Keratin, type II cytoskeletal 8 also known as cytokeratin-8 (CK-8) or keratin-8 (K8) is a

keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up Scale (anatomy), scales, hair, Nail ...

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

that is encoded in humans by the ''KRT8''

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

. It is often paired with

keratin 18 Keratin 18 is a type I cytokeratin. It is, together with its filament partner keratin 8, perhaps the most commonly found products of the intermediate filament gene family. They are expressed in single layer epithelial tissues of the body. Mutatio ...

Utility as an immunohistochemical stain

Antibodies An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of ...

to CK8 (e.g. CAM 5.2) can be used to differentiate lobular carcinoma of the breast from ductal carcinoma of the

breast The breast is one of two prominences located on the upper ventral region of a primate's torso. Both females and males develop breasts from the same embryological tissues. In females, it serves as the mammary gland, which produces and sec ...

. CAM 5.2, an antibody that reacts with an

epitope An epitope, also known as antigenic determinant, is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. The epitope is the specific piece of the antigen to which an antibody binds. The p ...

found on both CK8 and CK18, is used in

immunohistochemistry Immunohistochemistry (IHC) is the most common application of immunostaining. It involves the process of selectively identifying antigens (proteins) in cells of a tissue section by exploiting the principle of antibodies binding specifically to ant ...

to demonstrate certain forms of cancer. In normal tissue, it reacts mainly with secretory

epithelia Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellula ...

, but not with squamous epithelium, such as that found in the skin, cervix, and esophagus. However, it also reacts with a range of malignant cells, including those derived from secretory epithelia, but also some squamous

carcinoma Carcinoma is a malignancy that develops from epithelial cells. Specifically, a carcinoma is a cancer that begins in a tissue that lines the inner or outer surfaces of the body, and that arises from cells originating in the endodermal, mesoderm ...

ta, such as

spindle cell carcinoma Spindle cell carcinoma is a type of cancer that begins in the skin or in tissues that line or cover internal organs In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of l ...

. It is considered useful in identifying microscopic

metastases Metastasis is a pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, the ...

of breast carcinoma in lymph nodes, and in distinguishing Paget's disease from

malignant melanoma Melanoma, also redundantly known as malignant melanoma, is a type of skin cancer that develops from the pigment-producing cells known as melanocytes. Melanomas typically occur in the skin, but may rarely occur in the mouth, intestines, or eye ...

. It also reacts with

neuroendocrine Neuroendocrine cells are cells that receive neuronal input (through neurotransmitters released by nerve cells or neurosecretory cells) and, as a consequence of this input, release messenger molecules (hormones) into the blood. In this way they bri ...

tumors. Keratin 8 is often used together with keratin 18 and

keratin 19 Keratin, type I cytoskeletal 19 also known as cytokeratin-19 (CK-19) or keratin-19 (K19) is a 40 kDa protein that in humans is encoded by the ''KRT19'' gene. Keratin 19 is a type I keratin. Function Keratin 19 is a member of the keratin family. ...

to differentiate cells of epithelial origin from hematopoietic cells in tests that enumerate

circulating tumor cell A circulating tumor cell (CTC) is a cell that has shed into the vasculature or lymphatics from a primary tumor and is carried around the body in the blood circulation. CTCs can extravasate and become ''seeds'' for the subsequent growth of additio ...

s in blood.

Interactions

Keratin 8 has been shown to

interact Advocates for Informed Choice, doing business as, dba interACT or interACT Advocates for Intersex Youth, is a 501(c)(3) nonprofit organization using innovative strategies to advocate for the legal and human rights of children with intersex trai ...

with

MAPK14 Mitogen-activated protein kinase 14, also called p38-α, is an enzyme that in humans is encoded by the ''MAPK14'' gene. MAPK14 encodes p38α mitogen-activated protein kinase (MAPK) which is the prototypic member of the p38 MAPK family. p38 MAPKs ...

Pinin Pinin is a protein that in humans is encoded by the ''PNN'' gene. Interactions Pinin has been shown to interact with Keratin 8, Keratin 18, Keratin 19, CTBP1, RNPS1, PRPF4B, SFRS4, PPIG, SRRM2 Serine/arginine repetitive matrix protein 2 is a ...

and PPL.

References

External links

* {{Cytoskeletal proteins Keratins

Utility as an immunohistochemical stain

Interactions

See also

References

Further reading

External links