Hepatocellular adenomas (HCA) with activated ␤-catenin present a high risk of malignant transformation. To permit robust routine diagnosis to allow for HCA subtype classification, we searched new useful markers. We analyzed the expression of candidate genes by quantitative reverse transcription polymerase chain reaction QRT-PCR followed by immunohistochemistry to validate their specificity and sensitivity according to hepatocyte nuclear factor 1 alpha (HNF1␣) and ␤-catenin mutations as well as inflammatory phenotype. Quantitative RT-PCR showed that FABP1 (liver fatty acid binding protein) and UGT2B7 were downregulated in HNF1␣-inactivated HCA (P < 0.0002); GLUL (glutamine synthetase) and GPR49 overexpression were associated with ␤-catenin-activating mutations (P < 0.0005), and SAA2 (serum amyloid A2) and CRP (C-reactive protein) were upregulated in inflammatory HCA (P ‫؍‬ 0.0001). Immunohistochemistry validation confirmed that the absence of liver-fatty acid binding protein (L-FABP) expression rightly indicated HNF1␣ mutation (100% sensitivity and specificity), the combination of glutamine synthetase overexpression and nuclear ␤-catenin staining were excellent predictors of ␤-catenin-activating mutation (85% sensitivity, 100% specificity), and SAA hepatocytic staining was ideal to classify inflammatory HCA (91% sensitivity and specificity). Finally, a series of 93 HCA was unambiguously classified using our 4 validated immunohistochemical markers. Importantly, new associations were revealed for inflammatory HCA defined by SAA staining with frequent hemorrhages (P ‫؍‬ 0.003), telangiectatic phenotype (P < 0.001), high body mass index, and alcohol intake (P < 0.04). Previously described associations were confirmed and in particular the significant association between ␤-catenin-activated HCA and hepatocellular carcinomas (HCC) at diagnosis or during follow-up (P < 10 -5 ). Conclusion: We refined HCA classification and its phenotypic correlations, providing a routine test to classify hepatocellular adenomas using simple and robust immunohistochemistry. (HEPATOLOGY 2007;46:740-748.) H epatocellular adenomas (HCA) are rare benign liver tumors, most frequently occurring in women who are using oral contraception. Although HCA are mostly found as a single nodule, the presence of more than 10 in the liver indicates a specific nosological entity termed liver adenomatosis. 1 Two genetic alterations, the biallelic inactivation of hepatocyte nuclear factor 1 alpha (HNF1␣) and the activating mutation of ␤-catenin, have been described in HCA. 2,3 Recently, a comprehensive analysis of genetic, pathological, and clinical features in a series of 96 HCA enabled the identification of 4 HCA subtypes. 4 Biallelic HNF1␣ mutations defined the first group of HCA, phenotypically characterized by marked steatosis, lack of cytological abnormalities, and inflammatory infiltrates. Presence of a ␤-catenin-activating mutation defined the second group of HCA representing 15% of the cases generally characterized by a higher risk of malignant tr...

We took advantage of the reported genotype/phenotype classification to analyze our surgical series of hepatocellular adenoma (HCA). The series without specific known etiologies included 128 cases (116 women). The number of nodules varies from single, <5, and >5 in 78, 38, and 12 cases, respectively. The resection was complete in 95 cases. We identified 46 HNF1␣-inactivated HCAs (44 women), 63 inflammatory HCAs (IHCA, 53 women) of which nine were also ␤-catenin-activated, and seven ␤-catenin-activated HCAs (all women); six additional cases had no known phenotypic marker and six others could not be phenotypically analyzed. Twenty-three of 128 HCAs showed bleeding. No differences were observed in solitary or multiple tumors in terms of hemorrhagic manifestations between groups. In contrast, differences were observed between the two main groups. Steatosis (tumor), microadenomas (resected specimen), and additional benign nodules were more frequently observed in HNF1␣-inactivated HCAs (P < 0.01) than in IHCAs. Body mass index > 25, peliosis (tumor), and steatosis in background liver were more frequent in IHCA (P < 0.01). After complete resection, new HCAs in the centimetric range were more frequently found during follow-up (>1 year) in HNF1␣-inactivated HCA. After incomplete resection (HCA left in nonresected liver), the majority of HCA remained stable in the two main groups and even sometimes regressed. Six patients of 128 developed hepatocellular carcinoma (HCC) (all were ␤-catenin-activated, whether inflammatory or not). Conclusion: There were noticeable clinical differences between HNF1␣-inactivated HCA and IHCA; there was no increased risk of bleeding or HCC related to the number of HCAs; ␤-cateninactivated HCAs are at higher risk of HCC. As a consequence, we believe that management of HCA needs to be adapted to the phenotype of these tumors. (HEPATOLOGY 2009;50:481-489.)

