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J Hepatol. 2004 Feb;40(2):212-8.

The human organic anion transporting polypeptide 8 (SLCO1B3) gene is transcriptionally repressed by hepatocyte nuclear factor 3beta in hepatocellular carcinoma.

Author information

1
Laboratory of Molecular Gastroenterology and Hepatology, Division of Gastroenterology and Hepatology, University Hospital, CH-8091 Zurich, Switzerland.

Abstract

BACKGROUND/AIMS:

The organic anion transporting polypeptides (OATPs) mediate the uptake of numerous amphipathic compounds into hepatocytes. Our aim was to study the expression and regulation of OATP8 (OATP1B3, SLC21A8/SLCO1B3) and OATP-C (OATP1B1, SLC21A6/SLCO1B1) in hepatocellular carcinomas (HCC).

METHODS:

RNA and protein levels in 13 paired HCC and adjacent non-tumor liver samples were quantified by real-time polymerase chain reaction or Western blot, respectively. The OATP8 and OATP-C gene promoters were characterized by luciferase reporter assays and electrophoretic mobility shift assays (EMSA).

RESULTS:

The expression of OATP8 was decreased in 60% of HCC compared to surrounding non-tumor liver tissue, on both the mRNA and protein levels. Expression of the liver-enriched transcription factor hepatocyte nuclear factor 3beta (HNF3beta) was increased in 70% of HCC and correlated inversely with OATP8 mRNA (r=-0.75, P<0.05) and protein. In contrast to OATP8, expression of OATP-C was not significantly decreased in HCC. In transfected Huh7 cells, OATP8 promoter activity was inhibited by 70% when HNF3beta was cotransfected. An HNF3beta binding site was located at nt -39/-23 by EMSA. The OATP-C promoter was not inhibited by HNF3beta.

CONCLUSIONS:

HNF3beta represses transcription of the OATP8 but not the OATP-C gene, providing a mechanism for reduced expression of OATP8 in HCC.

PMID:
14739090
[Indexed for MEDLINE]

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