Related Experiment Video
Updated: Oct 6, 2025
Testing Targeted Therapies in Cancer using Structural DNA Alteration Analysis and Patient-Derived Xenografts
Published on: July 25, 2020
Differential Kinase Activity Across Prostate Tumor Compartments Defines Sensitivity to Target Inhibition
Nezihi Murat Karabacak1,2, Yu Zheng3, Taronish D Dubash3
1Center for Engineering in Medicine and Surgery, Department of Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
Abstract:
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.
Significance:
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.
Insights
Single-cell proteomics reveals how kinase signaling heterogeneity drives varied cancer drug responses. Understanding these differences in tumor cells and sites is key to improving targeted therapy effectiveness.
Area of Science:
- Oncology
- Molecular Biology
- Proteomics
Background:
- Cancer therapy responses vary significantly due to tumor heterogeneity.
- Limited sensitivity of current methods hinders understanding of cell signaling within tumors.
- Inter- and intratumor heterogeneity impacts therapeutic outcomes.
Purpose of the Study:
- To investigate kinase activity evolution in different tumor compartments using single-cell mass cytometry.
- To characterize the impact of microenvironment and cell state on drug sensitivity.
- To define a new paradigm for understanding drug responses to kinase inhibitors.
Main Methods:
- Applied single-cell mass cytometry with a 26-antibody panel.
- Utilized PTEN-deleted orthotopic prostate cancer xenograft models.
- Analyzed kinase activities in primary tumors, metastases, and circulating tumor cells (CTCs).
Main Results:
- Bone metastases showed elevated PI3K/mTOR signaling and c-MET overexpression compared to other sites.
- Suppression of c-MET inhibited bone tumor growth.
- Epithelial (EpCAM-high) and mesenchymal (EpCAM-low) cell populations exhibited distinct kinase activities and drug sensitivities.
- Mesenchymal CTCs in patients mirrored findings in xenograft models.
Conclusions:
- Microenvironment and cell state-dependent kinase activation create significant heterogeneity in drug sensitivity.
- Single-cell proteomics offers crucial insights into differential responses to targeted therapies.
- This study defines a new framework for understanding cancer drug responses across diverse tumor populations and sites.
More Related Videos
07:42Assessment of Resistance to Tyrosine Kinase Inhibitors by an Interrogation of Signal Transduction Pathways by Antibody Arrays
Published on: September 19, 2018
12:22The Use of Reverse Phase Protein Arrays RPPA to Explore Protein Expression Variation within Individual Renal Cell Cancers
Published on: January 22, 2013