Intercellular Contractile Force Attenuates Chemosensitivity Through Notch-MVP-Mediated Nuclear Drug Export

Bioengineering Biophysics Cell Biology Oncology Life Sciences Medicine
intercellular force contractility cell mechanics mechanotransduction chemosensitivity

Academic Background

Chemotherapy resistance is one of the major challenges in cancer treatment. Traditional research has primarily focused on biochemical mechanisms (e.g., drug efflux pumps, DNA repair, etc.), but in recent years, the role of biomechanical factors in tumor progression and drug resistance has gained increasing attention. Studies have shown that cancer stem cells (CSCs) and metastatic cancer cells often exhibit stronger contractility, but the exact relationship between contractility and chemosensitivity remains controversial. This study is the first to systematically reveal the molecular mechanism by which intercellular mechanical force transmission mediates nuclear drug export through the Notch-MVP signaling pathway, providing a new target for cancer “mechanotherapeutics.”

Source of the Paper

This paper was collaboratively completed by a team from The Hong Kong Polytechnic University Shenzhen Research Institute, Research Institute of Smart Aging, and other institutions, including Pengyu Du, Kai Tang, and Youhua Tan (corresponding author). It was published in PNAS in May 2025 (Vol. 122, No. 19), DOI: 10.1073/pnas.2417626122.

Research Process and Results

1. Correlation Between Contractility and Chemosensitivity

Experimental Design:
- Model Systems: Breast cancer cell lines (SK-BR-3, MDA-MB-231, etc.), primary breast cancer cells, and patient biopsy tissues
- Key Methods:
- Traction force microscopy to quantify cellular contractility
- Half-maximal inhibitory concentration (IC50) determination
- Cancer stem cell (CSC) sorting (EPCAM+/CD44+CD24-/ALDH1+ markers)

Key Findings:
- High-contractility cells (e.g., CSCs) exhibited IC50 values over 2-fold higher than ordinary tumor cells (p < 0.0001).
- Clinical data analysis revealed significantly upregulated actin-binding protein expression in chemotherapy non-responders (GSE155478 dataset).
- Substrate stiffness experiments confirmed: Cells cultured on 20 kPa stiff substrates showed 3-fold higher contractility and correspondingly increased IC50 values compared to those on 1 kPa soft substrates.

2. Mechanism of Contractility-Regulated Chemosensitivity

Innovative Methods:
- Dual-Cell Co-Culture System: Notch signaling reporter cells (tdTomato-CBF) co-cultured with cells of varying contractility levels.
- Gradient-Stiffness PA Gels: Jagged-1-coated polyacrylamide (PA) gels with 0.5–50 kPa stiffness gradients to mimic mechanical microenvironments.

Key Evidence Chain:
1. Intercellular Force Transmission Dependency:
- High-contractility cells enhanced Notch activity in neighboring cells only at 50% confluency (p < 0.001).
- Silencing α-catenin blocked this effect.

  1. Notch-MVP Pathway Activation:

    • Contractility upregulated Notch1/3 receptors and ligands (DLL1/JAG2) by 2–4-fold.
    • MVP (major vault protein) was significantly activated as a downstream effector (validated by Western blot).

  2. Nuclear Drug Export Mechanism:

    • High-contractility cells showed 40% lower nuclear doxorubicin concentration (fluorescence quantification, p < 0.01).
    • Nuclear export inhibitor leptomycin B reversed this phenomenon.

3. Animal Model Validation

Experimental Protocol:
- Subcutaneous transplantation of MDA-MB-231 cells (n = 3/group).
- Induction of contractility modulation at day 14 (doxycycline-activated CA/DN plasmids).
- Doxorubicin treatment (2.5 mg/kg, once weekly).

Translational Findings:
- High-contractility tumors were 3-fold larger in volume than controls (p < 0.001).
- Notch inhibitor DAPT or MVP silencing reduced tumors to control levels.
- TCGA database analysis showed: High NOTCH1/ACTB/MYH9 expression correlated significantly with shorter relapse-free survival (HR = 2.1, p = 0.003).

Research Highlights

  1. Mechanistic Innovation:

    • First to reveal the “mechanical force → Notch → MVP → nuclear drug export” cascade pathway.
    • Clarified the critical role of intercellular force transmission (rather than single-cell autonomous effects).

  2. Methodological Breakthroughs:

    • Developed Jagged-1-coated gradient-stiffness gels to simulate mechanical microenvironments.
    • Established a dual-cell Notch reporter system to validate paracrine mechanisms.

  3. Clinical Value:

    • Proposed a combination therapy strategy targeting the actomyosin-Notch-MVP axis.
    • Identified ACTB/MYH9 as potential mechanical biomarkers for chemotherapy response.

Research Significance

  1. Theoretical Impact:

    • Integrated biomechanical factors into the framework of chemotherapy resistance research.
    • Provided a paradigm for interdisciplinary “mechanobiology-epigenetics” studies.

  2. Application Prospects:

    • Clinical potential for combining Rock inhibitors (e.g., Y-27632) with conventional chemotherapy.
    • MVP expression levels may serve as a novel prognostic indicator.

Limitations:
- The specific transporters mediating MVP-dependent nuclear export remain unresolved.
- Animal models did not fully replicate the mechanical microenvironment of human tumors.