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Oncol Lett. 2017 Oct;14(4):4158-4166. doi: 10.3892/ol.2017.6724. Epub 2017 Aug 4.

Specific expression of proton-coupled oligopeptide transporter 1 in primary hepatocarcinoma-a novel strategy for tumor-targeted therapy.

Author information

1
Department of Gastroenterology, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China.
2
Department of Gastroenterology, Tianjin Nankai Hospital, Tianjin 300100, P.R. China.
3
Central Laboratory, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China.
4
Clinical Laboratory, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China.
5
Department of Immunology, School of Basic Medical Science, Tianjin Medical University, Tianjin 300070, P.R. China.

Abstract

Proton-coupled oligopeptide transporter 1 (PEPT1) is a membrane protein which expressed predominantly in intestine and recognized as the target of dietary nutrients (di/tripeptide) or peptidomimetic drug for delivery. The information on the existence of PEPT1 in carcinomas were limited. Our study aimed to investigate the expression profile and transport activity of PEPT1 both in human hepatocarcinoma tissues and cell lines. Western blotting and an immunofluorescence assay revealed the high level of PEPT1 protein expression in hepatocarcinoma Bel-7402, SMMC-7721, HepG2, HEP3B, SK-HEP-1 cell lines. Quantitative real time PCR showed the mRNA expression of PEPT1 in Bel-7402, SMMC-7721, HepG2, HEP3B, SK-HEP-1 cells. High level PEPT1 expression in hepatocarcinoma patient samples were observed by Immunohistology and showed a significant correlation between protein level and pathological grade. Functional activities were also studied using D-Ala-Lys-AMCA (a substrate of peptide transporter) in above five hepatocarcinoma cell lines. The uptake tests performed by fluorescent microscopy suggested that PEPT1 can transport both D-Ala-Lys-AMCA into the hepatocarcinoma cells and the uptake can be competitively inhibited by three PEPT1 substrates (Gly-sar, Gly-gln and Glyglygly). In conclusion, our findings provided the novel information on the expression and function of PEPT1 in human hepatocarcinoma and expanded the potential values for tumor specific drug delivery.

KEYWORDS:

expression; primary hepatocarcinoma; proton-coupled oligopeptide transporter 1; tumor-targeted therapy

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