Anoikis

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.

Etymology

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.

In metastasis

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). It seems that TrkB could make tumor cells resistant to anoikis by activating phosphatidylinositol 3-kinase (PI3K) signaling cascade. 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.

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.

See also

References

  1. ^ Frisch SM, Screaton RA (October 2001). "Anoikis mechanisms". Current Opinion in Cell Biology. 13 (5): 555–62. doi:10.1016/S0955-0674(00)00251-9. PMID 11544023.
  2. ^ Frisch, SM.; Francis, H. (Feb 1994). "Disruption of epithelial cell-matrix interactions induces apoptosis". J Cell Biol. 124 (4): 619–26. doi:10.1083/jcb.124.4.619. PMC 2119917. PMID 8106557.
  3. ^ Mawji IA, Simpson CD, Gronda M, et al. (September 2007). "A chemical screen identifies anisomycin as an anoikis sensitizer that functions by decreasing FLIP protein synthesis". Cancer Research. 67 (17): 8307–15. doi:10.1158/0008-5472.CAN-07-1687. PMID 17804746.
  4. ^ Mawji IA, Simpson CD, Hurren R, et al. (May 2007). "Critical role for Fas-associated death domain-like interleukin-1-converting enzyme-like inhibitory protein in anoikis resistance and distant tumor formation". Journal of the National Cancer Institute. 99 (10): 811–22. doi:10.1093/jnci/djk182. PMID 17505076.
  5. ^ Paoli P, Giannoni E, Chiarugi P (2013). "Anoikis molecular pathways and its role in cancer progression". Biochim Biophys Acta. 1833 (12): 3481–3498. doi:10.1016/j.bbamcr.2013.06.026. PMID 23830918.

Further reading

Algor mortis

Algor mortis (Latin: algor—coldness; mortis—of death), the second stage of death, is the change in body temperature post mortem, until the ambient temperature is matched. This is generally a steady decline, although if the ambient temperature is above the body temperature (such as in a hot desert), the change in temperature will be positive, as the (relatively) cooler body acclimates to the warmer environment. External factors can have a significant influence.

The term was first used by Dowler in 1849. The first published measurements of the intervals of temperature after death were done by Dr John Davey in 1839.

BMF (gene)

Bcl-2-modifying factor is a protein that in humans is encoded by the BMF gene.The protein encoded by this gene belongs to the BCL2 protein family. BCL2 family members form hetero- or homodimers and act as anti- or pro-apoptotic regulators that are involved in a wide variety of cellular activities. This protein contains a single BCL2 homology domain 3 (BH3), and has been shown to bind BCL2 proteins and function as an apoptotic activator. This protein is found to be sequestered to myosin V motors by its association with dynein light chain 2, which may be important for sensing intracellular damage and triggering apoptosis. Alternatively spliced transcript variants encoding different isoforms have been identified.

BRMS1

Breast cancer metastasis suppressor 1 is a protein that in humans is encoded by the BRMS1 gene.This gene reduces the metastatic potential, but not the tumorogenicity, of human breast cancer and melanoma cell lines. The protein encoded by this gene localizes primarily to the nucleus, and is a component of the mSin3a family of histone deacetylase complexes (HDAC). The protein contains two coiled-coil motifs and several imperfect leucine zipper motifs. Alternative splicing results in two transcript variants encoding different isoforms.

CEACAM5

Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) also known as CD66e (Cluster of Differentiation 66e), is a member of the carcinoembryonic antigen (CEA) gene family.

CEACAM6

Carcinoembryonic antigen-related cell adhesion molecule 6 (non-specific cross reacting antigen) (CEACAM6) also known as CD66c (Cluster of Differentiation 66c), is a member of the carcinoembryonic antigen (CEA) gene family..

Cell death

Cell death is the event of a biological cell ceasing to carry out its functions. This may be the result of the natural process of old cells dying and being replaced by new ones, or may result from such factors as disease, localized injury, or the death of the organism of which the cells are part. Apoptosis or Type I cell-death, and autophagy or Type II cell-death are both forms of programmed cell death, while necrosis is a non-physiological process that occurs as a result of infection or injury.

DYNLL2

Dynein light chain 2, cytoplasmic is a protein that in humans is encoded by the DYNLL2 gene.

Dead on arrival

Dead on arrival (DOA), also dead in the field and brought in dead (BID), indicates that a patient was found to be already clinically dead upon the arrival of professional medical assistance, often in the form of first responders such as emergency medical technicians, paramedics, or police.

In some jurisdictions, first responders must consult verbally with a physician before officially pronouncing a patient deceased, but once cardiopulmonary resuscitation is initiated, it must be continued until a physician can pronounce the patient dead.

Death messenger

Death messengers, in former times, were those who were dispatched to spread the news that an inhabitant of their city or village had died. They were to wear unadorned black and go door to door with the message, "You are asked to attend the funeral of the departed __________ at (time, date, and place)." This was all they were allowed to say, and were to move on to the next house immediately after uttering the announcement. This tradition persisted in some areas to as late as the mid-19th century.

