CMTM6 | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Aliases | CMTM6 , CKLFSF6, PRO2219, CKLF like MARVEL transmembrane domain containing 6, ayoube, gourari | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 607889 MGI: 2447165 HomoloGene: 9845 GeneCards: CMTM6 | ||||||||||||||||||||||||||||||||||||||||||||||||||
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CKLF like MARVEL transmembrane domain-containing 6 (i.e. CMTM6), previously termed chemokine-like factor superfamily 6 (i.e. CKLFSF6), is a transmembrane protein encoded in humans by the CMTM6 gene (also termed the CKLFSF6, PRO2219, ayoube, or gourari gene). This gene is located in band 22.3 on the short (or "p") arm of chromosome 3. [5] CMTM6 protein belongs to the CKLF-like MARVEL transmembrane domain-containing family of proteins. [6] This family consist of 9 member proteins: CKLF and CMTM1 through CMTM8. [7] [8] The CMTM family proteins are involved in autoimmune diseases, cardiovascular diseases, the male reproductive system, haematopoiesis, and cancer development. [8] CMTM6 protein regulates immune responses to normal and abnormal (particularly cancerous) cells. [9] [10]
Like the other members in the CMTM protein family, CMTM6 has a structure that contains domains (i.e. parts) similar to those in chemokine proteins; tetraspanin proteins (also termed transmembrane-4 superfamily proteins); the myelin and lymphocyte protein (also termed MAR protein); proteins that direct membrane vesicle trafficking; and proteins that are embedded across cell membranes. CMTM6 proteins are expressed in virtually all tissues [11] and are located in cell plasma membranes (i.e. cell surface membranes), lysosomes, endosomes, cytosol, attached to the cell's cytoskeleton, and in extracellular spaces. [8]
CMTM6 localizes with and binds to cell PD-L1 protein located on cell surface membranes thereby maintaining PD-L1'S expression at this site; it also localizes with PD-L1 protein located in recycling endosomes and thereby prevents PD-L1 from being degraded by lysosomal enzymes. These actions increase and maintain high levels of PD-L1 on cell surface membranes. [11] PD-L1 protein on the surface of normal cells binds to PD-1 receptors on a type of cytotoxic T cells (i.e. CD8+ T cells [11] ) and thereby blocks these T-cells from organizing an immune response that would kill them. This PD-L1/CD8+ T cell circuit is one of several immune checkpoint mechanisms for maintaining self-tolerance, i.e. for preventing CD8+ T cells from attacking normal cells. Tumor cells may employ this immune-evading tactic: they may express PD-L1 and thereby block CD8+ T cell-mediated immune responses to themselves. In effect, the robust expression of PD-L1 helps not only normal cells but also cancer cells to evade immune destruction. [12]
Various manufactured therapeutic monoclonal antibody drugs, e.g. pembrolizumab, [12] atezolizumab, durvalumab [13] nivolumab, [14] and avelumab, [9] bind to and inhibit the stimulation of PD-1 on CD8+ T cells by PD-L1. In effect, they block the ability of CMTMT6 to suppress PDL1/PD-1-stimulated CD8+ T-cell immune responses against tumor cells. One or more of these drugs are approved by the FDA for treating (as a single agent or in combination with adjuvant radiotherapy and/or chemotherapy) various cancers including certain types of Hodgkin's disease, melanomas, Merkel-cell carcinomas, cancers associated with microsatellite instability (e.g. certain types of colon, stomach, endometrial, ovarian, hepatobiliary tract, urinary tract, brain, and skin cancers), non-small cell lung cancer, head and neck cancers, esophageal cancers, bladder cancers, urinary track cancers, renal cell cancers, hepatocellular carcinomas, [14] triple-negative breast cancers, [15] undifferentiated pleomorphic sarcomas, and some forms of soft tissue sarcomas that have metastasized. [16] A phase II study of 56 patients with cancer of unknown primary origin, i.e. a very common (2% to 5% of all diagnosed cancers) and difficult to treat metastatic cancer in which the primary cancer is unknown) found that nivolumab had a small (overall complete plus partial response rate of ~20%) beneficial effect. [17] However, the use of any of these monoclonal antibody drugs as a single immunotherapy agent often benefits only a small percentage of cases with a particular disease, often lasts for only a short time, and may cause sever side-effects. Consequently, alternate methods of using these anti-PD-1 antibodies are being studied. Current preclinical studies and clinical trials are testing combinations of two anti-PD-1 antibodies or one anti-PD-1 antibody combined with an antibody that binds to and inhibits other immune response-regulating proteins, e.g. the CTLA4 protein (i.e. cytotoxic T-lymphocyte-associated protein 4), for their therapeutic effects in the just cited and other cancer types. [18]
Cancer immunotherapy is the stimulation of the immune system to treat cancer, improving on the immune system's natural ability to fight the disease. It is an application of the fundamental research of cancer immunology and a growing subspecialty of oncology.
