Abstract
Nitidine chloride (NC), a quaternary ammonium alkaloid, has numerous pharmacological effects, such as anticancer activity. However, it was found that NC also has hepatocellular toxicity. Because organic cation transporters 1 and 3 (OCT1 and OCT3) might mediate the influx of NC into hepatocytes, multidrug and toxin extrusion 1 (MATE1) probably mediates the efflux of NC from hepatocytes, while cytochrome P450 (P450) enzymes might contribute to NC metabolism, the present study was to evaluate the contribution of OCT1, OCT3, MATE1, and P450 enzymes to NC-induced hepatocellular toxicity. Our results showed that the uptake of NC in Madin-Darby canine kidney (MDCK) cells expressing human (h) OCT1 and OCT3 (MDCK-hOCT1 and MDCK-hOCT3) was significantly higher than that in mock cells; the hOCT1- and hOCT3-mediated uptake followed typical Michaelis-Menten kinetics. Meanwhile, NC was also a substrate of hMATE1, although its transport capacity was much lower than that of OCT1 NC-induced cytotoxicity in MDCK-hOCT1 or MDCK-hOCT3 cells was obviously higher than that in mock cells. Quinidine and (+)-tetrahydropalmatine [(+)-THP], OCT1 and OCT3 inhibitors, significantly reduced the uptake of NC in MDCK-hOCT1 cells, MDCK-hOCT3 cells, and rat primary hepatocytes, but only (+)-THP markedly attenuated the NC-induced toxicity. In addition, P450 enzymes, such as CYP3A4, mediated the metabolism of NC, and NC-induced toxicity in MDCK-hOCT1/hCYP3A4 cells was lower than that in MDCK-hOCT1 cells. Our results indicated that NC is a substrate of hOCT1, hOCT3, and CYP3A4; that OCT1 and OCT3 mediate the uptake of NC in hepatocytes and subsequently cause hepatotoxicity; and that NC-induced toxicity could be attenuated by CYP3A4-mediated metabolism.
Footnotes
- Received December 19, 2013.
- Accepted April 25, 2014.
L.L. and M.T. contributed equally to this work.
This work was supported by the National Natural Science Foundation of China [Grant 81373474], Research Fund for the Doctoral Program of Higher Education of China [Grant 20120101110095], and the Program for Zhejiang Leading Team of S&T Innovation [Grant 2011R50014].
- Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics
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