Am J Pathol

Epstein-Barr virus LMP1 modulates the malignant potential of gastric carcinoma cells involving apoptosis.

Sheu LF. Chen A. Wei YH. Ho KC. Cheng JY. Meng CL. Lee WH.
Department of Pathology, Tri-Service General Hospital, Taipei, Taiwan, Republic of China.
About 10% of gastric carcinomas including lymphoepithelioma-like carcinoma and adenocarcinoma are associated with Epstein-Barr virus (EBV) infection. In EBV-associated gastric carcinomas, the tumor cells express Epstein-Barr nuclear antigen 1 (EBNA-1) but not EBNA-2, -3A, -3B, or -3C, leader protein, or latent membrane proteins (LMPs) because of gene methylation. Only a few exceptional cases have LMP1 expression in tumor cells as demonstrated by immunohistochemical studies. To elucidate the biological effects of LMP1 and the significance of its restricted expression in EBV-associated gastric carcinomas, the LMP1 gene was transferred into EBV-negative gastric carcinoma cell lines (SCM1 and TMC1) and into EBV-negative nasopharyngeal carcinoma (NPC) cells (HONE-1) as a control. The biological effects of LMP1 in gastric carcinoma cells were monitored in vitro and in vivo. These results showed that the consequence of LMP1 expression is a growth enhancement in NPC cells, but it is a growth suppression in gastric carcinoma cells. The LMP1-expressing gastric carcinoma cells had a reduced growth rate, colony-forming efficiency, mean colony size, and tumorigenicity and a lower malignant cytological grade. The reduced growth rate, colony-forming efficiency, and mean colony size were partially reversible in vitro with treatment with LMP1 antisense oligonucleotide. In addition, enhanced apoptosis was found in the LMP1-expressing gastric carcinoma cells. This suggests that LMP1 may negatively modulate the malignant potential of gastric carcinoma cells via an enhancement of apoptosis. We concluded that the restriction of LMP1 expression in EBV-associated gastric carcinomas may lead to a growth advantage for tumor cells by avoiding LMP1 apoptotic effects and immunologically mediated elimination.

Consistent copy number gain in chromosome 12 in primary diffuse large cell lymphomas of the stomach.

Chan WY. Wong N. Chan AB. Chow JH. Lee JC.
Department of Anatomical & Cellular Pathology, Chinese University of Hong Kong, Shatin, N.T., Hong Kong. wingchan@cuhk.edu.hk
Fifteen cases of high grade primary gastric non-Hodgkin's lymphomas were studied using comparative genomic hybridization (CGH) and/or fluorescence in situ hybridization (FISH) techniques. A total of 10 cases of diffuse large cell lymphoma (DLCL) with no histologically identifiable or previous history of low grade mucosa-associated lymphoid tissue (MALT) lymphoma components were examined, four by CGH and validated by FISH, and the remaining six by FISH alone. All 10 tumors showed gains in chromosome 12. Other recurring CGH findings in DLCL included copy number gains of 1q and deletions of 6q. Five cases of high grade tumors with low grade MALT components (HGM) were also examined, three by CGH and validated by FISH and two by FISH only. Only one in five HGM showed gains of chromosome 12. Other recurring CGH findings in HGM included +7q and +11q. We conclude that high grade gastric lymphomas of DLCL type were associated with gains in chromosome 12. The change was much less frequent (P < 0.01) in the HGM type, which had a percentage similar to that observed in previously reported cytogenetics/FISH studies on low grade MALT lymphomas. Our findings suggested that many DLCL were not derived from transformation of low grade MALT lymphomas.

Activated CD4+ and CD8+ cytotoxic cells are present in increased numbers in the intestinal mucosa from patients with active inflammatory bowel disease.

