Graham, Rondell P

AimActivation of PKR‐like endoplasmic reticulum kinase (PERK), an endoplasmic reticulum stress sensor, is a feature of non‐alcoholic steatohepatitis (NASH), yet regulators of PERK signaling remain undefined in this context. The protein p58IPK regulates PERK; however, its role in NASH has not been examined. The aim of this study was to assess the in vivo role of p58IPK in the pathogenesis of dietary NASH.MethodsParameters of hepatocyte cell death, liver injury, inflammation, fibrosis, indirect calorimetry and PERK activation were assessed in p58IPK knockout (p58ipk−/−) mice and their wild‐type littermate controls. All animals were fed a diet enriched in fat, fructose, and cholesterol (FFC) for 20 weeks.ResultsActivation of PERK was attenuated in FFC‐fed p58ipk−/− mice. Accordingly, FFC‐fed p58ipk−/− mice showed a reduction in hepatocyte apoptosis and death receptor expression, with a significant reduction in serum alanine transaminase values. Correspondingly, macrophage accumulation and fibrosis were significantly lower in FFC‐fed p58ipk−/− mice.ConclusionWe have shown that, in an in vivo dietary NASH model, p58IPK mediates hepatocyte apoptosis and liver injury, likely through PERK phosphorylation. In the absence of p58IPK, PERK phosphorylation and NASH are attenuated. Inhibition of hepatic p58IPK could be a future target for NASH therapy.

Fibrolamellar carcinomas are characterized by activation of protein kinase A, a kinase composed of catalytic and regulatory subunits. PRKACA encodes a catalytic subunit of protein kinase A, and almost all fibrolamellar carcinomas have a heterozygous 400‐kb deletion that leads to the fusion of DNAJB1 and PRKACA . The resulting DNAJB1‐PRKACA fusion transcript is believed to activate protein kinase A by dysregulation of the catalytic portion of the protein. In contrast, PRKAR1A encodes one of the regulatory subunits of protein kinase A. We hypothesized that loss of function of this regulatory unit could also lead to protein kinase A activation and thus to fibrolamellar carcinoma. Because PRKAR1A mutations underlie the Carney complex, we searched for liver tumors in individuals with the Carney complex. We identified 3 individuals with fibrolamellar carcinomas and a personal history of the Carney complex. All three tumors displayed the typical morphology of fibrolamellar carcinoma and were positive for arginase, cytokeratin 7, and cluster of differentiation 68. Fluorescence in situ hybridization was negative for PRKACA rearrangements. However, PRKAR1A sequencing identified pathogenic mutations in two of two cases with successful sequencing. In addition, all three cases were negative for PRKAR1A protein expression, consistent with inactivation of this key regulatory unit of protein kinase A. We also identified one additional fibrolamellar carcinoma in an individual without a documented history of the Carney complex who was negative for PRKACA rearrangements but had loss of PRKAR1A protein expression as well as PRKAR1A mutations. Conclusion : Fibrolamellar carcinoma can be part of the Carney complex; in this setting, fibrolamellar carcinomas have inactivating PRKAR1A mutations instead of the DNAJB1‐PRKACA fusion gene found in sporadic fibrolamellar carcinomas, providing an alternate means for activation of protein kinase A. (H epatology 2017).

