Mesothelin also known as MSLN is a protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 that in humans is encoded by the MSLN gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

.

Function

Mesothelin is a 40kDa protein present on normal mesothelial

Mesothelium

The mesothelium is a membrane that forms the lining of several body cavities: the pleura , peritoneum and pericardium . Mesothelial tissue also surrounds the male internal reproductive organs and covers the internal reproductive organs of women...

 cells and overexpressed in several human tumors, including mesothelioma

Mesothelioma

Mesothelioma, more precisely malignant mesothelioma, is a rare form of cancer that develops from the protective lining that covers many of the body's internal organs, the mesothelium...

 and ovarian and pancreatic adenocarcinoma

Adenocarcinoma

Adenocarcinoma is a cancer of an epithelium that originates in glandular tissue. Epithelial tissue includes, but is not limited to, the surface layer of skin, glands and a variety of other tissue that lines the cavities and organs of the body. Epithelium can be derived embryologically from...

. The protein was first identified by its reactivity with monoclonal antibody K1. Subsequent cloning studies showed that the mesothelin gene encodes a precursor protein that is processed to yield mesothelin which is attached to the cell membrane by a glycophosphatidylinositol

Glycophosphatidylinositol

Glycosylphosphatidylinositol is a glycolipid that can be attached to the C-terminus of a protein during posttranslational modification...

 linkage and a 31-kDa shed fragment named megakaryocyte

Megakaryocyte

The megakaryocyte is a bone marrow cell responsible for the production of blood thrombocytes , which are necessary for normal blood clotting...

-potentiating factor (MPF). Although it has been proposed that mesothelin may be involved in cell adhesion

Cell adhesion

Cellular adhesion is the binding of a cell to a surface, extracellular matrix or another cell using cell adhesion molecules such as selectins, integrins, and cadherins. Correct cellular adhesion is essential in maintaining multicellular structure...

, its biological function is not known.

Therapeutic application

Mesothelin is a tumour differentiation antigen that is normally present on the mesothelial cells lining the pleura, peritoneum and pericardium. Since mesothelin is overexpressed in several cancers and is immunogenic

Immunogenicity

Immunogenicity is the ability of a particular substance, such as an antigen or epitope, to provoke an immune response in the body of a human or animal.- Immunogenicity :The ability to induce humoral and/or cell-mediated immune responses....

, the protein could be exploited as tumor marker or as the antigenic target of a therapeutic cancer vaccine.