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Updated: Nov 11, 2025
Isolation and Functional Assessment of Human Breast Cancer Stem Cells from Cell and Tissue Samples
Published on: October 2, 2020
The AXL-PYK2-PKCα axis as a nexus of stemness circuits in TNBC
Lohit Khera1, Yaron Vinik1, Flavio Maina2
1Molecular Cell Biology Department, Weizmann Institute of Science, Rehovot, Israel.
Abstract:
Cancer stem cells (CSCs) are implicated in tumor initiation, metastasis and drug resistance, and considered as attractive targets for cancer therapy. Here we identified a clinically relevant signaling nexus mediated by AXL receptor, PYK2 and PKCα and show its impact on stemness in TNBC. AXL, PYK2, and PKCα expression correlates with stemness signature in basal-like breast cancer patients, and their depletion in multiple mesenchymal TNBC cell lines markedly reduced the number of mammosphere-forming cells and cells harboring CSCs characteristic markers. Knockdown of PYK2 reduced the levels of AXL, PKCα, FRA1, and PYK2 proteins, and similar trend was obtained upon PKCα depletion. PYK2 depletion decreased AXL transcription through feedback loops mediated by FRA1 and TAZ, whereas PKCα inhibition induced redistribution of AXL to endosomal/lysosomal compartment and enhanced its degradation. PYK2 and PKCα cooperate at a convergence point of multiple stemness-inducing pathways to regulate AXL levels and concomitantly the levels/activation of STAT3, TAZ, FRA1, and SMAD3 as well as the pluripotent transcription factors Nanog and Oct4. Induction of stemness in TNBC sensitized cells to PYK2 and PKCα inhibition suggesting that targeting the AXL-PYK2-PKCα circuit could be an efficient strategy to eliminate CSCs in TNBC.
Insights
Targeting the AXL-PYK2-PKCα signaling nexus effectively reduces cancer stem cells (CSCs) in triple-negative breast cancer (TNBC). This pathway is crucial for maintaining stemness and drug resistance, offering a new therapeutic strategy.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- Cancer stem cells (CSCs) drive tumor initiation, metastasis, and drug resistance.
- Targeting CSCs is a promising strategy for effective cancer therapy.
- Triple-negative breast cancer (TNBC) presents significant therapeutic challenges.
Purpose of the Study:
- To identify and characterize a signaling nexus involving AXL receptor, PYK2, and PKCα in TNBC stemness.
- To investigate the impact of this nexus on CSC characteristics and therapeutic sensitivity.
Main Methods:
- Analysis of AXL, PYK2, and PKCα expression in basal-like breast cancer patients.
- Depletion of PYK2 and PKCα in TNBC cell lines.
- Assessment of mammosphere formation and CSC marker expression.
- Investigation of molecular mechanisms regulating AXL, STAT3, TAZ, FRA1, SMAD3, Nanog, and Oct4.
Main Results:
- AXL, PYK2, and PKCα expression correlated with stemness signatures in TNBC patients.
- Depletion of PYK2 or PKCα significantly reduced CSC populations and stemness markers.
- PYK2 and PKCα were found to cooperate in regulating AXL levels and downstream stemness pathways.
- Targeting this circuit sensitized TNBC cells to inhibition.
Conclusions:
- The AXL-PYK2-PKCα signaling nexus is a critical regulator of stemness in TNBC.
- Inhibition of this circuit represents a potential therapeutic strategy for eliminating CSCs in TNBC.
- This finding offers a novel approach to overcome drug resistance in TNBC.
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