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Event: 1269

Key Event Title

The KE title should describe a discrete biological change that can be measured. It should generally define the biological object or process being measured and whether it is increased, decreased, or otherwise definably altered relative to a control state. For example “enzyme activity, decreased”, “hormone concentration, increased”, or “growth rate, decreased”, where the specific enzyme or hormone being measured is defined. More help

Increase, COX-2 expression

Short name
The KE short name should be a reasonable abbreviation of the KE title and is used in labelling this object throughout the AOP-Wiki. The short name should be less than 80 characters in length. More help
Increase, COX-2 expression

Biological Context

Structured terms, selected from a drop-down menu, are used to identify the level of biological organization for each KE. Note, KEs should be defined within a particular level of biological organization. Only KERs should be used to transition from one level of organization to another. Selection of the level of biological organization defines which structured terms will be available to select when defining the Event Components (below). More help
Level of Biological Organization

Cell term

Further information on Event Components and Biological Context may be viewed on the attached pdf.The biological context describes the location/biological environment in which the event takes place.  For molecular/cellular events this would include the cellular context (if known), organ context, and species/life stage/sex for which the event is relevant. For tissue/organ events cellular context is not applicable.  For individual/population events, the organ context is not applicable. More help
Cell term
eukaryotic cell

Organ term

Further information on Event Components and Biological Context may be viewed on the attached pdf.The biological context describes the location/biological environment in which the event takes place.  For molecular/cellular events this would include the cellular context (if known), organ context, and species/life stage/sex for which the event is relevant. For tissue/organ events cellular context is not applicable.  For individual/population events, the organ context is not applicable. More help

Key Event Components

Further information on Event Components and Biological Context may be viewed on the attached pdf.Because one of the aims of the AOP-KB is to facilitate de facto construction of AOP networks through the use of shared KE and KER elements, authors are also asked to define their KEs using a set of structured ontology terms (Event Components). In the absence of structured terms, the same KE can readily be defined using a number of synonymous titles (read by a computer as character strings). In order to make these synonymous KEs more machine-readable, KEs should also be defined by one or more “event components” consisting of a biological process, object, and action with each term originating from one of 22 biological ontologies (Ives, et al., 2017; See List). Biological process describes dynamics of the underlying biological system (e.g., receptor signalling). The biological object is the subject of the perturbation (e.g., a specific biological receptor that is activated or inhibited). Action represents the direction of perturbation of this system (generally increased or decreased; e.g., ‘decreased’ in the case of a receptor that is inhibited to indicate a decrease in the signalling by that receptor).Note that when editing Event Components, clicking an existing Event Component from the Suggestions menu will autopopulate these fields, along with their source ID and description. To clear any fields before submitting the event component, use the 'Clear process,' 'Clear object,' or 'Clear action' buttons. If a desired term does not exist, a new term request may be made via Term Requests. Event components may not be edited; to edit an event component, remove the existing event component and create a new one using the terms that you wish to add. More help
Process Object Action
gene expression prostaglandin G/H synthase 2 increased

Key Event Overview

AOPs Including This Key Event

All of the AOPs that are linked to this KE will automatically be listed in this subsection. This table can be particularly useful for derivation of AOP networks including the KE. Clicking on the name of the AOP will bring you to the individual page for that AOP. More help
AOP Name Role of event in AOP Point of Contact Author Status OECD Status
AhR mediated mortality, via COX-2 KeyEvent Allie Always (send email) Open for citation & comment WPHA/WNT Endorsed


This is a structured field used to identify specific agents (generally chemicals) that can trigger the KE. Stressors identified in this field will be linked to the KE in a machine-readable manner, such that, for example, a stressor search would identify this as an event the stressor can trigger. NOTE: intermediate or downstream KEs in one AOP may function as MIEs in other AOPs, meaning that stressor information may be added to the KE description, even if it is a downstream KE in the pathway currently under development.Information concerning the stressors that may trigger an MIE can be defined using a combination of structured and unstructured (free-text) fields. For example, structured fields may be used to indicate specific chemicals for which there is evidence of an interaction relevant to this MIE. By linking the KE description to a structured chemical name, it will be increasingly possible to link the MIE to other sources of chemical data and information, enhancing searchability and inter-operability among different data-sources and knowledgebases. The free-text section “Evidence for perturbation of this MIE by stressor” can be used both to identify the supporting evidence for specific stressors triggering the MIE as well as to define broad chemical categories or other properties that classify the stressors able to trigger the MIE for which specific structured terms may not exist. More help

