title: Decreased PCSK9 expression in human hepatocellular carcinoma.
abstract: BACKGROUND
  The management of hepatocellular carcinoma (HCC) is limited by the lack of adequate screening biomarkers and chemotherapy. In response, there has been much interest in tumor metabolism as a therapeutic target. PCSK9 stimulates internalization of the LDL-receptor, decreases cholesterol uptake into hepatocytes and affects liver regeneration. Thus, we investigated whether PCSK9 expression is altered in HCC, influencing its ability to harness cholesterol metabolism.
  
  
  METHODS
  Thirty-nine patients undergoing partial hepatectomy or liver transplantation for HCC were consented for use of HCC tissue to construct a tissue microarray (TMA). The TMA was immunostained for PCSK9. Imagescope software was used to objectively determine staining, and assess for pathological and clinical correlations. PCSK9 and LDL receptor mRNA levels in flash-frozen HCC and adjacent liver tissue were determined by quantitative RT-PCR. Serum PCSK9 levels were determined by ELISA.
  
  
  RESULTS
  By immunohistochemistry, there was significantly lower expression of PCSK9 in HCC as compared to adjacent cirrhosis (p-value < 0.0001, wilcoxon signed-rank test). Significantly greater staining of PCSK9 was present in cirrhosis compared to HCC (p value <0.0001), and positivity (percentage of positive cells) was significantly greater in cirrhosis compared to HCC (p-value < 0.0001). Conversely, significantly higher expression of LDL-R was present in HCC as compared to the adjacent cirrhosis (p-value < 0.0001). There was no significant correlation of PCSK9 staining with grade of tumor, but there were significant correlations between PCSK9 staining and stage of fibrosis, according to spearman correlation test. PCSK9 mRNA levels were relatively less abundant within HCC compared to adjacent liver tissue (p-value =0.08) and normal control tissue (p-value =0.02). In contrast, serum PCSK9 levels were significantly increased among patients with HCC compared to those with chronic liver disease without HCC (p-value =0.029). LDL receptor mRNA was consistantly greater in HCC when compared to normal control tissue (p-value = 0.06) and, in general, was significantly greater in HCC when compared to adjacent liver (p-value = 0.04).
  
  
  CONCLUSIONS
  The decreased expression of PCSK9 and conversely increased LDL-R expression in HCC suggests that HCC modulates its local microenvironment to enable a constant energy supply. Larger-scale studies should be conducted to determine whether PCSK9 could be a therapeutic target for HCC.
authors.affiliation: Division of Gastroenterology, McGill University Health Centre, 687 Pine Avenue West, Montreal, H3A1A1, Canada. mamatha.bhat@mcgill.ca.
authors.forename: Mamatha
authors.initials: M
authors.lastname: Bhat
authors.affiliation: Department of Surgery, Indiana University School of Medicine, Indianapolis, IN, USA. nskill@iupui.edu.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Skill
authors.affiliation: Department of Pathology, McGill University Health Centre, Montreal, QC, Canada. victoria.marcus@muhc.mcgill.ca.
authors.forename: Victoria
authors.initials: V
authors.lastname: Marcus
authors.affiliation: Division of Gastroenterology, McGill University Health Centre, 687 Pine Avenue West, Montreal, H3A1A1, Canada. marc.deschenes@muhc.mcgill.ca.
authors.forename: Marc
authors.initials: M
authors.lastname: Deschenes
authors.affiliation: Biostatistics Core Facility, Research Institute, McGill University Health Centre, Montreal, QC, Canada. Xianming.tan@clinepi.mcgill.ca.
authors.forename: Xianming
authors.initials: X
authors.lastname: Tan
authors.affiliation: Hepatopancreatobiliary and Multi-Organ Transplant Surgery, McGill University Health Centre, Montreal, QC, Canada. Jeanne.bouteaud@mail.mcgill.ca.
authors.forename: Jeanne
authors.initials: J
authors.lastname: Bouteaud
authors.affiliation: Hepatopancreatobiliary and Multi-Organ Transplant Surgery, McGill University Health Centre, Montreal, QC, Canada. sarita.negi@gmail.com.
authors.forename: Sarita
authors.initials: S
authors.lastname: Negi
authors.affiliation: Department of Medical Biochemistry, King Abdulaziz University, Jeddah, Saudi Arabia. zuhier.awan@gmail.com.
authors.forename: Zuhier
authors.initials: Z
authors.lastname: Awan
authors.affiliation: Hepatopancreatobiliary and Multi-Organ Transplant Surgery, McGill University Health Centre, Montreal, QC, Canada. reidaikin@gmail.com.
authors.forename: Reid
authors.initials: R
authors.lastname: Aikin
authors.affiliation: Hepatopancreatobiliary and Multi-Organ Transplant Surgery, McGill University Health Centre, Montreal, QC, Canada. janet.kwan@mail.mcgill.ca.
authors.forename: Janet
authors.initials: J
authors.lastname: Kwan
authors.affiliation: Department of Surgery, Indiana University School of Medicine, Indianapolis, IN, USA. ramila.amre@muhc.mcgill.ca.
authors.forename: Ramila
authors.initials: R
authors.lastname: Amre
authors.affiliation: Department of Medicine, Goodman Cancer Research Centre, Montreal, QC, Canada. sebastien.tabaries@mcgill.ca.
authors.forename: Sebastien
authors.initials: S
authors.lastname: Tabaries
authors.affiliation: Department of Pathology, McGill University Health Centre, Montreal, QC, Canada. mazen.hassanain@mcgill.ca.|Department of Surgery, King Saud University, Riyadh, Saudi Arabia. mazen.hassanain@mcgill.ca.
authors.forename: Mazen
authors.initials: M
authors.lastname: Hassanain
authors.affiliation: Department of Medical Biochemistry, King Abdulaziz University, Jeddah, Saudi Arabia. nabil.seidah@ircm.qc.ca.
authors.forename: Nabil G
authors.initials: NG
authors.lastname: Seidah
authors.affiliation: Department of Surgery, Indiana University School of Medicine, Indianapolis, IN, USA. mmalucci@iupui.edu.
authors.forename: Mary
authors.initials: M
authors.lastname: Maluccio
authors.affiliation: Department of Medicine, Goodman Cancer Research Centre, Montreal, QC, Canada. peter.siegel@mcgill.ca.
authors.forename: Peter
authors.initials: P
authors.lastname: Siegel
authors.affiliation: Department of Pathology, McGill University Health Centre, Montreal, QC, Canada. peter.metrakos@mcgill.ca.
authors.forename: Peter
authors.initials: P
authors.lastname: Metrakos
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000097:blood*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008099:Liver / Q000473:pathology; D008103:Liver Cirrhosis / Q000097:blood; D008113:Liver Neoplasms / Q000097:blood*; D008297:Male; D008875:Middle Aged; D000071449:Proprotein Convertase 9; D043484:Proprotein Convertases / Q000097:blood*; D060888:Real-Time Polymerase Chain Reaction; D011973:Receptors, LDL / Q000097:blood; D012697:Serine Endopeptidases / Q000097:blood*; D018709:Statistics, Nonparametric
chemical_list: D011973:Receptors, LDL; C472125:PCSK9 protein, human; D000071449:Proprotein Convertase 9; D043484:Proprotein Convertases; D012697:Serine Endopeptidases