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A E Sirica

Publications and source records attributed to A E Sirica.

At least 19 recordsLinked to original sources
PubMed2001

Biliary cancer growth factor pathways, cyclo-oxygenase-2 and potential therapeutic strategies.

Cholangiocarcinoma is a hepatic biliary cancer of high morbidity and mortality, whose molecular pathogenesis is unknown. However, there is increasing evidence to suggest that alterations in selected growth factor pathways, including an overexpression of the growth factor receptor tyrosine kinases c-ErbB-2/c-Neu and c-Met, together with possible aberrant autocrine expression of hepatocyte growth factor/scatter factor, the ligand for c-Met, may be playing important roles associated with the development of cholangiocarcinoma in both the human liver and in the furan rat model of cholangiocarcinogenesis. Cyclo-oxygenase-2, whose regulation has been experimentally related to c-ErbB-2/c-Neu as well as to hepatocyte growth factor/scatter factor, and which has been demonstrated to be overexpressed in other cancers of the gastrointestinal tract, has also been observed in preliminary studies to be upregulated in human biliary cancers and in cholangiocarcinoma induced in the furan rat model. Moreover, new data from our laboratory have demonstrated the cyclo-oxygenase-2 inhibitor NS-398 to produce a significant dose-dependent growth inhibition of rat cholangiocarcinoma cells in vitro, as well as to suppress anchorage-independent growth of these cells in soft agar. Based on the data reviewed, we propose that the selective therapeutic targeting of aberrant growth factor receptor tyrosine kinase signaling and of cyclo-oxygenase-2, alone or in combination, has potential to become a useful new approach for the treatment and/or chemoprevention of cholangiocarcinoma. We further propose that the furan rat model may serve as a powerful preclinical model for testing therapeutic and chemopreventative strategies that selectively target c-ErbB-2/c-Neu, cyclo-oxygenase-2, and/or autocrine hepatocyte growth factor/c-Met, aberrantly expressed in cholangiocarcinogenesis.

Animals↗
PubMed2000

Expression of an intestine-specific transcription factor (CDX1) in intestinal metaplasia and in subsequently developed intestinal type of cholangiocarcinoma in rat liver.

CDX1 is a caudal-type homeobox intestine-specific transcription factor that has been shown to be selectively expressed in epithelial cells in intestinal metaplasia of the human stomach and esophagus and variably expressed in human gastric and esophageal adenocarcinomas (Silberg DG, Furth EE, Taylor JK, Schuck T, Chiou T, Traber PG: Gastroenterology 1997, 113: 478-486). Through the use of immunohistochemistry and Western blotting, we investigated whether CDX1 is also uniquely associated with the intestinal metaplasia associated with putative precancerous cholangiofibrosis induced in rat liver during furan cholangiocarcinogenesis, as well as expressed in neoplastic glands in a subsequently developed intestinal type of cholangiocarcinoma. In normal, control adult rat small intestine, specific nuclear immunoreactivity for CDX1 was most prominent in enterocytes lining the crypts. In comparison, epithelium from intestinal metaplastic glands within furan-induced hepatic cholangiofibrosis and neoplastic epithelium from later developed primary intestinal-type cholangiocarcinoma each demonstrated strong nuclear immunoreactivity for CDX1. CDX1-positive cells were detected in hepatic cholangiofibrotic tissue as early as 3 weeks after the start of chronic furan treatment. We further determined that the percentages of CDX1-positive neoplastic glands and glandular nuclei are significantly higher in primary tumors than in a derived, transplantable cholangiocarcinoma serially-propagated in vivo. Western blotting confirmed our immunohistochemical results, and no CDX1 immunoreactivity was detected in normal adult rat liver or in hyperplastic biliary epithelial cells. These findings indicate that CDX1 is specifically associated with early intestinal metaplasia and a later developed intestinal-type of cholangiocarcinoma induced in the liver of furan-treated rats.

Animals↗
PubMed2000

Unique epithelial cell production of hepatocyte growth factor/scatter factor by putative precancerous intestinal metaplasias and associated "intestinal-type" biliary cancer chemically induced in rat liver.