Taxonomic Applicability

Latin or common names of a species or broader taxonomic grouping (e.g., class, order, family) can be selected from an ontology. In many cases, individual species identified in these structured fields will be those for which the strongest evidence used in constructing the AOP was available in relation to this KE. More help
Term Scientific Term Evidence Link
Danio rerio Danio rerio High NCBI
Oryzias latipes Oryzias latipes High NCBI
Gallus gallus Gallus gallus High NCBI
mouse Mus musculus High NCBI
human Homo sapiens Moderate NCBI

Life Stages

The structured ontology terms for life-stage are more comprehensive than those for taxa, but may still require further description/development and explanation in the free text section. More help
Life stage Evidence
Embryo High

Sex Applicability

The authors must select from one of the following: Male, female, mixed, asexual, third gender, hermaphrodite, or unspecific. More help
Term Evidence
Unspecific High

Key Event Description

A description of the biological state being observed or measured, the biological compartment in which it is measured, and its general role in the biology should be provided. For example, the biological state being measured could be the activity of an enzyme, the expression of a gene or abundance of an mRNA transcript, the concentration of a hormone or protein, neuronal activity, heart rate, etc. The biological compartment may be a particular cell type, tissue, organ, fluid (e.g., plasma, cerebrospinal fluid), etc. The role in the biology could describe the reaction that an enzyme catalyses and the role of that reaction within a given metabolic pathway; the protein that a gene or mRNA transcript codes for and the function of that protein; the function of a hormone in a given target tissue, physiological function of an organ, etc. Careful attention should be taken to avoid reference to other KEs, KERs or AOPs. Only describe this KE as a single isolated measurable event/state. This will ensure that the KE is modular and can be used by other AOPs, thereby facilitating construction of AOP networks. More help

COX Pathway:

  • Prostaglandin-endoperoxide synthase (PTGS; KEGG ID E.C. is an enzyme that has two catalytic sites.
  • Cyclooxygenase site (COX) catalyzes conversion of arachidonic acid into endoperoxide prostaglandin G2 (Simmons et al 2004).
  • Peroxidase active site converts PGG2 to PGH2 (KEGG reactions 1599, 1590). PGH2 is a precursor for synthesis of other prostaglandins (PGEs, PGFs), prostacyclin, and thromboxanes (Simmons et al 2004; Botting & Botting 2011).
  • There are two isoforms, COX-1 and COX-2
  • COX-2 is inducible by certain chemical exposures, inflammation, during discrete stages of gamete maturation, and more (Green et al 2012).
  • However, COX biology is complex and important details of the pathway remain unknown (Grosser 2006).

COX Cardiovascular Roles:

  • Prostaglandins which are catalyzed by COX and have roles in cellular homeostasis and in promoting inflammatory responses (Chien et al 2015; Smith et al 2000; Tilley et al 2001; Vane et al 1994).
  • Significant evidence suggests a link between COX-2 mediated inflammatory responses and progression of alterations in cardiovascular development and function in murine models, humans, and zebrafish (Danio rerio) (Delgado et al 2004; Gullestad & Aukrust 2005; Hocherl et al 2002; Huang et al 2007; Wong et al 1998 ).
  • However, the precise mechanism by which prostaglandins produce alterations in cardiovascular development have not been clearly elucidated (Hocherl & Dreher 2002).

How It Is Measured or Detected

One of the primary considerations in evaluating AOPs is the relevance and reliability of the methods with which the KEs can be measured. The aim of this section of the KE description is not to provide detailed protocols, but rather to capture, in a sentence or two, per method, the type(s) of measurements that can be employed to evaluate the KE and the relative level of scientific confidence in those measurements. Methods that can be used to detect or measure the biological state represented in the KE should be briefly described and/or cited. These can range from citation of specific validated test guidelines, citation of specific methods published in the peer reviewed literature, or outlines of a general protocol or approach (e.g., a protein may be measured by ELISA).Key considerations regarding scientific confidence in the measurement approach include whether the assay is fit for purpose, whether it provides a direct or indirect measure of the biological state in question, whether it is repeatable and reproducible, and the extent to which it is accepted in the scientific and/or regulatory community. Information can be obtained from the OECD Test Guidelines website and the EURL ECVAM Database Service on Alternative Methods to Animal Experimentation (DB-ALM). ?
  • COX-2 can be measured as abundance of transcript by use of quantitative real-time polymerase chain reaction (q-RT PCR). Transcript abundance of COX-2 has been measured in whole embryos of fishes (Dong et al 2010; Huang et al 2007; Teraoka et al 2008; 2014) and embryonic hepatic and cardiac tissue of birds (Fujisawa et al 2014).
  • COX-2 could be measured by use of ELISA or Western Blot, but commercial kits are not currently available for fishes or birds.

