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, which can be impaired using Src kinase inhibitors. Here, we have developed new tools to assess (i) the spatiotemporal dynamics of epithelial tumour cell-cell junctions (E-cadherin biosensor mouse) and (ii) pro-invasive Src activity in migratory cells (Src biosensor mouse).
Utilizing a next-generation E-cadherin-GFP knock-in mouse, we have established Fluorescence Anisotropy Imaging Microscopy (FAIM) and Image Correlation Spectroscopy (ICS) to quantify the dynamics of E-cadherin clustering and mobility, respectively. This enables real-time, in-vivo assessment of E-cadherin-based cell-cell junction strength and integrity during cancer progression. Furthermore, we have generated a Src-FRET biosensor mouse to track changes in Src activity, a known driver of cancer invasion and metastasis. We demonstrate that fluctuations in Src activity can be quantified in any tissue of interest in physiological and pathological contexts and that the biosensor mouse, as well as primary cell lines isolated from the mouse, can serve as a platform from which to rapidly assess the efficacy of anti-invasive treatments.
Using subcellular imaging we show that:
(1) E-cadherin mobility and clustering become de-regulated in invasive and metastatic cancers compared to healthy tissues.
(2) These subcellular aberrations in E-cadherin dynamics can be targeted using anti-invasive treatment to re-stabilise cell-cell junctions.
(3) Our Src biosensor mouse can reveal changes in Src activity during invasive and metastatic cancer progression in native tissue.
We suggest that our new biosensor mouse models can be used as:
(1) novel tools to fundamentally expand our understanding of cell-cell junction dynamics and cancer invasiveness in vivo in native microenvironments.
(2) novel pre-clinical drug-screening platforms to predict cancer spread and to estimate the efficacy of anti-invasive treatment in vivo.