Matrix metalloproteinase (MMP)-3 is a protease involved in cancer progression and tissue remodeling. Using immunofluorescence and immunoelectron microscopy, we identified nuclear localization of MMP-3 in several cultured cell types and in human liver tissue sections. Western blot analysis of nuclear extracts revealed two immunoreactive forms of MMP-3 at 35 and 45 kd, with the 35-kd form exhibiting caseinolytic activity. By transient transfection, we expressed active MMP-3 fused to the enhanced green fluorescent protein (EGFP/aMMP-3) in Chinese hamster ovary cells. We showed that EGFP/aMMP-3 translocates into the nucleus. A functional nuclear localization signal was demonstrated by the loss of nuclear translocation after site-directed mutagenesis of a putative nuclear localization signal and by the ability of the MMP-3 nuclear localization signal to drive a heterologous protein into the nucleus. Finally, expression by Chinese hamster ovary cells of EGFP/aMMP-3 induced a twofold increase of apoptosis rate, compared with EGFP/pro-MMP-3, which does not translocate to the nucleus. Increased apoptosis was abolished by site-directed mutagenesis of the catalytic site of MMP-3 or by using the MMP inhibitor GM6001. This study elucidates for the first time the mechanisms of nuclear localization of a MMP and shows that nuclear MMP-3 can induce apoptosis via its catalytic activity.

Growing evidence supports a role for the unfolded protein response (UPR) in carcinogenesis; however, the precise molecular mechanisms underlying this phenomenon remain elusive. Herein, we identified the circadian clock PER1 mRNA as a novel substrate of the endoribonuclease activity of the UPR sensor IRE1α. Analysis of the mechanism shows that IRE1α endoribonuclease activity decreased PER1 mRNA in tumor cells without affecting PER1 gene transcription. Inhibition of IRE1α signaling using either siRNA-mediated silencing or a dominant-negative strategy prevented PER1 mRNA decay, reduced tumorigenesis, and increased survival, features that were reversed upon PER1 silencing. Clinically, patients showing reduced survival have lower levels of PER1 mRNA expression and increased splicing of XBP1, a known IRE-α substrate, thereby pointing toward an increased IRE1α activity in these patients. Hence, we describe a novel mechanism connecting the UPR and circadian clock components in tumor cells, thereby highlighting the importance of this interplay in tumor development.

Regardless of the FNH size or steatotic content, GS produced a similar and characteristic pattern and consequently represents a good marker for easily identifying resected FNH from other hepatocellular nodules.

