The impact of L-type amino acid transporter 1 (LAT1) in human hepatocellular carcinoma
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RESEARCH ARTICLE
The impact of L-type amino acid transporter 1 (LAT1) in human hepatocellular carcinoma Juan Li & Juan Qiang & Shu-Fen Chen & Xin Wang & Jing Fu & Yao Chen
Received: 28 April 2013 / Accepted: 10 May 2013 # International Society of Oncology and BioMarkers (ISOBM) 2013
Abstract Upregulation of L-type amino acid transporter 1 (LAT1) has been reported to be associated with a poor prognosis in a variety of malignant tumors. However, the impact of LAT1 in hepatocellular carcinoma (HCC) remains unclear. The objective of this study was to investigate whether the expression of LAT1 in HCC was associated with established clinicopathological features. Quantitative reverse transcription polymerase chain reaction was used to detect LAT1 mRNA expression in 23 pairs of freshfrozen HCC tissues and corresponding noncancerous tissues. Results showed that LAT1 mRNA expression level in HCC tissues was significantly higher than that in corresponding noncancerous tissues. To investigate the association between LAT1 protein expression and clinicopathological characteristics of HCC, immunohistochemistry was performed in 148 archived paraffin-embedded HCC samples. High LAT1 expression in HCC was associated significantly with tumor size (P=0.032), histological differentiation (P=0.003), and tumor stage (P=0.01). Kaplan–Meier curves demonstrated that patients with a high expression of LAT1 have a significantly increased risk of shortened survival time. Moreover, stepwise Cox regression showed that LAT1 expression may be an independent prognostic factor. Collectively, our study demonstrated that LAT1was overexpressed in HCC and could be served as a potential prognostic marker. J. Li (*) : J. Qiang : S.400 123 Tumor stage I–II 52 III–IV 96
We performed immunohistochemistry (IHC) assays to evaluate the expression of LAT1 in HCC according to standard protocols [21, 22]. Specimens were fixed in 10 % formalin for 12 h, and then paraffin-embedded. The paraffin-embedded tissues were stored at room temperature. All these collection methods were standardized. The paraffin sections were deparaffinized by sequential washing with xylene, graded ethanol, and phosphatebuffered saline (PBS). After quenching the endogenous peroxidase activity with 3 % hydrogen peroxide for 5 min at room temperature, the sections were treated for 1 h with 5 % bovine serum albumin to block nonspecific staining. LAT1 goat-antihuman polyclonal antibody was then added and incubated at 4 °C overnight. After washing with PBS, the secondary horseradish peroxidase-conjugated antibodies were incubated for 30 min at 37 °C. Antibody binding was visualized by incubating with fresh 3,3′-diaminobenzidine buffer. The sections were then washed in running water and counterstained with hematoxylin, followed by dehydration and mounting. The extent and intensity of IHC were assessed
Tumor Biol.
Results Expression of LAT1 mRNA in HCC tissues by qRT-PCR
Fig. 1 LAT1 mRNA expression in HCC tissues. LAT1 mRNA level in HCC tissues was significantly higher compared to that in ad
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