Domain of Applicability

This free text section should be used to elaborate on the scientific basis for the indicated domains of applicability and the WoE calls (if provided). While structured terms may be selected to define the taxonomic, life stage and sex applicability (see structured applicability terms, above) of the KE, the structured terms may not adequately reflect or capture the overall biological applicability domain (particularly with regard to taxa). Likewise, the structured terms do not provide an explanation or rationale for the selection. The free-text section on evidence for taxonomic, life stage, and sex applicability can be used to elaborate on why the specific structured terms were selected, and provide supporting references and background information.  More help

COX-2 Structure and Function:

  • There is a high level of conservation of COX-2, as well as its function, especially across vertebrates (Havird et al 2008; 2015), indicating that numerous vertebrate taxa might be susceptible to up-regulation in COX-2.
  • Typically, teleost fish genomes contain more than one COX-2 gene, likely a result of genome duplication after divergence of teleosts from tetrapods (Ishikawa et al 2007; Havird et al 2015). In zebrafish there are two isoforms, COX-2a and COX-2b (Teraoka et al 2014).
  • In invertebrates, COX is found in most crustaceans, the majority of molluscs, but only in specific lineages within Cnidaria and Annelida. COX genes are not found in Hemichordata, Echinodermata, or Platyhelminthes. Insecta COX genes lack in homology, but might function as COX enzymes based on structural analyses (Havird et al 2015).

Evidence for Perturbation by Stressor


List of the literature that was cited for this KE description. Ideally, the list of references, should conform, to the extent possible, with the OECD Style Guide ( (OECD, 2015). More help

Bacchi, S., Palumbo, P., Sponta, A., & Coppolino, M. F. (2012). Clinical pharmacology of non-steroidal anti-inflammatory drugs: a review. Anti-Inflammatory & Anti-Allergy Agents in Medicinal Chemistry (Formerly Current Medicinal Chemistry-Anti-Inflammatory and Anti-Allergy Agents), 11(1), 52-64.

Botting, R. M., & Botting, J. H. (2011). C14 Non-steroidal anti-inflammatory drugs. In Principles of Immunopharmacology (pp. 573-584). Birkhäuser Basel.

Chien, P.; Lin, C.; Hsiao, L.; Yang, C. (2015). c-SRC/Pyk2/EGFR/PI3K/Akt/CREB-activated pathway contributes to human cardiomyocyte hypertrophy: Role of COX-2 induction. Mol. Cell. Endocrin. 409. 59-72.

Chandrasekharan, N. V., Dai, H., Roos, K. L. T., Evanson, N. K., Tomsik, J., Elton, T. S., & Simmons, D. L. (2002). COX-3, a cyclooxygenase-1 variant inhibited by acetaminophen and other analgesic/antipyretic drugs: cloning, structure, and expression. Proceedings of the National Academy of Sciences,99(21), 13926-13931.

Crofford, L.J. (1997). COX-1 and COX-2 tissue expression: implications and predictions. J. Rheumatol. Suppl. 49, 15-90.

Degner, S.C.; Kemp, M.Q.; Hockings, J.K.; Romagnolo, D.F. (2007). Cyclooxygenase-2 promoter activation by the aromatic hydrocarbon receptor in breast cancer MCF-7 cells: Repressive effects of conjugated linoleic acid. Nutri. Canc. 56 (2), 248-257.

Delgado R.; Newar, M.; Zewail, A.; Kar, B.; Vaughn, W.; Wu, K.; Aleksic, N,; Sivasubramanian, N.; McKay, K.; Mann, D. (2004). Cyclooxygenase-2 inhibitor treatment improves left ventricle function and mortality in a murine model of doxorubicin-induced heart failure. Circulation. 109, 1428-1433.

Dong, W.; Matsumura, F.; Kullman, S.W. (2010). TCDD induced pericardial edema and relative COX-2 expression in medaka (Oryzias latipes) embryos. Toxicol. Sci. 118 (1), 213-223.

