Induction and Regulation of Xenobiotic-Metabolizing Cytochrome P450s in the Human A549 Lung Adenocarcinoma Cell Line

Hukkanen, Janne; Lassila, Arja; Päivärinta, Katja; Valanne, Susanna; Sarpo, Sari; Hakkola, Jukka; Pelkonen, Olavi; Raunio, Hannu

doi:10.1165/ajrcmb.22.3.3845

Cited by 144 publications

(82 citation statements)

References 56 publications

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“…This view was supported by the inability of 2,4,3′,5′-tetramethylstilbene, a P4501A1/1B1 inhibitor, to block anti-B [a]PDE adduct formation (unpublished data Gelhaus and Blair). Other P450's that are expressed in human lung cells include, 2A6, 2A13, 2B6, 2E1, 2C18, 2F1, 2J2, 2S1, 3A5 and 4B1 (56)(57)(58)(59)(60).…”

Section: Discussionmentioning

confidence: 99%

Metabolism of Benzo[a]pyrene in Human Bronchoalveolar H358 Cells Using Liquid Chromatography–Mass Spectrometry

Jiang

Gelhaus

Mangal

et al. 2007

Chem. Res. Toxicol.

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Benzo [a]pyrene (B[a]P), a representative polycyclic aromatic hydrocarbon (PAH), is metabolically activated by three enzymatic pathways; by peroxidases (e.g. cytochrome P450-peroxidase) to yield radical cations; by P4501A1/1B1 monoxygenation plus epoxide hydrolase to yield diol-epoxides; and by P4501A1/1B1 monoxygenation, epoxide hydrolase plus aldo-keto reductases (AKRs) to yield o-quinones. In humans, a major exposure site for environmental and tobacco smoke PAH is the lung, however, the profile of B[a]P metabolites formed at this site has not been well characterized. In this study, human bronchoalveolar H358 cells were exposed to B[a]P, and metabolites generated by peroxidase (B[a]P-1,6-and B[a]P-3,6-diones), from cytochrome P4501A1/1B1 monooxygenation (3-hydroxyl-B[a]P, B[a]P-7,8-and 9,10-trans-dihydrodiols, and B[a]P -r-7,t-8,t-9,c-10-tetrahydrotetrol (B[a]P -tetrol-1)), and from AKRs (B[a]P-7,8-dione) were detected and quantified by RP-HPLC-with in line photo-diode array and radiometric detection, and identified by LC-MS. Progress curves showed a lag-phase in the formation of 3-hydroxy-B[a]P, B[a]P-7,8-transdihydrodiol, B[a]P-tetraol-1 and B[a]P-7,8-dione over 24 h. Northern blot analysis showed that B [a]P induced P4501B1 and AKR1C isoforms in H358 cells in a time-dependent manner providing an explanation for the lag-phase. Pretreatment of H358 cells with 10 nM 2,3,7,8-tetrachlorodibenzop-dioxin, (TCDD) eliminated this lag-phase, but did not alter the levels of the individual metabolites observed, suggesting that both B[a]P and TCDD induction ultimately yield the same B[a]P-metabolic profile. The one exception was B[a]P-3,6-dione which was formed without a lag-phase in the absence and presence of TCDD, suggesting that the peroxidase responsible for its formation was neither P4501A1 nor 1B1. Candidate peroxidases that remain include PGH synthases and uninduced P450 isoforms. This study shows that the P4501A1/1B1 and AKR pathways are inducible in human lung cells and that the peroxidase pathway was not. It also provides evidence that each of the pathways of PAH-activation yield their distinctive metabolites in H358 human lung cells and that each pathway may contribute to the carcinogenic process.

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Section: Discussionmentioning

confidence: 99%

Metabolism of Benzo[a]pyrene in Human Bronchoalveolar H358 Cells Using Liquid Chromatography–Mass Spectrometry

Jiang

Gelhaus

Mangal

et al. 2007

Chem. Res. Toxicol.

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“…In addition, there may be limited application for this strategy to succeed in treating lung cancer due to difficulties in administering and targeting siRNA. A549 is found to express telomerase and several CYP forms including CYP1A1 and possesses metabolic activities toward xenobiotics [21][22]. Furthermore, A549 cell line is known to retain several characteristics of human lung epithelial cell CYP expression, which makes it a valuable model for mechanistic studies on the induction of the pulmonary CYP system [21][22][23].…”

Section: Discussionmentioning

confidence: 99%

Can CYP1A1 siRNA be an effective treatment for lung cancer?

