Plasma biomarker tool for the diagnosis of liver cancer comprising liver carboxylesterase 1 and liver cancer screening method

Abstract

The present invention relates to a plasma biomarker for diagnosing hepatocellular carcinoma (HCC), in particular to the discovery of a protein in plasma using 2-D fluorescence differential gel electrophoresis (2-D DIGE), immunoprecipitation and Nano-liquid chromatography mass spectrometry (Nano-LC-MS/MS) system that was unknown on the basis of conventional techniques. By demonstrating the presence of liver carboxylesterase 1 (hCE1) in human plasma and confirming that its secretion level is higher in patients with HCC than in healthy volunteers, this invention may be used as a screening method to diagnose HCC at an early stage.

The invention claimed is: 
     
       1. A screening method for hepatocellular carcinoma (HCC), comprising:
 collecting human blood, and   detecting the presence of human liver carboxylesterase 1(hCE1) protein in plasma of the human blood as a plasma biomarker for HCC diagnosis; wherein the level of hCE1 protein is increased more in the plasma of patients with HCC than in the plasma of healthy patients.   
     
     
       2. The method of  claim 1 , wherein the level of hCE1 protein is increased, on average, 2-5 fold more in the plasma of patients with HCC compared to the plasma of healthy patients. 
     
     
       3. The method of  claim 1 , wherein the presence of the hCE1 protein is detected by an anti-hCE1 antibody. 
     
     
       4. A method for diagnosing hepatocellular carcinoma (HCC) in a subject, the method comprising the steps of:
 a) collecting a sample of human blood from the subject;   b) contacting a portion of the blood sample with an antibody having specific binding affinity for human liver carboxylesterase 1 (hCE1), thereby forming a complex between the antibody and hCE1, the antibody having a detectable label;   c) separating the complex formed in said contacting step (b) from labeled antibody not comprising the complex;   d) quantifying a signal from the detectable label of the antibody comprising the complex formed in said contacting step (b), the signal being proportional to an amount of hCE1 in the blood sample, whereby the amount of hCE1 in the sample is calculated;   e) comparing the amount of hCE1 calculated in said quantifying step (d) to a hCE1 reference amount; and   f) providing a diagnosis of HCC in the subject if the amount of hCE1 in the sample calculated in said quantifying step (d) is greater than the hCE1 reference amount;   
       wherein the hCE1 reference amount is an amount of hCE1 in a blood sample from a subject not having HCC.  
     
     
       5. The method of claim 4, wherein the blood sample comprises plasma.  
     
     
       6. The method of claim 4, wherein the blood sample comprises serum.  
     
     
       7. The method of claim 4, further comprising the step of separating human liver carboxylesterase 1 (hCE1) protein from other remaining proteins in the blood sample, wherein said separating hCE1 protein step occurs between steps (a) and (b).  
     
     
       8. The method of claim 7, wherein the hCE1 protein is separated from other remaining proteins in the blood sample by immunoprecipitation.  
     
     
       9. The method of claim 7, wherein the step of separating hCE1 protein from other remaining proteins in the blood sample comprises the following steps:
 i) contacting a portion of the sample from the subject with an antibody having specific binding affinity for hCE1, thereby forming a complex between the antibody and hCE1; and   ii) precipitating the complex formed in said contacting step (i);   iii) separating the precipitated complex from the supernatant of the sample, the supernatant comprising the other remaining proteins and antibody not comprising the complex;   
       wherein the hCE1 protein is separated from the other remaining proteins in the blood sample.  
     
     
       10. The method of claim 9, wherein the antibody is linked to a magnetic molecule.  
     
     
       11. The method of claim 4, wherein the hCE1 reference amount is an amount of hCE1 in the blood of a healthy subject.