Invadopodia

Invadopodia are actin-rich protrusions of the plasma membrane that are associated with degradation of the extracellular matrix in cancer invasiveness and metastasis.

Invadopodia can also be used as a marker to quantify the invasiveness of cancer cell lines in vitro using a hyaluronic acid hydrogel assay.

[5] In the early 1980s, researchers noticed protrusions coming from the ventral membrane of cultured chicken embryo fibroblasts that had been transformed by the Rous Sarcoma Virus and that they were at the sites of cell-to-extracellular matrix (ECM) adhesion.

[1] They termed these structures podosomes, or cellular feet, but it was later noticed that degradation of the ECM was occurring at these sites and the name invadopodia was coined to highlight the invasive nature of these protrusions.

[3] Invadopodia formation is a complex process that involves multiple signaling pathways and can be described as having three steps: initiation, stabilization, and maturation.

Increased levels of tks5 have been detected in prostate cancer and overexpression of Tks5 was sufficient to induce invadopodia formation and degradation of the extracellular matrix in an Src-dependent manner.

In mice, inhibiting invadopodia formation directly, through RNAi against tks4 or tks5, significantly reduced cancer extravasation.