Muller S. Lory J. Corazza N. Griffiths GM. Z'graggen K. Mazzucchelli L. Kappeler A. Mueller C.
Department of Pathology, University of Bern, Switzerland.
The contribution of cell-mediated cytotoxicity to the pathogenesis of inflammatory bowel disease (IBD) is controversial, and results of in vitro assays vary according to experimental procedures. Therefore, we compared the frequency of cytotoxic effector cells in situ. On tissue sections of controls (n = 11), low frequencies of granzyme A and perforin mRNA-expressing cells are found in the lamina propria (1.77 +/- 0.15% and 1.46 +/- 0.12%, respectively) and in the epithelial cell layer (0.76 +/- 0.12% and 0.66 +/- 0.10%, respectively). In patients with IBD (n = 33), corresponding values were significantly (P < 0.02) higher, 6.1 +/- 0.40% and 5.92 +/- 0.57% for granzyme A and perforin expression in the lamina propria and 2.50 +/- 0.19% and 2.59 +/- 0.28%, respectively, in the epithelial compartment. Differences between ulcerative colitis and Crohn's disease are statistically not significant (P > 0.33). Activated cytotoxic cells are preferentially found at sites facing the intestinal lumen. Perforin mRNA-expressing cells are mainly CD8+ T cells. CD4+ T cells expressing perforin mRNA are mainly isolated from affected areas of patients with Crohn's disease. Immunostaining for perforin protein generally coincides with perforin mRNA in situ. These data demonstrate that cytotoxic cells are vigorously activated in situ in the intestinal mucosa of patients with active IBD.

Deletion of Epstein-Barr virus latent membrane protein 1 gene in Japanese and Brazilian gastric carcinomas, metastatic lesions, and reactive lymphocytes.

Hayashi K. Chen WG. Chen YY. Murakami I. Chen HL. Ohara N. Nose S. Hamaya K. Matsui S. Bacchi MM. Bacchi CE. Chang KL. Weiss LM.
Department of Pathology, City of Hope National Medical Center, Duarte, California 91010, USA.
A 30-bp deletion in the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) gene has been reported in nasopharyngeal carcinoma and EBV-associated malignant lymphomas. Information on this deletion in EBV-associated gastric carcinoma (EBVaGC) is limited. The association of gastric carcinoma (GC) with EBV was examined by EBV-encoded RNA (EBER) in situ hybridization in 510 patients from Japan and 80 patients from Brazil. We studied the prevalence of 30-bp LMP1 gene deletion in EBVaGC in Japan (29 cases) and Brazil (four cases) in comparison with the corresponding EBER1-positive metastatic lesions in lymph nodes (10 cases) and EBV-infected reactive lymphocytes from dissected nonmetastatic lymph nodes (22 cases), microdissected non-neoplastic gastric mucosa of EBVaGC (five cases), and EBV-nonassociated GC (25 cases). We studied the status of the LMP1 gene by Southern blot hybridization of polymerase chain reaction products obtained after amplification with primers flanking the site of the deletion. We also performed EBV typing and LMP1 protein immunohistochemistry. EBV DNA was amplified by polymerase chain reaction in 30 of 33 EBVaGC cases, 8 of 10 metastatic carcinomas, 14 non-neoplastic tissues from 27 EBVaGC cases, and 12 of 25 non-EBV-associated GC cases with EBER1-positive lymphocytes. The 30-bp LMP1 gene deletion was observed in 23 of 26 (88.5%) cases of EBVaGC from Japan and two of four (50%) cases of Brazilian EBVaGC as compared with EBER1-positive reactive lymphocytes from 11 of 14 (78.6%) EBVaGC cases and 9 of 12 (75%) cases of non-EBV-associated GC. The variant type (the 30-bp deletion variant or nondeleted wild type) of LMP1 gene was the same among reactive lymphocytes, primary and secondary lesions of EBVaGC in all cases for which all three tissue types were studied (six of six). There was no correlation between the presence of the 30-bp deletion with depth of cancer invasion or presence of metastasis. Type A was detected in all available EBV-positive cases. The similar high incidence of 30-bp deletion in LMP1 gene in both carcinoma cells and reactive lymphocytes in EBVaGC cases suggests that this deletion may not be relevant to the pathogenesis of EBVaGC.

Altered cadherin and catenin complexes in the Barrett''s esophagus-dysplasia-adenocarcinoma sequence: correlation with disease progression and dedifferentiation.

