Marie-Pierre Bralet

Hepatocellular carcinoma in WHV/N-myc2 transgenic mice: oncogenic mutations of beta-catenin and synergistic effect of p53 null alleles.

The intronless N-myc2 gene was originally identified as the major target of hepatitis virus insertion in woodchuck liver tumors. Here we report that transgenic mice carrying the N-myc2 gene controlled by woodchuck hepatitis virus (WHV) regulatory sequences are highly predisposed to liver cancer. In a WHV/N-myc2 transgenic line, hepatocellular carcinomas or adenomas arose in over 70% of mice, despite barely detectable expression of the methylated transgene in liver cells. Furthermore, a transgenic founder carrying unmethylated transgene sequences succumbed to a large liver tumor by the age of two months, demonstrating the high oncogenicity of the woodchuck N-myc2 retroposon. Stabilizing mutations or deletions of β-catenin were found in 25% of liver tumors and correlated with reduced tumor latency (P<0.05), confirming the important role of β-catenin activation in Myc-induced tumorigenesis. The ability of the tumor suppressor gene p53 to cooperate with N-myc2 in liver cell transformation was tested by introducing a p53-null allele into WHV/N-myc2 transgenic mice. The loss of one p53 allele in transgenic animals markedly accelerated the onset of liver cancer (P=0.0001), and most tumors of WHV/N-myc2 p53+/Δ mice harbored either a deletion of the wt p53 allele or a β-catenin mutation. These findings provide direct evidence that activation of N-myc2 and reduction of p53 levels act synergistically during multistage carcinogenesis in vivo and suggest that different genetic pathways may underlie liver carcinogenesis initiated by a myc transgene.

In vivo cell lineage analysis during chemical hepatocarcinogenesis in rats using retroviral-mediated gene transfer: evidence for dedifferentiation of mature hepatocytes.

Feeding adult rats with a diet containing 2-acetylaminofluorene (2-AAF) results in suppression of hepatocyte proliferation and stimulation of oval cell proliferation. Although oval cells may be facultative liver stem cells, the actual relationship between oval cells and liver cancer has not been clearly established in vivo. Our goal was to label hepatic cells in vivo using retroviral vectors and follow their fate during the early steps of chemically induced hepatocarcinogenesis. Oval cell proliferation was induced by continuous feeding with a carcinogenic diet containing 2-AAF. We used two different strategies to genetically label hepatic cells: (a) labeling of proliferating cells in rats fed 2-AAF by injecting recombinant retroviral vectors containing the β-galactosidase gene either in a peripheral vein or in the common bile duct at the peak of oval cell proliferation and (b) prelabeling of hepatocytes by intravenously injecting recombinant vectors 1 day after partial hepatectomy and 1 week before subsequent administration of 2-AAF. Using the first strategy, transgene expression occurred in both oval cells and hepatocytes. Using the second strategy, we could selectively label, and hence study the fate of, differentiated hepatocytes. In the latter case, we observed clusters of β-galactosidase–positive hepatocytes, some of them also expressing preneoplastic markers such as gamma-glutamyl transpeptidase as well as the placental form of glutathione-S-transferase. These results demonstrate that preneoplastic foci can originate from mature hepatocytes and are consistent with the hypothesis that dedifferentiation of mature hepatocytes may occur during the course of carcinogenic regimen.

Primary liver carcinoma in genetic hemochromatosis reveals a broad histologic spectrum.

Hepatocellular carcinoma (HCC) is a well-known complication of genetic hemochromatosis (GH). However, the frequency of primary liver carcinoma (PLC) with biliary differentiation, such as cholangiocarcinoma (CC) and combined hepatocholangiocarcinoma (CHCC), in GH remains unclear We analyzed the histologic type of 20 PLCs occurring in the background of GH; all patients were homozygotic for the C282Y mutation. Ten were depleted of iron by successive phlebotomies, while the remaining 10 were untreated. Histologically, 13 cases were classified as HCC, 3 as CC, and 4 as CHCC. Immunohistochemical detection of Hep Par 1, cytokeratin 19 (CK19), and MUC1 supported this classification; PLC with biliary differentiation was immunoreactive for MUC1 in 86% (6/7) of cases and for CK19 in 100% (7/7) of cases. The nontumoral liver exhibited no cirrhosis or extensive fibrosis in 6 cases. Von Meyenburg complexes were present in 11 cases and intraparenchymal bile duct adenomas in 3. These data suggest that PLCs in patients with GH present a wide histologic spectrum, with tumors showing frequent biliary differentiation; may arise on a nonfibrotic or a cirrhotic liver; and often are associated with Von Meyenburg complexes and to a lesser extent with bile duct adenomas.

Adjuvant Gemcitabine-Oxaliplatin (GEMOX) after Curative Surgery in High-risk Patients with Cholangiocarcinoma

Background There is no standard adjuvant chemotherapy to prevent recurrent cholangiocarcinoma (CCA), a rare cancer with poor prognosis. We assessed the efficacy and safety of GEMOX on intrahepatic and hilar CCA with high-risk factors after curative surgery. Patients and Methods Twenty two patients (mean age: 57 years old) with CCA received 6 cycles of GEMOX: gemcitabine 1,000 mg/m2 on day 1 and oxaliplatin 85 mg/m2 on day 2, q3w after a curative surgery. Results All patients completed 6 cycles of GEMOX. EGFR membranous expression was present in 20 CCA. The 5-year survival rate was 56% (CI 95%: 25.7–85.4); 2-year disease free survival rate was 28% (CI 95%: 3.4–52.6). Median time to progression was 15 months. The rate of recurrence after surgery and chemotherapy was 63% (14/22). Two patients died of disease progression. Twelve patients received cetuximab/GEMOX at the time of relapse. Six died after 12 months (9–48 months), three are still alive suggesting a clinical applicability of EGFR inhibitors in CCA. Conclusion Adjuvant chemotherapy with GEMOX alone seems ineffective in intrahepatic and hilar CCA with a high risk of relapse. Additional studies including targeted therapies to circumvent such poor chemosensitivity are needed.