Recently, we observed that Met, the receptor for hepatocyte growth factor/scatter factor (HGF/SF), is overexpressed in epithelial cells of both early-appearing intestinal metaplastic glands in precancerous hepatic cholangiofibrotic tissue and neoplastic glands in later developed intestinal-type of cholangiocarcinoma originated from the furan rat model of cholangiocarcinogenesis when compared with normal and hyperplastic intrahepatic biliary epithelia. We now show that HGF/SF is also aberrantly expressed in a manner closely paralleling that of its receptor in the neoplastic epithelial cells of furan-induced rat cholangiocarcinomas and in a majority of metaplastic epithelial cells within earlier formed precancerous hepatic cholangiofibrotic tissue. Using in situ hybridization and reverse transcription-polymerase chain reaction (RT-PCR), we further showed specific expression of HGF/SF messenger RNA (mRNA) in a novel rat cholangiocarcinoma epithelial cell line overexpressing Met. This cholangiocarcinoma cell line, termed C611B, was established from tumorigenic cells isolated from a furan-induced transplantable tumor. Moreover, we detected by in situ hybridization strong expression of HGF/SF mRNA transcripts in the cancerous epithelial glands of cholangiocarcinoma developed in recipient rats after in vivo cell transplantation of C611B cells. In contrast, mRNA transcripts and protein immunoreactivity for this cytokine were not detected in hepatocytes and biliary epithelial cells in adult normal rat liver nor in rat hyperplastic intrahepatic biliary epithelium. Our results clearly show that HGF/SF becomes aberrantly expressed in cholangiocarcinoma epithelium and in putative precancerous intestinal metaplastic epithelium induced in the liver of furan-treated rats.

Animals↗
PubMed1999

Overexpression of C-NEU and C-MET during rat liver cholangiocarcinogenesis: A link between biliary intestinal metaplasia and mucin-producing cholangiocarcinoma.

Based on limited but compelling immunohistochemical data demonstrating individual overexpression of the tyrosine kinase growth factor receptors, c-erbB-2 and c-met, in significant percentages of human cholangiocarcinoma (ChC), we investigated if combined overexpression of both c-neu, the rat homologue of c-erbB-2, and c-met, the receptor for hepatocyte growth factor/scatter factor (HGF/SF), might represent a characteristic, early event associated with furan-induced cholangiocarcinogenesis in rat liver. Specifically, through the use of immunohistochemistry, in situ hybridization (ISH), and Western and Northern blotting, we found that both c-neu and c-met are prominently overexpressed in intestinal metaplastic lesions in early putative precancerous cholangiofibrotic tissue formed in the livers of rats after 6 weeks of furan treatment when compared with normal and hyperplastic intrahepatic biliary epithelia. We further demonstrated that c-neu and c-met are concordantly overexpressed in neoplastic glandular epithelia in later-developed primary "intestinal-type" of ChC formed in the livers of furan-treated rats, as well as in subsequently derived transplantable mucin-producing tumors. Overexpression of c-neu and c-met correlated with increased proliferating cell nuclear antigen (PCNA)-labeling indices, which were determined to be three to four times higher in intestinal metaplastic glands in precancerous cholangiofibrotic tissue and in neoplastic glands in the primary "intestinal type" of ChC than in hyperplastic bile ductular structures within either cholangiofibrotic or bile duct-ligated (BDL) livers. The c-neu and c-met receptor proteins overexpressed in different in vivo passages of a transplantable ChC each contained immunoreactive phosphotyrosines, indicating an activated state. However, we did not detect evidence of either gene amplification of c-neu or c-met or of a common transmembrane-activating mutation in c-neu expressed in transplantable ChC. Our findings indicate that altered expression of c-neu and c-met occurs relatively early in the process of furan-induced cholangiocarcinogenesis in rat liver and may play a potentially important role in its pathogenesis. They further indicate a common alteration in tyrosine kinase growth factor receptor expression linking early putative precancerous intestinal metaplastic lesions in liver to later-developed mucin-producing biliary cancer.

Animals↗
PubMed1999

Establishment of a novel rat cholangiocarcinoma cell culture model.

