UDP-glucuronosyltransferase 1A compromises intracellular accumulation and anti-cancer effect of tanshinone IIA in human colon cancer cells.
OBJECTIVE
NAD(P)H: quinone oxidoreductase 1 (NQO1) mediated quinone reduction and subsequent UDP-glucuronosyltransferases (UGTs) catalyzed glucuronidation is the dominant metabolic pathway of tanshinone IIA (TSA), a promising anti-cancer agent. UGTs are positively expressed in various tumor tissues and play an important role in the metabolic elimination of TSA. This study aims to explore the role of UGT1A in determining the intracellular accumulation and the resultant apoptotic effect of TSA.


METHODS
We examined TSA intracellular accumulation and glucuronidation in HT29 (UGT1A positive) and HCT116 (UGT1A negative) human colon cancer cell lines. We also examined TSA-mediated reactive oxygen species (ROS) production, cytotoxicity and apoptotic effect in HT29 and HCT116 cells to investigate whether UGT1A levels are directly associated with TSA anti-cancer effect. UGT1A siRNA or propofol, a UGT1A9 competitive inhibitor, was used to inhibit UGT1A expression or UGT1A9 activity.


RESULTS
Multiple UGT1A isoforms are positively expressed in HT29 but not in HCT116 cells. Cellular S9 fractions prepared from HT29 cells exhibit strong glucuronidation activity towards TSA, which can be inhibited by propofol or UGT1A siRNA interference. TSA intracellular accumulation in HT29 cells is much lower than that in HCT116 cells, which correlates with high expression levels of UGT1A in HT29 cells. Consistently, TSA induces less intracellular ROS, cytotoxicity, and apoptotic effect in HT29 cells than those in HCT116 cells. Pretreatment of HT29 cells with UGT1A siRNA or propofol can decrease TSA glucuronidation and simultaneously improve its intracellular accumulation, as well as enhance TSA anti-cancer effect.


CONCLUSIONS
UGT1A can compromise TSA cytotoxicity via reducing its intracellular exposure and switching the NQO1-triggered redox cycle to metabolic elimination. Our study may shed a light in understanding the cellular pharmacokinetic and molecular mechanism by which UGTs determine the chemotherapy effects of drugs that are UGTs' substrates.
Key Lab of Drug Metabolism and Pharmacokinetics, State Key Lab of Natural Medicines, China Pharmaceutical University, Nanjing, China.
Miao
M
Liu
Qiong
Q
Wang
Fang
F
Liu
Xuefang
X
Cheng
Xiaolan
X
Wu
Hong
H
Wang
Mengqiu
M
Wu
Ying
Y
Ma
Guangji
G
Wang
Haiping
H
Hao
D045784:Abietanes / Q000493:pharmacokinetics* / Q000494:pharmacology; D018686:Anesthetics, Intravenous / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000493:pharmacokinetics* / Q000494:pharmacology; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D014453:Glucuronosyltransferase / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D006801:Humans; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000096:biosynthesis; D015742:Propofol / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D000090264:UDP-Glucuronosyltransferase 1A9; D000099148:UGT1A1 Enzyme
D045784:Abietanes; D018686:Anesthetics, Intravenous; D000972:Antineoplastic Agents, Phytogenic; D004791:Enzyme Inhibitors; D014453:Glucuronosyltransferase; D016660:NAD(P)H Dehydrogenase (Quinone); D015742:Propofol; D017382:Reactive Oxygen Species; D000090264:UDP-Glucuronosyltransferase 1A9; D000099148:UGT1A1 Enzyme; C000715591:UGT1A9 protein, human; C021751:tanshinone; C447479:NQO1 protein, human