Abstract
Human tumors grown as xenografts in immunodeficient nude mice are widely used to investigate the pharmacological activities of anticancer drugs. Drug-metabolizing enzymes and transporters are expressed in tumor cell lines and changes in drug metabolism and pharmacokinetics (DMPK)-related gene expression after inoculation of the tumor cell may affect the pharmacological activity of the drug under consideration. The aims of the current study were to characterize DMPK-related gene expression profiles and responses to typical cytochrome P450 inducers in monolayer carcinoma cells grown in tissue culture versus those inoculated into a xenograft model. We used the human hepatocellular carcinoma cell line PLC/PRF/5 for this study and comprehensively assessed changes in DMPK-related gene expression by reverse transcription-polymerase chain reaction quantitation. CYP3A4 and UDP-glucuronosyltransferase 1A protein amounts were also analyzed by immunoprecipitation followed by immunoblotting. We found that the expression of many DMPK-related genes was elevated in the inoculated tumor compared with the monolayer carcinoma cells, indicating changes in their gene regulation pathways, presumably due to modulation of the nuclear receptor family of transcription factors. In addition, monolayer carcinoma versus inoculated tumor cells showed different responses to rifampicin, but similar responses to dexamethasone or 3-methylcholanthrene. These results suggest that inoculation of tumor cells results in the activation of drug metabolism and transport function, leading to changes in the responses to pregnane X receptor ligands and consequent discrepancies in the pharmacological activities between in vitro monolayer carcinoma cells and in vivo xenograft models.
Footnotes
This work was supported by Eisai Co., Ltd.
Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
doi:10.1124/dmd.109.030668.
↵ The online version of this article (available at http://dmd.aspetjournals.org) contains supplemental material.
-
- P450
- cytochrome P450
- DMPK
- drug metabolism and pharmacokinetics
- PCR
- polymerase chain reaction
- MC
- 3-methylcholanthrene
- Dex
- dexamethasone
- Rif
- rifampicin
- DMSO
- dimethyl sulfoxide
- SLCO
- solute carrier organic anion transporter
- ABC
- ATP-binding cassette
- SLC
- solute carrier
- AhR
- arylhydrocarbon receptor
- ARNT
- AhR nuclear translocator
- HNF
- hepatic nuclear factor
- NR
- nuclear receptor
- PPAR
- peroxisome proliferator-activated receptor
- IPA
- Ingenuity Pathway Analysis
- UGT
- UDP glucuronosyltransferase
- PVDF
- polyvinylidene difluoride
- ALB
- albumin
- AFP
- α-fetoprotein
- FXR
- farnesoid X receptor
- PXR
- pregnane X receptor
- CAR
- constitutive androstane receptor
- LPS
- lipopolysaccharide
- IL
- interleukin
- SN-38
- 7-ethyl-10-hydroxycampothecin
- GW4064
- 3-[2-[2-chloro-4-[[3-(2,6-dichlorophenyl)-5-(1-methylethyl)-4-isoxazolyl]methoxy]phenyl]ethenyl]benzoic acid
- Ct
- cycle threshold.
- Received October 7, 2009.
- Accepted December 7, 2009.
- Copyright © 2010 by The American Society for Pharmacology and Experimental Therapeutics
DMD articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|