involvement of guanine nucleotide exchange factor Vav3 in tumor progression and in the prognosis of human gastric cancer. The two patient cohorts in this study consisted of 167 gastric cancer cases from 1997 through 2001, documenting pathologic and clinical factors, as well as the clinical outcomes. Immunohistochemistry, reverse transcription PCR, immunoblotting, and immunofluorescence were used to examine Vav3 expression in tumor and nontumor pairs of gastric tissues and gastric cell lines. Small hairpin RNA (shRNA) technology was used to study the effects of Vav3 knockdown on the growth and spread of gastric cancer cells. Finally, xenograph proliferation was used to study the tumor growth. Overexpression of Vav3 was associated with the depth of invasion (P = 0.0004), nodal status (P = 0.0260), distant metastasis (P = 0.0003), stage (P = 0.0002), and vascular invasion (P = 0.0286); and correlated with poor disease-free survival (P < 0.0001). Multivariate Cox regression analysis shows that overexpression of Vav3 is an independent prognostic marker for gastric cancer (P = 0.033). Disrupting the expression of Vav3 using shRNA technology inhibited gastric cancer cell growth, spread, and xenograph proliferation. This study suggests that overexpression of Vav3 can be a useful marker for predicting the outcome of patients with gastric cancer and that Vav3 targeting can represent a potential modality for treating gastric cancer.

The treatment of breast cancer using liposome technology

Liposome-based chemotherapeutics used in the treatment of breast cancer can in principle enhance the therapeutic index of otherwise unencapsulated anticancer drugs. This is partially attributed to the fact that encapsulation of cytotoxic agents within liposomes allows for increased concentrations of the drug to be delivered to the tumor site. In addition, the presence of the phospholipid bilayer prevents the encapsulated active form of the drug from being broken down in the body prior to reaching tumor tissue and also serves to minimize exposure of the drug to healthy sensitive tissue. While clinically approved liposome-based chemotherapeutics such as Doxil have proven to be quite effective in the treatment of breast cancer, significant challenges remain involving poor drug transfer between the liposome and cancerous cells. In this review, we discuss the recent advancements made in the development of liposome-based chemotherapeutics with respect to improved drug transfer for use in breast cancer therapy.

Rac signaling in breast cancer: a tale of GEFs and GAPs

Rac GTPases, small G-proteins widely implicated in tumorigenesis and metastasis, transduce signals from tyrosine-kinase, G-protein-coupled receptors (GPCRs), and integrins, and control a number of essential cellular functions including motility, adhesion, and proliferation. Deregulation of Rac signaling in cancer is generally a consequence of enhanced upstream inputs from tyrosine-kinase receptors, PI3K or Guanine nucleotide Exchange Factors (GEFs), or reduced Rac inactivation by GTPase Activating Proteins (GAPs). In breast cancer cells Rac1 is a downstream effector of ErbB receptors and mediates migratory responses by ErbB1/EGFR ligands such as EGF or TGFα and ErbB3 ligands such as heregulins. Recent advances in the field led to the identification of the Rac-GEF P-Rex1 as an essential mediator of Rac1 responses in breast cancer cells. P-Rex1 is activated by the PI3K product PIP3 and Gβγ subunits, and integrates signals from ErbB receptors and GPCRs. Most notably, P-Rex1 is highly overexpressed in human luminal breast tumors, particularly those expressing ErbB2 and estrogen receptor (ER). The P-Rex1/Rac signaling pathway may represent an attractive target for breast cancer therapy.

Inhibition of the Rho GTPase, Rac1, decreases estrogen receptor levels and is a novel therapeutic strategy in breast cancer

Rac1, a Rho GTPase, modulates diverse cellular processes and is hyperactive in some cancers. Estrogen receptor-alpha (ERα) in concert with intracellular signaling pathways regulates genes associated with cell proliferation, tumor development, and breast cancer cell survival. Therefore, we examined the possibility of Rac1 and ERα crosstalk in breast cancer cells. We found that Rac1 enhanced ERα transcriptional activity in breast cancer cells. Vav3, a Rho guanine nucleotide exchange factor that activates Rac1, was an upstream mediator, and P21/Cdc42/Rac1 activating kinase-1 (Pak-1) was a downstream effector of Rac1 enhancement of ERα activity. These results suggest that Rac1 may prove to be a therapeutic target. To test this hypothesis, we used a small molecule Rac inhibitor, EHT 1864, and found that EHT 1864 inhibited ERα transcriptional activity. Furthermore, EHT 1864 inhibited estrogen-induced cell proliferation in breast cancer cells and decreased tamoxifen-resistant breast cancer cell growth. EHT 1864 decreased activity of the promoter of the ERα gene resulting in down-regulation of ERα mRNA and protein levels. Therefore, ERα down-regulation by EHT 1864 is the likely mechanism of EHT 1864-mediated inhibition of ERα activity and estrogen-stimulated breast cancer cell proliferation. Since ERα plays a critical role in the pathogenesis of breast cancer and the Rac inhibitor EHT 1864 down-regulates ERα expression and breast cancer cell proliferation, further investigation of the therapeutic potential of Rac1 targeting in the treatment of breast cancer is warranted.

