Dimerization of EGFR and HER2 induces breast cancer cell motility through STAT1-dependent ACTA2 induction (original) (raw)
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npj Breast Cancer, 2015
Background: Activins belong to the transforming growth factor-β (TGF-β) superfamily of cytokines. Although the role of TGF-β in cancer progression has been highly advocated, the role of activin signaling in cancer is not well known. However, overexpression of activin-A has been observed in several cancers. Aims: The gene expression profile indicated higher expression of Activin-A in breast tumors. Hence the aim of this study was to evaluate the status and role of Activin signaling pathway in these tumors. Methods: Microarray analysis was performed to reveal gene expression changes in breast tumors. The results were validated by quantitative PCR and immunohistochemical analysis in two independent sets of normal and tumor samples. Further, correlation of activin expression with survival and distant metastasis was performed to evaluate its possible role in tumor progression. We used recombinant activin-A, inhibitors, overexpression, and knockdown strategies both in vitro and in vivo, t...
Journal of cell communication and signaling, 2017
Because of differences in the downstream signaling patterns of its pathways, the role of the human epidermal growth factor family of receptors (HER) in promoting cell growth and survival is cell line and context dependent. Using two model cell lines, we have studied how the regulatory interaction network among the key proteins of HER signaling pathways may be rewired upon normal to cancerous transformation. We in particular investigated how the transcription factor STAT3 and several key kinases' involvement in cancer-related signaling processes differ between normal 184A1L5 human mammary epithelial (HME) and MDA-MB-231 breast cancer epithelial cells. Comparison of the responses in these cells showed that normal-to-cancerous cellular transformation causes a major re-wiring of the growth factor initiated signaling. In particular, we found that: i) regulatory interactions between Erk, p38, JNK and STAT3 are triangulated and tightly coupled in 184A1L5 HME cells, and ii) STAT3 is onl...
STAT3 activation in HER2‐positive breast cancers: Analysis of data from a large prospective trial
International Journal of Cancer, 2020
The JAK/STAT3 signaling pathway may be aberrantly activated and have various and conflicting roles in breast cancer. The current study explored prognostic implications of activated STAT3 in human epidermal growth factor receptor 2 (HER2)‐positive primary breast cancers in the context of a large prospective study (ALTTO). Activated STAT3 was determined by immunohistochemical analysis of STAT3 phosphorylation (Y705) performed on the primary tumors. This analysis evaluated whether patients with activated STAT3 had disease‐free survival (DFS) and overall survival (OS) different from patients without activated STAT3. A total of 5694 patients out of the 8381 patients enrolled in ALTTO were included in this analysis (67.9%), and 2634 of them (46%) had evidence of STAT3 activation (minimum tumor Allred score ≥2). The median follow‐up was 6.93 years (6.85‐6.97 years), at the end of which 1035 (18.18%) and 520 (9.13%) patients experienced DFS and OS events, respectively. Patients with STAT3 a...
Molecular Carcinogenesis, 2009
The oncogenic transcription factor Stat3 is constitutively active in a high percentage of human tumors including mammary adenocarcinomas and is reported to participate in the ErbB-2 oncogene signaling. In order to assess the role of signal transducer and activator of transcription 3 (Stat3) in mammary tumorigenesis downstream of ErbB-2, we generated mice expressing the activated rat ErbB-2 (neu) but lacking Stat3 in the mammary epithelium. Stat3 is apparently not required for neu-driven mammary tumorigenesis as tumors developed similarly in both Stat3-sufficient and Stat3-deficient glands. However, short hairpin RNA (shRNA)-mediated Stat3 silencing in a neu-overexpressing tumor-derived cell line completely abolished both neu-driven anchorage-independent growth and lung metastasis. Our data suggest that Stat3 might be a useful therapeutic target in breast tumors showing amplification and/or overexpression of the ErbB-2 oncogene, which normally display aggressive, metastatic behavior. ß