Furan cholangiocarcinogenesis in rat liver is proving to be a unique and useful animal model for investigating important aspects of the cellular and molecular pathogenesis of cholangiocarcinoma potentially relevant to the human disease. We now describe the first culture model of rat cholangiocarcinoma cells derived from a transplantable cholangiocarcinoma originally induced in the liver of a furan-treated rat. An epithelial cell isolate highly enriched in viable cholangiocarcinoma cells was consistently obtained from transplantable cholangiocarcinoma tissue utilizing a similar procedure to that recently developed by us to establish a new rat hyperplastic bile ductular epithelial cell culture model characterized by the appearance of polarized bile ducts in vitro. Primary cholangiocarcinoma cell cultures could be readily established with these isolated cells and, in addition, we established from one such culture a novel rat cholangiocarcinoma cell line designated C611B. Cultured C611B cholangiocarcinoma cells retained a number of important characteristic features of the carcinoma cells of the parent tumor, including marked expression of the tyrosine kinase growth factor receptor proteins c-Met and c-Neu. Under basal culture conditions, the C611B cell line exhibited a cell doubling time of approximately 24 h and was aneuploid, with a predominant chromosomal count of 43. Moreover, C611B cells on collagen gels were 100% tumorigenic when transplanted into inguinal fat pads of syngeneic rats. All tumors formed at the transplantation site were cytokeratin 19-positive, mucin-producing tubular adenocarcinomas whose histological and phenotypic features closely resembled those of the furan-induced parent transplantable rat cholangiocarcinoma. Based on our findings, we believe that this novel rat cholangiocarcinoma cell culture model can serve as a valuable resource for investigating aberrant growth properties and tumor progression in biliary cancer.

Animals↗
PubMed1998

Immunohistochemical demonstration of MET overexpression in human intrahepatic cholangiocarcinoma and in hepatolithiasis.

Expression of MET, the c-met-encoded receptor for hepatocyte growth factor, has not been investigated in proliferative biliary diseases of human liver, including hepatolithiasis and cholangiocarcinoma. Comparatively, we analyzed by immunohistochemistry the expression of MET in normal adult human livers (n = 20), normal postnatal preadult livers (n = 21), fetal livers (n = 36), hepatolithiatic livers (n = 32), and intrahepatic cholangiocarcinomas (n = 26). In normal adult livers, obvious MET immunoreactivity was not found in any cell types. In fetal liver, MET was weakly expressed in primitive biliary cells (ductal plate and immature bile ducts) and immature hepatocytes during 8 to 30 gestational weeks but was essentially negative thereafter. In hepatolithiasis, a condition of risk for cholangiocarcinoma development, MET was overexpressed in proliferated biliary cells in 26 of 32 cases (81%). In this nonneoplastic proliferative biliary condition, MET immunoreactivity was observed to be most prominent in the hyperplastic septal and large bile ducts of liver, and in the proliferated peribiliary glands associated with intrahepatic large bile ducts. In intrahepatic cholangiocarcinoma, MET overexpression in neoplastic biliary epithelium was observed in 15 of 26 cases (58%) and correlated with the degree of tumor differentiation, being highest in well-differentiated tumors and relatively low in poorly differentiated tumors. These data show for the first time that overexpression of MET is a common feature of hyperplastic and neoplastic biliary epithelial cells in human liver and suggest that MET/hepatocyte growth factor may be playing an important role in human biliary hyperplasia and in cholangiocarcinogenesis in vivo.

Adult↗
PubMed1997

A new rat bile ductular epithelial cell culture model characterized by the appearance of polarized bile ducts in vitro.

The rat treated with bile duct ligation (BDL) and furan is a unique animal model of massive bile ductular hyperplasia in which normal liver parenchyma is largely replaced with well-differentiated proliferated bile ductules. We have now developed a simple cell isolation procedure to obtain and culture viable bile ductular epithelial cells in high numbers and with a high degree of purity from the livers of BDL/furan-treated rats. Primary monolayer cell cultures were readily established when the isolated bile ductular epithelial cells were cultured in plastic tissue culture wells coated with rat tail tendon type I collagen plus bovine plasma fibronectin. Under these conditions, epidermal growth factor (EGF) was mitogenic for the cultured cells, and they retained phenotypic features typical of hyperplastic bile ductular epithelium but did not show evidence of ductal morphogenesis in vitro. In contrast, when the isolated bile ductular cells were cultured for 7 to 16 days in the presence of 25 ng EGF/mL and 10% fetal bovine serum on type I collagen gels, they formed into branching ductal structures whose ultrastructural features very closely resembled those of polarized hyperplastic bile ductules/ducts in vivo. Histological preparations of these gel cultures further showed that numerous ductal structures with defined lumens were present. Phenotypically, these ductal structures were completely surrounded by a thickened basement membrane that was strongly immunoreactive for laminin. Like their in vivo biliary cell counterparts, the epithelial cells comprising these ductal structures in culture also exhibited strong immunocytochemical staining reactions for cytokeratins 8 and 19, for glutathione S-transferase pi 7, and for luminal gamma-glutamyl transpeptidase, but they did not express immunoreactive albumin or alpha-fetoprotein. Occasional epithelial cells of the ductal structures, when examined in 10-day-old primary gel culture, showed strong nuclear staining for incorporated 5-bromo-2'deoxyuridine, indicating active cell proliferation. Our results support the development of a novel biliary epithelial cell culture model that has the potential of serving as a powerful tool for investigation of factors that regulate hyperplastic bile ductular morphogenesis, cell proliferation, and polarized cell functions in a structural form in vitro that mimics that of hyperplastic bile ductules induced in vivo.

