The Ames test is a widely employed method that uses bacteria to test whether a given chemical can cause mutations in the DNA of the test organism. More formally, it is a biological assay to assess the mutagenic potential of chemical compounds. A positive test indicates that the chemical is mutagenic and therefore may act as a carcinogen, because cancer is often linked to mutation. The test serves as a quick and convenient assay to estimate the carcinogenic potential of a compound because standard carcinogen assays on mice and rats are time-consuming and expensive. However, false-positives and false-negatives are known.
A carcinogen is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruses and bacteria. Most carcinogens act by creating mutations in DNA that disrupt a cell's normal processes for regulating growth, leading to uncontrolled cellular proliferation. This occurs when the cell's DNA repair processes fail to identify DNA damage allowing the defect to be passed down to daughter cells. The damage accumulates over time. This is typically a multi-step process during which the regulatory mechanisms within the cell are gradually dismantled allowing for unchecked cellular division.
In genetics, a mutagen is a physical or chemical agent that permanently changes genetic material, usually DNA, in an organism and thus increases the frequency of mutations above the natural background level. As many mutations can cause cancer in animals, such mutagens can therefore be carcinogens, although not all necessarily are. All mutagens have characteristic mutational signatures with some chemicals becoming mutagenic through cellular processes.
p53, also known as Tumor protein P53, cellular tumor antigen p53, or transformation-related protein 53 (TRP53) is a regulatory protein that is often mutated in human cancers. The p53 proteins are crucial in vertebrates, where they prevent cancer formation. As such, p53 has been described as "the guardian of the genome" because of its role in conserving stability by preventing genome mutation. Hence TP53 is classified as a tumor suppressor gene.
Genotoxicity is the property of chemical agents that damage the genetic information within a cell causing mutations, which may lead to cancer. While genotoxicity is often confused with mutagenicity, all mutagens are genotoxic, but some genotoxic substances are not mutagenic. The alteration can have direct or indirect effects on the DNA: the induction of mutations, mistimed event activation, and direct DNA damage leading to mutations. The permanent, heritable changes can affect either somatic cells of the organism or germ cells to be passed on to future generations. Cells prevent expression of the genotoxic mutation by either DNA repair or apoptosis; however, the damage may not always be fixed leading to mutagenesis.
A polycyclic aromatic hydrocarbon (PAH) is a class of organic compounds that is composed of multiple aromatic rings. The simplest representative is naphthalene, having two aromatic rings, and the three-ring compounds anthracene and phenanthrene. PAHs are uncharged, non-polar and planar. Many are colorless. Many of them are found in coal and in oil deposits, and are also produced by the incomplete combustion of organic matter—for example, in engines and incinerators or when biomass burns in forest fires.
Benzo[a]pyrene (BaP or B[a]P) is a polycyclic aromatic hydrocarbon and the result of incomplete combustion of organic matter at temperatures between 300 °C (572 °F) and 600 °C (1,112 °F). The ubiquitous compound can be found in coal tar, tobacco smoke and many foods, especially grilled meats. The substance with the formula C20H12 is one of the benzopyrenes, formed by a benzene ring fused to pyrene. Its diol epoxide metabolites, more commonly known as BPDE, react with and bind to DNA, resulting in mutations and eventually cancer. It is listed as a Group 1 carcinogen by the IARC. In the 18th century a scrotal cancer of chimney sweepers, the chimney sweeps' carcinoma, was already known to be connected to soot.
Methylcholanthrene is a highly carcinogenic polycyclic aromatic hydrocarbon produced by burning organic compounds at very high temperatures. Methylcholanthrene is also known as 3-methylcholanthrene, 20-methylcholanthrene or the IUPAC name 3-methyl-1,2-dyhydrobenzo[j]aceanthrylene. The short notation often used is 3-MC or MCA. This compound forms pale yellow solid crystals when crystallized from benzene and ether. It has a melting point around 180 °C and its boiling point is around 280 °C at a pressure of 80 mmHg. Methylcholanthrene is used in laboratory studies of chemical carcinogenesis. It is an alkylated derivative of benz[a]anthracene and has a similar UV spectrum. The most common isomer is 3-methylcholanthrene, although the methyl group can occur in other places.
DAPI, or 4′,6-diamidino-2-phenylindole, is a fluorescent stain that binds strongly to adenine–thymine-rich regions in DNA. It is used extensively in fluorescence microscopy. As DAPI can pass through an intact cell membrane, it can be used to stain both live and fixed cells, though it passes through the membrane less efficiently in live cells and therefore provides a marker for membrane viability.
Cytochrome P450, family 1, subfamily A, polypeptide 1 is a protein that in humans is encoded by the CYP1A1 gene. The protein is a member of the cytochrome P450 superfamily of enzymes.
N-Nitrosodiethylamine (NDEA) is an organic compound with the formula Et2NNO (Et = C2H5). A member of the nitrosamines, it is a light-sensitive, volatile, clear yellow oil that is soluble in water, lipids, and other organic solvents. It has an amine or aromatic odor. It is used as gasoline and lubricant additive, antioxidant, and stabilizer for industry materials. When heated to decomposition, N-nitrosodiethylamine emits toxic fumes of nitrogen oxides. N-Nitrosodiethylamine affects DNA integrity, probably by alkylation, and is used in experimental research to induce liver tumorigenesis. It is carcinogenic and mutagenic. NDEA has also been found to perturb amino acid biosynthesis including arginine, as well as DNA damage repair and mitochondrial genome maintenance in yeast.
A benzopyrene is an organic compound with the formula C20H12. Structurally speaking, the colorless isomers of benzopyrene are pentacyclic hydrocarbons and are fusion products of pyrene and a phenylene group. Two isomeric species of benzopyrene are benzo[a]pyrene and the less common benzo[e]pyrene. They belong to the chemical class of polycyclic aromatic hydrocarbons.
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a polychlorinated dibenzo-p-dioxin (sometimes shortened, though inaccurately, to simply 'dioxin') with the chemical formula C12H4Cl4O2. Pure TCDD is a colorless solid with no distinguishable odor at room temperature. It is usually formed as an unwanted product in burning processes of organic materials or as a side product in organic synthesis.
Benzo[j]fluoranthene (BjF) is an organic compound with the chemical formula C20H12. Classified as a polycyclic aromatic hydrocarbon (PAH), it is a colourless solid that is poorly soluble in most solvents. Impure samples can appear off white. Closely related isomeric compounds include benzo[a]fluoranthene (BaF), bendo[b]fluoranthene (BbF), benzo[e]fluoranthene (BeF), and benzo[k]fluoranthene (BkF). BjF is present in fossil fuels and is released during incomplete combustion of organic matter. It has been traced in the smoke of cigarettes, exhaust from gasoline engines, emissions from the combustion of various types of coal and emissions from oil heating, as well as an impurity in some oils such as soybean oil.
Antimutagens are the agents that interfere with the mutagenicity of a substance. The interference can be in the form of prevention of the transformation of a promutagenic compound into actual active mutagen, inactivation, or otherwise the prevention of Mutagen-DNA reaction.
Eliezer Huberman is an American scietnist who is the founder, scientific director, and CEO of Novadrug LLC, a Chicago-based pharmaceutical firm. He is currently an adjunct professor in the College of Pharmacy at the University of Illinois.
Parthanatos is a form of programmed cell death that is distinct from other cell death processes such as necrosis and apoptosis. While necrosis is caused by acute cell injury resulting in traumatic cell death and apoptosis is a highly controlled process signalled by apoptotic intracellular signals, parthanatos is caused by the accumulation of Poly(ADP ribose) (PAR) and the nuclear translocation of apoptosis-inducing factor (AIF) from mitochondria. Parthanatos is also known as PARP-1 dependent cell death. PARP-1 mediates parthanatos when it is over-activated in response to extreme genomic stress and synthesizes PAR which causes nuclear translocation of AIF. Parthanatos is involved in diseases that afflict hundreds of millions of people worldwide. Well known diseases involving parthanatos include Parkinson's disease, stroke, heart attack, and diabetes. It also has potential use as a treatment for ameliorating disease and various medical conditions such as diabetes and obesity.
Benzo[c]fluorene is a polycyclic aromatic hydrocarbon (PAH) with mutagenic activity. It is a component of coal tar, cigarette smoke and smog and thought to be a major contributor to its carcinogenic properties. The mutagenicity of benzo[c]fluorene is mainly attributed to formation of metabolites that are reactive and capable of forming DNA adducts. According to the KEGG it is a group 3 carcinogen. Other names for benzo[c]fluorene are 7H-benzo[c]fluorene, 3,4-benzofluorene, and NSC 89264.
Bernd Kaina, born on 7 January 1950 in Drewitz, is a German biologist and toxicologist. His research is devoted to DNA damage and repair, DNA damage response, genotoxic signaling and cell death induced by carcinogenic DNA damaging insults.
(+)-Benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide is an organic compound with molecular formula C20H14O3. It is a metabolite and derivative of benzo[a]pyrene (found in tobacco smoke) as a result of oxidation to include hydroxyl and epoxide functionalities. (+)-Benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide binds to the N2 atom of a guanine nucleobase in DNA, distorting the double helix structure by intercalation of the pyrene moiety between base pairs through π-stacking. The carcinogenic properties of tobacco smoking are attributed in part to this compound binding and inactivating the tumor suppression ability of certain genes, leading to genetic mutations and potentially to cancer.
