Direct In Vivo Cell Lineage Analysis in the Retrorsine and 2AAF Models of Liver Injury after Genetic Labeling in Adult and Newborn Rats

BACKGROUNDS AND AIMS:When hepatocyte proliferation is impaired, liver regeneration proceeds from the division of non parenchymal hepatocyte progenitors. Oval cells and Small Hepatocyte-like Progenitor Cells (SHPCs) represent the two most studied examples of such epithelial cells with putative stem cell capacity. In the present study we wished to compare the origin of SHPCs proliferating after retrorsine administration to the one of oval cells observed after 2-Acetyl-Amino fluorene (2-AAF) treatment. METHODOLOGY/PRINCIPAL FINDINGS:We used retroviral-mediated nlslacZ genetic labeling of dividing cells to study the fate of cells in the liver. Labeling was performed either in adult rats before treatment or in newborn animals. Labeled cells were identified and characterised by immunohistochemistry. In adult-labeled animals, labeling was restricted to mature hepatocytes. Retrorsine treatment did not modify the overall number of labeled cells in the liver whereas after 2-AAF administration unlabeled oval cells were recorded and the total number of labeled cells decreased significantly. When labeling was performed in newborn rats, results after retrorsine administration were identical to those obtained in adult-labeled rats. In contrast, in the 2-AAF regimen numerous labeled oval cells were present and were able to generate new labeled hepatocytes. Furthermore, we also observed labeled biliary tracts in 2-AAF treated rats. CONCLUSIONS:Our results strongly suggest that SHPCs are derived from hepatocytes and we confirm that SHPCs and oval cells do not share the same origin. We also show that hepatic progenitors are labeled in newborn rats suggesting future directions for in vivo lineage studies

Assessment of epidermal growth factor receptor (EGFR) expression in primary colorectal carcinomas and their related metastases on tissue sections and tissue microarray

Metastatic colorectal carcinomas (CRC) resistant to chemotherapy may benefit from targeting monoclonal therapy cetuximab when they express the epidermal growth factor receptor (EGFR). Because of its clinical implications, we studied EGFR expression by immunohistochemistry on tissue sections of primary CRC (n=32) and their related metastases (n=53). A tissue microarray (TMA) was generated from the same paraffin blocks to determine whether this technique could be used for EGFR screening in CRC. On tissue sections, 84% of the primary CRC and 94% of the metastases were EGFR-positive. When matched, they showed a concordant EGFR-positive status in 78% of the cases. Moreover, staining intensity and extent of EGFR-positive cells in the primary CRC correlated with those observed in the synchronous metastases. On TMA, 65% of the primary CRC, 66% of the metastases, and 43% of the matched primary CRC metastases were EGFR-positive. There was no concordant EGFR status between the primary and the metastatic sites. A strong discrepancy of EGFR status was noted between TMA and tissue sections. In conclusion, EGFR expression measured in tissue sections from primary CRC and their related metastases was found to be similar and frequent, but it was significantly underestimated by the TMA technique

Immunohistochemical discrimination of wild-type EGFR from EGFRvIII in fixed tumour specimens using anti-EGFR mAbs ICR9 and ICR10

Background:The human epidermal growth factor receptor (EGFR) is an important therapeutic target in oncology, and three different types of EGFR inhibitors have been approved for the treatment of cancer patients. However, there has been no clear association between the expression levels of EGFR protein in the tumours determined by the FDA-approved EGFR PharmDx kit (Dako) or other standard anti-EGFR antibodies and the response to the EGFR inhibitors.Method:In this study, we investigated the potential of our anti-EGFR monoclonal antibodies (mAbs; ICR9, ICR10, ICR16) for immunohistochemical diagnosis of wild-type EGFR and/or the type-III deletion mutant form of EGFR (EGFRvIII) in formalin-fixed, paraffin-embedded human tumour specimens.Results:We found that the anti-EGFR mAb in the EGFR PharmDx kit stained both wild-type and EGFRvIII-expressing cells in formalin-fixed, paraffin-embedded sections. This pattern of EGFR immunostaining was also found with our anti-EGFR mAb ICR16. In contrast, mAbs ICR10 and ICR9 were specific for the wild-type EGFR.Conclusion:We conclude that mAbs ICR9 and ICR10 are ideal tools for investigating the expression patterns of wild-type EGFR protein in tumour specimens using immunohistochemistry, and to determine their prognostic significance, as well as predictive value for response to therapy with EGFR antibodies.British Journal of Cancer advance online publication, 7 February 2012; doi:10.1038/bjc.2012.27 www.bjcancer.com

The RSPO–LGR4/5–ZNRF3/RNF43 module controls liver zonation and size

LGR4/5 receptors and their cognate RSPO ligands potentiate Wnt/β-catenin signalling and promote proliferation and tissue homeostasis in epithelial stem cell compartments. In the liver, metabolic zonation requires a Wnt/β-catenin signalling gradient, but the instructive mechanism controlling its spatiotemporal regulation is not known. We have now identified the RSPO-LGR4/5-ZNRF3/RNF43 module as a master regulator of Wnt/β-catenin-mediated metabolic liver zonation. Liver-specific LGR4/5 loss of function (LOF) or RSPO blockade disrupted hepatic Wnt/β-catenin signalling and zonation. Conversely, pathway activation in ZNRF3/RNF43 LOF mice or with recombinant RSPO1 protein expanded the hepatic Wnt/β-catenin signalling gradient in a reversible and LGR4/5-dependent manner. Recombinant RSPO1 protein increased liver size and improved liver regeneration, whereas LGR4/5 LOF caused the opposite effects, resulting in hypoplastic livers. Furthermore, we show that LGR4(+) hepatocytes throughout the lobule contribute to liver homeostasis without zonal dominance. Taken together, our results indicate that the RSPO-LGR4/5-ZNRF3/RNF43 module controls metabolic liver zonation and is a hepatic growth/size rheostat during development, homeostasis and regeneration

Manejo terapêutico do hepatocarcinoma fibrolamelar

Fibrolamellar carcinoma of the liver is a distinct variant of hepatocellular carcinoma characterized by the lack of association with cirrhosis or other underlying liver diseases, as hepatitis B virus. The serum alpha-fetoprotein level is often not elevated, occuring typically in young patients. Distinction from conventional hepatocellular carcinoma is of clinical significance, because prognosis is far better due to higher ressecability and more indolent growth. We describe a case of a 26-year-old woman free of other liver diseases presenting with a large abdominal palpable mass. After ressection by vascular exclusion technique, the pathologic examination revealed fibrolamellar carcinoma. The former should not be confused with the hepatocellular carcinoma, since it is related with a more favorable prognosis