Animals↗
PubMed1997

NEU overexpression in the furan rat model of cholangiocarcinogenesis compared with biliary ductal cell hyperplasia.

Immunohistochemical studies have suggested that the tyrosine kinase growth factor receptor p185neu is overexpressed in a high percentage of human cholangiocarcinomas. To establish the specificity and temporal relationship between the expression of this receptor in cholangiocarcinogenesis, we investigated c-neu expression in precancerous cholangiofibrotic tissue and subsequently derived primary and transplantable cholangiocarcinomas originated in the livers of furan-treated rats. Proliferated bile ductules formed in rat models of bile ductular hyperplasia and the cell types of normal adult rat liver were also analyzed for c-neu expression. c-neu expression was not detected in normal adult rat liver by either Western blotting, immunohistochemistry, or in situ hybridization. In comparison, all of the cholangiocarcinomas analyzed, which were characterized by intestinal-type mucin-producing neoplastic glands, exhibited a prominent band with a molecular weight 185 kd, corresponding to p185neu. Only the neoplastic glandular epithelia of the cholangiocarcinomas showed a strong immunoreactivity for p185neu, which was predominantly localized to their cell surface but also observed cytoplasmically. In situ hybridization further revealed the cytoplasm of the tumor glandular epithelial cells to be strongly positive for c-neu mRNA transcripts. Of particular interest was our finding that c-neu is expressed early in furan cholangiocarcinogenesis, being more pronounced in the metaplastic intestinal glands of cholangiofibrotic tissue than in hyperplastic biliary epithelial cells in either the same tissue or in hyperplastic bile ductule tissue. Our results demonstrate that c-neu overexpression is a prominent feature of intestinal-type cholangiocarcinomas as well as of metaplastic intestinal glands that precede their development and is detected at lower levels in hyperplastic biliary epithelia. The overexpression of c-neu in the metaplastic and malignant neoplastic glands also correlated with their increased proliferating cell nuclear antigen (PCNA) labeling indices relative to those of hyperplastic biliary ducts and ductules and also appeared to correlate with their intestinal glandular pattern of differentiation.

Adenoma, Bile Duct↗
PubMed1995

Ductular hepatocytes.

Ductular hepatocytes are observed in the livers of both experimental animals and man under various conditions of severe toxin-, carcinogen- or viral-induced hepatic injury with prominent loss of parenchymal hepatocytes. These unique hepatic epithelial cells are characterized by phenotypic traits that are intermediate between those of hepatocytes and intrahepatic biliary epithelium. The origin of ductular hepatocytes is controversial, but it has been hypothesized that they may represent a transitional cell stage associated with either (1) a ductular metaplasia of parenchymal hepatocytes into intrahepatic biliary epithelium, (2) a metaplastic conversion of intrahepatic bile duct or ductular epithelium into hepatocytes, or (3) differentiation of a putative liver stem cell along the hepatocyte lineage. Depending on the liver disease state being investigated, evidence is presented to support all three of these possibilities. Of particular interest is the increasing evidence supporting the existence of a facultative pluripotent stem-like cell associated with the intrahepatic biliary tract, which appears capable of differentiating into various gut endoderm-derived cell types, including hepatocytes, small intestinal mucosal cells, and pancreatic acinar cells. Ductular cells of pancreas have also been demonstrated to alter their differentiation commitment under various induced conditions of pancreatic injury and regeneration, so as to give rise to pancreatic hepatocytes. The presence of a putative stem-like cell in liver together with the plasticity exhibited by some hepatocytes and biliary epithelial cells in various forms of severe hepatic and biliary tract injury can have important implications for carcinogenesis and aberrant regenerative responses in liver. In addition, novel in vivo and cell culture models have been developed, which are serving as potentially powerful tools for investigating the effects of specific growth factors, extracellular matrix components, hormones and other agents on the ability of nonparenchymal epithelial liver cell types to differentiate into hepatocyte-like cells.

