Mitotoxin

Last updated

A mitotoxin is a cytotoxic molecule targeted to specific cells by a mitogen. Generally found in snake venom. Mitotoxins are responsible for mediating cell death [1] by interfering with protein or DNA synthesis. [2] Some mechanisms by which mitotoxins can interfere with DNA or protein synthesis include the inactivation of ribosomes [1] or the inhibition of complexes in the mitochondrial electron transport chain. [3] These toxins have a very high affinity and level of specificity for the receptors that they bind to. Mitotoxins bind to receptors on cell surfaces and are then internalized into cells via receptor-mediated endocytosis. Once in the endosome, the receptor releases its ligand and a mitotoxin can mediate cell death. [1]

There are different classes of mitotoxins, each acting on a different type of cell or system. The mitotoxin classes that have been identified thus far include: interleukin-based, transferrin based, epidermal growth factor-based, nerve growth factor-based, insulin-like growth factor-I-based, and fibroblast growth factor-based mitotoxins. [1] Because of the high affinity and specificity of mitotoxin binding, they present the possibility of creating precise therapeutic agents. [1] A major one of these possibilities is the potential usage of growth factor-based mitotoxins as anti-neoplastic [4] agents that can modulate the growth of melanomas. [5]

Related Research Articles

<span class="mw-page-title-main">Natural killer cell</span> Type of cytotoxic lymphocyte

Natural killer cells, also known as NK cells, are a type of cytotoxic lymphocyte critical to the innate immune system. They are a kind of large granular lymphocytes (LGL), and belong to the rapidly expanding family of known innate lymphoid cells (ILC) and represent 5–20% of all circulating lymphocytes in humans. The role of NK cells is analogous to that of cytotoxic T cells in the vertebrate adaptive immune response. NK cells provide rapid responses to virus-infected cells, stressed cells, tumor cells, and other intracellular pathogens based on signals from several activating and inhibitory receptors. Most immune cells detect the antigen presented on major histocompatibility complex I (MHC-I) on infected cell surfaces, but NK cells can recognize and kill stressed cells in the absence of antibodies and MHC, allowing for a much faster immune reaction. They were named "natural killers" because of the notion that they do not require activation to kill cells that are missing "self" markers of MHC class I. This role is especially important because harmful cells that are missing MHC I markers cannot be detected and destroyed by other immune cells, such as T lymphocyte cells.

<span class="mw-page-title-main">Eosinophil</span> Variety of white blood cells

Eosinophils, sometimes called eosinophiles or, less commonly, acidophils, are a variety of white blood cells and one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates. Along with mast cells and basophils, they also control mechanisms associated with allergy and asthma. They are granulocytes that develop during hematopoiesis in the bone marrow before migrating into blood, after which they are terminally differentiated and do not multiply.

<span class="mw-page-title-main">Platelet-derived growth factor</span> Signaling glycoprotein regulating cell proliferation

Platelet-derived growth factor (PDGF) is one among numerous growth factors that regulate cell growth and division. In particular, PDGF plays a significant role in blood vessel formation, the growth of blood vessels from already-existing blood vessel tissue, mitogenesis, i.e. proliferation, of mesenchymal cells such as fibroblasts, osteoblasts, tenocytes, vascular smooth muscle cells and mesenchymal stem cells as well as chemotaxis, the directed migration, of mesenchymal cells. Platelet-derived growth factor is a dimeric glycoprotein that can be composed of two A subunits (PDGF-AA), two B subunits (PDGF-BB), or one of each (PDGF-AB).

<span class="mw-page-title-main">Cancer immunotherapy</span> Artificial stimulation of the immune system to treat cancer

Cancer immunotherapy (immuno-oncotherapy) is the stimulation of the immune system to treat cancer, improving the immune system's natural ability to fight the disease. It is an application of the fundamental research of cancer immunology (immuno-oncology) and a growing subspecialty of oncology.

<span class="mw-page-title-main">Targeted therapy</span> Type of therapy

Targeted therapy or molecularly targeted therapy is one of the major modalities of medical treatment (pharmacotherapy) for cancer, others being hormonal therapy and cytotoxic chemotherapy. As a form of molecular medicine, targeted therapy blocks the growth of cancer cells by interfering with specific targeted molecules needed for carcinogenesis and tumor growth, rather than by simply interfering with all rapidly dividing cells. Because most agents for targeted therapy are biopharmaceuticals, the term biologic therapy is sometimes synonymous with targeted therapy when used in the context of cancer therapy. However, the modalities can be combined; antibody-drug conjugates combine biologic and cytotoxic mechanisms into one targeted therapy.