Bailey T. Biddlestone L. Shepherd N. Barr H. Warner P. Jankowski J.
Cranfield Biotechnology Centre, Cranfield University, Beds, United Kingdom.
The maintenance of adult tissue architecture is largely dependent on the function of cadherins. E-cadherin is expressed in most epithelia, although it may be co-expressed with P-cadherin in basal layers of stratified epithelia. Adhesive function of cadherins relies on interactions with catenins. Many reports have characterized reduced expression of cadherins and catenins in tumors, including those of the gastrointestinal tract. This study aimed to characterize expression of E- and P-cadherins, and the catenins, in the progression of Barrett's esophagus to adenocarcinoma. Immunohistochemical analysis and Western blotting were performed on paraffin-embedded and fresh-frozen tissue using antisera to the selected cadherins and catenins. The results of this study have shown inappropriate expression of cadherins and catenins in neoplastic Barrett's mucosa. There was a significant reduction of E-cadherin expression as the Barrett's metaplasia-dysplasia-adenocarcinoma sequence progressed (P < 0.01). In contrast, P-cadherin, expressed in basal layers of squamous esophagus, was usually absent from Barrett's and dysplasia but was expressed in 17 of 24 carcinomas, especially at the advancing tumor edge. Reduced expression of catenins was also seen, but in some specimens, immunoreactivity was observed in neoplastic nuclei, suggesting mediation of a nuclear function such as transcriptional regulation.

Expression of interleukin-8 correlates with vascularity in human gastric carcinomas.

Kitadai Y. Haruma K. Sumii K. Yamamoto S. Ue T. Yokozaki H. Yasui W. Ohmoto Y. Kajiyama G. Fidler IJ. Tahara E.
First Department of Internal Medicine, Hiroshima University School of Medicine, Japan.
Interleukin (IL)-8 is a multifunctional cytokine that can stimulate the division of endothelial cells. We examined the expression of IL-8 mRNA using Northern blot analysis and in situ mRNA hybridization (ISH) and protein production using enzyme-linked immunosorbent assay and immunohistochemistry in 8 human gastric carcinoma cell lines and 39 gastric carcinomas and corresponding normal mucosa (34 surgical specimens and 5 biopsy specimens). Of the 8 human gastric carcinoma cell lines, 6 expressed 1.8-kb IL-8 mRNA and secreted various levels of IL-8 protein. The expression of IL-8 by TMK-1 cells was induced by exposure to IL-1 alpha, epidermal growth factor, and transforming growth factor-alpha, shown previously to be autocrine growth stimulators for human gastric carcinoma cells. In tumor tissues, most of the tumors (28 of 34 surgical specimens and 4 of 5 biopsy specimens) expressed IL-8 at higher levels than the corresponding normal mucosa. ISH and immunohistochemical analyses revealed that IL-8 mRNA and protein were localized in the cytoplasm of tumor cells. The number of blood vessels in the gastric carcinomas was determined by using antibodies against CD34. The level of IL-8 mRNA in the neoplasms strongly correlated with vascularization (Spearman correlation, r = 0.812; P = 0.001). The data suggest that IL-8 produced by tumor cells may regulate neovascularization and, hence, the growth and spread of human gastric carcinoma.

Increased expression of monocyte chemotactic protein-1 during active hepatic fibrogenesis: correlation with monocyte infiltration.

