Overexpression Of Vav3 Research Articles

The role of STAT3/VAV3 in glucolipid metabolism during the development of HFD-induced MAFLD.

Metabolic-associated fatty liver disease (MAFLD) is a globally prevalent chronic hepatic disease. Previous studies have indicated that the activation of the signal transducer and activator of transcription3 (STAT3) plays a vital role in MAFLD progression at the very beginning. However, the specific association between STAT3 and abnormal hepatic metabolism remains unclear. In this study, activated inflammation was observed to induce abnormal glucolipid metabolic disorders in the hepatic tissues of high-fat diet (HFD)-fed ApoE-/- mice. Furthermore, we found that the activation of STAT3 induced by HFD might function as a transcriptional factor to suppress the expression of VAV3, which might participate in intracellular glucolipid metabolism and the regulation of glucose transporter 4 (GLUT4) storage vesicle traffic in the development of MAFLD both in vitro and in vivo. We verified that VAV3 deficiency could retard the GLUT4 membrane translocation and impair the glucose homeostasis. Additionally, VAV3 participates in cholesterol metabolism in hepatocytes, eventually resulting in the accumulation of intracellular cholesterol. Moreover, rAAV8-TBG-VAV3 was conducted to restore the expression of VAV3 in HFD-fed ApoE-/- mice. VAV3 overexpression was observed to improve glucose homeostasis as well as attenuate hepatic cholesterol accumulation in vivo. In conclusion, the STAT3/VAV3 signaling pathway might play a significant role in MAFLD by regulating glucose and cholesterol metabolism, and VAV3 might be a potential therapeutic strategy which could consequently ameliorate MAFLD.

VAV3 regulates glioblastoma cell proliferation, migration, invasion and cancer stem‑like cell self‑renewal.

Glioblastoma multiforme (GBM; World Health Organization grade IV) is one of the most common and aggressive malignant brain tumors and has no effective treatment. Therefore, elucidation of the molecular mechanism of glioma development is very important for finding new therapeutic strategies. The present study evaluated the expression level of Vav guanine nucleotide exchange factor 3 (VAV3) using bioinformatics analysis and demonstrated that VAV3 was overexpressed in human glioblastoma and associated with patient survival. Knock down of VAV3 using shRNA in glioblastoma cells significantly inhibited glioblastoma cell migration, invasion and proliferation. Furthermore, downregulation of VAV3 expression inhibited the stem cell self‑renewal capacity and decreased the expression levels of the stem cell markers Nestin and Sox2. Bioinformatic analysis demonstrated that VAV3 was a target gene of miR‑218. Furthermore, overexpression of VAV3 markedly reversed the tumor suppressor effect of miR‑218 in glioblastoma cell. These findings suggested that VAV3 could be a potential biomarker and therapeutic target for glioblastoma.

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.

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

ObjectivesMyocardial 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. MethodHere, 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. ResultsVav3 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. ConclusionsVav3 might serve as a target to reduce ischemia damage by suppressing the inflammation and apoptosis of cardiomyocytes.

Truncated isoform Vav3.1 is highly expressed in ovarian cancer stem cells and clinically relevant in predicting prognosis and platinum-response.

Vav3 is a key modulator of GTP-hydrolases of the Rho/Rac family, which are crucially involved in cell proliferation. Vav3 is alternatively spliced in full-length Vav3-alpha and N-terminal truncated Vav3.1 lacking its self-regulatory domains. The aim of our study was to estimate the clinical impact of Vav3 and all other Vav family members in ovarian cancer. Purification of a stem-cell like side-population (SP) from ovarian cancer cell lines was performed by flow cytometry/FACS. Differences in gene expression between SP and NSP were assessed by Gene Array analysis and confirmed by RT-PCR and immunoblot. In addition, Vav mRNA expression was determined in 150 epithelial ovarian cancers. Clinicopathological parameters, platinum-sensitivity and survival were analyzed and associated with Vav expression. SP fractions of ovarian cancer cell lines exhibited marked overexpression of Vav3.1 (p < 0.001). Vav1 and Vav2 did not prove to be of clinicopathologic relevance in ovarian cancer. High Vav3.1 expression correlated with higher FIGO stage and residual disease. Furthermore, Vav3.1 overexpression was associated with poor progression-free (HR = 2.820, p = 0.0001) and overall survival (HR = 2.842, p = 0.0001). Subgroup analyses revealed an impact of Vav3.1 on survival in Type-II but not in Type-I cancers. Notably, platinum-refractory cancers showed marked overexpression of Vav3.1 compared to other subsets of platinum-sensitivity (15.848 vs. 6.653, p = 0.0001). In conclusion, Vav3.1 is over-expressed in stem-cell like SP fractions and is clinically relevant in the pathophysiology of ovarian cancer. The N-terminal truncated Vav3.1 may be decisively involved in mechanisms causing genuine multi-drug resistance.