<span class="mw-page-title-main">Fc receptor</span> Surface protein important to the immune system

In immunology, an Fc receptor is a protein found on the surface of certain cells – including, among others, B lymphocytes, follicular dendritic cells, natural killer cells, macrophages, neutrophils, eosinophils, basophils, human platelets, and mast cells – that contribute to the protective functions of the immune system. Its name is derived from its binding specificity for a part of an antibody known as the Fc region. Fc receptors bind to antibodies that are attached to infected cells or invading pathogens. Their activity stimulates phagocytic or cytotoxic cells to destroy microbes, or infected cells by antibody-mediated phagocytosis or antibody-dependent cell-mediated cytotoxicity. Some viruses such as flaviviruses use Fc receptors to help them infect cells, by a mechanism known as antibody-dependent enhancement of infection.

Fibroblast growth factors (FGF) are a family of cell signalling proteins produced by macrophages; they are involved in a wide variety of processes, most notably as crucial elements for normal development in animal cells. Any irregularities in their function lead to a range of developmental defects. These growth factors typically act as systemic or locally circulating molecules of extracellular origin that activate cell surface receptors. A defining property of FGFs is that they bind to heparin and to heparan sulfate. Thus, some are sequestered in the extracellular matrix of tissues that contains heparan sulfate proteoglycans and are released locally upon injury or tissue remodeling.

<span class="mw-page-title-main">Antibody-dependent cellular cytotoxicity</span> Cell-mediated killing of other cells mediated by antibodies

Antibody-dependent cellular cytotoxicity (ADCC), also referred to as antibody-dependent cell-mediated cytotoxicity, is a mechanism of cell-mediated immune defense whereby an effector cell of the immune system kills a target cell, whose membrane-surface antigens have been bound by specific antibodies. It is one of the mechanisms through which antibodies, as part of the humoral immune response, can act to limit and contain infection.

<span class="mw-page-title-main">Low-affinity nerve growth factor receptor</span> Human protein-coding gene

The p75 neurotrophin receptor (p75NTR) was first identified in 1973 as the low-affinity nerve growth factor receptor (LNGFR) before discovery that p75NTR bound other neurotrophins equally well as nerve growth factor. p75NTR is a neurotrophic factor receptor. Neurotrophic factor receptors bind Neurotrophins including Nerve growth factor, Neurotrophin-3, Brain-derived neurotrophic factor, and Neurotrophin-4. All neurotrophins bind to p75NTR. This also includes the immature pro-neurotrophin forms. Neurotrophic factor receptors, including p75NTR, are responsible for ensuring a proper density to target ratio of developing neurons, refining broader maps in development into precise connections. p75NTR is involved in pathways that promote neuronal survival and neuronal death.

<span class="mw-page-title-main">Neurotrophin-3</span> Protein-coding gene in the species Homo sapiens

Neurotrophin-3 is a protein that in humans is encoded by the NTF3 gene.

<span class="mw-page-title-main">Platelet-derived growth factor receptor</span> Cell surface receptors

Platelet-derived growth factor receptors (PDGF-R) are cell surface tyrosine kinase receptors for members of the platelet-derived growth factor (PDGF) family. PDGF subunits -A and -B are important factors regulating cell proliferation, cellular differentiation, cell growth, development and many diseases including cancer. There are two forms of the PDGF-R, alpha and beta each encoded by a different gene. Depending on which growth factor is bound, PDGF-R homo- or heterodimerizes.

Lymphotoxin is a member of the tumor necrosis factor (TNF) superfamily of cytokines, whose members are responsible for regulating the growth and function of lymphocytes and are expressed by a wide variety of cells in the body.

<span class="mw-page-title-main">Hepatocyte growth factor</span> Mammalian protein found in Homo sapiens

Hepatocyte growth factor (HGF) or scatter factor (SF) is a paracrine cellular growth, motility and morphogenic factor. It is secreted by mesenchymal cells and targets and acts primarily upon epithelial cells and endothelial cells, but also acts on haemopoietic progenitor cells and T cells. It has been shown to have a major role in embryonic organ development, specifically in myogenesis, in adult organ regeneration, and in wound healing.

<span class="mw-page-title-main">Fibroblast growth factor receptor 2</span> Protein-coding gene in the species Homo sapiens

Fibroblast growth factor receptor 2 (FGFR-2) also known as CD332 is a protein that in humans is encoded by the FGFR2 gene residing on chromosome 10. FGFR2 is a receptor for fibroblast growth factor.