The use of ultra-dense array CGH analysis for the discovery of micro-copy number alterations and gene fusions in the cancer genome

Background

Molecular alterations critical to development of cancer include mutations, copy number alterations (amplifications and deletions) as well as genomic rearrangements resulting in gene fusions. Massively parallel next generation sequencing, which enables the discovery of such changes, uses considerable quantities of genomic DNA (> 5 ug), a serious limitation in ever smaller clinical samples. However, a commonly available microarray platforms such as array comparative genomic hybridization (array CGH) allows the characterization of gene copy number at a single gene resolution using much smaller amounts of genomic DNA. In this study we evaluate the sensitivity of ultra-dense array CGH platforms developed by Agilent, especially that of the 1 million probe array (1 M array), and their application when whole genome amplification is required because of limited sample quantities.

Methods

We performed array CGH on whole genome amplified and not amplified genomic DNA from MCF-7 breast cancer cells, using 244 K and 1 M Agilent arrays. The ADM-2 algorithm was used to identify micro-copy number alterations that measured less than 1 Mb in genomic length.

Results

DNA from MCF-7 breast cancer cells was analyzed for micro-copy number alterations, defined as measuring less than 1 Mb in genomic length. The 4-fold extra resolution of the 1 M array platform relative to the less dense 244 K array platform, led to the improved detection of copy number variations (CNVs) and micro-CNAs. The identification of intra-genic breakpoints in areas of DNA copy number gain signaled the possible presence of gene fusion events. However, the ultra-dense platforms, especially the densest 1 M array, detect artifacts inherent to whole genome amplification and should be used only with non-amplified DNA samples.

Conclusions

This is a first report using 1 M array CGH for the discovery of cancer genes and biomarkers. We show the remarkable capacity of this technology to discover CNVs, micro-copy number alterations and even gene fusions. However, these platforms require excellent genomic DNA quality and do not tolerate relatively small imperfections related to the whole genome amplification.

Identification of the Rac-GEF P-Rex1 as an essential mediator of ErbB signaling in breast cancer

While the small GTPase Rac1 and its effectors are well-established mediators of mitogenic and motile signaling by tyrosine kinase receptors and have been implicated in breast tumorigenesis, little is known regarding the exchange factors (Rac-GEFs) that mediate ErbB receptor responses. Here, we identify the PIP(3)-Gβγ-dependent Rac-GEF P-Rex1 as an essential mediator of Rac1 activation, motility, cell growth, and tumorigenesis driven by ErbB receptors in breast cancer cells. Notably, activation of P-Rex1 in breast cancer cells requires the convergence of inputs from ErbB receptors and a Gβγ- and PI3Kγ-dependent pathway. Moreover, we identified the GPCR CXCR4 as a crucial mediator of P-Rex1/Rac1 activation in response to ErbB ligands. P-Rex1 is highly overexpressed in human breast cancers and their derived cell lines, particularly those with high ErbB2 and ER expression. In addition to the prognostic and therapeutic implications, our findings reveal an ErbB effector pathway that is crucial for breast cancer progression.

Guanine nucleotide exchange factors for RhoGTPases: good therapeutic targets for cancer therapy?

Rho guanosine triphosphatases (GTPases) are a family of small proteins which function as molecular switches in a variety of signaling pathways following stimulation of cell surface receptors. RhoGTPases regulate numerous cellular processes including cytoskeleton organization, gene transcription, cell proliferation, migration, growth and cell survival. Because of their central role in regulating processes that are dysregulated in cancer, it seems reasonable that defects in the RhoGTPase pathway may be involved in the development of cancer. RhoGTPase activity is regulated by a number of protein families: guanine nucleotide exchange factors (GEFs), GTPase activating proteins (GAPs) and guanine nucleotide-dissociation inhibitors (GDIs). This review discusses the participation of RhoGTPases and their regulators, especially GEFs in human cancers. In particular, we focus on the involvement of the RhoGTPase GEF, Vav1, a hematopoietic specific signal transducer which is involved in human neuroblastoma, pancreatic ductal carcinoma and lung cancer. Finally, we summarize recent advances in the design and application of a number of molecules that specifically target individual RhoGTPases or their regulators or effectors, and discuss their potential for cancer therapy.