Marra F. DeFranco R. Grappone C. Milani S. Pastacaldi S. Pinzani M. Romanelli RG. Laffi G. Gentilini P.
Istituto di Medicina Interna, Universita di Firenze, Florence, Italy. f.marra@dfc.unifi.it
Monocyte chemotactic protein (MCP)-1 is a chemoattractant and activator for circulating monocytes and T lymphocytes. We investigated MCP-1 protein and gene expression during chronic liver disease at different stages, using immunohistochemistry and in situ hybridization, respectively. In normal liver, a modest expression of MCP-1 was confined to few peri-sinusoidal cells and to bile duct epithelial cells. During chronic hepatitis, MCP-1 immunostaining and gene expression were evident in the inflammatory infiltrate of the portal tract. In tissue from patients with active cirrhosis, MCP-1 expression was clearly up-regulated and was present in the portal tract, in the epithelial cells of regenerating bile ducts, and in the active septa surrounding regenerating nodules. A combination of in situ hybridization for MCP-1 and immunohistochemistry showed that activated stellate cells and monocyte/macrophages contribute to MCP-1 expression in vivo together with bile duct epithelial cells. Comparison of serial sections of liver biopsies from patients with various degrees of necro-inflammatory activity showed that infiltration of the portal tracts with monocytes/macrophages is directly correlated with the expression of MCP-1. These data expand previous in vitro studies showing that secretion of MCP-1 may contribute to the formation and maintenance of the inflammatory infiltrate observed during chronic liver disease.

Interleukin-12 expression is focally enhanced in the gastric mucosa of pediatric patients with Crohns disease.

Year 1998
Berrebi D. Besnard M. Fromont-Hankard G. Paris R. Mougenot JF. De Lagausie P. Emilie D. Cezard JP. Navarro J. Peuchmaur M.
Services d'Anatomie et de Cytologie Pathologiques, Hopital Robert Debre, Paris, France.
The stomach is frequently involved in children suffering from Crohn's disease (CD). Diagnosis of specific gastritis may be difficult when granulomas are absent. We have used in situ hybridization to examine the expression of interleukin (IL)-12, a key cytokine in the Th1 response. IL-12 p35 and p40 antisense probes were used to examine ileal specimens from 9 children with CD and gastric biopsies from 24 children (13 with CD, 6 with Helicobacter pylori chronic gastritis, and 5 with a normal gastric mucosa). In all patients with CD, many clusters of IL-12-positive cells were present in the lamina propria. This was the case in the ileal specimens as well as in gastric mucosa showing granulomatous gastritis or nongranulomatous gastritis. The same distribution patterns were found for the IL-12 p35 and p40. In three patients with Helicobacter pylori gastritis, few scattered IL-12-positive cells were found. No positive cells were found in the normal gastric mucosa. The focally enhanced IL-12 expression in the gastric mucosa of pediatric patients with CD, with or without specific lesions, suggests that both are indeed linked to the disease and supports the major part of IL-12 in initiating and maintaining of the cascade resulting in the Th1 responses.

Somatic deletion of the 5 ends of both the COL4A5 and COL4A6 genes in a sporadic leiomyoma of the esophagus.

Year 1998
Heidet L. Boye E. Cai Y. Sado Y. Zhang X. Flejou JF. Fekete F. Ninomiya Y. Gubler MC. Antignac C.
INSERM U423, Hopital Necker-Enfants Malades, Universite Rene Descartes, Paris, France.
Leiomyomata of the esophagus are sporadic benign tumors of unknown etiology. We studied a collection of nine tumors for the expression of extracellular matrix components and found the same aberrant expression pattern as previously observed in inherited diffuse leiomyomatosis. We demonstrate here the occurrence of a somatic deletion at the COL4A5/COL4A6 locus at Xq22 in a frozen leiomyoma sample. These data confirm the hypothesis that the same underlying etiology is responsible for circumscribed smooth muscle proliferation in sporadic leiomyomata as for diffuse smooth muscle cell proliferation in inherited diffuse leiomyomatosis.

Immunolocalization of putative human liver progenitor cells in livers from patients with end-stage primary biliary cirrhosis and sclerosing cholangitis using the monoclonal antibody OV-6.

