Dataset Information

Extracellular alkaline pH leads to increased metastatic potential of estrogen receptor silenced endocrine resistant breast cancer cells.

ABSTRACT:

Introduction

Endocrine resistance in breast cancer is associated with enhanced metastatic potential and poor clinical outcome, presenting a significant therapeutic challenge. We have established several endocrine insensitive breast cancer lines by shRNA induced depletion of estrogen receptor (ER) by transfection of MCF-7 cells which all exhibit enhanced expression profile of mesenchymal markers with reduction of epithelial markers, indicating an epithelial to mesenchymal transition. In this study we describe their behaviour in response to change in extracellular pH, an important factor controlling cell motility and metastasis.

Methods

Morphological changes associated with cell exposure to extracellular alkaline pH were assessed by live cell microscopy and the effect of various ion pumps on this behavior was investigated by pretreatment with chemical inhibitors. The activity and expression profile of key signaling molecules was assessed by western blotting. Cell motility and invasion were examined by scratch and under-agarose assays respectively. Total matrix metalloproteinase (MMP) activity and specifically of MMP2/9 was assessed in conditioned medium in response to brief alkaline pH exposure.

Results

Exposure of ER -ve but not ER +ve breast cancer cells to extracellular alkaline pH resulted in cell shrinkage and spherical appearance (termed contractolation); this was reversed by returning the pH back to 7.4. Contractolation was blocked by targeting the Na(+)/K(+) and Na(+)/H(+) pumps with specific chemical inhibitors. The activity and expression profile of key signaling molecules critical for cell adhesion were modulated by the exposure to alkaline pH. Brief exposure to alkaline pH enhanced MMP2/9 activity and the invasive potential of ER -ve cells in response to serum components and epithelial growth factor stimulation without affecting unhindered motility.

Conclusions

Endocrine resistant breast cancer cells behave very differently to estrogen responsive cells in alkaline pH, with enhanced invasive potential; these studies emphasise the crucial influence of extracellular pH and caution against indiscriminate application of alkalinising drug therapy.

SUBMITTER: Khajah MA

PROVIDER: S-EPMC3788134 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Publications

Extracellular alkaline pH leads to increased metastatic potential of estrogen receptor silenced endocrine resistant breast cancer cells.

Khajah Maitham A MA Almohri Iman I Mathew Princy M PM Luqmani Yunus A YA

PloS one 20131001 10

<h4>Introduction</h4>Endocrine resistance in breast cancer is associated with enhanced metastatic potential and poor clinical outcome, presenting a significant therapeutic challenge. We have established several endocrine insensitive breast cancer lines by shRNA induced depletion of estrogen receptor (ER) by transfection of MCF-7 cells which all exhibit enhanced expression profile of mesenchymal markers with reduction of epithelial markers, indicating an epithelial to mesenchymal transition. In t ...[more]

PMID: 24098477

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Project description:Proteomic profiling of the estrogen/tamoxifen-sensitive MCF-7 cell line and its partially sensitive (MCF-7/LCC1) and fully resistant (MCF-7/LCC9) variants was performed to identify modifiers of endocrine sensitivity in breast cancer. Analysis of the expression of 120 paired phosphorylated and non-phosphorylated epitopes in key oncogenic and tumor suppressor pathways revealed that STAT1 and several phosphorylated epitopes (phospho-STAT1(Tyr701) and phospho-STAT3(Ser727)) were differentially expressed between endocrine resistant and parental controls, confirmed by qRT-PCR and western blotting. The STAT1 inhibitor EGCG was a more effective inhibitor of the endocrine resistant MCF-7/LCC1 and MCF-7/LCC9 lines than parental MCF-7 cells, while STAT3 inhibitors Stattic and WP1066 were equally effective in endocrine-resistant and parental lines. The effects of the STAT inhibitors were additive, rather than synergistic, when tested in combination with tamoxifen in vitro. Expression of STAT1 and STAT3 were measured by quantitative immunofluorescence in invasive breast cancers and matched lymph nodes. When lymph node expression was compared to its paired primary breast cancer expression, there was greater expression of cytoplasmic STAT1 (?3.1 fold), phospho-STAT3(Ser727) (?1.8 fold), and STAT5 (?1.5 fold) and nuclear phospho-STAT3(Ser727) (?1.5 fold) in the nodes. Expression levels of STAT1 and STAT3 transcript were analysed in 550 breast cancers from publicly available gene expression datasets (GSE2990, GSE12093, GSE6532). When treatment with tamoxifen was considered, STAT1 gene expression was nearly predictive of distant metastasis-free survival (DMFS, log-rank p?=?0.067), while STAT3 gene expression was predictive of DMFS (log-rank p<0.0001). Analysis of STAT1 and STAT3 protein expression in a series of 546 breast cancers also indicated that high expression of STAT3 protein was associated with improved survival (DMFS, p?=?0.006). These results suggest that STAT signaling is important in endocrine resistance, and that STAT inhibitors may represent potential therapies in breast cancer, even in the resistant setting.

Project description:Metastatic breast cancer (MBC) results in substantial morbidity and mortality for women afflicted with this disease. A majority of MBCs are hormone-responsive and estrogen receptor-positive, making endocrine therapy (ET) an integral component of systemic therapy. With a primary goal of minimizing the effects of estrogen on hormone-responsive MBC, ETs are among the first targeted treatments that aim to inhibit the influence of estrogen receptor activation on tumor proliferation. Several biochemical mechanisms have been the focus of drug development for treatment, including selective estrogen-receptor modulation, aromatase inhibition, and selective estrogen-receptor degradation. Treatments that exploit these mechanisms have improved survival and quality of life for women with MBC. However, in many cases, resistance to ET limits their effectiveness. Elucidation of the complex cellular signal cascades involved in the development of acquired resistance to ET and the interrelationship of growth factor signaling and estrogen responsiveness have characterized components of these pathways as attractive targets for drug development. Based on these insights and with the aim of overcoming hormone resistance, targeted therapies are emerging as useful treatments for MBC. This article reviews current endocrine treatments of MBC as well as recent and ongoing study of combination treatments and targeted therapies that interfere with cellular proliferation pathways as means of overcoming resistance. The Oncologist 2017;22:507-517 IMPLICATIONS FOR PRACTICE: This review provides medical oncologists and other oncology health care providers with a current understanding of the rationale for endocrine therapy in estrogen receptor-positive metastatic breast cancer and the efficacy and safety profile of available treatment options. Additionally, current concepts regarding the development of treatment resistance and the treatment strategies for overcoming resistance are discussed. Enhancing the current information and the understanding of these topics will assist clinicians in evaluating optimal treatment options for their patients.

Dataset Information

Extracellular alkaline pH leads to increased metastatic potential of estrogen receptor silenced endocrine resistant breast cancer cells.

Introduction

Methods

Results

Conclusions

Publications

Extracellular alkaline pH leads to increased metastatic potential of estrogen receptor silenced endocrine resistant breast cancer cells.

Similar Datasets

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