Fas ligand is a type-II transmembrane protein expressed on cytotoxic T lymphocytes and natural killer (NK) cells. Its binding with Fas receptor (FasR) induces programmed cell death in the FasR-carrying target cell. Fas ligand/receptor interactions play an important role in the regulation of the immune system and the progression of cancer.
Undifferentiated pleomorphic sarcoma (UPS), also termed pleomorphic myofibrosarcoma, high-grade myofibroblastic sarcoma, and high-grade myofibrosarcoma, is characterized by the World Health Organization (WHO), 2020, as a rare, poorly differentiated neoplasm, i.e. an abnormal growth of cells that have an unclear identity and/or cell of origin. WHO classified it as one of the undifferentiated/unclassified sarcomas in the category of tumors of uncertain differentiation. Sarcomas are cancers known or thought to derive from mesenchymal stem cells that typically develop in bone, muscle, fat, blood vessels, lymphatic vessels, tendons, and ligaments. More than 70 sarcoma subtypes have been described. The UPS subtype of these sarcomas consists of tumor cells that are poorly differentiated and may appear as spindle-shaped cells, histiocytes, and giant cells. UPS is considered a diagnosis that defies formal sub-classification after thorough histologic, immunohistochemical, and ultrastructural examinations fail to identify the type of cells involved.
Programmed cell death protein 1, also known as PD-1 and CD279, is a protein on the surface of T and B cells that has a role in regulating the immune system's response to the cells of the human body by down-regulating the immune system and promoting self-tolerance by suppressing T cell inflammatory activity. This prevents autoimmune diseases, but it can also prevent the immune system from killing cancer cells.
Programmed cell death 1 ligand 2 is a protein that in humans is encoded by the PDCD1LG2 gene. PDCD1LG2 has also been designated as CD273. PDCD1LG2 is an immune checkpoint receptor ligand which plays a role in negative regulation of the adaptive immune response. PD-L2 is one of two known ligands for Programmed cell death protein 1 (PD-1).
Tumor necrosis factor receptor superfamily member 18 (TNFRSF18), also known as glucocorticoid-induced TNFR-related protein (GITR) or CD357. GITR is encoded and tnfrsf18 gene at chromosome 4 in mice. GITR is type I transmembrane protein and is described in 4 different isoforms. GITR human orthologue, also called activation-inducible TNFR family receptor (AITR), is encoded by the TNFRSF18 gene at chromosome 1.
Chemokine-like factor (CKLF) is a member of the CKLF-like MARVEL transmembrane domain-containing family of proteins that in humans is encoded by the CKLF gene. This gene is located on band 22.1 in the long arm of chromosome 16.
CKLF-like MARVEL transmembrane domain-containing protein 2, previously termed chemokine-like factor superfamily 2, is a member of the CKLF-like MARVEL transmembrane domain-containing family (CMTM) of proteins. In humans, it is encoded by the CMTM2 gene located in band 22 on the long arm of chromosome 16. CMTM2 protein is expressed in the bone marrow and various circulating blood cells. It is also highly expressed in testicular tissues: The CMTM2 gene and CMTM2 protein, it is suggested, may play an important role in testicular development.
Treatment of lung cancer refers to the use of medical therapies, such as surgery, radiation, chemotherapy, immunotherapy, percutaneous ablation, and palliative care, alone or in combination, in an attempt to cure or lessen the adverse impact of malignant neoplasms originating in lung tissue.
TIGIT is an immune receptor present on some T cells and natural killer cells (NK). It is also identified as WUCAM and Vstm3. TIGIT could bind to CD155 (PVR) on dendritic cells (DCs), macrophages, etc. with high affinity, and also to CD112 (PVRL2) with lower affinity.
Nivolumab, sold under the brand name Opdivo, is a medication used to treat a number of types of cancer. This includes melanoma, lung cancer, malignant pleural mesothelioma, renal cell carcinoma, Hodgkin lymphoma, head and neck cancer, urothelial carcinoma, colon cancer, esophageal squamous cell carcinoma, liver cancer, gastric cancer, and esophageal or gastroesophageal junction (GEJ) cancer. It is used by slow injection into a vein.