Animals↗
PubMed1994

Ductular hepatocytes. Evidence for a bile ductular cell origin in furan-treated rats.

Cholangiolar-like structures composed of biliary epithelial cells and typically a single ductular hepatocytic cell in various stages of maturation appeared in association with an extensive bile ductular reaction within the atrophied right liver lobe of young adult Fischer 344 rats that had been subjected to a severely hepatotoxic treatment with furan. In contrast to normal cholangioles, these cholangiolar-like structures were completely surrounded by a basement membrane, which gave strong immunohistochemical staining reactions for both laminin and type IV collagen. All of the biliary epithelial cells and ductular hepatocytic cells exhibited a strongly positive immunohistochemical staining for gamma-glutamyl transpeptidase and for cytokeratin 8. Cytokeratin 19 was also strongly expressed in all of the biliary epithelial cells, but in just some of the ductular hepatocytic cells, whereas only the latter cells were immunohistochemically positive for albumin and contained peroxisomes in their cytoplasm. Cell junctions were formed between individual ductular hepatocytic cells and adjacent biliary epithelial cells of the same cholangiolar-like structures. In this novel model of severe hepatic injury, the range of cell and nuclear diameters characterizing the ductular hepatocytic cells, together with their phenotypic features, are consistent with a differentiation of rare bile ductular-like cells to transitional ductular cells to more mature ductular hepatocytes.

Animals↗
PubMed1994

A unique rat model of bile ductular hyperplasia in which liver is almost totally replaced with well-differentiated bile ductules.

A novel rat model was developed in which furan combined in a unique synergistic manner with bile duct ligation to induce replacement of most of liver with well-differentiated hyperplastic bile ductules. Multiple tissue sections of liver from Fischer 344 male rats first subjected to a bile duct ligation and 1 week later given furan by gavage at 45 mg/kg body weight, once a day, five times weekly for 5 to 6 weeks, exhibited a mean percent of bile ductule tissue per total liver section area of 72.6 +/- 16.3% compared to control values of 20.0 +/- 4.2% for bile duct-ligated rats that received corn oil by gavage instead of furan and 11.9 +/- 3.1% for rats that were given a sham operation followed by furan. This dramatic difference was also reflected by the very high mean gamma-glutamyl transpeptidase specific activity of liver homogenates from the bile duct-ligated/furan-treated rats, which was approximately 8 x 10(3) nmoles p-nitroaniline/mg protein/hour versus values of approximately 2 x 10(3) for bile duct-ligated/corn oil control, approximately 1 x 10(3) for sham-operated/furan-treated control, and 44.9 for untreated rat. The data presented support a potentially powerful experimental model for investigating bile ductular cell functions, differentiation, and proliferation.

Animals↗
PubMed1993

"Intestinal-type" of adenocarcinoma preferentially induced in right/caudate liver lobes of rats treated with furan.

