Department of Pharmacy, University of Bonn, Germany.
Department of Pharmacy, University of Bonn, Germany.
Biochim Biophys Acta Mol Cell Res. 2020 May;1867(5):118663. doi: 10.1016/j.bbamcr.2020.118663. Epub 2020 Jan 25.
Molecular interactions of tumor cells with the microenvironment are regarded as onset of chemotherapy resistance, referred to as cell adhesion mediated drug resistance (CAM-DR). Here we elucidate a mechanism of CAM-DR in breast cancer cells in vitro. We show that human MCF-7 and MDA-MB-231 breast cancer cells decrease their sensitivity towards cisplatin, doxorubicin, and mitoxantrone cytotoxicity upon binding to collagen type 1 (COL1) or fibronectin (FN). The intracellular concentrations of doxorubicin and mitoxantrone were decreased upon cell cultivation on COL1, while cellular cisplatin levels remained unaffected. Since doxorubicin and mitoxantrone are transporter substrates, this refers to ATP binding cassette (ABC) efflux transporter activities. The activation of the transporters BCRP, P-gp and MRP1 was shown by fluorescence assays to distinguish the individual input of these transporters to resistance in presence of COL1 and related to their expression levels by western blot. An ABC transporter inhibitor was able to re-sensitize COL1-treated cells for doxorubicin and mitoxantrone toxicity. Antibody-blocking of β-integrin (ITGB1) induced sensitization towards the indicated cytostatic drugs by attenuating the increased ABC efflux activity. This refers to a key role of ITGB1 for matrix binding and subsequent transporter activation. A downregulation of αβ integrin following COL1 binding appears as clear indication for the relationship between ITGB1 and ABC transporters in regulating resistance formation, while knockdown of ITGB1 leads to a significant upregulation of all three transporters. Our data provide evidence for a role of CAM-DR in breast cancer via an ITGB1 - transporter axis and offer promising therapeutic targets for cancer sensitization.
肿瘤细胞与微环境的分子相互作用被认为是化疗耐药的开始，称为细胞黏附介导的药物耐药（CAM-DR）。在这里，我们在体外阐明了乳腺癌细胞中 CAM-DR 的一种机制。我们表明，人 MCF-7 和 MDA-MB-231 乳腺癌细胞在与胶原类型 1（COL1）或纤维连接蛋白（FN）结合后，对顺铂、阿霉素和米托蒽醌的细胞毒性敏感性降低。当在 COL1 上培养细胞时，阿霉素和米托蒽醌的细胞内浓度降低，而细胞内顺铂水平不受影响。由于阿霉素和米托蒽醌是转运体的底物，这涉及到 ABC 转运体的外排转运体活性。荧光测定法显示，转运体 BCRP、P-gp 和 MRP1 的激活能够区分在 COL1 和相关存在下这些转运体对耐药性的单独输入，并通过 Western blot 区分其表达水平。ABC 转运体抑制剂能够使 COL1 处理的细胞重新对阿霉素和米托蒽醌的毒性敏感。通过减弱增加的 ABC 外排活性，β-整联蛋白（ITGB1）的抗体阻断诱导对所述细胞毒药物的敏感性。这表明 ITGB1 对于基质结合和随后的转运体激活具有关键作用。COL1 结合后 αβ 整联蛋白的下调是 ITGB1 和 ABC 转运体在调节耐药形成中的关系的明确迹象，而 ITGB1 的敲低导致所有三种转运体的显著上调。我们的数据为通过 ITGB1-转运体轴在乳腺癌中 CAM-DR 的作用提供了证据，并为癌症增敏提供了有前途的治疗靶标。
