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CLICK IMAGE FOR MORE INFORMATIONThe KIT gene (also known as CD117) encodes a transmembrane receptor that binds the ligand known as stem cell factor (SCF). Binding of the ligand SCF on the outside of the cell leads to the activation of the KIT receptor tyrosine kinase inside the cell. When tyrosine kinases are activated, they become phosphorylated, meaning they have phosphate added at specific sites on the portion of the receptor that is inside the cell. These phosphorylation sites serve as docking sites for the assembly of signal proteins that then cause the activation of several signal pathways. When KIT is activated, it specifically activates the MAP kinase pathway, the PI3K/AKT/mTOR pathway, and the JAK/STAT pathway. When activated, these signal pathways promote cellular proliferation and survival.
In studies examining the KIT protein in cancers, mutations in KIT have been identified that lead to the production of an altered protein that cannot be regulated normally. Invariably, the mutated KIT protein found in tumors no longer needs SCF ligand binding to the external portion of the receptor to be activated. Instead, mutated KIT stays in a constantly activated state. This constant stimulation of growth and survival signal pathways can leads to the development of cancer. Mutations and other genetic alterations in the gene encoding KIT have been found in several tumor types. Mutations in the KIT protein are frequently found in GastroIntestinal Stromal Tumors (GIST), in some types of Acute Myeloid Leukemia (AML), in melanoma, and less frequently in some other types of tumors. Clinical trials involving KIT inhibitors, as well as KIT inhibitors used in combination with other therapeutic agents are underway at the MGH Cancer Center. Further studies are needed to prevent the growth of tumors containing KIT alterations.
The KIT gene (also known as CD117) encodes a transmembrane receptor that binds the ligand known as stem cell factor (SCF). Binding of the ligand SCF on the outside of the cell leads to the activation of the KIT receptor tyrosine kinase inside the cell. When tyrosine kinases are activated, they become phosphorylated, meaning they have phosphate added at specific sites on the portion of the receptor that is inside the cell. These phosphorylation sites serve as docking sites for the assembly of signal proteins that then cause the activation of several signal pathways. When KIT is activated, it specifically activates the MAP kinase pathway, the PI3K/AKT/mTOR pathway, and the JAK/STAT pathway. When activated, these signal pathways promote cellular proliferation and survival.
In studies examining the KIT protein in cancers, mutations in KIT have been identified that lead to the production of an altered protein that cannot be regulated normally. Invariably, the mutated KIT protein found in tumors no longer needs SCF ligand binding to the external portion of the receptor to be activated. Instead, mutated KIT stays in a constantly activated state. This constant stimulation of growth and survival signal pathways can leads to the development of cancer. Mutations and other genetic alterations in the gene encoding KIT have been found in several tumor types. Mutations in the KIT protein are frequently found in GastroIntestinal Stromal Tumors (GIST), in some types of Acute Myeloid Leukemia (AML), in melanoma, and less frequently in some other types of tumors. Clinical trials involving KIT inhibitors, as well as KIT inhibitors used in combination with other therapeutic agents are underway at the MGH Cancer Center. Further studies are needed to prevent the growth of tumors containing KIT alterations.
PubMed ID's
9438854,
15339674,
15948115,
16647948,
17372901,
16908931Genetic alterations in the KIT gene have been identified in specific types of cancer. These genetic changes include gene amplification, where segments of the gene have developed multiple copies, and the transcriptional machinery "reads" all of them, producing a much higher level of the KIT protein. Other mechanisms also result in overexpression of the protein. Whether through gene amplification or other mechanisms that result in overexpression, the result is an increased amount of the KIT protein in tumor cells. KIT overexpression produces an activated form of the protein, which leads to activation of several growth signal pathways. The result is that the tumor cells are getting constant signals to grow and proliferate.
Genetic alterations in the KIT gene have been identified in specific types of cancer. These genetic changes include gene amplification, where segments of the gene have developed multiple copies, and the transcriptional machinery "reads" all of them, producing a much higher level of the KIT protein. Other mechanisms also result in overexpression of the protein. Whether through gene amplification or other mechanisms that result in overexpression, the result is an increased amount of the KIT protein in tumor cells. KIT overexpression produces an activated form of the protein, which leads to activation of several growth signal pathways. The result is that the tumor cells are getting constant signals to grow and proliferate.