The clinical value of Vav3 in peripheral blood for predicting lymphatic metastasis of gastric cancer

Background: Overexpression of Vav3, a gene involved in signal transduction, promotes invasion and inhibits apoptosis in several cancers. The clinical value of the protein product of this gene, Vav3, in the peripheral blood of gastric cancer patients is unknown. We hypothesised increased serum Vav3 that related to tissue levels and lymph node metastases. In addition, we further explored its clinical value in respect of linked molecules Rac-1, MMP-7 and ICAM-1Methods: 120 gastric cancer patients who had radical surgery were enrolled. Immunohistochemistry was used to determine the expressions of Vav3, Rac-1, MMP-7 and ICAM-1 in gastric cancer mucosa and normal mucosa. ELISA was used to detect these proteins in peripheral blood of gastric cancer patients and 100 age- and sex-matched healthy controls.Results: Vav3, Rac-1 and MMP-7 (P < 0.001), but not ICAM-1 (P = 0.303) were more highly expressed by cancer tissues than normal gastric mucosa. Serum levels of all molecules were higher than those in healthy subjects (P < 0.001). Levels of Vav3, Rac-1 and MMP-7 decreased 2 weeks postoperatively (all P < 0.001) but there was no change in ICAM-1 (P = 0.192). Similarly, increased levels of Vav3, Rac-1 and MMP-7 were present in patients with lymphatic metastasis than those without (all P < 0.001) but there was no difference in ICAM-1 levels (P = 0.378). There were positive correlations between Vav3 with Rac-1 and MMP-7 in cancer tissues (P < 0.001), and also between Vav3 and Rac-1 in pre-surgery blood (P = 0.003).Conclusions: Vav3 in peripheral blood may serve as a biomarker for gastric cancer, and to predict the lymphatic metastasis in gastric cancer.

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

BackgroundAstragaloside 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. MethodsThe 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. ResultsAS-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. ConclusionThe 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 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.

Abstract 1069: Vav3 enhances androgen receptor splice variant activity and is critical for castration resistant prostate cancer growth and survival.

Abstract Advanced or metastatic prostate cancer is treated by androgen deprivation; however, patients inevitably relapse with castration resistant prostate cancer (CRPC) that grows independently of androgen. However, CRPC remains dependent on androgen receptor (AR) signaling, which includes constitutive, ligand–independent action of naturally occurring AR splice variants. For example, the AR splice variant AR3 (also termed AR–V7) is expressed in CRPC and is linked to poor prognosis. Vav3, a Rho GTPase guanine nucleotide exchange factor, is an AR coactivator that is up–regulated in human prostate cancer as compared to benign tissue as well as in pre–clinical models of CRPC. Vav3 confers castration–resistant growth to androgen–dependent human prostate cancer cells and increased expression has been linked to increased clinical biochemical relapse. Despite the importance of AR coactivators in promoting CRPC, the potential role of these regulatory proteins in modulating AR splice variant activity is unknown. We examined the contributions of Vav3 to AR activity in two CRPC cell lines that naturally express relatively high levels of Vav3 and AR3. Vav3 or AR3 knockdown greatly attenuated cell proliferation, soft agar growth and ligand–independent AR activity. Vav3 potently enhanced the transcriptional activity of AR3 and another clinically relevant AR splice variant ARv567es. Furthermore, Vav3 enhanced AR splice variant activity through a distinctly different mechanism than Vav3 coactivation of full length AR. Vav3 knockdown resulted in lowered nuclear AR3 levels while total AR3 protein and mRNA levels remained static. Conversely, overexpression of Vav3 resulted in increased nuclear AR3. Co–immunoprecipitation revealed that AR3 and Vav3 interact. These novel data demonstrating physical and functional interactions between Vav3, a unique AR coactivator, and an AR splice variant provide insights into the mechanisms by which Vav3 exploits and enhances AR signaling in the progression to CRPC. Citation Format: Stephanie Peacock, Cale D. Fahrenholtz, Kerry L. Burnstein. Vav3 enhances androgen receptor splice variant activity and is critical for castration resistant prostate cancer growth and survival. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1069. doi:10.1158/1538-7445.AM2013-1069