CD16, also known as FcγRIII, is a cluster of differentiation molecule found on the surface of natural killer cells, neutrophils, monocytes, macrophages, and certain T cells. CD16 has been identified as Fc receptors FcγRIIIa (CD16a) and FcγRIIIb (CD16b), which participate in signal transduction. The most well-researched membrane receptor implicated in triggering lysis by NK cells, CD16 is a molecule of the immunoglobulin superfamily (IgSF) involved in antibody-dependent cellular cytotoxicity (ADCC). It can be used to isolate populations of specific immune cells through fluorescent-activated cell sorting (FACS) or magnetic-activated cell sorting, using antibodies directed towards CD16.

<span class="mw-page-title-main">Fibroblast growth factor receptor 1</span> Protein found in humans

Fibroblast growth factor receptor 1 (FGFR-1), also known as basic fibroblast growth factor receptor 1, fms-related tyrosine kinase-2 / Pfeiffer syndrome, and CD331, is a receptor tyrosine kinase whose ligands are specific members of the fibroblast growth factor family. FGFR-1 has been shown to be associated with Pfeiffer syndrome, and clonal eosinophilias.

<span class="mw-page-title-main">Heparin-binding EGF-like growth factor</span> Protein-coding gene in the species Homo sapiens

Heparin-binding EGF-like growth factor (HB-EGF) is a member of the EGF family of proteins that in humans is encoded by the HBEGF gene.

<span class="mw-page-title-main">GPER</span> Protein-coding gene in the species Homo sapiens

G protein-coupled estrogen receptor 1 (GPER), also known as G protein-coupled receptor 30 (GPR30), is a protein that in humans is encoded by the GPER gene. GPER binds to and is activated by the female sex hormone estradiol and is responsible for some of the rapid effects that estradiol has on cells.

<span class="mw-page-title-main">Fibroblast growth factor receptor 4</span> Protein-coding gene in the species Homo sapiens

Fibroblast growth factor receptor 4 (FGFR-4) is a protein that in humans is encoded by the FGFR4 gene. FGFR4 has also been designated as CD334.

<span class="mw-page-title-main">Tumor microenvironment</span> Surroundings of tumors including nearby cells and blood vessels

The tumor microenvironment is a complex ecosystem surrounding a tumor, composed of cancer cells, stromal tissue and the extracellular matrix. Mutual interaction between cancer cells and the different components of the tumor microenvironment support its growth and invasion in healthy tissues which correlates with tumor resistance to current treatments and poor prognosis. The tumor microenvironment is in constant change because of the tumor's ability to influence the microenvironment by releasing extracellular signals, promoting tumor angiogenesis and inducing peripheral immune tolerance, while the immune cells in the microenvironment can affect the growth and evolution of cancerous cells.

References

  1. 1 2 3 4 5 Lappi, Douglas A.; Baird, Andrew (January 1990). "Mitotoxins: Growth factor-targeted cytotoxic molecules". Progress in Growth Factor Research. 2 (4): 223–236. doi:10.1016/0955-2235(90)90020-k. ISSN   0955-2235. PMID   2133290.
  2. Lappi, Douglas A.; Maher, Pamela A.; Martineau, Darlene; Baird, Andrew (April 1991). "The basic fibroblast growth factor-saporin mitotoxin acts through the basic fibroblast growth factor receptor". Journal of Cellular Physiology. 147 (1): 17–26. doi:10.1002/jcp.1041470104. ISSN   0021-9541. PMID   1645359. S2CID   30877555.
  3. Souders, Christopher L.; Wei, Chi; Schmidt, Jordan T.; Da Fonte, Dillon F.; Xing, Lei; Trudeau, Vance L.; Martyniuk, Christopher J. (May 2021). "Mitochondria of teleost radial glia: A novel target of neuroendocrine disruption by environmental chemicals?". Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology. 243: 108995. doi:10.1016/j.cbpc.2021.108995. ISSN   1532-0456. PMID   33545344. S2CID   231918972.
  4. Kreitman, Robert J (February 2000). "Chimeric toxins in cancer treatment". Emerging Drugs. 5 (1): 61–71. doi:10.1517/14728214.5.1.61. ISSN   1361-9195. S2CID   85995595.
  5. Ying, Martineau (1 August 1994). "Anti-B16-F10 melanoma activity of a basic fibroblast growth factor-saporin mitotoxin". Cancer. 74 (3): 848–853. doi:10.1002/1097-0142(19940801)74:3<848::AID-CNCR2820740310>3.0.CO;2-J. PMID   8039113. S2CID   25353960.