Golgi protein-73: A biomarker for assessing cirrhosis and prognosis of liver disease patients

Abstract

Background: Reliable biomarkers of cirrhosis, hepatocellular carcinoma (HCC), or progression of chronic liver diseases are missing. In this context, Golgi protein-73 (GP73) also called Golgi phosphoprotein-2, was originally defined as a resident Golgi type II transmembrane protein expressed in epithelial cells. As a result, GP73 expression was found primarily in biliary epithelial cells, with only slight detection in hepatocytes. However, in patients with acute or chronic liver diseases and especially in HCC, the expression of GP73 is significantly up-regulated in hepatocytes. So far, few studies have assessed GP73 as a diagnostic or prognostic marker of liver fibrosis and disease progression.

Aim: To assess serum GP73 efficacy as a diagnostic marker of cirrhosis and/or HCC or as predictor of liver disease progression.

Methods: GP73 serum levels were retrospectively determined by a novel GP73 ELISA (QUANTA Lite^® GP73, Inova Diagnostics, Inc., Research Use Only) in a large cohort of 632 consecutive patients with chronic viral and non-viral liver diseases collected from two tertiary Academic centers in Larissa, Greece (n = 366) and Debrecen, Hungary (n = 266). Aspartate aminotransferase (AST)/Platelets (PLT) ratio index (APRI) was also calculated at the relevant time points in all patients. Two hundred and three patients had chronic hepatitis B, 183 chronic hepatitis C, 198 alcoholic liver disease, 28 autoimmune cholestatic liver diseases, 15 autoimmune hepatitis, and 5 with other liver-related disorders. The duration of follow-up was 50 (57) mo [median (interquartile range)]. The development of cirrhosis, liver decompensation and/or HCC during follow-up were assessed according to internationally accepted guidelines. In particular, the surveillance for the development of HCC was performed regularly with ultrasound imaging and alpha-fetoprotein (AFP) determination every 6 mo in cirrhotic and every 12 mo in non-cirrhotic patients.

Results: Increased serum levels of GP73 (> 20 units) were detected at initial evaluation in 277 out of 632 patients (43.8%). GP73-seropositivity correlated at baseline with the presence of cirrhosis (96.4% vs 51.5%, P < 0.001), decompensation of cirrhosis (60.3% vs 35.5%, P < 0.001), presence of HCC (18.4% vs 7.9%, P < 0.001) and advanced HCC stage (52.9% vs 14.8%, P = 0.002). GP73 had higher diagnostic accuracy for the presence of cirrhosis compared to APRI score [Area under the curve (AUC) (95%CI): 0.909 (0.885-0.934) vs 0.849 (0.813-0.886), P = 0.003]. Combination of GP73 with APRI improved further the accuracy (AUC: 0.925) compared to GP73 (AUC: 0.909, P = 0.005) or APRI alone (AUC: 0.849, P < 0.001). GP73 levels were significantly higher in HCC patients compared to non-HCC [22.5 (29.2) vs 16 (20.3) units, P < 0.001) and positively associated with BCLC stage [stage 0: 13.9 (10.8); stage A: 17.1 (16.8); stage B: 19.6 (22.3); stage C: 32.2 (30.8); stage D: 45.3 (86.6) units, P < 0.001] and tumor dimensions [very early: 13.9 (10.8); intermediate: 19.6 (18.4); advanced: 29.1 (33.6) units, P = 0.004]. However, the discriminative ability for HCC diagnosis was relatively low [AUC (95%CI): 0.623 (0.570-0.675)]. Kaplan-Meier analysis showed that the detection of GP73 in patients with compensated cirrhosis at baseline, was prognostic of higher rates of decompensation (P = 0.036), HCC development (P = 0.08), and liver-related deaths (P < 0.001) during follow-up.

Conclusion: GP73 alone appears efficient for detecting cirrhosis and superior to APRI determination. In combination with APRI, its diagnostic performance can be further improved. Most importantly, the simple GP73 measurement proved promising for predicting a worse outcome of patients with both viral and non-viral chronic liver diseases.

Keywords: Aspartate aminotransferase/Platelets ratio index score; Biomarker; Cirrhosis; Golgi protein-73; Hepatic fibrosis; Hepatitis B; Hepatitis C; Hepatocellular carcinoma.

Figure 1

Flow-sheet of the 632 patients participated in the study and liver-related events (development of cirrhosis, liver decompensation, hepatocellular carcinoma development) observed during follow up.

Figure 2

Golgi protein 73 values distribution in different stages of chronic liver diseases. (a) non-cirrhotic patients, 8.4 (4.6) units vs compensated cirrhotic patients, 18.7 (15.3) units vs decompensated cirrhotic or patients with hepatocellular carcinoma (HCC), 29.5 (27.6) units; P < 0.001; and (b) cirrhotic (compensated and decompensated), 22.8 (22.9) units vs HCC patients, 25 (33.7) units; P = 0.07 (Tukey box-and-whisker plots; y-axis is presented in log scale). GP73: Golgi protein 73; HCC: Hepatocellular carcinoma.

Figure 3

Golgi protein 73 vs aspartate aminotransferase to platelets index as diagnostic markers of cirrhosis. Receiver operating characteristic curves for the prediction of cirrhosis according to Golgi protein 73 (GP73) levels and aspartate aminotransferase to platelets index (APRI) score. Combination of GP73 and APRI had a higher diagnostic accuracy for cirrhosis), compared to GP73 (P = 0.005) or APRI score alone (P < 0.001). GP73: Golgi protein 73; APRI: Aspartate aminotransferase to platelets index; AUC: Area under the curve.

Figure 4

Golgi protein values distribution among hepatocellular carcinoma stages according to. A: BCLC staging system [stage 0, 13.9 (10.8) units; stage A, 17.1 (16.8) units; stage B, 19.6 (22.3) units; stage C, 32.2 (30.8) units; stage D, 45.3 (86.6) units; P < 0.001]. B: Tumor dimensions [very early, 13.9 (10.8) units; intermediate, 19.6 (18.4) units; advanced, 29.1 (33.6) units; P = 0.004] (Tukey box-and-whisker plots). GP73: Golgi protein 73; BCLC: Barcelona clinic liver cancer.

Figure 5

Kaplan-Meier analysis of patients according to Golgi protein 73 detection. Only 14 patients (one GP73 positive and 13 GP73 negative) developed cirrhosis during follow-up A. GP73 positive patients were characterized by higher decompensation B, HCC development C and liver-related mortality rates D. GP73: Golgi protein 73 detection; HCC: hepatocellular carcinoma.