Death rattle

Terminal respiratory secretions (or simply terminal secretions), known colloquially as a death rattle, are sounds often produced by someone who is near death as a result of fluids such as saliva and bronchial secretions accumulating in the throat and upper chest. Those who are dying may lose their ability to swallow and may have increased production of bronchial secretions, resulting in such an accumulation. Usually, two or three days earlier, the symptoms of approaching death can be observed as saliva accumulates in the throat, making it very difficult to take even a spoonful of water. Related symptoms can include shortness of breath and rapid chest movement. While death rattle is a strong indication that someone is near death, it can also be produced by other problems that cause interference with the swallowing reflex, such as brain injuries.It is sometimes misinterpreted as the sound of the person choking to death, or alternatively, that they are gargling.

Dignified death

Dignified death is a somewhat elusive concept often related to suicide. One factor that has been cited as a core component of dignified death is maintaining a sense of control. Another view is that a truly dignified death is an extension of a dignified life. There is some concern that assisted suicide does not guarantee a dignified death, since some patients may experience complications such as nausea and vomiting. There is some concern that age discrimination denies the elderly a dignified death.

Dysthanasia

In medicine, dysthanasia means "bad death" and is considered a common fault of modern medicine.Dysthanasia occurs when a person who is dying has their biological life extended through technological means without regard to the person's quality of life. Technologies such as an implantable cardioverter defibrillator, artificial ventilation, ventricular assist devices, and extracorporeal membrane oxygenation can extend the dying process.

Dysthanasia is a term generally used when a person is seen to be kept alive artificially in a condition where, otherwise, they cannot survive; sometimes for some sort of ulterior motive. The term was used frequently in the investigation into the death of Formula One driver Ayrton Senna in 1994.

GPR31

G-protein coupled receptor 31 also known as 12-(S)-HETE receptor is a protein that in humans is encoded by the GPR31 gene. The human gene is located on chromosome 6q27 and encodes a G-protein coupled receptor protein composed of 319 amino acids.

Integrin alpha 5

Integrin alpha-5 is a protein that in humans is encoded by the ITGA5 gene.The product of this gene belongs to the integrin alpha chain family. Integrins are heterodimeric integral membrane proteins composed of an alpha chain and a beta chain. This gene encodes the integrin alpha 5 chain. Alpha chain 5 undergoes post-translational cleavage in the extracellular domain to yield disulfide-linked light and heavy chains that join with beta 1 to form a fibronectin receptor. In addition to adhesion, integrins are known to participate in cell-surface mediated signalling.

Lazarus sign

The Lazarus sign or Lazarus reflex is a reflex movement in brain-dead or brainstem failure patients, which causes them to briefly raise their arms and drop them crossed on their chests (in a position similar to some Egyptian mummies). The phenomenon is named after the Biblical figure Lazarus of Bethany, whom Jesus raised from the dead in the Gospel of John.

Megadeath

Megadeath (or megacorpse) is one million human deaths, usually caused by a nuclear explosion. The term was used by scientists and thinkers who strategized likely outcomes of all-out nuclear warfare.

Obituary

An obituary (obit for short) is a news article that reports the recent death of a person, typically along with an account of the person's life and information about the upcoming funeral. In large cities and larger newspapers, obituaries are written only for people considered significant. In local newspapers, an obituary may be published for any local resident upon death. A necrology is a register or list of records of the deaths of people related to a particular organization, group or field, which may only contain the sparsest details, or small obituaries. Historical necrologies can be important sources of information.

Two types of paid advertisements are related to obituaries. One, known as a death notice, omits most biographical details and may be a legally required public notice under some circumstances. The other type, a paid memorial advertisement, is usually written by family members or friends, perhaps with assistance from a funeral home. Both types of paid advertisements are usually run as classified advertisements.

Pallor mortis

Pallor mortis (Latin: pallor "paleness", mortis "of death"), the first stage of death, is an after-death paleness that occurs in those with light/white skin.

U0126

U0126 is a highly selective inhibitor of both MEK1 and MEK2, a type of MAPK/ERK kinase. U0126 was found to functionally antagonize AP-1 transcriptional activity via noncompetitive inhibition of the dual specificity kinase MEK with IC50 of 72 nM for MEK1 and 58 nM for MEK2. U0126 inhibited anchorage-independent growth of Ki-ras-transformed rat fibroblasts by simultaneously blocking both extracellular signal-regulated kinase (ERK) and mammalian target of rapamycin (mTOR)-p70(S6K) pathways. The effects of U0126 on the growth of eight human breast cancer cell lines shown that U0126 selectively repressed anchorage-independent growth of MDA-MB231 and HBC4 cells, two lines with constitutively activated ERK. Loss of contact with substratum triggers apoptosis in many normal cell types, a phenomenon termed anoikis. U0126 sensitized MDA-MB231 and HBC4 to anoikis, i.e., upon treatment with U0126, cells deprived of anchorage entered apoptosis.

U0126 is also a weak inhibitor of PKC, Raf, ERK, JNK, MEKK, MKK-3, MKK-4/SEK, MKK-6, Cdk2 and Cdk4.

Its potential for wiping long-term memories in rats has been studied at the Center for Neural Science at New York University.

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