E-cadherin-mediated cell-cell junctions play a prominent role in maintaining epithelial architecture. Their dysregulation in cancer can lead to the collapse of tumour epithelia and subsequent invasion and metastasis. Recent evidence suggests that, apart from modulating E-cadherin expression, cells are able to mobilise E-cadherin within their cell-cell junctions upon migration and invasion. We have developed new tools to assess the spatiotemporal dynamics of epithelial tumour cell-cell junctions and also to assess Src activity to study the earliest stages of invasion and metastasis.
Here, we have generated an endogenous knock-in E-cadherin-GFP mouse, which enables intravital quantification of E-cadherin clustering and mobility through Fluorescence Anisotropy Imaging Microscopy and Image Correlation Spectroscopy, to provide insight into tumour cell-cell junction strength and integrity in intact tissues and tumours. In addition, we have generated a Src-FRET biosensor mouse to track changes in Src activity, a known driver of cancer invasion and metastasis.
We reveal that:
(1) E-cadherin mobility and clustering become de-regulated in invasive and metastatic tumours compared to healthy tissues and non-invasive pancreatic tumours.
(2) These subcellular aberrations in E-cadherin dynamics can be targeted with the anti-invasive treatment Dasatinib to re-stabilise cell-cell junctions and to reduce cancer invasiveness.
(3) Using a Src biosensor mouse we can track in real-time in native tissue, changes in Src activity, during cancer development and subsequent metastasis.
We suggest that these techniques can be used as:
(1) novel tools to fundamentally expand our understanding of cell-cell junction dynamics in vivo in native microenvironments.
(2) novel pre-clinical drug-screening platform to predict cancer spread and to estimate the efficacy of anti-invasive treatment in vivo.