Quantitative in vivo imaging of the effects of inhibiting integrin signalling via Src and FAK on cancer cell movement; effects on E-cadherin dynamics

摘要

Most cancer related deaths are due to the development of metastatic disease and several new molecularly targeted agents in clinical development have the potential to prevent disease progression. However, it remains difficult to assess the efficacy of anti-metastatic agents in the clinical setting and an increased understanding of how such agents work at different stages of the metastatic cascade is important in guiding their clinical use. We have used optical window chambers combined with the use of photobleaching, photoactivation, and photoswitching to quantitatively measure a) tumor cell movement and proliferation by tracking small groups of cells in the context of the whole tumor, and b) E-cadherin molecular dynamics in vivo following perturbation of integrin signaling by inhibiting focal adhesion kinase (FAK) and Src. We show that inhibition of Src and FAK suppresses E-cadherin dependent collective cell movement in a complex 3D tumor environment, and modulate cell-cell adhesion strength and endocytosis in vitro. This demonstrates a novel role for integrin signaling in the regulation of E-cadherin internalization, which is linked to regulation of collective cancer cell movement. This work highlights the power of fluorescent, direct, in vivo imaging approaches in the pre-clinical evaluation of chemotherapeutic agents, and shows that inhibition of the Src/FAK signaling axis may provide a strategy to prevent tumor cell spread by de-regulating E-cadherin-mediated cell-cell adhesions.