ToxSci Advance Access published online on December 14, 2006
Toxicological Sciences, doi:10.1093/toxsci/kfl184
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In vitro Detection of PLD Potential Based on Gene Expression
UCB SA, Non-Clinical Development, Chemin du Foriest, 1420 Braine-l'Alleud, Belgium
* Corresponding author, Name: Atienzar, Franck Address: UCB SA, Non-Clinical Development, Chemin du Foriest, 1420 Braine-l'Alleud, Belgium, Telephone: +32 (0)2 3863831, Fax: +32 (0)2 3862798, E-mail: franck.atienzar{at}ucb-group.com, Address for reprint requests: UCB SA, Non-Clinical Development, Chemin du Foriest, 1420 Braine-l'Alleud, Belgium
Received September 11, 2006; accepted November 27, 2006
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Abstract |
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Phospholipidosis (PLD) is characterized by an intracellular accumulation of phospholipids in lysosomes and the concurrent development of concentric lamellar bodies. Recently, Sawada et al. (2005) identified 17 genes as potential biomarkers of PLD in HepG2 cells. The present study was undertaken to determine if this set of genes measured by quantitative PCR could be validated in the same cell line. The objective was also to investigate the dose response relationship to further validate the assay and to select the concentrations to use for screening activities. In a first experiment (one concentration tested), out of the 17 genes, the best gene biomarkers of PLD (i.e. 11 genes) were selected for practical screening reasons. Based on these genes, 91.6 % (i.e. 11 out of 12) of the compounds known to induce PLD were identified as positive and all the negative compounds (i.e. 5 out of 5) were also confirmed. When the data obtained in the first experiment were compared to Sawada's data, the coefficient of correlation calculated was slightly higher than 75%. In the second experiment [26 compounds (all 17 compounds from the first experiment plus 9 other compounds) tested at a minimum of 3 concentrations], 93.3 % (14/15) of the compounds known to induce PLD were identified as such and all the negative controls (6 compounds) were also confirmed. Three compounds likely to induce PLD were identified as positive in our assay. Finally, two compounds for which no data are available were also tested. When both experiments 1 and 2 were compared, the coefficient of correlation for 16 compounds tested at the same concentrations reached 87.7 %. In conclusion, the present study further confirms the utility of gene expression in HepG2 cells to identify a potential to induce PLD. Finally, based on the data presented, researchers are encouraged to use a range of minimum 3 concentrations (e.g. 12.5, 25 and 50 µM) to screen for PLD in the human HepG2 cell line.
Key Words: Phospholipidosis; HepG2 cells; gene expression; biomarkers; screening activities.