Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Tamoxifen treatment of MCF-7 breast cancer cells

ABSTRACT: Tamoxifen is an anti-estrogen drug used in the treatment of Estrogen Receptor (ER) positive breast cancer. Effects and side effects of tamoxifen is the sum of tamoxifen and all its metabolites. Using concentrations that mimic the clinical situation we examined effects of 4OHtam, 4OHNDtam and NDtam on global gene expression in 17beta-estradiol (E2) treated MCF-7 cells.

ORGANISM(S): Homo sapiens

SUBMITTER: Rita Holdhus

PROVIDER: E-MTAB-2729 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

The active tamoxifen metabolite endoxifen (4OHNDtam) strongly down-regulates cytokeratin 6 (CK6) in MCF-7 breast cancer cells.

Helland Thomas T Gjerde Jennifer J Dankel Simon S Fenne Ingvild S IS Skartveit Linn L Drangevåg Andreas A Bozickovic Olivera O Flågeng Marianne Hauglid MH Søiland Håvard H Mellgren Gunnar G Lien Ernst A EA

PloS one 20150413 4

<h4>Introduction</h4>Tamoxifen is an anti-estrogen drug used in treatment of Estrogen Receptor (ER) positive breast cancer. Effects and side effects of tamoxifen is the sum of tamoxifen and all its metabolites. 4-Hydroxytamoxifen (4OHtam) and 4-hydroxy-N-demethyltamoxifen (4OHNDtam, endoxifen) both have ER affinity exceeding that of the parent drug tamoxifen. 4OHNDtam is considered the main active metabolite of tamoxifen. Ndesmethyltamoxifen (NDtam) is the major tamoxifen metabolite. It has low ...[more]

PMID: 25867603

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Project description:Tamoxifen, a selective estrogen receptor modulator (SERM), is commonly used in the treatment of hormone-responsive cancers. The effects of tamoxifen in anabolic tissues harboring estrogen-receptors, such as skeletal muscle, are poorly understood. As estrogen and estrogen receptors play an important role in skeletal muscle development and repair, we hypothesize that tamoxifen may have specific effects on myogenesis, the developmental process underlying muscle cells differentiation and repair. Myogenesis is characterized by fine-tuned changes in protein expression as embryonic myoblasts and adult satellite cells transition from pluripotent stem cells to multinucleated, contractile muscle fibers: we undertake a quantitative proteomic analysis of tamoxifen-induced changes in developing skeletal muscle cells which we expect may also shed light on the effect of tamoxifen on muscle repair. We report a tandem mass-tag (TMT) approach to tamoxifen-treated myogenesis in C2C12 cells, a well-characterized model of in vitro murine skeletal muscle differentiation. A longitudinal analysis of >10,000 proteins identified in C2C12 myogenesis revealed a novel subset of 1,239 myogenically-regulated proteins. This set of regulatory proteins clustered into five distinct longitudinal expression trends which significantly overlap those obtained in similar analyses performed in human myocytes. A longitudinal analysis of myogenesis in the presence of tamoxifen, when contrasted with a similar analysis in untreated myogenesis finds that while the vast majority of myogenically-regulated proteins were unaffected by tamoxifen treatment, specific pathways and networks are affected. We document a specific functional enrichment for adiponectin-signaling, whereby a set of 198 proteins were differentially expressed relative to controls at one or more stages of myogenesis, the majority of which were involved in steroid biosynthesis, lipid storage and/or metal ion homeostasis. Interestingly, the only protein that was differentially expressed in the tamoxifen-treated cells at every stage of myogenesis was metallothionein-1 (MT1). Elevated levels of MT1 have been correlated with tamoxifen resistance and increased patient mortality and relapse in breast cancer, as well as with cachexia and muscle atrophy in rodent models. Increased MT1 expression levels may contribute to the musculoskeletal effects reported by patients undergoing tamoxifen treatment. Finally, we present a powerful, self-validating pipeline for analyzing the total proteomic response to in vitro treatment across every stage of muscle cells development which can be easily adapted to study the effects of other drugs on myogenesis.

Project description:Tamoxifen, an antagonist to estrogen receptor (ER), is a first line drug used in breast cancer treatment. However, this therapy is complicated by the fact that a substantial number of patients exhibit either de novo or acquired resistance. To characterize the signaling mechanisms underlying the resistance to tamoxifen, we established a tamoxifen-resistant cell line by treating the MCF7 breast cancer cell line with tamoxifen for over 6 months. We showed that this cell line exhibited resistance to tamoxifen both in vitro and in vivo. In order to quantify the phosphorylation alterations associated with tamoxifen resistance, we performed SILAC-based quantitative phosphoproteomic profiling on the resistant and vehicle-treated sensitive cell lines where we identified >5,600 unique phosphopeptides. We found phosphorylation levels of 1,529 peptides were increased (>2 fold) and 409 peptides were decreased (<0.5-fold) in tamoxifen resistant cells compared to tamoxifen sensitive cells. Gene set enrichment analysis revealed that focal adhesion pathway was the top enriched signaling pathway activated in tamoxifen resistant cells. We observed hyperphosphorylation of the focal adhesion kinases FAK1 and FAK2 in the tamoxifen resistant cells. Of note, FAK2 was not only hyperphosphorylated but also transcriptionally upregulated in tamoxifen resistant cells. Suppression of FAK2 by specific siRNA knockdown could sensitize the resistant cells to the treatment of tamoxifen. We further showed that inhibiting FAK activity using the small molecule inhibitor PF562271 repressed cellular proliferation in vitro and tumor formation in vivo. More importantly, our survival analysis revealed that high expression of FAK2 significantly associated with short metastasis-free survival of ER-positive breast cancer patients treated with tamoxifen-based hormone therapy. Our studies suggest that FAK2 is a great potential target for the development of therapy for the treatment of hormone refractory breast cancers.

Dataset Information

Tamoxifen treatment of MCF-7 breast cancer cells

Publications

The active tamoxifen metabolite endoxifen (4OHNDtam) strongly down-regulates cytokeratin 6 (CK6) in MCF-7 breast cancer cells.

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