Year 1998
Crosby HA. Hubscher S. Fabris L. Joplin R. Sell S. Kelly D. Strain AJ.
Department of Biochemistry, University of Birmingham, Queen Elizabeth and Children's Hospital, United Kingdom.
The term oval cell describes small cells with oval nuclei that arise in the periphery of the portal tracts in rat models of hepatocarcinogenesis and injury and can differentiate into either hepatocytes or bile duct cells, ie, are bipotential. The presence of such cells in human liver is controversial. Here, immunolocalization of OV-6 and two biliary markers, cytokeratin 19 (CK-19) and human epithelial antigen 125 (HEA-125) is compared in normal adult human livers and in primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) liver sections. CK-19 and HEA-125 stained bile ducts and ductules in normal liver as well as proliferating ductular structures in diseased livers. OV-6 did not label ducts or ductules in normal liver, but in PBC and PSC stained numerous proliferating ductular and periductular cells and lobular hepatocytes. In PBC, discrete OV-6-positive cells with a mature biliary-cell-like morphology were seen integrated into some intact bile ducts as well as occasional small immature oval-like cells. In addition, in PSC, hepatocytes in regenerating lobules were also strongly stained with OV-6, and on close inspection, in both PBC and PSC, oval cells and small hepatocytes at the margins of the lobules were strongly labeled. In contrast to the rat liver, OV-6 and CK-19 staining did not always co-localize. It is proposed that the small OV-6-positive oval cells are analogous to those seen in rat models and may represent human liver progenitor cells that may differentiate into OV-6-positive ductal cells or lobular hepatocytes.

Regulation of uveal melanoma interconverted phenotype by hepatocyte growth factor/scatter factor (HGF/SF).

Year 1998
Hendrix MJ. Seftor EA. Seftor RE. Kirschmann DA. Gardner LM. Boldt HC. Meyer M. Pe'er J. Folberg R.
Department of Anatomy and Cell Biology, Iowa Cancer Center, The University of Iowa College of Medicine, Iowa City 52242-1109, USA. mary-hendrix@uiowa.edu
Human uveal melanoma disseminates initially and preferentially to the liver. This study describes the relationship between the expression of the c-met proto-oncogene (receptor for hepatocyte growth factor/scatter factor (HGF/SF)) in interconverted uveal melanoma cells (co-expressing vimentin and keratin intermediate filaments) and the regulation of their motogenic response to HGF/SF, a key step in local invasion and targeted dissemination to the liver. Expression of c-met in uveal melanoma cell lines correlates with both the appearance of an interconverted phenotype and invasive ability (measured in vitro). Using chemotactic checkerboard analysis, the greatest motogenic response to HGF/SF was achieved by invasive, interconverted, c-met-positive uveal melanoma cells. C-met was observed histologically in a uveal melanoma containing interconverted cells but was absent in a tumor composed of non-interconverted cells (vimentin positive/keratin negative). The c-met ligand, HGF/SF, although not expressed by uveal melanoma cell lines, was localized in tissue sections of primary uveal melanomas and metastatic melanoma to the liver. In the primary tumor, staining for HGF/SF was most intense at the level of the choriocapillaris, a finding that is significant because 1) highly remodeled neovascular loops and networks, which appear in tumors likely to disseminate, can be traced to the choriocapillaris and the draining vortex veins and 2) HGF/SF plays a role in tumor angiogenesis. Foci of metastatic melanoma to the liver stain diffusely for HGF/SF. Regulation of the uveal melanoma interconverted phenotype by HGF/SF may play an important role in the dissemination of this tumor.

Compound heterozygosity for missense (L156P) and nonsense (R554X) mutations in the beta4 integrin gene (ITGB4) underlies mild, nonlethal phenotype of epidermolysis bullosa with pyloric atresia.

Year 1998
Pulkkinen L. Bruckner-Tuderman L. August C. Uitto J.
Department of Dermatology and Cutaneous Biology, Jefferson Medical College, and Jefferson Institute of Molecular Medicine, Philadelphia, Pennsylvania 19107, USA.
Mutations in the genes encoding the subunit polypeptides of the alpha6beta4 integrin (ITGA6 and ITGB4, respectively) have been previously demonstrated in patients with a lethal form of epidermolysis bullosa with congenital pyloric atresia (OMIM #226730). In this study, we demonstrate for the first time ITGB4 mutations in nonlethal phenotype of epidermolysis bullosa with congenital pyloric atresia. Specifically, the proband was shown to be a compound heterozygote for a missense mutation (L156P) and a nonsense mutation (R554X). The leucine substitution by proline was shown to affect a residue, which was precisely conserved in different human, rodent, and drosophila integrin-beta polypeptides, and consequently disrupts the alpha-helix formation of the polypeptide segment as determined by Garnier alpha-helicity plot. The nonsense mutation in another allele was accompanied by undetectable levels of the corresponding mRNA transcript, as determined by reverse transcription-polymerase chain reaction. The presence of a missense mutation, when combined with a premature termination codon mutation, may explain the milder blistering tendency of the skin in this patient.

