Elevated Levels of Epidermal Growth Factor Receptor/c-erbB2 Heterodimers Mediate an Autocrine Growth Regulatory Pathway in Tamoxifen-Resistant MCF-7 Cells

Knowlden, Janice Mary; Hutcheson, Iain Robert; Jones, Helen; Madden, Tracie-Ann; Gee, Julia Margaret Wendy; Harper, M. E.; Barrow, Denise; Wakeling, A. E.; Nicholson, Robert Ian

doi:10.1210/en.2002-220620

Cited by 497 publications

(521 citation statements)

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“…Activation of AKT and overexpression of EGF and ERBB receptors are consistent with previous observations in MCF7-LTED cells and related breast cancer conditions (Masamura et al, 1995;Jeng et al, 1998;Shim et al, 2000;McClelland et al, 2001;Knowlden et al, 2003;Osborne et al, 2005;Yue et al, 2005;Song et al, 2006;Beeram et al, 2007;LewisWambi et al, 2008;Santen et al, 2008;Ghayad et al, 2009). Notably, ERBB2 amplification was associated with resistance to endocrine therapies (Ellis et al, 2006), and treatment with the mTOR inhibitor RAD001 increased letrozole efficacy in a neoadjuvant setting of ERa-positive breast cancer (Baselga et al, 2009).…”

Section: Resultssupporting

confidence: 85%

Biological reprogramming in acquired resistance to endocrine therapy of breast cancer

et al. 2010

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Endocrine therapies targeting the proliferative effect of 17b-estradiol through estrogen receptor a (ERa) are the most effective systemic treatment of ERa-positive breast cancer. However, most breast tumors initially responsive to these therapies develop resistance through molecular mechanisms that are not yet fully understood. The longterm estrogen-deprived (LTED) MCF7 cell model has been proposed to recapitulate acquired resistance to aromatase inhibitors in postmenopausal women. To elucidate this resistance, genomic, transcriptomic and molecular data were integrated into the time course of MCF7-LTED adaptation. Dynamic and widespread genomic changes were observed, including amplification of the ESR1 locus consequently linked to an increase in ERa. Dynamic transcriptomic profiles were also observed that correlated significantly with genomic changes and were predicted to be influenced by transcription factors known to be involved in acquired resistance or cell proliferation (for example, interferon regulatory transcription factor 1 and E2F1, respectively) but, notably, not by canonical ERa transcriptional function. Consistently, at the molecular level, activation of growth factor signaling pathways by EGFR/ERBB/AKT and a switch from phospho-Ser118 (pS118)-to pS167-ERa were observed during MCF7-LTED adaptation. Evaluation of relevant clinical settings identified significant associations between MCF7-LTED and breast tumor transcriptome profiles that characterize ERa-negative status, early response to letrozole and tamoxifen, and recurrence after tamoxifen treatment. In accordance with these profiles, MCF7-LTED cells showed increased sensitivity to inhibition of FGFR-mediated signaling with PD173074. This study provides mechanistic insight into acquired resistance to endocrine therapies of breast cancer and highlights a potential therapeutic strategy.

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Section: Resultssupporting

confidence: 85%

Biological reprogramming in acquired resistance to endocrine therapy of breast cancer

et al. 2010

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“…The wild type MCF-7 (WT-MCF-7) breast cancer cells (originally a gift from AstraZeneca Pharmaceuticals, Cheshire UK) were routinely cultured in phenol red-free RPMI medium supplemented with 5% foetal calf serum (FCS) plus penicillin-streptomycin (10iU/ml-10 lg/ml), fungizone (2.5 lg/ml) and glutamine (4 mM). The TAM-R cell line was derived from WT-MCF-7 as previously reported [11] and was grown in phenol-red-free RPMI medium containing 5% charcoal-stripped steroid-depleted FCS, antibiotics, glutamine (4 mM) and 4-hydroxytamoxifen (4-OH-TAM, 100nM in ethanol). Their respective growth media were replaced every 4 days and cultures were maintained at 37°C in a humidified, 5% CO 2 atmosphere.…”

Section: Cell Culturementioning

confidence: 99%

“…Their respective growth media were replaced every 4 days and cultures were maintained at 37°C in a humidified, 5% CO 2 atmosphere. The TAM-R cell line represents a stable tamoxifen-resistant phenotype acquired between 6 and 12 months of continual tamoxifen exposure [11].…”

Section: Cell Culturementioning

confidence: 99%

“…Indeed, in MCF-7 breast cancer cell lines displaying acquired resistance to the growth inhibitory effects of either tamoxifen, or the pure anti-oestrogen fulvestrant ('Faslodex'), increased EGFR/c-erbB2/ERK signalling activity is evident. As a corollary these tamoxifen-resistant cells display enhanced sensitivity to the growth inhibitory actions of the EGFR tyrosine kinase inhibitor gefitinib, as well as the anti-c-erbB2 monoclonal antibody trastuzumab, and the MEK inhibitor, PD098059 [10,11].…”

Section: Introductionmentioning

confidence: 99%

“…Alternatively, the loss of caveolin-1 in the tamoxifenresistant subtype may afford increased EGFR/ERK signalling and breast tumour growth. To discriminate between these possibilities and to fully define a role for caveolin-1 in tamoxifen-resistant breast cancer we undertook a series of mechanistic studies using a well characterised preclinical human tamoxifen-resistant breast cancer cell model [10,11,31].…”

