Dataset Information

Overexpression of GAB2 in ovarian cancer cells promotes tumor growth and angiogenesis by upregulating chemokine expression.

ABSTRACT: We previously found that the scaffold adapter GRB2-associated binding protein 2 (GAB2) is amplified and overexpressed in a subset of primary high-grade serous ovarian cancers and cell lines. Ovarian cancer cells overexpressing GAB2 are dependent on GAB2 for activation of the phosphatidylinositol 3-kinase (PI3K) pathway and are sensitive to PI3K inhibition. In this study, we show an important role of GAB2 overexpression in promoting tumor angiogenesis by upregulating expression of multiple chemokines. Specifically, we found that suppression of GAB2 by inducible small hairpin RNA in ovarian cancer cells inhibited tumor cell proliferation, angiogenesis and peritoneal tumor growth in immunodeficient mice. Overexpression of GAB2 upregulated the secretion of several chemokines from ovarian cancer cells, including CXCL1, CXCL2 and CXCL8. The secreted chemokines not only signal through endothelial CXCR2 receptor in a paracrine manner to promote endothelial tube formation, but also act as autocrine growth factors for GAB2-induced transformation of fallopian tube secretory epithelial cells and clonogenic growth of ovarian cancer cells overexpressing GAB2. Pharmacological inhibition of inhibitor of nuclear factor kappa-B kinase subunit ? (IKK?), but not PI3K, mechanistic target of rapamycin (mTOR) or mitogen-activated protein kinase (MEK), could effectively suppress GAB2-induced chemokine expression. Inhibition of IKK? augmented the efficacy of PI3K/mTOR inhibition in suppressing clonogenic growth of ovarian cancer cells with GAB2 overexpression. Taken together, these findings suggest that overexpression of GAB2 in ovarian cancer cells promotes tumor growth and angiogenesis by upregulating expression of CXCL1, CXCL2 and CXCL8 that is IKK?-dependent. Co-targeting IKK? and PI3K pathways downstream of GAB2 might be a promising therapeutic strategy for ovarian cancer that overexpresses GAB2.

SUBMITTER: Duckworth C

PROVIDER: S-EPMC4977484 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Overexpression of GAB2 in ovarian cancer cells promotes tumor growth and angiogenesis by upregulating chemokine expression.

Duckworth C C Zhang L L Carroll S L SL Ethier S P SP Cheung H W HW

Oncogene 20151214 31

We previously found that the scaffold adapter GRB2-associated binding protein 2 (GAB2) is amplified and overexpressed in a subset of primary high-grade serous ovarian cancers and cell lines. Ovarian cancer cells overexpressing GAB2 are dependent on GAB2 for activation of the phosphatidylinositol 3-kinase (PI3K) pathway and are sensitive to PI3K inhibition. In this study, we show an important role of GAB2 overexpression in promoting tumor angiogenesis by upregulating expression of multiple chemok ...[more]

PMID: 26657155

Similar Datasets

Project description:BackgroundGrb2-associated binder 2 (Gab2) is a scaffolding protein that serves as a critical signaling amplifier downstream of tyrosine kinase receptors. Our previous study has shown that Gab2 induces epithelial-to-mesenchymal transition (EMT) and promotes metastasis in colorectal cancer (CRC). However, the role of Gab2 in CRC growth and angiogenesis remains unclear.MethodsThe expression of vascular endothelial growth factor (VEGF) in different colorectal tissues was detected by immunohistochemistry and qRT-PCR to evaluate its correlation with Gab2. Lentiviral vectors bearing Gab2 gene and its small interfering RNAs were constructed and transfected into CRC cell lines. The effects of Gab2 on the cell proliferation in vitro and tumorigenesis in vivo, were examined via CCK‑8 assay, colony formation assay as well as tumorigenicity assay respectively. Moreover, to assess its potential role in tumor growth and angiogenesis, the expression of Ki67, CD34 and vascular endothelial growth factor receptor-2 (VEGFR2) were detected by immunohistochemistry in CRC cells tumors. Finally, we evaluated the impact of Gab2 on the expression of c-Myc and VEGF, and the probable effect of mechanistic targeted extracellular signal-regulated kinase (ERK) pathway in suppressing tumor growth and angiogenesis.ResultsUp-regulation of Gab2 expression was found to be positively correlated with VEGF in CRC tissues. Exogenous expression of Gab2 obviously promoted, whereas silencing of Gab2 inhibited, proliferation and clone formation of human CRC cells in vitro. Of note, Gab2 enhanced tumorigenesis and tumor growth in mouse xenografts with high Ki67 expression, and led to an increased vessel density with strong CD34 and VEGFR2 activity. In addition, elevated Gab2 expression obviously up-regulated the expression of VEGF, and stimulated the activation of its downstream genes, ERK1/2 and c-Myc in CRC cells. Instead, down-regulated Gab2 expression significantly reduced the levels of VEGF, and inhibited the transduction of ERK/c-Myc pathway. Finally, we revealed that mechanistic target of mitogen-activated protein kinase (MEK) could attenuate Gab2-induced tumor growth and angiogenesis via altering VEGF and c-Myc levels.ConclusionsThe results from our study suggest that Gab2 promotes intestinal tumor growth and angiogenesis through upregulation of VEGF expression mediated by the MEK/ERK/c-Myc pathway.

Project description:PurposeAngiogenesis actively contributes to tumor growth and metastasis. MACC1 was reported to be associated with tumor progression. In the present study, we aimed to investigate the expression and role of MACC1 in cholangiocarcinoma (CCA) and its correlation with angiogenesis.Patients and methodsWe investigated the expression and correlation of MACC1 and VEGFA in The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets and in 7 paired frozen CCA and matched paracarcinoma tissues. Immunohistochemistry (IHC) was used to examine MACC1 and VEGFA expression as well as microvessel density (MVD) in 122 paraffin-embedded CCA samples. Western blotting, real-time qPCR and ELISA were performed to investigate the effect of MACC1 knockdown on VEGFA expression and secretion in CCA cells. Subsequently, we collected conditioned medium from cells with MACC1 knockdown and used it in angiogenesis assays.ResultsThe expression levels of both MACC1 and VEGFA were significantly upregulated in the TCGA and GEO datasets and in the 7 paired frozen CCA tissues compared to the matched paracarcinoma tissues, and MACC1 was significantly correlated with VEGFA. IHC showed that high expression of MACC1 and VEGFA was significantly correlated with lymph node metastasis (P<0.05 and P<0.01) and worse survival (P<0.01, P<0.05) in patients with CCA. We further verified that MACC1 was significantly correlated with VEGFA (P<0.01) and MVD (P<0.01) in clinical samples. Western blotting, real-time qPCR and ELISA results showed that MACC1 knockdown in CCA cells significantly decreased the protein and mRNA expression of VEGFA and reduced the VEGFA concentration in conditioned medium. Moreover, angiogenesis assays showed that conditioned medium from CCA cells with MACC1 knockdown decreased the number of tubes formed.ConclusionOur results indicate that MACC1 and VEGFA expression are upregulated in CCA. Moreover, MACC1 is an independent predictor of overall survival and facilitates angiogenesis in CCA by upregulating of VEGFA.

Dataset Information

Overexpression of GAB2 in ovarian cancer cells promotes tumor growth and angiogenesis by upregulating chemokine expression.

Publications

Overexpression of GAB2 in ovarian cancer cells promotes tumor growth and angiogenesis by upregulating chemokine expression.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets