Biomaterial Database

Acidic cellular microenvironment modifies carcinogen-induced DNA damage and repair. 2017

Q Shi, and L Maas, and C Veith, and F J Van Schooten, and R W Godschalk

Department of Pharmacology and Toxicology, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University, PO Box 616, 6200 MD, Maastricht, The Netherlands.

Chronic inflammation creates an acidic microenvironment, which plays an important role in cancer development. To investigate how low pH changes the cellular response to the carcinogen benzo[a]pyrene (B[a]P), we incubated human pulmonary epithelial cells (A549 and BEAS-2B) with nontoxic doses of B[a]P using culturing media of various pH's (extracellular pH (pHe) of 7.8, 7.0, 6.5, 6.0 and 5.5) for 6, 24 and 48 h. In most incubations (pHe 7.0-6.5), the pH in the medium returned to the physiological pH 7.8 after 48 h, but at the lowest pH (pHe < 6.0), this recovery was incomplete. Similar changes were observed for the intracellular pH (pHi). We observed that acidic conditions delayed B[a]P metabolism and at t = 48 h, and the concentration of unmetabolized extracellular B[a]P and B[a]P-7,8-diol was significantly higher in acidic samples than under normal physiological conditions (pHe 7.8) for both cell lines. Cytochrome P450 (CYP1A1/CYP1B1) expression and its activity (ethoxyresorufin-O-deethylase activity) were repressed at low pHe after 6 and 24 h, but were significantly higher at t = 48 h. In addition, a DNA repair assay showed that the incision activity was ~80% inhibited for 6 h at low pHe and concomitant exposure to B[a]P. However, at t = 48 h, the incision activity recovered to more than 100% of the initial activity observed at neutral pHe. After 48 h, higher B[a]P-DNA adduct levels and γ-H2AX foci were observed at low pH samples than at pHe 7.8. In conclusion, acidic pH delayed the metabolism of B[a]P and inhibited DNA repair, ultimately leading to increased B[a]P-induced DNA damage.

UI	MeSH Term	Description	Entries
D002273	Carcinogens	Substances that increase the risk of NEOPLASMS in humans or animals. Both genotoxic chemicals, which affect DNA directly, and nongenotoxic chemicals, which induce neoplasms by other mechanism, are included.	Carcinogen,Oncogen,Oncogens,Tumor Initiator,Tumor Initiators,Tumor Promoter,Tumor Promoters,Initiator, Tumor,Initiators, Tumor,Promoter, Tumor,Promoters, Tumor
D004249	DNA Damage	Injuries to DNA that introduce deviations from its normal, intact structure and which may, if left unrepaired, result in a MUTATION or a block of DNA REPLICATION. These deviations may be caused by physical or chemical agents and occur by natural or unnatural, introduced circumstances. They include the introduction of illegitimate bases during replication or by deamination or other modification of bases; the loss of a base from the DNA backbone leaving an abasic site; single-strand breaks; double strand breaks; and intrastrand (PYRIMIDINE DIMERS) or interstrand crosslinking. Damage can often be repaired (DNA REPAIR). If the damage is extensive, it can induce APOPTOSIS.	DNA Injury,DNA Lesion,DNA Lesions,Genotoxic Stress,Stress, Genotoxic,Injury, DNA,DNA Injuries
D004260	DNA Repair	The removal of DNA LESIONS and/or restoration of intact DNA strands without BASE PAIR MISMATCHES, intrastrand or interstrand crosslinks, or discontinuities in the DNA sugar-phosphate backbones.	DNA Damage Response
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000072283	A549 Cells	An immortalized cell line derived from human ADENOCARCINOMA, ALVEOLAR basal epithelial cells isolated from the lungs of a male patient in 1972. The cell line is positive for KERATIN, can synthesize LECITHIN, and contains high levels of POLYUNSATURATED FATTY ACIDS in its PLASMA MEMBRANE. It is used as a model for PULMONARY ALVEOLI function and virus infections, as a TRANSFECTION host, and for PRECLINICAL DRUG EVALUATION.	A549 Cell Line,A549 Cell,A549 Cell Lines,Cell Line, A549,Cell Lines, A549,Cell, A549,Cells, A549
D001564	Benzo(a)pyrene	A potent mutagen and carcinogen. It is a public health concern because of its possible effects on industrial workers, as an environmental pollutant, an as a component of tobacco smoke.	3,4-Benzopyrene,3,4-Benzpyrene,3,4 Benzopyrene,3,4 Benzpyrene
D053858	Metabolic Networks and Pathways	Complex sets of enzymatic reactions connected to each other via their product and substrate metabolites.	Metabolic Networks,Metabolic Pathways,Metabolic Network,Metabolic Pathway,Network, Metabolic,Networks, Metabolic,Pathway, Metabolic,Pathways, Metabolic
D060833	Cellular Microenvironment	Local surroundings with which cells interact by processing various chemical and physical signals, and by contributing their own effects to this environment.	Cell Microenvironment,Cell Microenvironments,Cellular Microenvironments,Microenvironment, Cell,Microenvironment, Cellular,Microenvironments, Cell,Microenvironments, Cellular
D018929	Cell Culture Techniques	Methods for maintaining or growing CELLS in vitro.	Cell Culture,Cell Culture Technique,Cell Cultures,Culture Technique, Cell,Culture Techniques, Cell