Mohammed

Shervington

2008

Cellular and Molecular Biology Letters

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Previously, we identified a novel correlation between the upregulated expression of telomerase (hTERT) and cytochrome P450 1A1 (CYP1A1) in A549 human lung cancer cell line. The expression correlation was confirmed by silencing CYP1A1 expression using siRNA technology and observing a silencing of hTERT transcription. Furthermore, silencing CYP1A1 and subsequently downregulating hTERT resulted in the reduction of cancer cell viability by more than 40%, which appeared as early as 24 hours after the treatment. The concomitant downregulation of CYP1A1 and hTERT resulted in rapid cell death. This finding can be further exploited to develop new molecular targets for the treatment of lung cancer.

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“…1,15 The lung is a primary site of exposure for inhaled toxins along with carcinogens that can ultimately yield lung carcinomas. 16 CYP1A1 is strongly induced by cigarette smoking. 15 Many compounds, including some found in cigarette smoke, are not hazardous until metabolized by CYP1A1.…”

Section: Nih Public Accessmentioning

confidence: 99%

“…15 Many compounds, including some found in cigarette smoke, are not hazardous until metabolized by CYP1A1. 16,17 Accordingly, CYP1A1 levels could be correlated with human disease.…”

Section: Nih Public Accessmentioning

confidence: 99%

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A highly sensitive fluorogenic probe for cytochrome P450 activity in live cells

Yatzeck

Lavis

Chao

et al. 2008

Bioorganic & Medicinal Chemistry Letters

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A derivative of rhodamine 110 has been designed and assessed as a probe for cytochrome P450 activity. This probe is the first to utilize a "trimethyl lock" that is triggered by cleavage of an ether bond. In vitro, fluorescence was manifested by the CYP1A1 isozyme with k cat /K M = 8.8 × 10 3 M −1 s −1 and K M = 0.09 µM. In cellulo, the probe revealed the induction of cytochrome P450 activity by the carcinogen 2,3,7,8-tetrachlorodibenzo-p-dioxin, and its repression by the chemoprotectant resveratrol. KeywordsCarcinogen; CYP1A1 Isozyme; Cytochrome P450; Dioxin; Fluorogenic Substrate; Prodrug; Resveratrol; Rhodamine 110; Trimethyl LockThe cytochrome P450 (P450) family of enzymes is responsible for the oxidative metabolism of a wide variety of compounds, including chemotherapeutic agents and environmental toxins. 1,2 The catalytic activity of P450 enzymes controls the rate of xenobiotic metabolism, and can produce undesirable byproducts. 3 Originally, this activity had been assessed by using HPLC or other methods to separate and quantify metabolites. In the 1970's, 7-ethoxycoumarin and 7-ethoxyresorufin were introduced as the first fluorogenic substrates for assays of P450 activity. 4 Although these and other fluorogenic substrates have been used to assay P450 activity in vitro and enable assays in cellulo ,5,6 they suffer from background fluorescence. 7 For example, alkoxycoumarins exhibit moderate fluorescence and are used frequently as fluorophores in peptidase substrates based on Forster resonance energy transfer (FRET). 8 In addition, both 7-ethoxyresorufin and resorufin fluoresce brightly. 6 This problem arises because O-alkylation of the hydroxyl group of fluorophores such as coumarin and resorufin does little to deter the oxygen electrons from participating in the resonance that gives rise to fluorescence.Here, we report on a superior small-molecule probe for assessing P450 activity. Our probe employs the trimethyl lock. 9-11 The trimethyl lock is an o-hydroxycinnamic acid derivative in which severe crowding of three methyl groups induces rapid lactonization to form a hydrocoumarin. 12 In this strategy, the phenolic oxygen of the o-hydroxycinnamic acid is modified to create a functional group that is a substrate for a designated enzyme, and the carboxyl group is condensed with the amino group of a dye. Unmasking of the phenolic oxygen leads to rapid lactonization with concomitant release of the dye. An important attribute of this The human genome contains 27 genes encoding P450 isozymes, along with many pseudogenes. 13 Of these isozymes, cytochrome P450 1A1 (CYP1A1) is known to be especially important in the metabolism of xenobiotics. 14 Unlike most P450 isoforms, which are found primarily in the liver, CYP1A1 is present mainly in the lungs, where it plays an important role in the metabolic activation of chemical carcinogens. 1,15 The lung is a primary site of exposure for inhaled toxins along with carcinogens that can ultimately yield lung carcinomas. 16 CYP1A1 is strongly induced by cigarette smo...

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Induction and Regulation of Xenobiotic-Metabolizing Cytochrome P450s in the Human A549 Lung Adenocarcinoma Cell Line

Cited by 144 publications

References 56 publications

Metabolism of Benzo[a]pyrene in Human Bronchoalveolar H358 Cells Using Liquid Chromatography–Mass Spectrometry

Metabolism of Benzo[a]pyrene in Human Bronchoalveolar H358 Cells Using Liquid Chromatography–Mass Spectrometry

Can CYP1A1 siRNA be an effective treatment for lung cancer?

A highly sensitive fluorogenic probe for cytochrome P450 activity in live cells

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