The Vav3 oncogene enhances the malignant potential of prostate cancer cells under chronic hypoxia

ObjectivesWe had previously reported that chronic hypoxia induces androgen-independent growth in the human prostate cancer cell line LNCaP. In this study, we have identified a key molecule, the Vav3 oncogene, and investigated the effects of Vav3 overexpression on cancer cell growth and malignant behavior and the possible apoptosis-inducing effect of Vav3 expression knockdown by small interfering ribonucleic acid (siRNA) in LNCaP cells under chronic hypoxia (LNCaP/CH). Methods and materialsHypoxia-inducible oncogenes were identified by complementary deoxyribonucleic acid (cDNA) microarray and Ingenuity Pathway Analysis in order to investigate gene ontology and functional pathways and networks. siRNA was used to knockdown the Vav3 target gene and analyze the effects on proliferation, invasion, migration, and apoptosis of LNCaP/CH cells. Vav3 cDNA was transfected into LNCaP cells under normoxia (LNCaP/N) to establish Vav3-overexpressing clonal cell lines, whose proliferation, invasion, and migration was then examined. Immunoblot analysis was used to investigate the activation of Akt, a Vav3 downstream target molecule. ResultscDNA microarray analysis and Ingenuity Pathway Analysis identified Vav3 as a hypoxia-inducible oncogene that was highly associated with malignant behavior. Vav3 messenger RNA and protein expression in LNCaP/CH cells were higher than in LNCaP/N and LNCaP cells cultured under acute hypoxia (LNCaP/AH). The growth rate of LNCaP/CH cells was lower than that of LNCaP/N cells but higher than that of LNCaP/AH cells. LNCaP/CH cells showed higher invasion and migration than LNCaP/N and LNCaP/AH cells. Interrupting Vav3 expression strongly suppressed the proliferation, invasion, and migration of LNCaP/CH cells. Furthermore, siRNA led to apoptosis with increased caspase-3 and cleaved poly (adenosine diphosphate-ribose) polymerase activation in LNCaP/CH cells. Stable Vav3 overexpression in LNCaP cells promoted cell proliferation, invasion, and migration with Akt activation. ConclusionsOur results demonstrate that Vav3 plays a crucial role in prostate cancer growth and malignant behavior, thus revealing a novel potential therapeutic target.

Novel Interaction between the Co-chaperone Cdc37 and Rho GTPase Exchange Factor Vav3 Promotes Androgen Receptor Activity and Prostate Cancer Growth*

