The novel CYRI protein family cooperatively modulates cancer cell migration and invasion via endocytosis of Integrins
Session type: Poster / e-Poster / Silent Theatre session
After more than 50 years of research and development, metastasis remains the most lethal aspect of cancer. The novel protein CYRI-B has recently been demonstrated to be the first negative regulator of the Scar/WAVE complex by sequestering active RAC1 – a small Rho GTPase that has been shown to be involved in many stages of cancer progression. Here we demonstrate a new function of both CYRI-A and B in the process of endocytosis with a consequence of promoting invasion in cancer cells.
(Methods are included in the Result section)
Deleting both CYRI-A and B using either siRNA and CRISPR-Cas9 technology double the migration ability of Ewing’s sarcoma A-673 cells in 2D random migration and in 3D spheroid and cell-derived matrix, while decreases their proliferation rate. Flow cytometry analysis revealed a 1.5x increase in the surface expression of Integrin α5β1 in the double knockout cells. Western blots and zymography also demonstrated a consistent upregulation of the Matrix metalloprotease MMP14 as well as the secreted matrix metalloprotease MMP2 and the matrix protein Collagen VI. This results in approximately 2x increase in the matrix degradation ability of CYRI-AB double knockout cells in vitro. Super-resolution live-cell imaging in COS-7 shows a striking dynamic of both CYRI-A and B. Both proteins colocalise with actin surrounding endosomes. However, while CYRI-B persists its colocalization with the endosomal regulator RAB5A, CYRI-A is seen to be recruited at the beginning of the endocytosis process, which is then sequentially followed by RAB5A localisation
In conclusion, this study hinted to a novel connection between the two novel actin dynamic regulator CYRI-A and B and the endosomal network. This adds another layer of regulation to the endosomal trafficking process, which is known to be important both in the context of normal cell physiology and in cancer progression and invasion.