Journal of Biological Chemistry, 2004
We have examined if overexpression of the human epidermal growth factor receptor 2 (HER2) modifies the anti-proliferative effect of TGFβ against MCF-10A human mammary epithelial cells. Exogenous TGFβ inhibited cell proliferation and induced Smad-dependent transcriptional reporter activity in both MCF-10A/HER2 and MCF-10A/vector control cells. Ligand-induced reporter activity was 7-fold higher in HER2-overexpressing cells. In wound closure and transwell assays, TGFβ induced motility of HER2-transduced but not control cells. The HER2blocking antibody trastuzumab (Herceptin) prevented TGFβ-induced cell motility. Expression of a constitutively active TGFβ type I receptor (ALK5 T204D ) induced motility of MCF-10A/HER2 but not MCF-10A/vector cells. TGFβ-induced motility was blocked by coincubation with either the phosphatidylinositol-3 kinase (PI3K) inhibitor LY294002, the mitogen-activated protein kinase (MAPK) inhibitor U0126, the p38 MAPK inhibitor SB202190, and an integrin β1 blocking antibody. Rac1 activity was higher in HER2-overexpressing cells, where both Rac1 and Pak1 proteins were constitutively associated with HER2. Both exogenous TGFβ and transduction with constitutively active ALK5 enhanced this association. TGFβ induced actin stress fibers as well as lamellopodia within the leading edge of wounds. Herceptin blocked basal
Interactions of STAP-2 with Brk and STAT3 Participate in Cell Growth of Human Breast Cancer Cells
Journal of Biological Chemistry, 2010
Signal transducing adaptor protein-2 (STAP-2) is a recently identified adaptor protein, which contains pleckstrin homology (PH) and Src homology 2 (SH2)-like domains, as well as a signal transducer and an activator of transcription 3 (STAT3)-binding motif in its C-terminal region. STAP-2 is also a substrate of breast tumor kinase (Brk). In breast cancers, Brk expression is deregulated and it promotes STAT3-dependent cell proliferation. In the present study, manipulated STAP-2 expression demonstrated essential roles of STAP-2 in Brk-mediated STAT3 activation. STAP-2 interacts with both Brk and STAT3. In addition, small-interfering RNA-mediated reduction of endogenous STAP-2 expression strongly decreased Brk-mediated STAT3 activation in T47D breast cancer cells. The PH domain of STAP-2 is involved in multiple steps; the binding between Brk and STAP-2, the activation and tyrosine phosphorylation of STAT3, and the activation of Brk. Notably, a STAP-2 PH-Brk fusion protein exhibited robust kinase activity and increased activation and tyrosine phosphorylation of STAT3. Finally, STAP-2-knockdown in T47D cells induced a significant decrease of proliferation, as strong as that of Brkor STAT3-knockdown. Taken together, our findings are likely to inform the development of a novel therapeutic strategy, as well as the determination of novel prognostic values, in breast carcinomas.
Activator Protein-2β Promotes Tumor Growth and Predicts Poor Prognosis in Breast Cancer
Cellular Physiology and Biochemistry, 2018
Background/Aims: Activator protein-2 (AP-2) transcription factors have been proved to be essential in maintaining cellular homeostasis and regulating the transformation from normal growth to neoplasia. However, the role of AP-2β, a key member of AP-2 family, in breast cancer is rarely reported. Methods: The effect of AP-2 on cell growth, migration and invasion in breast cancer cells were measured by MTT, colony formation, wound-healing and transwell assays, respectively. The expression levels of AP-2β and other specific markers in breast cancer cell lines and tissue microarrays from the patients were detected using RT-PCR, Western blot and immunohistochemical staining. The regulation of AP-2β on tumor growth in vivo was analyzed in a mouse xenograft model. Results: We demonstrated the tumor-promoting function of AP-2β in breast cancer. AP-2β was found to be highly expressed in breast cancer cell lines and tumor tissues of breast cancer patients. The shRNA-mediated silencing of AP-2β...