Elevated androgen receptor (AR) activity in castration-resistant prostate cancer may occur through increased levels of AR co-activator proteins. Vav3, a guanine nucleotide exchange factor, is up-regulated following progression to castration resistance in preclinical models and is overexpressed in a significant number of human prostate cancers. Vav3 is a novel co-activator of the AR. We sought to identify Vav3 binding partners in an effort to understand the molecular mechanisms underlying Vav3 enhancement of AR activity and to identify new therapeutic targets. The cell division cycle 37 homolog (Cdc37), a protein kinase-specific co-chaperone for Hsp90, was identified as a Vav3 interacting protein by yeast two-hybrid screening. Vav3-Cdc37 interaction was confirmed by GST pulldown and, for native proteins, by co-immunoprecipitation experiments in prostate cancer cells. Cdc37 potentiated Vav3 co-activation of AR transcriptional activity and Vav3 enhancement of AR N-terminal-C-terminal interaction, which is essential for optimal receptor transcriptional activity. Cdc37 increased prostate cancer cell proliferation selectively in Vav3-expressing cells. Cdc37 did not affect Vav3 nucleotide exchange activity, Vav3 protein levels, or subcellular localization. Disruption of Vav3-Cdc37 interaction inhibited Vav3 enhancement of AR transcriptional activity and AR N-C interaction. Diminished Vav3-Cdc37 interaction also caused decreased prostate cancer cell proliferation selectively in Vav3-expressing cells. Taken together, we identified a novel Vav3 interacting protein that enhances Vav3 co-activation of AR and prostate cancer cell proliferation. Vav3-Cdc37 interaction may provide a new therapeutic target in prostate cancer.

Vav3 Enhances Androgen Receptor Splice Variant Activity and Is Critical for Castration-Resistant Prostate Cancer Growth and Survival

Advanced or metastatic prostate cancer is treated by androgen deprivation; however, patients inevitably relapse with castration-resistant prostate cancer (CRPC). CRPC remains dependent on androgen receptor (AR) signaling, which may include constitutive, ligand-independent action of naturally occurring AR splice variants. For example, the AR splice variant AR3 (also termed AR-V7) is expressed in CRPC and is linked to poor prognosis. Vav3, a Rho GTPase guanine nucleotide exchange factor, is an AR coactivator that is up-regulated in human prostate cancer compared with benign tissue and in preclinical models of CRPC. Vav3 confers castration-resistant growth to androgen-dependent human prostate cancer cells. Despite the importance of AR coactivators in promoting CRPC, the potential role of these regulatory proteins in modulating AR splice variant activity is unknown. We examined the contributions of Vav3 to AR activity in two CRPC cell lines that naturally express relatively high levels of Vav3 and AR3. Vav3 or AR3 knockdown greatly attenuated cell proliferation, soft agar growth, and ligand-independent AR activity. Vav3 potently enhanced the transcriptional activity of AR3 and another clinically relevant AR splice variant, ARv567es. Vav3 knockdown resulted in lowered nuclear AR3 levels, whereas total AR3 levels remained similar. Conversely, overexpression of Vav3 resulted in increased nuclear AR3. Coimmunoprecipitation revealed that AR3 and Vav3 interact. These novel data demonstrating physical and functional interactions between Vav3, a unique AR coactivator, and an AR splice variant provide insights into the mechanisms by which Vav3 exploits and enhances AR signaling in the progression to CRPC.

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.

Abstract 1651: Targeting Vav3 oncogene enhances docetaxel-induced apoptosis in LNCaP cells under chronic hypoxia

Abstract Introduction and Objective: We previously reported that chronic hypoxic condition (1% oxygen for over six months) induced Vav3 oncogene expression with androgen-independent growth and malignant behavior in LNCaP cells. And overexpression of Vav3 oncogene promoted the growth of LNCaP cells with increased invasion and migration under normoxic condition. The objective of this study was to examine the effect of Vav3 siRNA on cell proliferation and apoptosis in docetaxel-treated LNCaP cells under chronic hypoxic condition. Methods: We analyzed the sensitivity of docetaxel in LNCaP cells under normoxic and chronic hypoxic conditions by 2-(4-lodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt (WST-1) and flow cytometric analyses. The effects of Vav3 siRNA on cell growth and apoptosis were examined under chronic hypoxia with or without docetaxel treatment. To seek a molecular understanding of Vav3 siRNA induced apoptosis, we analyzed alterations in the growth signaling components in the PI3K/Akt and ERK mediated pathways by immunoblot analysis. Results: Overexpression of Vav3 was observed in LNCaP cells under chronic hypoxia compared with its expression under normoxia. Although the growth rates were reduced in a dose- and time-dependent manner by docetaxel in LNCaP cells under both normoxic and chronic hypoxic conditions, these effects were significantly decreased in LNCaP cells under chronic hypoxia. In addition, we found that docetaxel induced apoptosis following activation of caspase-3 and cleaved poly (ADP-ribose) polymerase, and that the interrupting the Vav3 signaling pathway using siRNA enhanced docetaxel sensitivity of LNCaP cells under chronic hypoxia and led to apoptosis. A profound activation of PI3K/Akt pathway was observed under chronic hypoxic condition. Treatment with Vav3 siRNA showed weak inhibition of Akt phosphorylation and treatment with Vav3 siRNA plus docetaxel strongly inhibited this signaling. Conclusions: Our results showed that Vav3 siRNA enhances docetaxel-induced apoptosis in LNCaP cells under chronic hypoxia and that targeting Vav3 oncogene may have important practical implications for managing hormone refractory prostate cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1651. doi:10.1158/1538-7445.AM2011-1651

