Division of Surgery, Oncology, and Pathology, Department of Clinical Sciences, Lund University, Solvegatan 19, 22362, Lund, Sweden.
Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK.
Sci Rep. 2024 Mar 22;14(1):6873. doi: 10.1038/s41598-024-56412-8.
Three quarters of all breast cancers express the estrogen receptor (ER, ESR1 gene), which promotes tumor growth and constitutes a direct target for endocrine therapies. ESR1 mutations have been implicated in therapy resistance in metastatic breast cancer, in particular to aromatase inhibitors. ESR1 mutations promote constitutive ER activity and affect other signaling pathways, allowing cancer cells to proliferate by employing mechanisms within and without direct regulation by the ER. Although subjected to extensive genetic and transcriptomic analyses, understanding of protein alterations remains poorly investigated. Towards this, we employed an integrated mass spectrometry based proteomic approach to profile the protein and phosphoprotein differences in breast cancer cell lines expressing the frequent Y537N and Y537S ER mutations. Global proteome analysis revealed enrichment of mitotic and immune signaling pathways in ER mutant cells, while phosphoprotein analysis evidenced enriched activity of proliferation associated kinases, in particular CDKs and mTOR. Integration of protein expression and phosphorylation data revealed pathway-dependent discrepancies (motility vs proliferation) that were observed at varying degrees across mutant and wt ER cells. Additionally, protein expression and phosphorylation patterns, while under different regulation, still recapitulated the estrogen-independent phenotype of ER mutant cells. Our study is the first proteome-centric characterization of ESR1 mutant models, out of which we confirm estrogen independence of ER mutants and reveal the enrichment of immune signaling pathways at the proteomic level.
四分之三的乳腺癌表达雌激素受体（ER，ESR1 基因），它促进肿瘤生长，是内分泌治疗的直接靶点。ESR1 突变与转移性乳腺癌的治疗耐药性有关，特别是与芳香酶抑制剂耐药性有关。ESR1 突变促进 ER 活性的组成型激活，并影响其他信号通路，使癌细胞通过在 ER 直接调节之外和之内利用机制增殖。尽管已经进行了广泛的遗传和转录组分析，但对蛋白质改变的理解仍研究不足。为此，我们采用了一种基于质谱的综合蛋白质组学方法，对表达常见 Y537N 和 Y537S ER 突变的乳腺癌细胞系中的蛋白质和磷酸化蛋白质差异进行了分析。全蛋白质组分析显示，ER 突变细胞中存在有丝分裂和免疫信号通路的富集，而磷酸化蛋白质分析则表明与增殖相关的激酶（特别是 CDK 和 mTOR）活性增强。蛋白质表达和磷酸化数据的整合揭示了不同程度存在于突变和 wt ER 细胞中的依赖于途径的差异（运动性与增殖性）。此外，尽管受到不同的调节，蛋白质表达和磷酸化模式仍然再现了 ER 突变细胞的雌激素非依赖性表型。我们的研究是对 ESR1 突变模型进行的首个以蛋白质组为中心的特征描述，从中我们证实了 ER 突变体的雌激素独立性，并在蛋白质组水平上揭示了免疫信号通路的富集。
