The lack of the organic cation transporter OCT1 at the plasma membrane of tumor cells precludes a positive response to sorafenib in patients with hepatocellular carcinoma.
BACKGROUND
Sorafenib is the drug of choice in the treatment of advanced hepatocellular carcinoma (HCC). Beneficial effects are limited by mechanisms of chemoresistance, which include downregulation and/or impaired function of plasma membrane transporters accounting for drug uptake. The organic cation transporter 1 (OCT1) plays a major role in sorafenib uptake and decreased expression in HCC has been associated with poorer response.


METHODS
The multicenter retrospective TRANSFER study involved tumor biopsies from 39 patients with advanced HCC and sorafenib therapy for ≥4 wk. Endpoint was the relationship between clinicopathological features and immunohistological result. Immunostaining was performed using specific primary anti-OCT1-head and anti-OCT1-tail antibodies. Tumors were classified according to a simplified staining score as absent, weak, moderate or strong, taking into account the localization of the staining at the plasma membrane as positive or negative.


RESULTS
Results confirmed OCT1 downregulation in half of the cases investigated (10% absent, 38% weak). However, only one third of tumors expressing OCT1 displayed plasma membrane location (15% vs. 36% cytosolic expression). When comparing HCC with and without OCT1 expression, no different sorafenib response was found. When tumors expressing OCT1 at the plasma membrane were considered separately, a marked longer survival was found (Log Rank p<0.001). No association between OCT1 expression at the plasma membrane with tumor stage, previous treatment with TACE or radiological response was seen.In conclusion, these results indicate that the presence of OCT1 at the plasma membrane, rather than its expression levels, is related to better outcome of HCC patients treated with sorafenib.
Division of Hepatology, Department of Medicine II, University Hospital Würzburg, Würzburg, Germany.
Andreas
A
Geier
Experimental Hepatology and Drug Targeting, CIBERehd, IBSAL, University of Salamanca, Salamanca, Spain.
Rocio I R
RI
Macias
Department of Medicine II, University Hospital Freiburg, Freiburg, Germany.
Dominik
D
Bettinger
Division of Hepatology, Department of Medicine II, University Hospital Würzburg, Würzburg, Germany.
Johannes
J
Weiss
Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany.
Heike
H
Bantel
Division of Hepatology, Department of Medicine II, University Hospital Würzburg, Würzburg, Germany.
Daniel
D
Jahn
Experimental Hepatology and Drug Targeting, CIBERehd, IBSAL, University of Salamanca, Salamanca, Spain.
Ruba
R
Al-Abdulla
Experimental Hepatology and Drug Targeting, CIBERehd, IBSAL, University of Salamanca, Salamanca, Spain.
Jose J G
JJ
Marin
D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D002462:Cell Membrane / Q000378:metabolism; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009536:Niacinamide / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000627:therapeutic use; D050811:Octamer Transcription Factor-1 / Q000172:deficiency / Q000378:metabolism*; D010671:Phenylurea Compounds / Q000493:pharmacokinetics / Q000627:therapeutic use*; D047428:Protein Kinase Inhibitors / Q000493:pharmacokinetics / Q000627:therapeutic use*; D012189:Retrospective Studies; D000077157:Sorafenib
D050811:Octamer Transcription Factor-1; C494165:POU2F1 protein, human; D010671:Phenylurea Compounds; D047428:Protein Kinase Inhibitors; D009536:Niacinamide; D000077157:Sorafenib
chemoresistance; hepatocellular carcinoma; organic cation transporter; sorafenib; tyrosine-kinase inhibitor