Department of Thyroid, Breast Surgery, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China.
Department of Thyroid, Breast Surgery, Longgang District Central Hospital, Shenzhen, China.
Acta Biochim Pol. 2023 Apr 17;70(2):261-269. doi: 10.18388/abp.2020_6357.
More than 1 million women worldwide are diagnosed with breast cancer (BC) each year. This study aims to explore the molecular mechanisms of β-catenin affecting the trastuzumab tolerance in HER2-positive BC. β-catenin in BC and non-BC tissue samples were assessed by immunohistochemistry. β-catenin and HER2 were over-expressed and knockdown to evaluate their role in tumorigenicity and trastuzumab resistance in cell and animal models using soft-agar and xenograft assays. Confocal laser immunofluorescence assay and co-immunoprecipitation were used to assess protein-protein binding. Expression of genes was detected using Western blot analysis. β-catenin was highly expressed in primary and metastatic BC, overexpression of β-catenin increased the colony formation of MCF7 cells when it was co-expressed with HER2 and synergically increased the tumor size in immunodeficient mice. Overexpression of β-catenin also increased the phosphorylation of HER2 and HER3 and increased the size of tumor derived from HER2-elevated cells. Confocal laser immunofluorescence assay showed that β-catenin and HER2 were co-localized on the membrane of MDA-MB-231 cells, suggesting that β-catenin binds HER2 to activate the HER2 signaling pathway. Immunoprecipitation of β-catenin and HER2 also confirmed this binding. On the other hand, knockdown of β-catenin in MDA-MB-231 cell lines decreased the activity of SRC and decreased phosphorylation of HER2 at Y877 and Y1248. The interaction between HER2 and SRC was enhanced when β-catenin was overexpressed, and β-catenin increased the resistance of tumor derived from HER2 elevated BT474 cells to trastuzumab. Further analysis showed that trastuzumab inhibited the activation of HER3, but SRC was still highly expressed in cells overexpressing β-catenin. Our work demonstrates that β-catenin is highly expressed in BC and it synergically promotes formation and progress of BC with HER2. β-catenin binds with HER2 leading to enhanced interaction with SRC and resistance to trastuzumab.
全球每年有超过 100 万名女性被诊断患有乳腺癌（BC）。本研究旨在探索β-连环蛋白影响曲妥珠单抗在 HER2 阳性 BC 中的耐受性的分子机制。通过免疫组织化学评估 BC 和非 BC 组织样本中的β-连环蛋白。使用软琼脂和异种移植测定法在细胞和动物模型中过表达和敲低β-连环蛋白和 HER2，以评估它们在肿瘤发生和曲妥珠单抗耐药性中的作用。使用共聚焦激光免疫荧光测定和免疫共沉淀评估蛋白-蛋白结合。使用 Western blot 分析检测基因的表达。β-连环蛋白在原发性和转移性 BC 中高表达，当与 HER2 共表达时，β-连环蛋白过表达增加 MCF7 细胞的集落形成，并且协同增加免疫缺陷小鼠中的肿瘤大小。β-连环蛋白的过表达还增加了 HER2 和 HER3 的磷酸化，并增加了源自 HER2 升高细胞的肿瘤的大小。共聚焦激光免疫荧光测定显示，β-连环蛋白和 HER2 在 MDA-MB-231 细胞的膜上共定位，表明β-连环蛋白与 HER2 结合以激活 HER2 信号通路。β-连环蛋白和 HER2 的免疫沉淀也证实了这种结合。另一方面，在 MDA-MB-231 细胞系中敲低β-连环蛋白降低了 SRC 的活性，并降低了 HER2 在 Y877 和 Y1248 处的磷酸化。当β-连环蛋白过表达时，HER2 和 SRC 之间的相互作用增强，β-连环蛋白增加了源自 HER2 升高的 BT474 细胞的肿瘤对曲妥珠单抗的耐药性。进一步分析表明，曲妥珠单抗抑制了 HER3 的激活，但在过表达β-连环蛋白的细胞中 SRC 仍然高度表达。我们的工作表明，β-连环蛋白在 BC 中高度表达，它与 HER2 协同促进 BC 的形成和进展。β-连环蛋白与 HER2 结合，导致与 SRC 的相互作用增强，并且对曲妥珠单抗产生耐药性。
