Dataset Information

Breast Cancer

ABSTRACT: Endocrine resistance in breast cancer is a major clinical problem with poorly understood mechanisms. Mass spectrometry-based proteomics of a clinically-relevant tamoxifen-resistant cell line model identified increased levels of minichromosome maintenance proteins (MCM), including MCM3, as central in cell cycle and DNA replication protein-protein interaction networks associated with tamoxifen resistance. Lowering MCM3 protein expression in tamoxifen-resistant cells restored tamoxifen sensitivity and altered phosphorylation of several cell cycle regulators, such as p53(Ser315, 33), CHK1(Ser317) and cdc25b(Ser323), suggesting that MCM3 activation of important cell cycle-associated proteins overcomes tamoxifen’s anti-proliferative effects. High MCM3 expression in primary tumor tissue from two independent cohorts of ER+ breast cancer patients receiving adjuvant tamoxifen mono-therapy was an independent prognostic marker significantly associated with a shorter recurrence-free survival.

INSTRUMENT(S): LTQ Orbitrap Velos

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Epithelial Cell, Cell Culture

DISEASE(S): Breast Cancer

SUBMITTER: Jens Andersen

LAB HEAD: Henrik J. Ditzel

PROVIDER: PXD001087 | Pride | 2022-02-22

REPOSITORIES: Pride

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MCM3 upregulation confers endocrine resistance in breast cancer and is a predictive marker of diminished tamoxifen benefit.

Løkkegaard Sanne S Elias Daniel D Alves Carla L CL Bennetzen Martin V MV Lænkholm Anne-Vibeke AV Bak Martin M Gjerstorff Morten F MF Johansen Lene E LE Vever Henriette H Bjerre Christina C Kirkegaard Tove T Nordenskjöld Bo B Fornander Tommy T Stål Olle O Lindström Linda S LS Esserman Laura J LJ Lykkesfeldt Anne E AE Andersen Jens S JS Leth-Larsen Rikke R Ditzel Henrik J HJ

NPJ breast cancer 20210104 1

Resistance to endocrine therapy in estrogen receptor-positive (ER+) breast cancer is a major clinical problem with poorly understood mechanisms. There is an unmet need for prognostic and predictive biomarkers to allow appropriate therapeutic targeting. We evaluated the mechanism by which minichromosome maintenance protein 3 (MCM3) influences endocrine resistance and its predictive/prognostic potential in ER+ breast cancer. We discovered that ER+ breast cancer cel ...[more]