Short-term chronic exposures of rats to furan were recently found by us to preferentially induce a unique liver lobe pattern of development of small intestinal metaplasia and subsequent cholangiofibrosis, being essentially localized to the caudate and right liver lobes (L. W. Elmore, and A. E. Sirica, Cancer Res., 51: 5752-5759, 1991). We now demonstrate the preferential development of primary hepatic adenocarcinomas exhibiting small intestine mucosal cell differentiation, which have arisen at 70 to 90% incidences from the right/caudate liver lobes of Fischer 344 adult male rats by 16 months after their receiving furan by gavage at a daily dose of 30 mg/kg of body weight, five times a week, for 9, 12, and 13 weeks, respectively. In contrast, the incidences of primary hepatocellular carcinomas that developed in the furan-treated rats ranged from 0 to 20%, with the two hepatocellular carcinomas observed to be originating from the median/left liver lobes. Twenty-six of 27 hepatic adenocarcinomas analyzed exhibited glands containing on average 30.2% goblet cells, 2.1% Paneth cells, and 0.5% serotonin-positive neuroendocrine cells. Phenotypically, the glandular epithelial cells of the furan-induced intestinal-type adenocarcinomas were immunohistochemically positive for cytokeratin 19, but exhibited a heterogeneous pattern of immunohistochemical staining for gamma-glutamyl transpeptidase and showed no detectable immunostaining for transforming growth factor alpha. In addition, many of the glandular structures within these primary hepatic adenocarcinomas showed evidence of basement membrane disruption, as demonstrated by both electron microscopy and immunohistochemical staining for basement membrane laminin. While these intestinal-type adenocarcinomas appeared to have spread intrahepatically, none showed evidence of extrahepatic metastases. However, six of eight randomly selected adenocarcinomas grew progressively and retained their intestinal pattern of differentiation following serial transplantation into the fat pads of young adult Fischer 344 recipient rats. In this study, we also observed one primary hepatic cholangiocarcinoma that was characterized by a more native biliary rather than intestinal-type of differentiation. Interestingly, this was the only primary liver cancer observed by us to exhibit extrahepatic metastasis. In conclusion, our current findings clearly indicate that the small intestinal metaplasia and subsequent cholangiofibrosis developing early in the right/caudate liver lobes of furan-treated rats do not simply reflect reactive changes, but strongly correlate with the high incidences of intestinal-type of primary hepatic adenocarcinoma that occurs in the right/caudate liver lobes of rats after long-term exposures to furan.

Adenocarcinoma↗
PubMed1992

Appearance of ductular hepatocytes in rat liver after bile duct ligation and subsequent zone 3 necrosis by carbon tetrachloride.

Intrahepatic biliary cell plasticity was investigated in a rat model that combined prior bile ductular cell hyperplasia after bile duct ligation with subsequent CCl4-induced hepatonecrosis. Morphometric analysis of histologic liver sections from rats at 4 to 6 weeks after bile duct ligation and 3 to 5 days after CCl4 demonstrated the total section area to be occupied by near-equal amounts of hyperplastic bile ductular tissue area and hepatonecrotic area. Of particular significance was the unique presence, albeit infrequent, of newly appearing hepatic cell cholangioles composed of both biliary epithelial cells and one or more 'ductular hepatocytes' exclusively within the hyperplastic bile ductular tissue area of liver sections from the bile-duct-ligated/CCl4-treated rats, but not observed in control liver sections. This finding is compatible with the possibility of a 'transdifferentiation' of some hyperplastic biliary epithelial cells into 'ductular hepatocytes' in response to an extreme hepatic injury.

Animals↗
PubMed1992

Sequential appearance of intestinal mucosal cell types in the right and caudate liver lobes of furan-treated rats.

Furan rapidly induces in rat liver a unique, lobe-specific pattern of development of intestinal metaplasia and associated cholangiofibrosis. To establish early cell-precursor relationships in the genesis of this cholangiofibrosis, a time-course study was conducted in which young adult male Fisher 344 rats received furan by gavage at a daily dose of 45 mg/kg body wt over a 32-day treatment period. An analysis of individual liver lobes obtained at different time points from these animals during furan treatment revealed the following sequence of histopathological changes, which were located mainly in the right and, to a lesser extent, the caudate liver lobes: day 1, severe hepatonecrosis in zone 3 extending into zone 2 of the liver acini; days 3 to 5, presence of a diffuse inflammatory cell infiltrate in hepatonecrotic areas, which gradually resolved; day 7, prominent bile ductule hyperplasia in tissue sections exhibiting marked loss of normal liver parenchyma; day 9, continued replacement of injured liver by hyperplastic bile ductule tissue, which now contained occasional metaplastic glandular structures composed of columnar basophilic epithelial cells; days 12 to 16, increasing cell diversity in the developing metaplastic glands, with the sequential appearance of goblet cells, Paneth cells and serotonin-positive neuroendocrine cells; and day 32, typical cholangiofibrosis defined by hyperplastic bile ductule-type structures in association with an increased number of metaplastic intestinal glands and progressively more dense fibrotic stroma. Interestingly, at 16 and 32 days the cellular composition of the newly formed metaplastic intestinal glands in liver closely resembled that of the crypts of Lieberkühn in the normal adult rat small intestine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Phenotypic characterization of metaplastic intestinal glands and ductular hepatocytes in cholangiofibrotic lesions rapidly induced in the caudate liver lobe of rats treated with furan.

