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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Specific host-graft interactions, as well as intrinsic properties of transferred cell, determine tumorigenicity in xenogeneic systems. We compared the growth characteristics of human B-lymphoid cell lines in SCID mice with the well characterized growth pattern in nude mice and observed striking differences in malignancy in the respective hosts. Two cell lines derived from the same individual, the Epstein-Barr-virus(EBV)-positive Burkitt's lymphoma BL 60 (BL) and the autologous EBV-immortalized lymphoblastoid cell line IARC 277 (LCL) were used. In addition, we tested somatic cell hybrids (HYB) of both cell lines, which despite the LCL-like differentiation phenotype show the de-regulated c-myc expression pattern of the parental BL line, assumed to be a critical factor in BL pathogenesis. Subcutaneously (s.c.) injected BL cells produced local progressively growing tumor masses at the injection site without distant metastases in both nude and SCID mice. Although both mouse strains possess the same genetic background (BALB/c) and differ only in the B-cell sub-set, the growth patterns of the LCL and hybrids were completely different. In contrast to the regressive behaviour of LCL and hybrids in nude mice, these lines show invasive and disseminated progressive growth in SCID mice. Peripheral lymph nodes an thymic tissue were preferentially colonized, whereas mucosal-associated lymphoid tissue (Peyer's patches and appendix) and spleen were not infiltrated. The preferential migration of lymphocytes to certain tissues is termed homing in a syngeneic system and mediated by homing receptors and vascular addressins. The "homing" of LCL and hybrids into lymphoid SCID mouse tissue suggests a strong interaction with the endothelial cells of the host. Detailed phenotypic analysis of BL, LCL and 3 different hybrids was performed using an antibody panel against differentiation and adhesion markers. Overall dominance of the LCL phenotype was observed in the hybrids, as indicated by cytology, tumor growth, dissemination and the pattern of surface-marker expression. The c-myc activation in hybrids does not appear to influence growth behavior.
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PMID:Local growth of a Burkitt's lymphoma versus disseminated invasive growth of the autologous EBV-immortalized lymphoblastoid cells and their somatic cell hybrids in SCID mice. 130 26

Epstein-Barr virus DNA was detected in a case of lymphoepithelioma-like thymic carcinoma. A homogeneous terminal structure of the viral DNA was demonstrated in this case, indicating the presence of the viral genome in clonally expanded tumor cells. Since all of 26 other thymic epithelial tumors (eight non-invasive, 13 invasive thymomas and four non-lymphoepithelioma-like thymic carcinomas) in Japanese were negative by polymerase chain reaction, it is suggested that lymphoepithelioma-like thymic carcinoma may represent a unique pathological entity distinct from Epstein-Barr virus-negative thymic epithelial tumors, which are in the majority in Japan.
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PMID:Detection of Epstein-Barr virus DNA in a Japanese case of lymphoepithelioma-like thymic carcinoma. 131 8

Previous studies investigating the role of Epstein-Barr virus (EBV) in undifferentiated nasopharyngeal carcinoma (NPC) have been performed on extracts from biopsies. The authors analyzed expression and localization of viral gene products in 18 undifferentiated NPCs at the cellular level using immunohistology and in situ hybridization. All cases were EBV-positive. The small nuclear EBV-encoded RNAs, EBERs, were regularly expressed whereas the latent membrane protein, LMP1, and EBV was detectable only in four cases (22%) and the nuclear antigen 2 was not detectable. The BZLF-1 protein of EBV which disrupts viral latency, was not detectable, confirming that the virus is latent in the tumor cells. Although the expression of the CD23 antigen in transplantable NPCs has been reported, our study demonstrates that expression of this antigen in human undifferentiated NPCs is rare. In contrast, almost all cases expressed the CDw70 antigen. Since in normal tissues this antigen is present only in activated lymphoid blasts, this finding may be relevant for the differential diagnosis of undifferentiated NPCs.
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PMID:Expression of Epstein-Barr virus genes and of lymphocyte activation molecules in undifferentiated nasopharyngeal carcinomas. 131 28

Seventeen nodal lymphomas (originally diagnosed as T-cell lymphomas based on histological features and immunohistochemical staining results) were studied for the presence of Epstein-Barr virus (EBV) genome, and the results correlated with immunoglobulin and T-cell receptor gene rearrangement analyses performed on the same tissue samples. All four EBV positive cases had clonal rearrangement of the joining region of the immunoglobulin heavy chain (IgJH) gene without clonal T-cell receptor beta-chain (TCR beta) gene rearrangement. Of these, two cases also showed clonally rearranged light chain gene, and they were reclassified as T-cell rich B-cell lymphomas (TRBL). The other two cases lacked clonal kappa or lambda light chain rearrangement and they were reclassified as T-cell rich lymphomas of probable B lineage, based on their isolated IgJH clonal rearrangement. These B-cell lymphomas may be easily misdiagnosed as T-cell lymphomas owing to the presence of an abundant reactive T-cell infiltrate masking the tumor population. The florid T-cell reaction may represent an unusual host response towards a clonal proliferation of EBV bearing B cells.
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PMID:Clonal Epstein-Barr virus genome in T-cell-rich lymphomas of B or probable B lineage. 131 29