Human CTLA-4 is expressed in situ on T lymphocytes in germinal centers, in cutaneous graft-versus-host disease, and in Hodgkins disease.

Year 1998
Vandenborre K. Delabie J. Boogaerts MA. De Vos R. Lorre K. De Wolf-Peeters C. Vandenberghe P.
Laboratory for Experimental Hematology, University of Leuven, Belgium.
Cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4, CD152) is a molecule expressed on in vitro activated T cells. CTLA-4 shares important sequence homology with CD28 and binds to the same ligands, CD80 (B7-1) and CD86 (B7-2). CTLA-4 probably functions as a negative regulator of T lymphocyte activation in the mouse, although this remains to be proven for human T lymphocytes. We have developed new monoclonal antibodies against human CTLA-4 and have investigated the in situ expression of CTLA-4 in a wide variety of normal and pathological human tissues expressing CD80 and CD86. As revealed in this study, CTLA-4 is expressed on thymocytes in thymic medulla, on a subset of CD4+ T lymphocytes in germinal centers of follicular hyperplasia, on T cells, mainly CD8+, infiltrating skin affected by graft-versus-host disease, and on T cells, mainly CD4+, infiltrating Hodgkin's disease lesions. In immunoelectron microscopy, CTLA-4 was found on the plasma membrane as well as in the hyaloplasm and cytoplasmic vesicles, in agreement with its pattern of expression on in vitro activated T cells. Interestingly, no or at most scarce expression of CTLA-4 was found in granulomatous lymph nodes, T-cell-mediated inflammatory diseases, or non-Hodgkin's lymphomas, regardless of their expression of CD80 or CD86. Thus, expression of CTLA-4 appears to be induced in selective pathological conditions in vivo. The pathways leading to selective induction of CTLA-4 and its role in the pathophysiology of these conditions need to be further investigated.

Dysregulated expression of CD66a (BGP, C-CAM), an adhesion molecule of the CEA family, in endometrial cancer.

Year 1998
Bamberger AM. Riethdorf L. Nollau P. Naumann M. Erdmann I. Gotze J. Brummer J. Schulte HM. Wagener C. Loning T.
Department of Gynecopathology, University Hospital Eppendorf, Hamburg, Germany.
CD66a (BGP, C-CAM) is an adhesion molecule of the carcinoembryonic antigen family that has been shown to be down-regulated in colorectal, prostate, and breast cancers. The purpose of the present study was to determine its expression pattern in the normal human endometrium and in endometrial neoplasia. For this purpose, we performed immunohistochemistry using the 4D1/C2 monoclonal antibody on a series of 24 normal endometrial samples and 47 endometrial carcinomas. Strong CD66a expression was observed in glandular and luminal epithelial cells of the normal endometrium with a consistent localization at the apical poles of these cells throughout the cycle. In late secretory (premenstrual) phase, loss of cellular polarity resulted in a membranous expression pattern in some glandular cells. In the analyzed tumor samples increasing areas with a complete loss of expression were observed with increasing malignancy grade. The apical expression pattern of the normal epithelium was changed to a membranous all-around pattern in 55% of the tumors, mostly in solid areas. This change correlated with malignancy grade and could be observed in 3 of 15 G1 tumors, 4 of 12 G2 tumors, 11 of 12 G3 tumors, and 8 of 8 serous-papillary carcinomas. Areas with membranous expression pattern could be observed along with areas with a normal apical expression pattern in lower grade carcinomas and with areas with complete loss of expression in high grade tumors. Northern blot analysis showed a loss of mRNA expression in tumor samples and HEC-1B endometrial adenocarcinoma cells. Loss of protein expression in the tumor samples was also observed by Western blot. In conclusion, CD66a protein expression is dysregulated in endometrial carcinomas, showing reduction or loss of expression with increasing malignancy grade and a change from the apical to a membranous localization.