PMID: 33398005

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Project description:Purpose: Development of resistance to tamoxifen is an important clinical issue in the treatment of patients with breast cancer. Tamoxifen resistance may be the result of the acquisition of epigenetic regulation such as DNA methylation within breast cancer cells resulting in changed mRNA expression of genes being pivotal for estrogen dependent growth. Alternatively, tamoxifen resistance may be due to selection of preexisting resistant cells, which may exhibit cancer stem-like characteristics or a combination of the two mechanisms. Methods: To evaluate the contribution of these possible mechanisms to tamoxifen resistance, we applied modified DNA methylation-specific digital karyotyping (MMSDK) and digital gene expression (DGE) in combination with massively parallel sequencing to analyze a well-established tamoxifen resistant cell line model: MCF-7/S0.5 (tamoxifen sensitive parental cell line) and 4 high-dosage tamoxifen selected resistant offspring sublines (MCF-7/TAMR-1, MCF-7/TAMR-4, MCF-7/TAMR-7 and MCF-7/TAMR-8). MMSDK uses BssHII as mapping enzyme (DNA methylation sensitive enzyme). Both MMSDK and DGE use NlaIII and MmeI to produce 20-21 bp tag. The indexed single-end sequencing was performed by Illumina HiSeq 2000 in BGI-Shenzhen. A dynamic programming algorithm-FASTX-Toolkit implemented in Perl was used to trim the adaptor sequence. The trimmed tags were subjected to quality filtering, so that only tags with sequencing quality higher than 30 for more than 80% of the nucleotides were used for subsequent analysis. For MMSDK tag mapping, we generated a simulated reference library, i.e., BssHII reference library, by in silico enzyme digestion of the human genome (hg19, UCSC) regardless of the methylation state. This library was used as reference for subsequent mapping of the tags in the MMSDK analysis. In the DGE analysis, refMrna (hg19, UCSC) was used as reference for mapping cDNA tags. Subsequently, the BurrowsM-bM-^@M-^SWheeler Aligner (BWA) procedure for aligning the MMSDK and DGE tags to the simulated BssHII reference library and refMrna reference library, respectively, was applied. Results: MMSDK libraries using BssHII/NlaIII were generated from the parental tamoxifen sensitive subline MCF-7/S0.5 and the 4 TAMR cell lines: TAMR-1, TAMR-4, TAMR-7 and TAMR-8. The 5 indexed MMSDK libraries were sequenced in one lane and 1.38 Gb clean tag data for all 5 cell lines were obtained, with an average sequencing amount of ~270 Mb per library. On average, 59.5 % of the tags with mapping quality M-bM-^IM-% 20 were mapped back to the simulated BssHII/NlaIII reference library. DGE libraries were also generated from MCF-7/S0.5 and the 4 TAMR cell lines. The 5 indexed DGE libraries were sequenced in one lane and obtained 1.71 Gb clean tag data for all 5 cell lines with an average sequencing amount of ~340 Mb per library. On average, 40.8 % with mapping quality M-bM-^IM-% 20 were mapped back to the simulated NlaIII human transcriptome (refMrna reference library). Our present study demonstrates large differences in global gene expression and DNA methylation profiles between parental tamoxifen-sensitive cell line and 4 high-dosage tamoxifen treatment selected resistant sublines. The tamoxifen resistant cell lines exhibited globally higher methylation level than the parental cell line and an inverse relationship between gene expression and DNA methylation in the promoter regions were noticed. High expression of SOX2 and alterations of other SOX gene family members, E2F gene family members and RB-related pocket protein genes as well as highlighted stem cell pathways imply that cancer initiating cells/stem cells are involved in the resistance to tamoxifen. DNA methylation and mRNA expression profiles from tamoxifen sensitive parental cell line MCF-7/S0.5 and 4 high dosage of tamoxifen selected resistant offspring sublines (MCF-7/TAMR-1, MCF-7/TAMR-4, MCF-7/TAMR-7 and MCF-7/TAMR-8) were analyzed by MMSDK and DGE methods, respectively, in combination of massively parallel sequencing, using Illumina HiSeq 2000

Project description:MCM3 is one of several genes whose expression profile is markedly altered in tamoxifen-resistant breast cancer cell lines. We observed that increased MCM3 expression is associated with tamoxifen resistance. Knockdown of MCM3 resulted in increased susceptibility of tamoxifen-resistant breast cancer cell lines. Moreover, MCM3 expression is significantly associated with clinical outcome of endocrine treated receptor positive breast cancer. To understand the effect of MCM3 on the mechanism of endocrine resistance, we performed gene expression array on tamoxifen-resistant breast cancer cell lines. Here we show that MCM3 knockdown affects the expression of hundreds of genes. Resistance to endocrine therapy in estrogen receptor-positive (ER+) breast cancer is a major clinical problem with poorly understood mechanisms. There is an unmet need for prognostic and predictive biomarkers to allow appropriate therapeutic targeting. We evaluated the mechanism by which minichromosome maintenance protein 3 (MCM3) influences endocrine resistance and its predictive/prognostic potential in ER+ breast cancer. We discovered that ER+ breast cancer cells survive tamoxifen and letrozole treatments through upregulation of minichromosome maintenance proteins (MCMs), including MCM3, which are key molecules in cell cycle and DNA replication. Lowering MCM3 expression in endocrine-resistant cells restored drug sensitivity and altered phosphorylation of cell cycle regulators, including p53(Ser315,33), CHK1(Ser317) and cdc25b(Ser323), suggesting that the interaction of MCM3 with cell cycle proteins is an important mechanism of overcoming replicative stress and anti-proliferative effects of endocrine treatments. Evaluation of MCM3 levels in primary tumors from four independent cohorts of breast cancer patients receiving adjuvant tamoxifen mono-therapy or no adjuvant treatment, including the Stockholm tamoxifen (STO-3) trial, showed MCM3 to be an independent prognostic adding information beyond Ki67. In addition, MCM3 was shown to be a predictive marker of response to endocrine treatment. Our study reveals a coordinated signaling network centered around MCM3 that limits response to endocrine therapy in ER+ breast cancer and identifies MCM3 as a clinically useful prognostic and predictive biomarker that allows personalized treatment of ER+ breast cancer patients.