Section: Introductionmentioning

confidence: 99%

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Growth of hormone-dependent MCF-7 breast cancer cells is promoted by constitutive caveolin-1 whose expression is lost in an EGF-R-mediated manner during development of tamoxifen resistance

Thomas

Hutcheson

Campbell

et al. 2009

Breast Cancer Res Treat

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Growth of hormone-dependent MCF-7 breast cancer cells is promoted by constitutive caveolin-1 whose expression is lost in an EGF-R-mediated manner during development of tamoxifen resistance. Breast Cancer Research and Treatment, Springer Verlag, 2009, 119 (3) Abstract Caveolin-1 displays both tumour-suppressor and tumour-promoter properties in breast cancer. Using characterised preclinical cell models for the transition of oestrogen-sensitive (WT-MCF-7 cells) to a tamoxifenresistant (TAM-R cells) phenotype we examined the role caveolin-1 in the development of hormone-resistant breast cancer. The WT-MCF-7 cells showed abundant expression of caveolin-1 which potentiated oestrogen-receptor (ERa) signalling and promoted cell growth despite caveolin-1 mediating inhibition of ERK signalling. In TAM-R cells caveolin-1 expression was negligible, repressed by EGF-R/ERK signalling. Pharmacological inhibition of EGFR/ERK in TAM-R cells restored caveolin-1 and also resulted in the emergence of pools of phosphorylated caveolin-1. WT-MCF-7 cells exposed to tamoxifen for upto 12 weeks displayed increased caveolin-1 (peaking by week 2) followed (after week 8) by a marked decrease as the cells progress to develop a stable tamoxifen-resistant phenotype. The targeted down-regulation (siRNA) of caveolin-1 in WT-MCF-7 cells reduced growth but did not affect their sensitivity to tamoxifen, suggesting loss of caveolin-1 alone is not sufficient to confer tamoxifen-resistance. Hyperactivation of EGFR/ERK is a feature of tamoxifen-resistant breast cancer cells, a principal driver of cell growth. Recombinant expression of caveolin-1 in TAM-R cells did not affect EGFR/ERK activity, potentially due to mislocalisation of caveolin-1 through hyperactivation of the mTOR pathway or altered caveolin-1 phosphorylation. This work defines a novel role for caveolin-1 with implications for the clinical course of breast cancer and identifies caveolin-1 as a potential drug target for the treatment of early oestrogen-dependent breast cancers. Further, the loss of caveolin-1 may have benefit as a molecular signature for tamoxifen resistance.

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Research Highlights

2012

Biopolymers

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Nucleosomes act as a roadblock to transcription, but there are a number of mechanisms by which RNA polymerase II can successfully bypass histone complexes. For example, chemical modifications to the 'tails' of histone subunits can enhance transcription, as can changes in DNA-protein interactions within a nucleosome. However, little is known about how these various factors collectively impact transcription.A series of single-molecule experiments by Bintu et al. offer new insights into this process, yielding a multi-step model to explain how the polymerase complex negotiates its way past the nucleosome. The authors used an optical tweezers setup to monitor the pausing behavior of the RNA polymerase II elongation complex (EC) as it travels along DNA containing a single nucleosome positioning sequence (NPS), and identified three different NPS regions that they termed 'entry' , 'center' and 'exit' . Histone manipulation revealed that the absence of tail domains or introduction of conditions simulating acetylation of histone lysine residues specifically reduced pausing in the entry region, whereas point mutations to the H3 and H4 histones that loosen their association with DNA decreased pausing at the NPS center. These effects were subsequently replicated in experiments that tested how different modifications modulate the 'tightness' of DNA wrapping around the nucleosome complex.Previous work suggests that transcription is dependent on ongoing fluctuations in nucleosome structure, and that the EC will backtrack along the nascent RNA strand when forward progress is thwarted. The authors also observed this, and obtained evidence that the local DNA sequence can modulate this backtracking based on the extent to which newly-transcribed RNA forms stable secondary structure. The interplay between these various factors can thus collectively have a profound effect on the transcriptional dynamics within a given stretch of chromatin. Bintu, L. et al. Cell 151, 738-749 (2012). Understanding Developmental DisruptionsChromodomain helicase DNA-binding 7 (CHD7) is the vertebrate homolog of kismet, a fruit fly gene that plays a prominent role in body development via the regulation of homeotic gene expression. Accordingly, CHD7 mutations are linked with a host of developmental defects in humans, including a pattern of severe and potentially fatal abnormalities collectively described as CHARGE syndrome.The CHD7 protein has proven challenging to purify and characterize due to its large size, but Bouazone and Kingston recently made important headway in clarifying its functional role. Previous evidence has indicated that CHD7 participates in chromatin remodeling, and the researchers confirmed that this protein can directly induce changes in nucleosome mobility via an ATP-dependent mechanism. Comparative assays with other remodeling factors indicated that CHD7 tends to act more like ISWI than hSWI/SNF, and exhibits a strong preference for acting on individual nucleosomes flanked by histone-free DNA and a partial dependence on histone tail i...

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Elevated Levels of Epidermal Growth Factor Receptor/c-erbB2 Heterodimers Mediate an Autocrine Growth Regulatory Pathway in Tamoxifen-Resistant MCF-7 Cells

Cited by 497 publications

References 48 publications

Biological reprogramming in acquired resistance to endocrine therapy of breast cancer

Biological reprogramming in acquired resistance to endocrine therapy of breast cancer

Growth of hormone-dependent MCF-7 breast cancer cells is promoted by constitutive caveolin-1 whose expression is lost in an EGF-R-mediated manner during development of tamoxifen resistance

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