Invadopodia
Encyclopedia
Invadopodia or invasive feet are protrusions in the cell membrane
of some cells that are rich in actin
and extend into the extracellular matrix
(ECM). Researchers have reported that invadopodia formation is initiated with the assembly of actin core structures, followed by the accumulation of mtrix metalloproteinase for ECM degradation. They are associated with high levels of proteolysis
and cell signaling
and are frequently seen in metastatic
cancer
cells that are invading surrounding tissues.
These structures are very similar to the podosomes formed by normal cells that need to cross tissue barriers, such as macrophage
s and monocyte
s, or cells such as osteoclast
s that remodel tissue. However, podosomes are short-lived and do not cause major degradation of the ECM.
In the case of breast cancer
cell lines, the ability to form invadopodia is closely related to their invasive and metastatic properties. Additionally, during intravasation, invadopodia-like protrusions in tumor cells have been observed in vivo by intravital imaging. Therefore, invadopodia are proposed to function in local ECM degradation during cancer invasion and metastasis, although the in vivo relevance of invadopodia has yet to be determined.
Cell membrane
The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...
of some cells that are rich in actin
Actin
Actin is a globular, roughly 42-kDa moonlighting protein found in all eukaryotic cells where it may be present at concentrations of over 100 μM. It is also one of the most highly-conserved proteins, differing by no more than 20% in species as diverse as algae and humans...
and extend into the extracellular matrix
Extracellular matrix
In biology, the extracellular matrix is the extracellular part of animal tissue that usually provides structural support to the animal cells in addition to performing various other important functions. The extracellular matrix is the defining feature of connective tissue in animals.Extracellular...
(ECM). Researchers have reported that invadopodia formation is initiated with the assembly of actin core structures, followed by the accumulation of mtrix metalloproteinase for ECM degradation. They are associated with high levels of proteolysis
Proteolysis
Proteolysis is the directed degradation of proteins by cellular enzymes called proteases or by intramolecular digestion.-Purposes:Proteolysis is used by the cell for several purposes...
and cell signaling
Cell signaling
Cell signaling is part of a complex system of communication that governs basic cellular activities and coordinates cell actions. The ability of cells to perceive and correctly respond to their microenvironment is the basis of development, tissue repair, and immunity as well as normal tissue...
and are frequently seen in metastatic
Metastasis
Metastasis, or metastatic disease , is the spread of a disease from one organ or part to another non-adjacent organ or part. It was previously thought that only malignant tumor cells and infections have the capacity to metastasize; however, this is being reconsidered due to new research...
cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
cells that are invading surrounding tissues.
These structures are very similar to the podosomes formed by normal cells that need to cross tissue barriers, such as macrophage
Macrophage
Macrophages are cells produced by the differentiation of monocytes in tissues. Human macrophages are about in diameter. Monocytes and macrophages are phagocytes. Macrophages function in both non-specific defense as well as help initiate specific defense mechanisms of vertebrate animals...
s and monocyte
Monocyte
Monocytes are a type of white blood cell and are part of the innate immune system of vertebrates including all mammals , birds, reptiles, and fish. Monocytes play multiple roles in immune function...
s, or cells such as osteoclast
Osteoclast
An osteoclast is a type of bone cell that removes bone tissue by removing its mineralized matrix and breaking up the organic bone . This process is known as bone resorption. Osteoclasts were discovered by Kolliker in 1873...
s that remodel tissue. However, podosomes are short-lived and do not cause major degradation of the ECM.
In the case of breast cancer
Breast cancer
Breast cancer is cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas; those originating from lobules are known as lobular carcinomas...
cell lines, the ability to form invadopodia is closely related to their invasive and metastatic properties. Additionally, during intravasation, invadopodia-like protrusions in tumor cells have been observed in vivo by intravital imaging. Therefore, invadopodia are proposed to function in local ECM degradation during cancer invasion and metastasis, although the in vivo relevance of invadopodia has yet to be determined.
External links
- Podosomes and Invadopodia at Scirus Topic Pages