Differential transport of platinum compounds by the human organic cation transporter hOCT2 (hSLC22A2).
BACKGROUND
Solute carriers (SLCs), in particular organic cation transporters (OCTs), have been implicated in the cellular uptake of platinum-containing anticancer compounds. The activity of these carriers may determine the pharmacokinetics and the severity of side effects, including neuro- and nephrotoxicity of platinum-based chemotherapy. As decreased drug accumulation is a key mechanism of platinum resistance, SLCs may also contribute to the development of resistance. Here, we define the role of hSLC22A2 (OCT2) in the cellular uptake of platinum compounds.


METHODS
Human embryonic kidney (HEK) 293 cells stably expressing the hSLC22A2 gene (HEK293/hSLC22A2) were used in platinum accumulation studies. Following a 2 h exposure to various platinum compounds (100 microM), intracellular platinum levels were determined by flameless atomic absorption spectrometry.


RESULTS
HEK293/hSLC22A2 cells, compared with HEK293/Neo control cells, displayed significant increases in oxaliplatin (28.6-fold), Pt[DACH]Cl(2) (20.6-fold), ormaplatin (8.1-fold), tetraplatin (4.5-fold), transplatin (3.7-fold) and cisplatin (1.3-fold), but not carboplatin. SLC22A2-mediated transport could be inhibited by 1-methyl-4-phenylpyridinium. Furthermore, hSLC22A2-mediated oxaliplatin and cisplatin accumulation was time- and concentration-dependent, but non-saturable. Expression of hSLC22A2 in HEK293 cells resulted in enhanced sensitivity to oxaliplatin (12-fold) and cisplatin (1.8-fold). Although, hSLC22A2 mRNA expression was frequently found in ovarian cancer cell lines, its expression in clinical ovarian cancer specimens (n= 80) was low and did not correlate with the treatment outcome of platinum-based regimens.


CONCLUSIONS
The hSLC22A2 drug transporter is a critical determinant in the uptake and cytotoxicity of various platinum compounds, particularly oxaliplatin.
Burger
H
H
Department of Medical Oncology, Erasmus Medical Center Rotterdam - Josephine Nefkens Institute and Daniel den Hoed Cancer Center, Rotterdam, The Netherlands. h.burger@erasmusmc.nl
Zoumaro-Djayoon
A
A
Boersma
A W M
AW
Helleman
J
J
Berns
E M J J
EM
Mathijssen
R H J
RH
Loos
W J
WJ
Wiemer
E A C
EA
D000970:Antineoplastic Agents / Q000378:metabolism* / Q000494:pharmacology / Q000627:therapeutic use; D001692:Biological Transport; D016190:Carboplatin / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D007700:Kinetics; D027701:Organic Cation Transport Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000075102:Organic Cation Transporter 2; D009944:Organoplatinum Compounds / Q000378:metabolism* / Q000494:pharmacology / Q000627:therapeutic use; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D000077150:Oxaliplatin; D017671:Platinum Compounds / Q000378:metabolism* / Q000494:pharmacology / Q000627:therapeutic use; D012333:RNA, Messenger / Q000378:metabolism; D013054:Spectrophotometry, Atomic; D014162:Transfection; D016896:Treatment Outcome
D000970:Antineoplastic Agents; D027701:Organic Cation Transport Proteins; D000075102:Organic Cation Transporter 2; D009944:Organoplatinum Compounds; D017671:Platinum Compounds; D012333:RNA, Messenger; C491013:SLC22A2 protein, human; D000077150:Oxaliplatin; D016190:Carboplatin; D002945:Cisplatin; C049777:ormaplatin