In order to investigate the early cellular changes in liver associated with furan cholangiocarcinogenesis, young adult male Fischer 344 rats were administered furan by gavage once a day, 5 days a wk for 2 to 3 wk at doses ranging from 15 to 60 mg/kg of body weight per day. The most conspicuous feature observed in the liver of animals receiving the higher doses of furan was a rapidly developed cholangiofibrosis characterized by the presence of bile ductular hyperplasia, intestinal metaplasia, and fibrosis. Moreover, this lesion was found to be almost exclusively localized to the caudate liver lobe, which by morphometric analysis was further determined to be largely replaced by cholangiofibrotic tissue. Both the hyperplastic bile ductular epithelial cells and the intestinal-like epithelial cells in these areas selectively exhibited a strongly positive immunohistochemical staining for cytokeratin 19 and were supported by well-developed basement membranes enriched in both laminin and type IV collagen. However, in contrast to the hyperplastic bile ductules, electron microscopy of the metaplastic intestinal glands revealed them to be composed mostly of columnar epithelial cells with well-developed striated borders, less numerous mucin-secreting goblet cells, and occasional neuroendocrine-like cells, thus closely resembling in their cellular composition that of intestinal mucosa. These metaplastic glands also showed a more heterogeneous pattern of staining for both gamma-glutamyl transpeptidase and the placental form of glutathione S-transferase than did the hyperplastic bile ductules. At the 60-mg/kg/day furan dose, cholangiolar-like structures composed of biliary epithelial cells and ductular hepatocytic cells at different stages of morphological differentiation were also observed. Phenotypically, the biliary epithelial and "ductular hepatocytes" of these cholangioles shared a common basement membrane containing laminin and type IV collagen, as well as a luminal plasma membrane gamma-glutamyl transpeptidase. On the other hand, only the biliary epithelial cells of the newly appearing mixed cell cholangioles stained positive for cytokeratin 19. Interestingly, unlike hepatocarcinogen-induced oval cells, alpha-fetoprotein expression was not detected in any of the cell types comprising the furan-induced cholangiofibrotic tissue. These results support a novel in vivo model for investigating cell lineages in the development in liver of intestinal metaplasia, "ductular hepatocytes," and cholangiofibrosis in relation to intrahepatic cholangiocarcinogenesis.

Adenoma, Bile Duct↗
PubMed1991

Expression of multiple proteins structurally related to gamma-glutamyl transpeptidase in non-neoplastic adult rat hepatocytes in vivo and in culture.

Freshly isolated hepatocytes from normal adult rat liver do not express measurable gamma-glutamyl transpeptidase (GGT) mRNA in contrast to the significant GGT mRNA levels expressed by normal adult rat kidney and hyperplastic bile ductular tissue from bile duct-ligated rats. However, the induction of GGT activity in rat hepatocytes by two-thirds hepatectomy was accompanied by the appearance of a high level of GGT mRNA. We are now able to demonstrate that normal adult rat hepatocytes express 5 protein bands which cross-react with 2 different anti-rat kidney GGT antisera. The apparent molecular weights were 26.9, 58.0, 63.9, 73.5, and 83.4 kDa, respectively. Expression of the 26.9- and 58.0-kDa proteins strikingly parallels the pattern of induction of GGT enzymatic activity. This suggests that these 2 proteins correspond to the active dimeric enzyme previously described in kidney and neoplastic hepatocellular tissue. In normal hepatocytes, the 73.5-kDa protein represents 50% of the total GGT-immunoreactive protein, in contrast to kidney, where this band contains less than 4% of the GGT protein. The kinetics of expression of the 73.5-kDa protein upon induction of GGT activity in hepatocytes, as well as in culture turnover studies, suggests that this protein is a precursor form of the active enzyme, such as the described 78/79-kDa single-chain glycoprotein propeptide of GGT. It appears that in normal hepatocytes, this precursor is not processed to the same extent as in kidney or in hyperplastic bile ductular tissue.

Animals↗