Pathology of Hepatocellular Carcinoma and Tumor-Bearing Liver Tissue in Association with hTERT Promoter Mutation

Abstract

Background: The hTERT promoter mutation represents a common and early event in hepatocarcinogenesis, but its linkage to the morphological status of the underlying liver tissue is poorly understood. We analyzed the connection between the histopathological changes in tumor-bearing liver tissue and the occurrence of the hTERT promoter mutation in hepatocellular carcinoma (HCC), correlated with clinical data.

Methods: The study cohort comprised 160 histologically confirmed HCC in patients with or without cirrhosis that were investigated for the hTERT promoter mutation. We evaluated the frequency of the hTERT promoter mutation in patients with HCC with or without cirrhosis and correlated it with potential clinical and histopathological drivers. In particular, we examined tumor-bearing noncirrhotic liver tissue regarding inflammation; the modified histological activity index (mHAI), fibrosis, and steatosis; and its correlation with the frequency of the hTERT promoter mutation in HCC. We evaluated overall survival with multivariate Cox regression. Furthermore, we compared hTERT antibody immunohistochemistry and molecular hTERT promoter mutation analysis of both HCC and background liver tissue.

Results: The hTERT promoter mutation was especially related to HCC in cirrhotic compared with noncirrhotic liver (p < 0.001) and independently of cirrhosis in patients ≥ 60 years (p = 0.005). Furthermore, the hTERT promoter mutation was associated with cirrhosis caused by alcohol toxicity and hepatitis C virus infection. In noncirrhotic liver tissue, the frequency of hTERT-promoter-mutated HCC increased with the degree of inflammation and fibrosis. Nevertheless, 25% of the hTERT-promoter-mutated HCC developed in normal liver tissue without HCC risk factors. Multivariate Cox regression analysis did not reveal an influence of the hTERT promoter mutation in HCC on overall survival at 3, 5, and 16 years. Immunohistochemical analysis with the hTERT antibodies LS-B95 and 2D8 in hTERT-promoter-mutated HCC and hTERT-wildtype HCC showed a mildly stronger immunoreaction compared with the tumor-bearing liver tissue (LS-B95: p < 0.01, 2D8: p < 0.01).

Conclusions: Our study reveals a connection between pathological changes in tumor-bearing liver tissue and the hTERT promoter mutation in most HCC, even in noncirrhotic liver tissue. Immunohistochemical hTERT antibodies do not discriminate between hTERT-promoter-mutated and wildtype HCC.

Figure 1

Histological type and grade of the examined hepatocellular carcinoma (HCC): conventional type, pseudoglandular G2 (a, b); steatohepatitic type G1 (c, d); fibrolamellar carcinoma G2 (e); chromophobe type G2 (f); and solid, lymphocyte-rich type G3 (g, h). Except for fibrolamellar carcinoma, all cases have hTERT promoter mutation.

Figure 2

Survival of hTERT-wildtype (hTERTwt) and hTERT-promoter-mutated (hTERTmut) hepatocellular carcinoma (HCC), independent of the background liver tissue (a), and of hTERTwt and hTERTmut HCC in cirrhotic and noncirrhotic liver tissue. Based on age-matched Cox regression analysis (1 and 2), patients with hTERTmut HCC in cirrhotic and noncirrhotic liver tissue do not show a significant difference in overall survival at 3 years (b), 5 years (c), and 16 years (d).

Figure 3

Staining intensity of hTERT antibodies in hepatocellular carcinoma (HCC): strong nuclear staining in a trabecular HCC G2, antibody 2D8 (a). Heterogeneous nuclear staining in HCC G2, antibody LS-B95 (b). Week staining of nuclear membrane in HCC G1, antibody 2D8 (c). Negative staining result in HCC G1, antibody LS-B95 (d).