Transient expression of megakaryocyte-derived protein immunoreactive with an antiserum to cartilage oligomeric matrix protein in developing rat liver

Cartilage oligomeric matrix protein: A novel non-invasive marker for assessing cirrhosis and risk of hepatocellular carcinoma

AIM

To assess serum cartilage oligomeric matrix protein (COMP) as a marker of cirrhosis and risk of progression to hepatocellular carcinoma (HCC).

METHODS

A COMP enzyme-linked immunosorbent assay was used to test 187 patients with chronic liver diseases at the time point of first evaluation. The selected patients included 72 with chronic hepatitis B infection, 75 with chronic hepatitis C infection, 22 with primary biliary cirrhosis, 7 with autoimmune hepatitis type 1, and 11 with alcoholic liver disease. Demographic, biochemical, histological and clinical characteristics of the patients were recorded at the first evaluation. One hundred and forty-seven patients were followed for a median [interquartile range (IQR)] duration of 96.5 (102) mo. The clinical, biochemical and histological data, as well as the development of cirrhosis, HCC according to internationally accepted criteria and in case of death, a liver-related cause during the follow-up period, were recorded at the electronic database of our clinic. COMP determination was also performed in 43 healthy individuals who served as the control study group.

RESULTS

COMP positivity (> 15 U/L) was detected in 22%-36% among chronic liver disease groups. Strikingly, almost 83% of COMP-positive patients were cirrhotic at baseline, independently of cause of liver disease. Among the patients who developed HCC during follow-up, 73.7% (14/19) were COMP positive at baseline. COMP positivity was significantly associated with older age (P < 0.001), advanced fibrosis (P = 0.001) and necroinflammatory activity (P = 0.001), higher aspartate aminotransferase (P < 0.001), alanine aminotransferase (P < 0.02), γ-glutamyl transpeptidase (P = 0.003), alkaline phosphatase (P = 0.001), bilirubin (P < 0.05), international normalized ratio (P = 0.002) and alpha-fetoprotein levels (P < 0.02), and lower albumin (P < 0.001), and platelet count (P = 0.008). COMP levels [median (IQR)] were significantly higher in cirrhotics compared to non-cirrhotics [13.8 (7.9) U/L vs 9.8 (4.6) U/L, respectively; P < 0.001]. On multivariate logistic regression analysis, COMP-positivity was independently associated only with cirrhosis (OR = 4.40, 95%CI: 1.33-14.69, P = 0.015). Kaplan-Meier analysis showed that COMP positivity was significantly associated with HCC development (P = 0.007) and higher incidence of liver-related death (P < 0.001).

CONCLUSION

Elevated COMP levels are strongly associated with cirrhosis and HCC progression. Serum COMP is a new promising non-invasive biomarker for HCC risk assessment in surveillance programs.

Cartilage oligomeric matrix protein expression in hepatocellular carcinoma and the cirrhotic liver

BACKGROUND

Cartilage oligomeric matrix protein (COMP) is the fifth member of the thrombospondin family of extracellular, calcium-binding proteins. It was initially isolated and characterized in cartilage tissue, where it is thought to contribute to the extracellular matrix composition and cell-extracellular matrix interaction. In the present study the expression of COMP was investigated in normal liver (n=19), liver cirrhosis (n=14) and hepatocellular carcinoma (HCC; n=16) tissues, both at the mRNA and protein level.

METHODS AND RESULTS

By northern blot and western blot analysis, COMP was absent or rarely expressed in the normal liver and liver cirrhosis tissues, but significantly overexpressed in HCC tissue samples. The COMP mRNA overexpression in HCC was not related to the clinical stage or tumor grade. By in situ hybridization and immunohistochemistry analysis, COMP mRNA and protein expression were localized within the cytoplasm of the tumor cells.

CONCLUSION

COMP is highly expressed within the tumor cells of HCC, suggesting that COMP might play a role in the pathophysiology of this disease.