Repolarization Precedes Oval Cell-mediated Hepatocytic Regeneration in the CDE Diet Mouse Model.

The liver has a unique ability to recover from injury unlike any other organ. A poorly understood aspect of liver regeneration is the role of hepatocellular polarization. Neighbor of Punc E11 (Nope) is an oncofetal stem/progenitor cell marker, which is expressed by depolarized adult hepatocytes after cholestatic liver injury and in hepatocellular carcinoma. Liver injury induced by a choline-deficient and ethionine-supplemented diet is reversible if followed by an additional dietary stop interval and enabled us to study the expression of Nope during the induction of chronic liver injury and during subsequent liver regeneration. We could show by quantitative RT-PCR, Western blotting, and immunohistochemistry that the expression of Nope is induced in depolarized adult hepatocytes during injury. However, after another 2 weeks of a normal diet, the polarization of hepatocytes was almost completely restored and the expression of Nope remained limited to bile ducts and oval cells. Using an inducible CK19-lineage tracing model, we could demonstrate that oval cell-mediated hepatocyte regeneration is rare and was preceded by repolarization of hepatocytes. In conclusion, polarization of hepatocytes is an important part of liver regeneration and precedes oval cell-mediated regeneration of the liver. This process can be visualized by a characteristic expression pattern of Nope.

First evaluation of Neighbor of Punc E11 (NOPE) as a novel marker in human hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is the second most common cause of cancer death worldwide and the search for clinically useful biomarkers is ongoing. Neighbor of Punc E11 (NOPE) is an established biomarker of murine HCC that remains undetectable in normal liver and at preneoplastic stages. OBJECTIVE: The aim of our study was to evaluate the presence of NOPE in human HCC. METHODS: Histologically confirmed HCC and corresponding non-tumor liver samples from 20 patients were analyzed for expression of NOPE using qRT-PCR and mRNA-in-situ technology in a conserved tissue context. RESULTS: In our cohort, 30% of HCC samples were expressing NOPE which proved particularly useful in non-cirrhotic HCC samples with up to 155-fold higher expression than in adult liver. Using mRNA-in-situ technology, NOPE was clearly identified within epithelial tumor cells of NOPE positive human HCCs. In our analyzed cohort, the combination of AFP with NOPE did not reach more than 40% sensitivity while GPC-3 and NOPE were complementary to each other reaching a combined sensitivity of 85.7%. CONCLUSIONS: This is the first characterization of NOPE as a potential biomarker for human HCC. Our results underline the value of NOPE as a complementing biomarker for human HCC.