Within tissues, cells are continuously exposed to mechanical stress induced by the surrounding stroma and reciprocate by generating actomyosin-dependent forces. In pancreatic cancer, an abundant deposition of fibrotic tissue occurs and the tumour-stroma mechanical feedback is enhanced. This contributes to cancer initiation, progression, invasion and metastasis. In particular, the extracellular matrix is stiffer and provides cancer cells with a protective niche.
Here, we hypothesise that targeting Rho kinase-driven ECM stiffness in pancreatic cancer will deprive tumour cells from this protective niche and improve response to chemotherapy.
We used 3D organotypic assays – to recapitulate the interactions between cancer cells, stromal cells and the ECM in vitro along with live xenograft and intrasplenic models of pancreatic cancer coupled with state-of-the-art intravital imaging. We assessed how targeting tumour-stromal feedback with the ROCK inhibitor Fasudil improves standard-of-care treatment with Gemcitabine and Abraxane. A FLIM-FRET CDK1 biosensor was used in vitro and in vivo to monitor in a live and dynamic manner the spatio-temporal efficacy of chemotherapy following priming of the stroma with Fasudil.
Intravital analysis of CDK1 activity and simultaneous second harmonic generation (SHG) imaging of the ECM demonstrated that targeting ROCK (1) impairs the integrity of the ECM, (2) decreases cancer cell invasion and metastasis and (3) increases the efficacy of Gemcitabine and Abraxane. Our results show that priming of pancreatic tumour with Fasudil disrupts the mechanical tumour-stroma feedback and in turns improves Gemcitabine and Abraxane efficacy. We propose that using FLIM-FRET in this capacity could provide a useful preclinical tool in animal models prior to clinical translation. Furthermore, we suggest that ECM stiffness could be used as a biomarker to identify patients that would benefit most from ECM targeting treatment prior to chemotherapy.