Vav3 oncogene is involved in regulation of secretory phospholipase A2-IIa expression in prostate cancer

Our previous study revealed that Vav3 oncogene and secretory phospholipase A2-IIa (sPLA2-IIa) are overexpressed in androgen-independent prostate cancer cells relative to their androgen-dependent counterparts and contribute to development of hormone refractory prostate cancer. Vav3 is a multiple function protein with both signaling molecule and coactivator activities. sPLA2-IIa is a downstream effector of HER/HER2-PI3K-Akt-NF-κB signaling and involved in inflammatory response and tumorigenesis. The aim of the current study was to determine whether Vav3 is involved in up-regulation of sPLA2-IIa expression, given that Vav3 signals in the HER/HER2-elicited pathway. Among 46 prostate cancer specimens examined, Vav3 and sPLA2-IIa are overexpressed in 48 and 83% human prostate cancers, respectively. Vav3 overexpression is significantly associated with a high level expression of sPLA2-IIa. In addition, significant Vav3 nuclear localization is observed in two prostate cancer specimens, supporting a coactivator activity in prostate cancer cells. Further analysis revealed that Vav3 up-regulates expression of the sPLA2-IIa gene at the transcriptional level via HER/HER2-PI3K-Akt-NF-κB signaling. These data revealed that Vav3 overexpression as an additional underlying mechanism contributes to elevated sPLA2-IIa expression in prostate cancer.

405 VAV3, A POSSIBLE KEY MOLECULE, ENHANCES ANDROGEN-INDEPENDENT GROWTH AND THE MALIGNANT POTENTIAL OF PROSTATE CANCER CELLS UNDER CHRONIC HYPOXIA

