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Aliases | MKI67 , marker of proliferation Ki-67, KIA, MIB-, MIB-1, PPP1R105 | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 176741 MGI: 106035 HomoloGene: 1814 GeneCards: MKI67 | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Antigen Kiel 67, also known as Ki-67 or MKI67 (marker of proliferation Kiel 67), is a protein that in humans is encoded by the MKI67 gene (antigen identified by monoclonal antibody Ki-67). [5] [6] [7]
Antigen KI-67 is a nuclear protein that is associated with cellular proliferation and ribosomal RNA transcription. [7] Inactivation of antigen KI-67 leads to inhibition of ribosomal RNA synthesis, [8] but does not significantly affect cell proliferation in vivo: Ki-67 mutant mice developed normally and cells lacking Ki-67 proliferated efficiently. [9]
The Ki-67 protein (also known as MKI67) is a cellular marker for proliferation, [10] and can be used in immunohistochemistry. It is strictly associated with cell proliferation. During interphase, the Ki-67 antigen can be exclusively detected within the cell nucleus, whereas in mitosis most of the protein is relocated to the surface of the chromosomes. [11] Ki-67 protein is present during all active phases of the cell cycle (G1, S, G2, and mitosis), but is absent in resting (quiescent) cells (G0). [12] Cellular content of Ki-67 protein markedly increases during cell progression through S phase of the cell cycle. [13] In breast cancer Ki67 identifies a high proliferative subset of patients with ER-positive breast cancer who derive greater benefit from adjuvant chemotherapy. [14] [15]
Ki-67 is an excellent marker to determine the growth fraction of a given cell population. The fraction of Ki-67-positive tumor cells (the Ki-67 labeling index) is often correlated with the clinical course of cancer. The best-studied examples in this context are prostate, brain and breast carcinomas, as well as nephroblastoma and neuroendocrine tumors. For these types of tumors, the prognostic value for survival and tumor recurrence have repeatedly been proven in uni- and multivariate analysis.
Ki-67 and MIB-1 monoclonal antibodies are directed against different epitopes of the same proliferation-related antigen. Ki-67 and MIB-1 may be used on fixed sections. [16] MIB-1 is used in clinical applications to determine the Ki-67 labelling index. One of its primary advantages over the original Ki-67 antibody (and the reason why it has essentially supplanted the original antibody for clinical use) is that it can be used on formalin-fixed paraffin-embedded sections, after heat-mediated antigen retrieval (see next section below).
The Ki-67 protein was originally defined by the prototype monoclonal antibody Ki-67, [17] which was generated by immunizing mice with nuclei of the Hodgkin lymphoma cell line L428. The name is derived from the city of origin (Kiel, Germany) and the number of the original clone in the 96-well plate.
Trastuzumab, sold under the brand name Herceptin among others, is a monoclonal antibody used to treat breast cancer and stomach cancer. It is specifically used for cancer that is HER2 receptor positive. It may be used by itself or together with other chemotherapy medication. Trastuzumab is given by slow injection into a vein and injection just under the skin.
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 antigens in biological tissues. IHC takes its name from the roots "immuno", in reference to antibodies used in the procedure, and "histo", meaning tissue. Albert Coons conceptualized and first implemented the procedure in 1941.
Mucin-16(MUC-16) also known as Ovarian cancer-related tumor marker CA125 is a protein that in humans is encoded by the MUC16 gene. MUC-16 is a member of the mucin family glycoproteins. MUC-16 has found application as a tumor marker or biomarker that may be elevated in the blood of some patients with specific types of cancers, most notably ovarian cancer, or other conditions that are benign.
Hybridoma technology is a method for producing large numbers of identical antibodies. This process starts by injecting a mouse with an antigen that provokes an immune response. A type of white blood cell, the B cell, produces antibodies that bind to the injected antigen. These antibody producing B-cells are then harvested from the mouse and, in turn, fused with immortal myeloma cancer cells, to produce a hybrid cell line called a hybridoma, which has both the antibody-producing ability of the B-cell and the longevity and reproductivity of the myeloma. The hybridomas can be grown in culture, each culture starting with one viable hybridoma cell, producing cultures each of which consists of genetically identical hybridomas which produce one antibody per culture (monoclonal) rather than mixtures of different antibodies (polyclonal). The myeloma cell line that is used in this process is selected for its ability to grow in tissue culture and for an absence of antibody synthesis. In contrast to polyclonal antibodies, which are mixtures of many different antibody molecules, the monoclonal antibodies produced by each hybridoma line are all chemically identical.
