Hepatocellular adenomas (HCA) are benign liver tumors predominantly developed in women using oral contraceptives. Here, exome sequencing identified recurrent somatic FRK mutations that induce constitutive kinase activity, STAT3 activation, and cell proliferation sensitive to Src inhibitors. We also found uncommon recurrent mutations activating JAK1, gp130, or β-catenin. Chromosome copy number and methylation profiling revealed patterns that correlated with specific gene mutations and tumor phenotypes. Finally, integrative analysis of HCAs transformed to hepatocellular carcinoma revealed β-catenin mutation as an early alteration and TERT promoter mutations as associated with the last step of the adenoma-carcinoma transition. In conclusion, we identified the genomic diversity in benign hepatocyte proliferation, several therapeutic targets, and the key genomic determinants of the adenoma-carcinoma transformation sequence.

We found that spadin, a natural peptide derived from sortilin, blocks the mouse TREK-1 channel and might be an efficient and fast-acting antidepressant.

e ATF6␣, a membrane-anchored transcription factor from the endoplasmic reticulum (ER) that modulates the cellular response to stress as an effector of the unfolded-protein response (UPR), is a key player in the development of tumors of different origin. ATF6␣ activation has been linked to oncogenic transformation and tumor maintenance; however, the mechanism(s) underlying this phenomenon remains elusive. Here, using a phenotypic small interfering RNA (siRNA) screening, we identified a novel role for ATF6␣ in chemoresistance and defined the protein disulfide isomerase A5 (PDIA5) as necessary for ATF6␣ activation upon ER stress. PDIA5 contributed to disulfide bond rearrangement in ATF6␣ under stress conditions, thereby leading to ATF6␣ export from the ER and activation of its target genes. Further analysis of the mechanism demonstrated that PDIA5 promotes ATF6␣ packaging into coat protein complex II (COPII) vesicles and that the PDIA5/ATF6␣ activation loop is essential to confer chemoresistance on cancer cells. Genetic and pharmacological inhibition of the PDIA5/ATF6␣ axis restored sensitivity to the drug treatment. This work defines the mechanisms underlying the role of ATF6␣ activation in carcinogenesis and chemoresistance; furthermore, it identifies PDIA5 as a key regulator ATF6␣-mediated cellular functions in cancer. P rotein folding in the endoplasmic reticulum (ER) can be particularly affected by the presence of mutations in secretory proteins or by dynamic changes in the cellular microenvironment, events which are often encountered in cancers. In the ER, these events are sensed by specific sensors, which in turn trigger select signaling pathways, collectively named the unfolded-protein response (UPR) (1). The UPR is an adaptive response that allows the cells to either overcome the stress or promote cell death in the case of overwhelming burden (1). Three ER-resident proteins, namely, the protein kinase PKR-like ER kinase (PERK), the inositol-requiring protein 1 alpha (IRE1␣), and the activating transcription factor 6 alpha (ATF6␣), have been identified as the major transducers of the UPR in mammals. They display an ER luminal domain that senses misfolded proteins and are activated by a common mechanism involving the dissociation of the ER chaperone BiP/GRP78. PERK is responsible for translational attenuation through the phosphorylation of the alpha subunit of the eukaryotic translation initiation factor 2 (eIF2␣) (2). IRE1␣ mediates the unconventional splicing of X-box binding protein 1 (Xbp1) mRNA (3) as well as mRNA expression levels through regulated IRE1␣-dependent mRNA decay (RIDD) (4) and controls the activation of the c-jun N-terminal kinase (JNK) pathway. The third arm of the UPR is controlled by ATF6␣. This membrane-anchored transcription factor is a type II transmembrane protein regulated by intramembrane proteolysis by the Golgi apparatuslocalized site 1 and site 2 proteases (S1P and S2P) upon ER stress (5). Indeed, upon ER stress, BiP dissociates from the luminal domain of ATF6␣, thereby unmaski...

Neisseria meningitidis is a cause of meningitis epidemics worldwide and of rapidly progressing fatal septic shock. A crucial step in the pathogenesis of invasive meningococcal infections is the adhesion of bloodborne meningococci to both peripheral and brain endothelia, leading to major vascular dysfunction. Initial adhesion of pathogenic strains to endothelial cells relies on meningococcal type IV pili, but the endothelial receptor for bacterial adhesion remains unknown. Here, we report that the immunoglobulin superfamily member CD147 (also called extracellular matrix metalloproteinase inducer (EMMPRIN) or Basigin) is a critical host receptor for the meningococcal pilus components PilE and PilV. Interfering with this interaction potently inhibited the primary attachment of meningococci to human endothelial cells in vitro and prevented colonization of vessels in human brain tissue explants ex vivo and in humanized mice in vivo. These findings establish the molecular events by which meningococci target human endothelia, and they open new perspectives for treatment and prevention of meningococcus-induced vascular dysfunctions.

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.

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.

We propose that overweight/obesity may soon represent a major risk of malignant transformation of HCA, possibly via the IL-6 pathway.

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