Pembrolizumab, sold under the brand name Keytruda, is a humanized antibody used in cancer immunotherapy that treats melanoma, lung cancer, head and neck cancer, Hodgkin lymphoma, stomach cancer, cervical cancer, and certain types of breast cancer. It is given by slow injection into a vein.
PD-1 inhibitors and PD-L1 inhibitors are a group of checkpoint inhibitor anticancer drugs that block the activity of PD-1 and PDL1 immune checkpoint proteins present on the surface of cells. Immune checkpoint inhibitors are emerging as a front-line treatment for several types of cancer.
CKLF like MARVEL transmembrane domain-containing 7, previously termed chemokine-like factor superfamily 7, is a protein that in humans is encoded by the CMTM7 gene. This gene, which is located in band 22 on the short arm of chromosome 3, and the protein that it encodes belong to the CKLF-like MARVEL transmembrane domain-containing family. Through the process of alternative splicing, the CMTM7 gene encodes two isoforms, CMTM7-v1 and CMTM7-v2, with CMTM7-v1 being the main form expressed and studied. CMTM7 proteins are widely expressed in normal human tissues.
Checkpoint inhibitor therapy is a form of cancer immunotherapy. The therapy targets immune checkpoints, key regulators of the immune system that when stimulated can dampen the immune response to an immunologic stimulus. Some cancers can protect themselves from attack by stimulating immune checkpoint targets. Checkpoint therapy can block inhibitory checkpoints, restoring immune system function. The first anti-cancer drug targeting an immune checkpoint was ipilimumab, a CTLA4 blocker approved in the United States in 2011.
CKLF-like MARVEL transmembrane domain-containing protein 3, also termed chemokine-like factor superfamily 3, is a member of the CKLF-like MARVEL transmembrane domain-containing family of proteins. In humans, CMTM2 protein is encoded by the CMTM3 gene located in band 22.1 on the long arm of chromosome 16. This protein is expressed in a wide range of tissues, including fetal tissues. It is highly expressed in the male reproductive system, particularly testicular tissues and may play a role in the development of this tissue. It is also highly expressed in the immune system including circulating blood cells, i.e. B lymphocytes, CD4+ T lymphocytes, and monocytes. However, CMTM3 protein is weakly expressed or unexpressed in the malignant tissues of several types of cancers. In many but not all of theses cancers, this decreased or lack of expression appears due to methylation of the GpC islands in the promoter region, and thereby the silencing, of the CMTM3 gene.
The CKLF-like MARVEL transmembrane domain-containing family (CMTM), previously termed the chemokine-like factor superfamily (CKLFSF), consists of 9 proteins, some of which have various isoforms due to alternative splicing of their respective genes. These proteins along with their isoforms are:
CKLF-like MARVEL transmembrane domain-containing 5 (CMTM5), previously termed chemokine-like factor superfamily 5, designates any one of the six protein isoforms encoded by six different alternative splices of its gene, CMTM5; CMTM5-v1 is the most studied of these isoforms. The CMTM5 gene is located in band 11.2 on the long arm of chromosome 14.
CKLF like MARVEL transmembrane domain-containing 8, previously termed chemokine-like factor superfamily 8 has at least two isoforms, the CMTM8 and CMTM8-v2 proteins. Protein isoforms are variant products that are made by the alternative splicing of a single gene. The gene for these isoforms, CMTM8, is located in band 22 on the short arm of chromosome 3. The CMTM8 gene and its CMTM8 and CMTM8-v2 proteins belong to the CKLF-like MARVEL transmembrane domain-containing family of structurally and functionally related genes and proteins. The CMTM8 protein is the full-length and predominant product of the CMTM8 gene. This protein is expressed in a wide range of normal adult and fetal tissues while relatively little is known about the CMTM8-v2 protein. Studies suggest that the CMTM8 protein may be involved in the development of various cancers.
CKLF like MARVEL transmembrane domain-containing 4, formerly termed chemokine-like factor superfamily 4, is a small transmembrane protein which passes the plasma membrane four times. It has 3 known isoforms, the CMTM4-v1 to CMTM4-v3 proteins. Protein isoforms are variant products that are made by alternative splicing of a single gene. The gene for the CMTM4 isoforms is located in band 22 on the long arm of chromosome 16. The CMTM4 gene and its 3 isoform proteins belong to the CKLF-like MARVEL transmembrane domain-containing family of structurally and functionally related genes and proteins. CMTM4-v1 and CMTM4-v2 are widely expressed in multiple human tissue while CMTM4-v3 has been detected only in the kidney and placental tissues.
This article incorporates text from the United States National Library of Medicine, which is in the public domain.