Anoikis is a form of programmed cell death that occurs in anchorage-dependent cells when they detach from the surrounding extracellular matrix (ECM). [1] Usually cells stay close to the tissue to which they belong since the communication between proximal cells as well as between cells and ECM provide essential signals for growth or survival. When cells are detached from the ECM, there is a loss of normal cell–matrix interactions, and they may undergo anoikis. However, metastatic tumor cells may escape from anoikis and invade other organs.
The word "anoikis" was coined by Frisch and Francis in a paper published in the Journal of Cell Biology in 1994. [2] "Anoikis", in their words, means "(…the state of being without a home) to describe the cells' apoptotic response to the absence of cell–matrix interactions". The word apparently is a neologism construction consisting of three Greek morphemes agglutinated together: ἀν- "without", οἰκ- "house", and the suffix -ις.
The mechanism by which invading tumor cells survive the anoikis process remains largely unknown. Recent findings suggest that the protein TrkB, best known for its role in the nervous system, might be involved together with its ligand, brain-derived neurotrophic factor (BDNF) [ citation needed ]. It seems that TrkB could make tumor cells resistant to anoikis by activating phosphatidylinositol 3-kinase (PI3K) signaling cascade [ citation needed ]. In squamous cell carcinoma, researchers have found that anoikis resistance can be induced through hepatocyte growth factor (HGF) activating BOTH extracellular signalling-receptor kinase (ERK) and PI3K [ citation needed ].
Using a novel high-throughput screening assay, Mawji et al. showed that anisomycin can sensitize metastatic epithelial cells to anoikis and reduce circulating tumor cell implantation in vivo. [3] Anisomycin achieved this anti-metastatic activity in part by decreasing the abundance of the death receptor inhibiting protein FLIP. In related work, Schimmer's team showed that FLIP levels are higher in metastatic cells than non-metastatic cells, and that reducing FLIP levels using RNAi (RNA Interference) or other small molecule inhibitors of FLIP can sensitize metastatic cells to anoikis. [4] Given that FLIP is an inhibitor of anoikis, and that reducing FLIP can sensitize metastatic cells to anoikis, Mawji et al. hypothesize that FLIP reduction may be a viable therapeutic strategy against cancer metastasis.
Cancer cells develop anoikis resistance by several mechanisms, including changes in integrin and matrix signaling, metabolic deregulation, and stress responses of cancer cells. [5] One key mechanism that renders cancer cells independent from tissue adherence is dysregulation of the pathway network that controls transcription factor NF-κB.
A tyrosine kinase is an enzyme that can transfer a phosphate group from ATP to the tyrosine residues of specific proteins inside a cell. It functions as an "on" or "off" switch in many cellular functions.
In biology, the extracellular matrix (ECM), also called intercellular matrix, is a network consisting of extracellular macromolecules and minerals, such as collagen, enzymes, glycoproteins and hydroxyapatite that provide structural and biochemical support to surrounding cells. Because multicellularity evolved independently in different multicellular lineages, the composition of ECM varies between multicellular structures; however, cell adhesion, cell-to-cell communication and differentiation are common functions of the ECM.
Hepatocyte growth factor receptor is a protein that in humans is encoded by the MET gene. The protein possesses tyrosine kinase activity. The primary single chain precursor protein is post-translationally cleaved to produce the alpha and beta subunits, which are disulfide linked to form the mature receptor.
Biological crosstalk refers to instances in which one or more components of one signal transduction pathway affects another. This can be achieved through a number of ways with the most common form being crosstalk between proteins of signaling cascades. In these signal transduction pathways, there are often shared components that can interact with either pathway. A more complex instance of crosstalk can be observed with transmembrane crosstalk between the extracellular matrix (ECM) and the cytoskeleton.
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.
Tropomyosin receptor kinase C (TrkC), also known as NT-3 growth factor receptor, neurotrophic tyrosine kinase receptor type 3, or TrkC tyrosine kinase is a protein that in humans is encoded by the NTRK3 gene.
The ErbB family of proteins contains four receptor tyrosine kinases, structurally related to the epidermal growth factor receptor (EGFR), its first discovered member. In humans, the family includes Her1, Her2 (ErbB2), Her3 (ErbB3), and Her4 (ErbB4). The gene symbol, ErbB, is derived from the name of a viral oncogene to which these receptors are homologous: erythroblastic leukemia viral oncogene. Insufficient ErbB signaling in humans is associated with the development of neurodegenerative diseases, such as multiple sclerosis and Alzheimer's disease, while excessive ErbB signaling is associated with the development of a wide variety of types of solid tumor.