Project description:Breast Cancer (BC) is one of the main causes of cancer-related death in women. The most widespread BC subtype (75%) is the hormone-dependent, characterized by high expression of Estrogen Receptor Alpha (ERa). ERa exerts its oncogenic activity through the interaction with different co-regulators, carrying out a direct control on gene transcription and thus being the target of specific anticancer therapies. Despite the efficiency of these drugs, 30% of patients develop de novo or acquired resistance mechanisms, caused by alternative mechanisms that bypass antiestrogenic effects determining the onset of relapse. In order to identify new and potentially drugable Era molecular partners, essential genes for BC progression in luminal cell lines assessed by CRISPR-cas assay were compared to ERa interactome, dropping our focus on the tyrosine-protein kinase BAZ1B. BAZ1B is an essential component of the WICH complex and plays a crucial role in chromatin remodelling acting also as transcription regulator. In order to characterize the functional role of BAZ1B in luminal BC, we first employed a TCGA analysis that showed higher expression of BAZ1B in luminal BC associated with a worst overall survival and progression free survival of patient affected by this disease. A transcriptome profiling after BAZ1B silencing was performed in MCF-7 cells, highlighting an impact of modulated genes in key BC pathways including the estrogen signalling. BAZ1B silencing showed also an effect on cell growth, inhibiting cell proliferation and increasing apoptosis activation mechanisms promoted by the loss of ERa protein expression coupled to a reduction of the receptor transactivation activity. Interesting, these effects were confirmed also in antiestrogen (Tamoxifen and Fulvestrant) resistant BC cell models that retain ERa expression, suggesting BAZ1B as a novel and potentially exploitable therapeutic target in the treatment of both hormone dependent and resistant mammary tumours.

Project description:The transcription factor FOXM1 coordinates the expression of cell cycle-related genes and plays a pivotal role in tumorigenesis and cancer progression. We have previously shown that FOXM1 acts downstream of 14-3-3ζ signaling, which correlates with a more aggressive tumor phenotype. However, the role that FOXM1 might play in engendering the resistance to endocrine treatments in estrogen receptor-positive (ER+) patients when tumor FOXM1 is high, has not been clearly defined. To understand the role of FOXM1 in endocrine resistance and cancer aggressiveness, we analyzed FOXM1 protein expression by IHC in 501 ER-positive breast cancers; this revealed high FOXM1 expression in 20% of the tumors and a significantly reduced survival in these patients (p=0.003, log rank Mantel-Cox). We also mapped genome-wide FOXM1 binding events by chromatin immunoprecipitation, followed by high-throughput sequencing (ChIP-seq), in hormone-sensitive and resistant breast cancer cells after tamoxifen treatment. FOXM1 binding sites were enriched at the transcription start site of genes involved in cell cycle progression, maintenance of stem cell properties, and invasion and metastasis, all of which are correlated with the worst prognosis in ERα-positive patients treated with tamoxifen. Binding profiles were also integrated with gene expression data from cells before and after FOXM1 knockdown to highlight specific FOXM1 transcriptional networks. By modulating the levels of FOXM1 and newly discovered FOXM1-regulated genes [in breast cancer cells], we demonstrate that increased expression of FOXM1 was associated with an expansion of the cancer stem-like cell population and with increased cell invasiveness and resistance to endocrine treatments. Use of a selective FOXM1 inhibitor proved very effective in restoring endocrine therapy sensitivity and decreasing breast cancer aggressiveness. Collectively, our findings uncover novel roles for FOXM1 and FOXM1-regulated genes in promoting cancer stem-like cell properties and therapy resistance, and highlight the relevance of FOXM1 as a therapeutic target to be considered for reducing invasiveness and enhancing breast cancer response to endocrine treatments. MCF-7 human breast adenocarcinoma cells were tranfected with control, and FOXM1 siRNA for 72 hours and treated with 0.1% EtOH (Vehicle) or 1 uM TOT for 24 hours, and cDNA microarray analyses were carried out using Affymetrix [HG-U133A_2] Affymetrix Human Genome U133A 2.0 Array.

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