Center for Engineering in Medicine and Surgery, Department of Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
Shriners Hospital for Children, Boston, Massachusetts.
Cancer Res. 2022 Mar 15;82(6):1084-1097. doi: 10.1158/0008-5472.CAN-21-2609.
Cancer therapy often results in heterogeneous responses in different metastatic lesions in the same patient. Inter- and intratumor heterogeneity in signaling within various tumor compartments and its impact on therapy are not well characterized due to the limited sensitivity of single-cell proteomic approaches. To overcome this barrier, we applied single-cell mass cytometry with a customized 26-antibody panel to PTEN-deleted orthotopic prostate cancer xenograft models to measure the evolution of kinase activities in different tumor compartments during metastasis or drug treatment. Compared with primary tumors and circulating tumor cells (CTC), bone metastases, but not lung and liver metastases, exhibited elevated PI3K/mTOR signaling and overexpressed receptor tyrosine kinases (RTK) including c-MET protein. Suppression of c-MET impaired tumor growth in the bone. Intratumoral heterogeneity within tumor compartments also arose from highly proliferative EpCAM-high epithelial cells with increased PI3K and mTOR kinase activities coexisting with poorly proliferating EpCAM-low mesenchymal populations with reduced kinase activities; these findings were recapitulated in epithelial and mesenchymal CTC populations in patients with metastatic prostate and breast cancer. Increased kinase activity in EpCAM-high cells rendered them more sensitive to PI3K/mTOR inhibition, and drug-resistant EpCAM-low populations with reduced kinase activity emerged over time. Taken together, single-cell proteomics indicate that microenvironment- and cell state-dependent activation of kinase networks create heterogeneity and differential drug sensitivity among and within tumor populations across different sites, defining a new paradigm of drug responses to kinase inhibitors.
Single-cell mass cytometry analyses provide insights into the differences in kinase activities across tumor compartments and cell states, which contribute to heterogeneous responses to targeted therapies.
癌症治疗通常会导致同一患者的不同转移病灶产生异质性反应。由于单细胞蛋白质组学方法的灵敏度有限，各种肿瘤区室之间的信号转导及其对治疗的影响存在的种间和种内异质性尚不清楚。为了克服这一障碍，我们应用单细胞质谱流式细胞术和定制的 26 抗体面板，对 PTEN 缺失的原位前列腺癌异种移植模型进行了研究，以测量转移或药物治疗过程中不同肿瘤区室的激酶活性的演变。与原发性肿瘤和循环肿瘤细胞（CTC）相比，骨转移瘤，但不是肺和肝转移瘤，表现出升高的 PI3K/mTOR 信号和过表达的受体酪氨酸激酶（RTK），包括 c-MET 蛋白。抑制 c-MET 会损害骨中的肿瘤生长。肿瘤区室内部的肿瘤内异质性也源于具有较高增殖性的 EpCAM-高上皮细胞，这些细胞具有增加的 PI3K 和 mTOR 激酶活性，与增殖能力较差的 EpCAM-低间充质群体共存，这些群体的激酶活性降低；这些发现与转移性前列腺癌和乳腺癌患者的上皮和间充质 CTC 群体中得到了重现。EpCAM-高细胞中激酶活性的增加使它们对 PI3K/mTOR 抑制更为敏感，并且随着时间的推移，出现了具有降低激酶活性的耐药性 EpCAM-低群体。总之，单细胞蛋白质组学表明，激酶网络的微环境和细胞状态依赖性激活在不同部位的肿瘤群体之间和内部产生了异质性和对药物敏感性的差异，为激酶抑制剂的药物反应定义了一个新的范例。
单细胞质谱流式细胞术分析提供了对肿瘤区室和细胞状态之间激酶活性差异的深入了解，这些差异有助于对靶向治疗产生异质性反应。