72 kDa type IV collagenase also known as matrix metalloproteinase-2 (MMP-2) and gelatinase A is an enzyme that in humans is encoded by the MMP2 gene. The MMP2 gene is located on chromosome 16 at position 12.2.
Insulin receptor substrate 1(IRS-1) is a signaling adapter protein that in humans is encoded by the IRS1 gene. It is a 131 kDa protein with amino acid sequence of 1242 residues. It contains a single pleckstrin homology (PH) domain at the N-terminus and a PTB domain ca. 40 residues downstream of this, followed by a poorly conserved C-terminus tail. Together with IRS2, IRS3 (pseudogene) and IRS4, it is homologous to the Drosophila protein chico, whose disruption extends the median lifespan of flies up to 48%. Similarly, Irs1 mutant mice experience moderate life extension and delayed age-related pathologies.
Trk receptors are a family of tyrosine kinases that regulates synaptic strength and plasticity in the mammalian nervous system. Trk receptors affect neuronal survival and differentiation through several signaling cascades. However, the activation of these receptors also has significant effects on functional properties of neurons.
RhoC is a small signaling G protein, and is a member of the Rac subfamily of the family Rho family of GTPases. It is encoded by the gene RHOC.
WNT1-inducible-signaling pathway protein 1 (WISP-1), also known as CCN4, is a matricellular protein that in humans is encoded by the WISP1 gene.
Periostin is a protein that in humans is encoded by the POSTN gene. Periostin functions as a ligand for alpha-V/beta-3 and alpha-V/beta-5 integrins to support adhesion and migration of epithelial cells.
Sulfatase 1, also known as SULF1, is an enzyme which in humans is encoded by the SULF1 gene.
Invadopodia are actin-rich protrusions of the plasma membrane that are associated with degradation of the extracellular matrix in cancer invasiveness and metastasis. Very similar to podosomes, invadopodia are found in invasive cancer cells and are important for their ability to invade through the extracellular matrix, especially in cancer cell extravasation. Invadopodia are generally visualized by the holes they create in ECM -coated plates, in combination with immunohistochemistry for the invadopodia localizing proteins such as cortactin, actin, Tks5 etc. Invadopodia can also be used as a marker to quantify the invasiveness of cancer cell lines in vitro using a hyaluronic acid hydrogel assay.
Metastatic breast cancer, also referred to as metastases, advanced breast cancer, secondary tumors, secondaries or stage IV breast cancer, is a stage of breast cancer where the breast cancer cells have spread to distant sites beyond the axillary lymph nodes. There is no cure for metastatic breast cancer; there is no stage after IV.
XB130 is a cytosolic adaptor protein and signal transduction mediator. XB130 regulates cell proliferation, cell survival, cell motility and gene expression. XB130 is highly similar to AFAP and is thus known as actin filament associated protein 1-like 2 (AFAP1L2). XB130 is a substrate and regulator of multiple tyrosine kinase-mediated signaling. XB130 is highly expressed in the thyroid and spleen.
Gedatolisib (PF-05212384) is an experimental drug for treatment of cancer in development by Celcuity, Inc. The mechanism of action is accomplished by binding the different p110 catalytic subunit isoforms of PI3K and the kinase site of mTOR.
Invasion is the process by which cancer cells directly extend and penetrate into neighboring tissues in cancer. It is generally distinguished from metastasis, which is the spread of cancer cells through the circulatory system or the lymphatic system to more distant locations. Yet, lymphovascular invasion is generally the first step of metastasis.
Lipofibromatosis-like neural tumor (LPF-NT) is an extremely rare soft tissue tumor first described by Agaram et al in 2016. As of mid-2021, at least 39 cases of LPF-NT have been reported in the literature. LPF-NT tumors have several features that resemble lipofibromatosis (LPF) tumors, malignant peripheral nerve sheath tumors, spindle cell sarcomas, low-grade neural tumors, peripheral nerve sheath tumors, and other less clearly defined tumors; Prior to the Agaram at al report, LPF-NTs were likely diagnosed as variants or atypical forms of these tumors. The analyses of Agaram at al and subsequent studies uncovered critical differences between LPF-NT and the other tumor forms which suggest that it is a distinct tumor entity differing not only from lipofibromatosis but also the other tumor forms.