You have accessJournal of UrologyProstate Cancer: Basic Research1 Apr 2011405 VAV3, A POSSIBLE KEY MOLECULE, ENHANCES ANDROGEN-INDEPENDENT GROWTH AND THE MALIGNANT POTENTIAL OF PROSTATE CANCER CELLS UNDER CHRONIC HYPOXIA Kenichi Hirai, Takeo Nomura, Mutsushi Yamasaki, Takanori Matsubara, Fuminori Sato, Masatsugu Moriyama, and Hiromitsu Mimata Kenichi HiraiKenichi Hirai Oita, Japan More articles by this author , Takeo NomuraTakeo Nomura Oita, Japan More articles by this author , Mutsushi YamasakiMutsushi Yamasaki Oita, Japan More articles by this author , Takanori MatsubaraTakanori Matsubara Oita, Japan More articles by this author , Fuminori SatoFuminori Sato Oita, Japan More articles by this author , Masatsugu MoriyamaMasatsugu Moriyama Oita, Japan More articles by this author , and Hiromitsu MimataHiromitsu Mimata Oita, Japan More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2011.02.494AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Hypoxia occurs in many solid tumors, including prostate cancer, and enhances tumor progression and treatment resistance. Our previous studies showed that chronic hypoxia promoted androgen-independent growth and malignant cell behavior in a human prostate cancer cell line. From the results of multi-pathway analysis of gene expression of LNCaP cells under a chronic hypoxic condition, we specifically focused on the biological functions of Vav3 gene in vitro. METHODS We analyzed the gene expression profiles of LNCaP cells under normoxic, acute hypoxic (1% oxygen for forty-eight hours), and chronic hypoxic conditions (cultured over six months). Comprehensive mRNA profiling was performed using an Agilent 44K array platform, and we investigated the association between elevated genes and tumor behavior by the applications of Ingenuity Pathways Analysis. From the results, we identified the Vav3 gene and closely analyzed the details of the gene in vitro. We validated the expression by quantitative RT-PCR and Western blot analyses. To analyze the function of Vav3, knockdown by siRNA was performed. Next, we transfected LNCaP with the Vav3 cDNA expression vector (control cells were transfected with neo expression vector) and isolated stable clones with high or low expression. The growth of cancer cells was evaluated in vitro. Also, we examined cell invasiveness and migration using the Matrigel invasion assay. For cell cycle analysis, flow cytometric analysis of propidium iodide-stained nuclei was carried out. RESULTS The results were as follows: (1) Vav3 mRNA and protein expression levels were increased in LNCaP cells under chronic hypoxia, respectively; (2) chronic hypoxia increased both the invasiveness and migration of LNCaP cells; (3) LNCaP cells under chronic hypoxia showed less invasiveness and cell motility as well as suppressed their growth rates by interrupting Vav3 expression using Vav3 siRNA; (4) Vav3 expression positively correlated with the growth, invasiveness, and motility of LNCaP cells; and (5) interrupting the Vav3 signaling axis with siRNA led to the apoptosis of LNCaP cells via the mitochondrial pathway, with increased activation of caspases-3, and -9 and cleaved PARP. CONCLUSIONS Our results showed that chronic hypoxia promoted the malignant potential of prostate cancer cells via the overexpression of Vav3. Therefore, targeting the Vav3 signaling pathway could prove to be a promising approach for the treatment of progressive or castration resistant prostate cancer. © 2011 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 185Issue 4SApril 2011Page: e163-e164 Advertisement Copyright & Permissions© 2011 by American Urological Association Education and Research, Inc.MetricsAuthor Information Kenichi Hirai Oita, Japan More articles by this author Takeo Nomura Oita, Japan More articles by this author Mutsushi Yamasaki Oita, Japan More articles by this author Takanori Matsubara Oita, Japan More articles by this author Fuminori Sato Oita, Japan More articles by this author Masatsugu Moriyama Oita, Japan More articles by this author Hiromitsu Mimata Oita, Japan More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

406 HIGH-THROUGHPUT SCREEN FOR GENES THAT SELECTIVELY PROMOTE GROWTH OF ANDROGEN INDEPENDENT PROSTATE CANCER CELLS

CaP cells under normoxic, acute hypoxic (1% oxygen for forty-eight hours), and chronic hypoxic conditions (cultured over six months). Comprehensive mRNA profiling was performed using an Agilent 44K array platform, and we investigated the association between elevated genes and tumor behavior by the applications of Ingenuity Pathways Analysis. From the results, we identified the Vav3 gene and closely analyzed the details of the gene in vitro. We validated the expression by quantitative RT-PCR and Western blot analyses. To analyze the function of Vav3, knockdown by siRNA was performed. Next, we transfected LNCaP with the Vav3 cDNA expression vector (control cells were transfected with neo expression vector) and isolated stable clones with high or low expression. The growth of cancer cells was evaluated in vitro. Also, we examined cell invasiveness and migration using the Matrigel invasion assay. For cell cycle analysis, flow cytometric analysis of propidium iodide-stained nuclei was carried out. RESULTS: The results were as follows: (1) Vav3 mRNA and protein expression levels were increased in LNCaP cells under chronic hypoxia, respectively; (2) chronic hypoxia increased both the invasiveness and migration of LNCaP cells; (3) LNCaP cells under chronic hypoxia showed less invasiveness and cell motility as well as suppressed their growth rates by interrupting Vav3 expression using Vav3 siRNA; (4) Vav3 expression positively correlated with the growth, invasiveness, and motility of LNCaP cells; and (5) interrupting the Vav3 signaling axis with siRNA led to the apoptosis of LNCaP cells via the mitochondrial pathway, with increased activation of caspases-3, and -9 and cleaved PARP. CONCLUSIONS: Our results showed that chronic hypoxia promoted the malignant potential of prostate cancer cells via the overexpression of Vav3. Therefore, targeting the Vav3 signaling pathway could prove to be a promising approach for the treatment of progressive or castration resistant prostate cancer.