Oncogene, 2001
Constitutive activation of signal transducer and activator of transcription (STAT) proteins has been detected in a wide variety of human primary tumor specimens and tumor cell lines including blood malignancies, head and neck cancer, and breast cancer. We have previously demonstrated a high frequency of Stat3 DNA-binding activity that is constitutively-induced by an unknown mechanism in human breast cancer cell lines possessing elevated EGF receptor (EGF-R) and c-Src kinase activities. Using tyrosine kinase selective inhibitors, we show here that Src and JAK family tyrosine kinases cooperate to mediate constitutive Stat3 activation in the absence of EGF stimulation in model human breast cancer cell lines. Inhibition of Src or JAKs results in dose-dependent suppression of Stat3 DNA-binding activity, which is accompanied by growth inhibition and induction of programmed cell death. In addition, transfection of a dominant-negative form of Stat3 leads to growth inhibition involving apoptosis of breast cancer cells. These results indicate that the biological eects of the Src and JAK tyrosine kinase inhibitors are at least partially mediated by blocking Stat3 signaling. While EGF-R kinase activity is not required for constitutive Stat3 activation in breast cancer cells, EGF stimulation further increases STAT DNA-binding activity, consistent with an important role for EGF-R in STAT signaling and malignant progression. Analysis of primary breast tumor specimens from patients with advanced disease revealed that the majority exhibit elevated STAT DNA-binding activity compared to adjacent non-tumor tissues. Our ®ndings, taken together, suggest that tyrosine kinases transduce signals through Stat3 protein that contribute to the growth and survival of human breast cancer cells in culture and potentially in vivo.
International Journal of Oncology, 2013
Clinically, HER2 proto-oncogene amplification is found in about 25-30% of human breast cancers, where it is correlated to a poor prognosis. Constitutive STAT3 activation is found in about 50-60% of the breast tumors and associated with tumorigenesis and drug resistance. In this study, we showed that STAT3 was phosphorylated in HER2-overexpressing, ER-positive human breast tumors and, furthermore, phosphorylated STAT3 promoted the stem-like cell phenotype. We examined the dysregulation of the stem cell markers (Oct-4, Sox-2 and CD44) and the tumorsphere formation in HER2overexpressing human breast cancer cell lines. We demonstrated that the STAT3 inhibitor, Stattic, treatment abolished the cancer stem cell phenotype in HER2-positive breast cancers. Combined treatment of Herceptin and Stattic showed the synergistic effect on the cancer cell growth in vitro. In addition, when the STAT3 gene was knocked down, the expression of the stem cell markers Oct-4, Sox-2 and CD44 were downregulated and tumorsphere formation was abolished. HER2-elicited STAT3 signaling may provide a potential model for drug resistance induced by stemlike cell characteristics. This mechanism may be responsible for acquiring resistance to Herceptin in the treatment of HER2overexpressing breast tumors. Based on our findings, targeting pSTAT3 could overcome Herceptin-induced resistance in HER2-overexpressing breast tumors.
Cancer Science, 2008
Signal transducer and activator of transcription (Stat) 5 appears to play a vital role in prolactin (PRL)-induced cell differentiation and normal mammary gland development. We previously showed that PRL-activated Stat5a induced expression of E-cadherin-β β β β-catenin complex in vitro and in xenotransplant tumors in vivo led to inhibition of breast cancer invasion. In the present study, we show that human breast cancer cells co-overexpressing Stat5a and its tyrosine kinase (Jak) 2 cultured in three-dimensional (3D) Matrigel culture demonstrate changes consistent with induction of mesenchymalepithelial redifferentiation. Jak2 and Stat5a-co-overexpressing cells treated with cocktail (PRL, dexamethasone, and insulin), effectively reverse epithelial-mesenchymal transition by stimulating 3D organoids more reminiscent of the acinar growth of normal mammary epithelial cells, compared with cells overexpressing only Stat5a or Jak2. In contrast, dominant-negative dominant-negative-Stat5 blocks 3D organoid formation, causing cells to grow in layers instead. Hyperactivation of Jak2 and Stat5a in T-47D cells induces alveolar-like structures, mamospheres, with marked lumen formation through central apoptosis and restores a polarized epithelial phenotype. However, Jak2 and Stat5a overexpression in BT-20 cells induces partially differentiated 3D organoids with no central lumen, but effectively re-expresses estrogen receptor α α α α. Jak2 and Stat5a-induced 3D differentiated organoids are accompanied by increased expression of E-cadherin, zonula occludens-1, and cytokeratins 8 and 18, and decreased levels of vimentin and Snail, indicating a shift from a mesenchymal phenotype toward an epithelial phenotype. Collectively, Jak2 and Stat5a co-overexpression cooperatively reverses epithelialmesenchymal transition and promotes differentiation in human breast cancer cells, which may provide a mechanism to explain the invasive suppressor role of PRL-activated Stat5a in mammary cancer cells. (Cancer Sci 2008; 99: 272-279)