AbstractThe Hippo pathway effector YAP is implicated in the pathogenesis of cholangiocarcinoma (CCA). The Hippo pathway relies on signaling cross talk for its regulation. Given the importance of platelet derived growth factor receptor (PDGFR) signaling in CCA biology, our aim was to examine potential YAP regulation by PDGFR. We employed human and mouse CCA specimens and cell lines for these studies. Initially, we confirmed upregulation of PDGFRβ and PDGFR ligands in human and mouse CCA specimens and cell lines. YAP, a transcriptional co‐activator, was localized to the nucleus in human CCA specimens and a cell line, as well as patient derived xenografts (PDX). PDGFR pharmacologic inhibition led to a redistribution of YAP from the nucleus to cytosol and downregulation of YAP target genes in a human CCA cell line. siRNA silencing of PDGFR‐β similarly downregulated YAP target genes. YAP activation (nuclear localization and target gene expression) was regulated by Src family kinases (SFKs) downstream of PDGFR. SFK activity resulted in phosphorylation of YAP on tyrosine357 (YAPY357). The importance of YAPY357 phosphorylation in regulating YAP activation was confirmed utilizing the SB‐1 cell line, a mouse cell line expressing YAP S127A precluding canonical serine phosphorylation. PDGFR inhibition decreased cellular abundance of the survival protein Mcl‐1, a known YAP target gene, and accordingly increased cell death in CCA cells in vitro and in vivo. These preclinical data demonstrate that a PDGFR‐SFK cascade regulates YAP activation via tyrosine phosphorylation in CCA. Inhibiting this cascade may provide a viable therapeutic strategy for this human malignancy.

BACKGROUNDThe cytologic features of undifferentiated pancreatic carcinoma with osteoclastic giant cells (UOC) are rarely described.METHODSCytologic and clinicopathologic characteristics in 15 UOC fine‐needle aspiration (FNA) specimens were analyzed.RESULTSFNA specimens were obtained from 6 men and 8 women with a mean age of 65 years who had UOCs (head, n = 7; body, n = 3; and tail, n = 4) with a mean radiologic size 7.3 cm, and some had a cystic component (n = 9). Three cell types (osteoclastic giant cells, pleomorphic tumor giant cells, and spindled/histiocytoid cells) were observed in 12 of 15 specimens (80%); and pancreatic ductal adenocarcinoma (PDAC) was present in 11 specimens. FNA diagnoses were UOC (n = 6), PDAC (n = 5), poorly differentiated carcinoma (n = 2), “suspicious for neoplasm” (n = 1), and “negative” (n = 1). Five of 5 specimens with osteoclastic giant cells were positive for cluster of differentiation 68 (CD68) (a glycoprotein that binds to low‐density lipoprotein). Pleomorphic tumor giant cells and spindled/histiocytoid cells were positive for pancytokeratin (6 of 7 specimens), CAM5.2 (2 of 3 specimens), and epithelial membrane antigen (2 of 2 specimens). INI‐1 protein expression was retained in 3 of 3 specimens. The Ki‐67 labeling index was assessed in 3 specimens and was 12%, 18%, and 40%; 4 of 12 resected UOCs were pure, and 8 were mixed with PDAC. One resection specimen had intraductal papillary mucinous neoplasm, and 2 had mucinous cystic neoplasms. The median overall survival (OS) of patients who had UOCs identified on FNA was 8 months (6 died [OS, 8 months; range, 2‐22 months], and 8 remained alive [OS, 3 months; range, 1‐27 months]), which was similar to the survival of 74 patients who had PDACs identified on FNA (OS, 15 months; P = .279) but worse than that of the 27 patients with UOCs who did not undergo FNA (OS, 92 months; P = .0135).CONCLUSIONSThe 3 classical UOC cell types are identifiable on FNA, making cytologic diagnosis possible if considered in the differential. A PDAC component is often also observed. The survival advantage of UOC over pure PDAC appears to be negated by FNA and requires further investigation. Cancer Cytopathol 2017;125:563–75. © 2017 American Cancer Society.