Carcinoembryonic antigen (CEA) describes a set of highly-related glycoproteins involved in cell adhesion. CEA is normally produced in gastrointestinal tissue during fetal development, but the production stops before birth. Consequently, CEA is usually present at very low levels in the blood of healthy adults. However, the serum levels are raised in some types of cancer, which means that it can be used as a tumor marker in clinical tests. Serum levels can also be elevated in heavy smokers.
Cluster of differentiation 40, CD40 is a type I transmembrane protein found on antigen-presenting cells and is required for their activation. The binding of CD154 (CD40L) on TH cells to CD40 activates antigen presenting cells and induces a variety of downstream effects.
Proliferating cell nuclear antigen (PCNA) is a DNA clamp that acts as a processivity factor for DNA polymerase δ in eukaryotic cells and is essential for replication. PCNA is a homotrimer and achieves its processivity by encircling the DNA, where it acts as a scaffold to recruit proteins involved in DNA replication, DNA repair, chromatin remodeling and epigenetics.
Monoclonal antibodies (mAbs) have varied therapeutic uses. It is possible to create a mAb that binds specifically to almost any extracellular target, such as cell surface proteins and cytokines. They can be used to render their target ineffective, to induce a specific cell signal, to cause the immune system to attack specific cells, or to bring a drug to a specific cell type.
CD68 is a protein highly expressed by cells in the monocyte lineage, by circulating macrophages, and by tissue macrophages.
Mesothelin, also known as MSLN, is a protein that in humans is encoded by the MSLN gene.
G2/mitotic-specific cyclin-B1 is a protein that in humans is encoded by the CCNB1 gene.
CD99 antigen, also known as MIC2 or single-chain type-1 glycoprotein, is a heavily O-glycosylated transmembrane protein that is encoded by the CD99 gene in humans. The protein has a mass of 32 kD. Unusually for a gene present on the X chromosome, the CD99 gene does not undergo X inactivation, and it was the first such pseudoautosomal gene to be discovered in humans.
The estrogen receptor test (ERT) is a laboratory test to determine whether cancer cells have estrogen receptors. This information can help establish how the cancer should be treated.
An oncoantigen is a surface or soluble tumor antigen that supports tumor growth. A major problem of cancer immunotherapy is the selection of tumor cell variants that escape immune recognition. The notion of oncoantigen was set forth in the context of cancer immunoprevention to define a class of persistent tumor antigens not prone to escape from immune recognition.
Inhibitor of growth protein 1 is a protein that in humans is encoded by the ING1 gene.
Epithelial cell adhesion molecule (EpCAM), also known as CD326 among other names, is a transmembrane glycoprotein mediating Ca2+-independent homotypic cell–cell adhesion in epithelia. EpCAM is also involved in cell signaling, migration, proliferation, and differentiation. Additionally, EpCAM has oncogenic potential via its capacity to upregulate c-myc, e-fabp, and cyclins A & E. Since EpCAM is expressed exclusively in epithelia and epithelial-derived neoplasms, EpCAM can be used as diagnostic marker for various cancers. It appears to play a role in tumorigenesis and metastasis of carcinomas, so it can also act as a potential prognostic marker and as a potential target for immunotherapeutic strategies.
Tumor-associated calcium signal transducer 2, also known as Trop-2 and as epithelial glycoprotein-1 antigen (EGP-1), is a protein that in humans is encoded by the TACSTD2 gene.
Protein Tob1 is a protein that in humans is encoded by the TOB1 gene.
Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) also known as CD66e, is a member of the carcinoembryonic antigen (CEA) gene family.
Proliferation, as one of the hallmarks and most fundamental biological processes in tumors, is associated with tumor progression, response to therapy, and cancer patient survival. Consequently, the evaluation of a tumor proliferative index has clinical significance in characterizing many solid tumors and hematologic malignancies. This has led investigators to develop different technologies to evaluate the proliferation index in tumor samples. The most commonly used methods in evaluating a proliferative index include mitotic indexing, thymidine-labeling index, bromodeoxyuridine assay, the determination of fraction of cells in various phases of cell cycle, and the immunohistochemical evaluation of cell cycle-associated proteins.