418 TARGETING VAV3 ONCOGENE ENHANCES DOCETAXEL SENSITIVITY VIA INDUCTION OF APOPTOSIS IN LNCAP CELLS UNDER CHRONIC HYPOXIA

You have accessJournal of UrologyProstate Cancer: Basic Research1 Apr 2011418 TARGETING VAV3 ONCOGENE ENHANCES DOCETAXEL SENSITIVITY VIA INDUCTION OF APOPTOSIS IN LNCAP CELLS UNDER CHRONIC HYPOXIA Takeo Nomura, Kenichi Hirai, Mutsushi Yamasaki, Fuminori Sato, and Hiromitsu Mimata Takeo NomuraTakeo Nomura Oita, Japan More articles by this author , Kenichi HiraiKenichi Hirai Oita, Japan More articles by this author , Mutsushi YamasakiMutsushi Yamasaki Oita, Japan More articles by this author , Fuminori SatoFuminori Sato Oita, Japan More articles by this author , and Hiromitsu MimataHiromitsu Mimata Oita, Japan More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2011.02.507AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The Vav family are Rho/Rac guanosine nucleotide exchange factor (GEFs) consisting of three members in mammalian cells and Vav3 enhances AR activity during progression to androgen independence. We previously reported that chronic hypoxic condition (1% oxygen for over six months) induced Vav3 oncogene expression with androgen-independent growth and malignant behavior in LNCaP cells. And overexpression of Vav3 oncogene promoted the growth of LNCaP cells with increased invasion and migration under normoxic condition. The objective of this study was to examine the effect of Vav3 siRNA on cell proliferation and apoptosis in docetaxel-treated LNCaP cells under chronic hypoxic condition. METHODS We analyzed the sensitivity of docetaxel in LNCaP cells under normoxic and chronic hypoxic conditions by 2-(4-lodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt (WST-1) analysis. The effects of Vav3 siRNA on cell growth and apoptosis were examined under chronic hypoxia with or without docetaxel treatment by WST-1 and flow cytometric analyses. To seek a molecular understanding of Vav3 siRNA induced apoptosis, we analyzed alterations in the growth signaling components in the PI3K/Akt and ERK mediated pathways and caspase activation by immunoblot analysis. RESULTS Overexpression of Vav3 was observed in LNCaP cells under chronic hypoxia compared with its expression under normoxia. Although the growth rates were reduced in a dose- and time-dependent manner by docetaxel in LNCaP cells under both normoxic and chronic hypoxic conditions, these effects were significantly decreased in LNCaP cells under chronic hypoxia. In addition, we found that docetaxel induced apoptosis following activation of caspase-3, -9 and cleaved poly (ADP-ribose) polymerase, and that the interrupting the Vav3 signaling pathway using siRNA enhanced docetaxel sensitivity of LNCaP cells under chronic hypoxia and led to apoptosis. Although a profound activation of PI3K/Akt pathway was observed under chronic hypoxic condition, treatment with Vav3 siRNA showed weak inhibition of Akt phosphorylation. CONCLUSIONS Our results showed that Vav3 siRNA enhances docetaxel-induced apoptosis in LNCaP cells under chronic hypoxia via activation of caspase cascade and that targeting Vav3 oncogene may have important practical implications for managing castration resistant prostate cancer. © 2011 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 185Issue 4SApril 2011Page: e168 Advertisement Copyright & Permissions© 2011 by American Urological Association Education and Research, Inc.MetricsAuthor Information Takeo Nomura Oita, Japan More articles by this author Kenichi Hirai Oita, Japan More articles by this author Mutsushi Yamasaki Oita, Japan More articles by this author Fuminori Sato Oita, Japan More articles by this author Hiromitsu Mimata Oita, Japan More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...