Pancreatic adenocarcinomas with DNA replication errors (RER+) are associated with wild-type K-ras and characteristic histopathology. Poor differentiation, a syncytial growth pattern, and pushing borders suggest RER+.

Year 1998
Goggins M. Offerhaus GJ. Hilgers W. Griffin CA. Shekher M. Tang D. Sohn TA. Yeo CJ. Kern SE. Hruban RH.
Department of Pathology, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
The clinical and pathological features of carcinomas of the pancreas with DNA replication errors (RER+) have not been characterized. Eighty-two xenografted carcinomas of the pancreas were screened for DNA replication errors using polymerase chain reaction amplification of microsatellite markers. Cases with microsatellite instability in at least two markers of a minimum of five tested were considered RER+. RER status was correlated with histological appearance, karyotype of the carcinomas when available, K-ras mutational status, and patient outcome. Three (3.7%) of the eighty-two carcinomas were RER+. In contrast to typical gland-forming adenocarcinomas of the pancreas, all three RER+ carcinomas were poorly differentiated and had expanding borders and a prominent syncytial growth pattern. Neither a Crohn's-like lymphoid infiltrate nor extracellular mucin production were prominent. Ductal adenocarcinomas of the pancreas typically contain a mutant K-ras gene, yet all three RER+ carcinomas had wild-type K-ras. One of the three RER+ carcinomas was karyotyped and showed a near diploid pattern. All three of the RER+ tumors were removed via Whipple resection. One of the three patients is free of disease 16 months after pancreaticoduodenectomy, one is alive and free of tumor at 52 months but developed two colon carcinomas during this period, and the third died of pancreatic cancer at 4 months. None of the three patients had a family history of colorectal carcinoma. A review of the K-ras wild-type carcinomas in a previously characterized series of pancreatic carcinomas with known K-ras mutational status identified two additional cancers with poor differentiation, a syncytial growth pattern, and pushing borders. Both of the cancers were diploid and both patients were longterm survivors (over 5 years). The inclusion of such patients in previous prognostic studies of pancreas cancer may explain the failure of histological grade to be a predictor of prognosis. These data suggest that DNA replication errors occur in a small percentage of resected carcinomas of the pancreas and that wild-type K-ras gene status and a medullary phenotype characterized by poor differentiation, and expanding pattern of invasion, and syncytial growth should suggest the possibility of DNA replication errors in carcinomas of the pancreas.

Gastrointestinal pacemaker cell tumor (GIPACT): gastrointestinal stromal tumors show phenotypic characteristics of the interstitial cells of Cajal.

Year 1998
Kindblom LG. Remotti HE. Aldenborg F. Meis-Kindblom JM.
Department of Pathology, Gothenburg Musculoskeletal Tumor Center, University of Gothenburg, Sahlgrenska University Hospital, Sweden.
The interstitial cells of Cajal (ICC) form a complex cell network within the gastrointestinal tract wall where they function as a pacemaker system. Expression of the kit proto-oncogene is essential for the development of this system. The aim of our study was to examine the hypothesis that gastrointestinal stromal tumors differentiate toward cells with an ICC phenotype. Ultrastructurally, 58 stromal tumors were characterized and found to share many features with ICC. Seventy-eight stromal tumors were immunophenotyped, particularly with regard to the kit receptor. All 78 tumors revealed strong, homogeneous immunoreactivity for the kit receptor as did ICC of adjacent and control gastrointestinal walls. Focal hyperplasia and hypertrophy of kit receptor positive cells were also observed in the gastrointestinal wall adjacent to the tumors. CD34 immunoreactivity observed in interstitial cells surrounding Auerbach's ganglia suggests that a subpopulation of ICC is CD34 positive and may explain why 56 of 78 stromal tumors were CD34 positive. Thirty control tumors, including gastrointestinal leiomyomas and leiomyosarcomas, were all negative for the kit receptor. We conclude that gastrointestinal stromal tumors show striking morphological and immunophenotypic similarities with ICC and that they may originate from stem cells that differentiate toward a pacemaker cell phenotype. We propose that the noncommittal name "gastrointestinal stromal tumor" be replaced by gastrointestinal pacemaker cell tumor.