Fujisaw, N.; Nakayama, S.M.M.; Ikenaka, Y.; Ishizuka, M. 2014. TCDD-induced chick cardiotoxicity is abolished by a selective cyclooxygenase-2 (COX-2) inhibitor NS398. Arch. Toxicol. 88, 1739-1748.

Gullestad, L.; Aukrust, P. (2005). Review of trials in chronic heart failure showing broad-spectrum anti-inflammatory approaches. Am. J. Cardiol. 95, 17C-23C; discussion 38C-40C.

Havird, J. C., Kocot, K. M., Brannock, P. M., Cannon, J. T., Waits, D. S., Weese, D. A., ... & Halanych, K. M. (2015). Reconstruction of Cyclooxygenase Evolution in Animals Suggests Variable, Lineage-Specific Duplications, and Homologs with Low Sequence Identity. Journal of molecular evolution, 1-16.

Havird, J. C., Miyamoto, M. M., Choe, K. P., & Evans, D. H. (2008). Gene duplications and losses within the cyclooxygenase family of teleosts and other chordates. Molecular biology and evolution, 25(11), 2349-2359.

Hocherl, K.; Dreher, F.; Kurtz, A.; Bucher, M. (2002). Cyclooxygenase-2 inhibition attenuates liposaccaride-induced cardiovascular failure. Hypertension. 40, 947-953.

Huang, C.; Chen, P., Huang, C.; Yu J. (2007). Aristolochic acid induces heart failure in zebrafish embryos that is mediated by inflammation. Toxicol, Sci. 100 (2), 486-494.

Ishikawa, T. O., Griffin, K. J., Banerjee, U., & Herschman, H. R. (2007). The zebrafish genome contains two inducible, functional cyclooxygenase-2 genes.Biochemical and biophysical research communications, 352(1), 181-187.

Jonsson, M.E.; Kubota, A.; Timme-Laragy, A.R.; Woodin, B.; Stegeman, J.J. (2012). Ahr2-dependence of PCB126 effects on the swim bladder in relation to expression of CYP1 and cox-2 genes in developing zebrafish. Toxicol. Appl. Pharmacol. 265 (2), 166-174.

Picot, D.; Loll, P.J.; Garavito, R.M. (1994). The X-ray crystal structure of the membrane protein prostaglandin H2 synthase-1. Nature. 367 (6460), 243-290.

Simmons, D. L., Botting, R. M., & Hla, T. (2004). Cyclooxygenase isozymes: the biology of prostaglandin synthesis and inhibition. Pharmacological reviews,56(3), 387-437.

Smith WL, DeWitt DL, Garavito RM. Cyclooxygenases: structural, cellular, and molecular biology. Annu Rev Biochem2000; 69: 145–182.

Streicher, J.M.; Kamei, K.; Ishikawa, T.; Herschman, H.; Wang, Y. (2010). Compensatory hypertrophy induced by ventricular cardiomyocyte specific COX-2 expression in mice. J. Mol. Cell. Cardiol. 49 (1), 88-94.

Teraoka, H.; Kubota, A.; Kawai, Y.; Hiraga, T. (2008). Prostanoid signaling mediates circulation failure caused by TCDD in developing zebrafish. Interdis. Studies Environ. Chem. Biol. Resp. Chem. Pollut. 61-80.

Teraoka, H.; Okuno, Y.; Nijoukubo, D.; Yamakoshi, A.; Peterson, R.E.; Stegeman, J.J.; Kitazawa, T.; Hiraga, T.; Kubota, A. (2014). Involvement of COX2-thromboxane pathway in TCDD-induced precardiac edema in developing zebrafish. Aquat. Toxicol. 154, 19-25.

Tilley SL, Coffman TM, Koller BH. Mixed messages: modulation of inflammation and immune responses by prostaglandins and thromboxanes. J Clin Invest2001; 108: 15–23.

Vane JR, Mitchell JA, Appleton I, Tomlinson A, Bishop-Bailey D, Croxtall J, Willoughby DA. Inducible isoforms of cyclooxygenase and nitric-oxide synthase in inflammation. Proc Natl Acad Sci U S A1994;91: 2046–2050.

Wong, S.; Fukuchi, M.; Melnyk, P.; Rodger, I.; Giaid, A. (1998). Induction of cyclooxygenase-2 and activation of nuclear factor-kappaB in myocardium of patients with congestive heart failure. Circulation, 98, 100-103.