Serum Apurinic/Apyrimidinic Endodeoxyribonuclease 1 (APEX1) Level as a Potential Biomarker of Cholangiocarcinoma.

Doungdean Tummanatsakun,Tanakorn Proungvitaya,Temduang Limpaiboon,Ongart Somintara,Atit Silsirivanit,Chaisiri Wongkham,Sakkarn Sangkhamanon,Sopit Wongkham,Siriporn Proungvitaya,Sittiruk Roytrakul

doi:10.3390/biom9090413

Abstract

Diagnostic and/or prognostic biomarkers for cholangiocarcinoma (CCA) are still insufficient with poor prognosis of patients. To discover a new CCA biomarker, we constructed our secretome database of three CCA cell lines and one control cholangiocyte cell line using GeLC-MS/MS. We selected candidate proteins by five bioinformatics tools for secretome analysis. The inclusion criteria were as follows: having predicted signal peptide or being predicted as non-classically secreted protein; together with having no transmembrane helix and being previously detected in plasma and having the highest number of signal peptide cleavage sites. Eventually, apurinic/apyrimidinic endodeoxyribonuclease 1 (APEX1) was selected for further analysis. To validate APEX1 as a bio-marker for CCA, serum APEX1 levels of 80, 39, and 40 samples collected from CCA, benign biliary diseases (BBD), and healthy control groups, respectively, were measured using dot blot analysis. The results showed that serum APEX1 level in CCA group was significantly higher than that in BBD or healthy control group. Among CCA patients, serum APEX1 level was significantly higher in patients having metastasis than in those without metastasis. The higher level of serum APEX1 was correlated with the shorter survival time of the patients. Serum APEX1 level might be a diagnostic and prognostic biomarker for CCA.

Highlights

Cholangiocarcinoma (CCA) is cancer originated from biliary epithelial cells
The secretomes of three CCA cell lines and their control immortalized cholangiocyte cell line named MMNK1 were quantitatively compared based on MS signal intensities using a DeCyderTM MS
1117 proteins were shared with at least two cell lines, 11 proteins were found to be unique in MMNK1 secretome, one protein was unique in KKU-100 secretome, four proteins unique in KKU-213 secretome, and five proteins unique in KKU- 214 secretome

Summary

Introduction

Cholangiocarcinoma (CCA) is cancer originated from biliary epithelial cells. The incidence of CCA is very high in northeastern Thailand [1], especially where people live close to the water reservoir and consume cyprinoid fish infected with metacercariae of the liver fluke, Opisthorchis viverrini (OV) [2].In addition to the epidemiological co-incidence of liver fluke infection and CCA, animal model experiments of CCA genesis demonstrated that OV, together with nitrosamine carcinogen treatment, caused CCA [3,4]. Cholangiocarcinoma (CCA) is cancer originated from biliary epithelial cells. The incidence of CCA is very high in northeastern Thailand [1], especially where people live close to the water reservoir and consume cyprinoid fish infected with metacercariae of the liver fluke, Opisthorchis viverrini (OV) [2]. In addition to the epidemiological co-incidence of liver fluke infection and CCA, animal model experiments of CCA genesis demonstrated that OV, together with nitrosamine carcinogen treatment, caused CCA [3,4]. Several serum markers, such as carbohydrate antigen 19-9 (CA19-9), Biomolecules 2019, 9, 413; doi:10.3390/biom9090413 www.mdpi.com/journal/biomolecules. Biomolecules 2019, 9, 413 carcinoembryonic antigen (CEA), and alkaline phosphatase (ALP), have been used for diagnosis of CCA. It is necessary to discover novel markers to improve the efficacy of CCA diagnosis and prognosis

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