Phenotypic identification of focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) subtypes using immunohistochemical markers has been developed from their molecular characteristics. Our objective was to evaluate the sensitivity of these markers in the definitive diagnosis of these lesions by core needle biopsies. A total of 239 needle biopsies paired with their surgical resection specimen (group A) or without an associated resection specimen (group B) were reviewed. Using a step-by-step algorithm after standard staining, appropriate immunostaining analyses were performed to determine the certainty of diagnosis of FNH, HNF1α-inactivated HCA, inflammatory HCA, β-catenin-activated HCA, or unclassified HCA. The diagnosis of FNH was certain or probable on routine stains in 53% of needle biopsies of group A, whereas after glutamine synthetase staining, the diagnosis was certain in 86.7% as compared with 100% on the corresponding surgical specimen (P=0.04). In needle biopsies of group A, the diagnosis of HCA was certain on routine stains in 58.6% as compared with 94.3% on surgical specimens. After specific immunostaining, diagnosis was established on biopsies with 74.3% certainty, including all HCA subtypes, with similar distribution in surgical specimens. For each "certain diagnosis" paired diagnostic test (biopsy and surgical specimen), a positive correlation was observed (P<0.001). No significant difference was observed between groups A and B for FNH (P=0.714) or for HCA subtypes (P=0.750). Compared with surgical specimens, immunohistochemical analysis performed on biopsies allowed the discrimination of FNH from HCA and the identification of HCA subtypes with good performance.

In this review, the authors focus on the use of immunohistochemistry to characterize the different types and subtypes of benign hepatocellular nodules. They describe the classical and currently accepted features leading to the easy and formal diagnosis of focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA). In addition, they report some atypical features and difficulties in the interpretation of section staining analyses, which represent important parameters for pathologists. A significant contribution of molecular biology to the characterization of FNH has been to reclassify some cases of FNH as inflammatory HCA. Furthermore, the pattern of overexpression of glutamine synthetase (GS), a target gene of β-catenin has been successfully used to identify FNH by immunohistochemistry. Molecular approaches have demonstrated that HCA is a heterogeneous entity. Genotype classification of HCA has allowed the identification of three subtypes: HNF1A-mutated HCA (H-HCA) in 35% of cases, β-catenin-mutated HCA (b-HCA) in 10%, and inflammatory HCA (IHCA) in 55%. Following molecular data, the diagnosis of H-HCA relies on the lack of liver fatty acid binding protein (LFABP) immunostaining. The diagnosis of b-HCA is straightforward when GS is strongly and diffusely expressed by lesional hepatocytes, and is accompanied by nuclear β-catenin immunoreactivity. In IHCA, serum amyloid protein and C- reactive protein are strongly and usually diffusely expressed by tumoral hepatocytes with a sharp limit with the surrounding nontumoral liver. IHCA can also be β-catenin activated (10%). Due to the strong association of b-HCA with hepatocellular carcinoma transformation, the identification of this HCA subtype is extremely important.

Thrombin inhibition protects against liver fibrosis. However, it is not known whether the thrombin profibrogenic effect is due to effects on blood coagulation or to signaling via protease-activated receptors (PARs). We took advantage of the lack of blood coagulation defects in PAR-1-knockout mice. Acute carbon tetrachloride (CCl4) toxicity was similar in wild-type (WT), PAR-1−/−, and PAR-1+/−mice as judged by aminotransferase levels, area of liver necrosis, and liver peroxidation measured by Fourier-transformed infrared spectroscopy. Fifteen mice/group received CCl4or its solvent for 6 wk (300 μl/kg, 3 times a week). Fibrosis area was increased 10-fold by CCl4treatment in WT mice. PAR-1 deficiency protected against fibrosis, with 36% and 56% decrease in PAR-1+/−and PAR-1−/−mice, respectively ( P < 0.001). Similar results were obtained for area of activated fibrogenic cells (64% and 79% decrease in PAR-1+/−and PAR-1−/−mice, respectively, P < 0.001). These findings were corroborated by measurements of type I collagen, matrix metalloproteinase-2, and PDGF-β receptor mRNA levels. There was also a significant decrease in T lymphocyte infiltration in PAR-1-deficient mice. Altogether, these results suggest that thrombin profibrogenic effects are independent of effects on blood coagulation and are instead due to direct effects on fibrogenic cells and possibly on T lymphocytes.