B-cell monoclonality precedes the development of gastric MALT lymphoma in Helicobacter pylori-associated chronic gastritis.

Year 1998
Nakamura S. Aoyagi K. Furuse M. Suekane H. Matsumoto T. Yao T. Sakai Y. Fuchigami T. Yamamoto I. Tsuneyoshi M. Fujishima M.
Second Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Little is known about the temporal changes in Helicobacter pylori density and B-cell clonality during the evolution from chronic gastritis to gastric mucosa-associated lymphoid tissue (MALT) lymphoma. Biopsied specimens from 28 patients with chronic gastritis who developed gastric MALT lymphoma (group A) and from 24 similar patients who did not (group B) during an equivalent follow-up period (mean, 42 months) were retrospectively scored for histological features of MALT lymphoma (0 to 5) and H. pylori density (0 to 3). B-cell clonality was analyzed by polymerase chain reaction (PCR). During the observation period, the H. pylori density in group A decreased significantly in comparison with group B; the mean change in H. pylori density (final minus initial density) per 1000 days was -1.4 for group A and +0.2 for group B (P < 0.005). Monoclonality was detected more frequently in group A (79%) than in group B (21%; P < 0.005), and it preceded the histological evidence of malignant transformation in 64% of those patients who showed monoclonality in group A. These results suggest that H. pylori is thus more closely associated with the precursor or initial phase in the genesis of gastric MALT lymphoma than with the later phase, as its density decreases as the tumor progresses. The detection of B-cell monoclonality by PCR is thus of possible use for predicting the histological genesis of gastric lymphoma.

Microsatellite instability and loss of heterozygosity in gastric carcinoma in comparison to family history.

Year 1998
Keller G. Rudelius M. Vogelsang H. Grimm V. Wilhelm MG. Mueller J. Siewert JR. Hofler H.
Institute of Pathology, Technische Universitat Munchen, Germany. gisela.keller@irz.tu-muenchen.de
We compared 29 gastric carcinomas from patients with a variably strong family history for gastric cancer (group 1) with 36 gastric carcinomas from patients without a family history of this disease (group 2) for microsatellite instability (MSI) and loss of heterozygosity (LOH) with 12 microsatellite markers. Both study groups had similar proportions of histological types and tumor locations. Widespread MSI (alterations at > or = 6 loci) was seen in 5 of 29 (17%) of the tumors belonging to group 1 and in 4 of 36 (11%) group 2 tumors. MSI at a low level (alterations at 1 to 3 loci) was observed in 12 of 29 (41%) of tumors in group 1 and in 10 of 36 (28%) of tumors in group 2, differences that were not statistically significant. A significant difference with respect to low level MSI was observed between the two groups when considering the overall mutation rate of microsatellites. Seventeen of 281 (6%) analyzed microsatellite loci showed alterations in group 1 and 11 of 381 (2.9%) in group 2 (P = 0.046). Comparison of both types of MSI to the clinicopathological parameters in both groups revealed a significant association of low level MSI with advanced tumor stages (P = 0.046) in the group 2, whereas no such association was observed in group 1. In respect to LOH, a significant difference between the two groups was observed at chromosome 17p12, as 13 of 22 (59%) informative cases of group 1 showed LOH in comparison with 7 of 26 (27%) (P = 0.024) in group 2. No correlation of LOH at chromosome 17p12 to the pathological or clinical data was observed either in the two groups or in the study as a whole. Our data show that gastric carcinomas of patients with a positive family history of gastric cancer in group 1 are characterized by a higher mutation rate in respect to low level MSI, particularly at dinucleotide repeats, and by a higher frequency of LOH at chromosome 17p12, indicating that different genetic pathways are involved in the pathogenesis of gastric carcinomas arising in patients with and without a familial background of this disease.