AimsMassive gastric polyposis is a rare entity that is often associated with juvenile polyposis syndrome (JPS). The aim of this study was to evaluate the clinicopathological features of 22 patients with abundant gastric juvenile‐type or hyperplastic‐like polyps.Methods and resultsThe study included 12 males and 10 females with a median age of 48 years (range: 13–79 years). Fourteen (64%) patients carried a diagnosis of JPS, and three had prior gastrointestinal adenocarcinomas. Patients without known JPS presented at an older median age (60 years versus 40 years; P = 0.0068). Clinical symptoms included nausea, vomiting, and abdominal pain; 23% of patients were asymptomatic. Eighteen cases showed complete or near‐complete carpeting of the gastric mucosa by innumerable polyps, ranging from a few millimetres to ~100 mm. Most polyps formed long, bulbous projections and had characteristic histological features, including a smooth outer contour, prominent stromal oedema, and widely spaced, often cystically dilated glands lined by foveolar epithelium; some polyps had less stroma and more hyperplastic foveolar epithelium. All had normal underlying or adjacent mucosa. Four (18%) cases harboured adenocarcinoma, and seven (32%) others showed dysplasia. SMAD4 immunohistochemical staining showed patchy loss in polyps from 19 of 20 cases tested. Five of six (84%) patients tested had a germline SMAD4 mutation.ConclusionsMassive gastric juvenile‐type polyposis can occur in patients with and without known JPS, and may mimic different conditions, such as other polyposis syndromes and Ménétrier disease. Pathologists play an important role in disease classification, as some patients lack a family or personal history of JPS, have few if any colonic polyps, and may not harbour diagnostic germline mutations.

AimsBiphenotypic sinonasal sarcoma (SNS) is a locally aggressive tumour that occurs in the sinonasal region. PAX3–MAML3 has recently been identified as a recurrent fusion gene event in this entity; however, a subset of tumours harbour alternative PAX3 rearrangement without the involvement of MAML3. In this study we sought to characterize the molecular profile of a large series of cases, with a special emphasis on tumours with alternative fusions.Methods and resultsForty‐four examples of SNS were screened by fluorescence in‐situ hybridization and reverse transcription polymerase chain reaction to better characterize its molecular profile and identify potential novel fusion genes. Twenty‐four were positive for PAX3–MAML3 (55%), 15 showed rearrangements of PAX3 without MAML3 involvement (34%), one showed rearrangement of MAML3 without PAX3 involvement, and four were negative for the involvement of either gene (9%). Among 15 cases with PAX3 involvement only, three were found to harbour PAX3–FOXO1. Two of these cases arose in the nasal cavities of female patients (aged 31 and 47 years), and one showed bilateral involvement of the nasal cavities of a 35‐year‐old male. A fourth case involved the skull base of a 47‐year‐old male, and was positive for PAX3–NCOA1. Patients with fusion‐negative tumours were slightly older.ConclusionMore than half of the SNSs in this series were positive for PAX3–MAML3. However, a subset of tumours may harbour alternative PAX3 fusion genes or show no involvement of PAX3. Except for a possible weak association between age and molecular profile, the overall morphological and immunophenotypic features of all cases seem to be similar. Because of the rarity of these tumours, the impact of the molecular profile on the clinical course of these tumours remains to be determined.

AimsFibrolamellar carcinoma is characterized by a recurrent DNAJB1–PRKACA chimeric transcript. The functional properties of the fusion are unknown, but are believed to include PRKACA up‐regulation. PRKCA is a subunit of protein kinase A. The downstream targets of protein kinase A are unknown, but may include interactions with fibroblast growth factor receptor (FGFR) pathways. In addition, inhibitors for FGFR proteins have been developed recently.Methods and resultsNineteen histologically confirmed fibrolamellar carcinomas were studied. All showed the characteristic DNAJB1–PRKACA transcript by reverse transcription–polymerase chain reaction (RT–PCR). Immunohistochemistry for FGFR1 was negative in 19 of 19 cases using a monoclonal antibody, while a polyclonal antibody showed no expression (n = 11) or weak and focal expression (n = 8). RNAin‐situ hybridization was 2+ in two cases, 1+ in four cases and negative in four cases. FGFR1 fluorescence in‐situ hybridization (FISH) revealed polysomy of chromosome 8 in 17 of 19 cases. Break‐apart FISH for FGFR2 was negative for rearrangements in 12 of 12 informative cases.ConclusionsFibrolamellar carcinomas show polysomy of chromosome 8 and the FGFR1 locus, and only modest mRNA expression and weak or absent expression at the protein level. FGFR2 rearrangement was not detected. These data reduce the likelihood that FGFR inhibitors will be effective in the treatment of most fibrolamellar carcinomas.