Epstein-Barr virus (EBV) is associated with B-cell malignancy in immunosuppressed humans and SCID mice receiving human peripheral blood leukocyte grafts (hu-PBL-SCID). We have further characterized the process of lymphoma development in hu-PBL-SCID mice. We report that EBV-seropositive donors differ markedly in the capacity of their PBL to give rise to immunoblastic lymphomas in SCID mice; some donors (high incidence) generated tumors rapidly in all hu-PBL-SCID mice, other donors (intermediate-low incidence) gave rise to sporadic tumors after a longer latent period (greater than 10 weeks), and some donors failed to produce tumors. B-cell lymphomas arising from high incidence donors were multiclonal in origin, and EBV replication was detected in all tumors. Tumors derived from intermediate-low incidence donors were monoclonal or oligoclonal and often had no evidence of viral replication. All tumors, regardless of the donor, resembled EBV-transformed lymphoblastoid cell lines in surface phenotype but differed from lymphoblastoid cell lines by having less Epstein-Barr nuclear antigen 2 and CD23 expression. The variable patterns of lymphomagenesis seen among different EBV-sero-positive donors may be explained by lower levels of specific immunity to EBV in high incidence donors, permitting activation of EBV replication and potential transformation of secondary B-cell targets. In addition, there may be differences in the transforming potential of EBV infecting different donors. The use of the hu-PBL-SCID model may help predict patients at high risk for posttransplant or acquired immunodeficiency syndrome-associated lymphomas.
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PMID:Heterogeneity among Epstein-Barr virus-seropositive donors in the generation of immunoblastic B-cell lymphomas in SCID mice receiving human peripheral blood leukocyte grafts. 131 93

Lymphocytic interstitial pneumonitis (LIP) and nonspecific interstitial pneumonitis (NIP) are pulmonary complications of human immunodeficiency virus (HIV) infection that occur in the absence of a detectable opportunistic infection or neoplasm. We reviewed lung biopsy specimens from 50 adult HIV-infected patients, of whom four had LIP and 46 had NIP. The majority (47 of 50) of specimens from patients with NIP showed mild chronic interstitial pneumonitis (CIP/NIP), with three showing features of diffuse alveolar damage, organizing phase. In contrast to CIP/NIP, the five specimens from four patients with LIP demonstrated more extensive lymphocytic interstitial infiltrates that extended into the alveolar septal interstitium. The majority of the interstitial lymphocytes in both NIP and LIP were of T-cell origin and stained for UCHL-1. The etiologies of NIP and LIP remain unknown. Since the common opportunistic infections were excluded by routine methods, we sought, with special techniques, to investigate whether HIV, Epstein-Barr virus (EBV), or cytomegalovirus (CMV) could be identified in lung biopsy specimens from these patients. By in situ hybridization, we found one LIP specimen with expression of large amounts of HIV RNA primarily within macrophages in germinal centers; in the remaining specimens, occasional cells expressing HIV RNA were found (two LIP and four NIP). Neither CMV nor EBV was found by in situ hybridization in seven specimens; in these same specimens EBV was detected using the polymerase chain reaction in only one case of NIP, similar to results in control specimens. These results, together with the knowledge that lymphocytic pulmonary lesions may be caused by lentiviruses in humans and animals, suggest that HIV plays a significant role in the pathogenesis of both NIP and LIP in adult HIV-infected patients; in contrast, our data do not demonstrate a direct role for either EBV or CMV.
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PMID:Lymphoid pneumonitis in 50 adult patients infected with the human immunodeficiency virus: lymphocytic interstitial pneumonitis versus nonspecific interstitial pneumonitis. 131 78

Lymphocytes adhere to cells or extracellular matrices to perform functions relating to cytotoxicity, extravasation and tissue localization, as well as modulation of lymphocyte growth and maturation. This adherence is mainly mediated by 3 families of cell-surface adhesion molecules: integrins, immunoglobulin-related molecules and selectins. Since variations in the degree of adherence may affect the pathophysiology of lymphoproliferative disorders, the expression of a large number of adhesion molecules was analysed on Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCLs), and on EBV-positive or EBV-negative Burkitt's lymphoma (BL) lines, by immunofluorescence flow cytometry and immunoprecipitation with monoclonal antibodies. With regard to the beta 1, beta 2 and beta 3 integrin subfamilies, LCLs strongly expressed CD49d/CD29 (VLA-4), CD11a/CD18 (Leu-CAMa, LFA-1) and CD51/CD61 (vitronectin receptor). These cells also abundantly expressed CD54 (ICAM-1) and CD58 (LFA-3) as well as the "homing receptors" L-selectin (LECAM-1) and CD44. BL lines had considerably lower amounts of VLA-4 than LCLs, and ICAM-1 was expressed only by some of the tumor lines. All other adhesion molecules were absent or minimally expressed in the BL cells.
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PMID:Expression of integrins and other adhesion molecules in Epstein-Barr virus-transformed B lymphoblastoid cells and Burkitt's lymphoma cells. 131 64

We have previously shown that the endemic (African) and sporadic (North American) forms of Burkitt's lymphoma (BL) differ at a molecular level. We have now extended our studies to the molecular epidemiology of BL in South America, specifically to two climatic regions: temperate (Argentina and Chile) and tropical (Brazil). We have examined the patterns of chromosomal breakpoint locations in 39 tumors with respect to geography and Epstein-Barr virus (EBV) association. The result of these analyses provide further support for the existence of pathogenetically distinct subtypes of BL in different world regions. The majority of breakpoints on chromosome 8 in South American BL (41%) occurred in the immediate flanking region of c-myc, ie, further 5' of the "typical" sporadic breakpoints, in the first exon/intron region, and further 3' of the "typical" endemic breakpoints, which are usually distant from c-myc. However, the distribution of breakpoints on chromosome 14 in tumors from the temperate and tropical regions of South America is similar to that observed in sporadic and endemic tumors. Interestingly, only one tumor with an unrearranged c-myc gene joined to the S mu region of chromosome 14 was observed. This combination was also rarely observed in our earlier series and presumably is either less readily generated by the mechanism that mediates 8;14 translocation or requires other, infrequent genetic changes to provide the necessary selective advantage for lymphomagenesis. The frequency of EBV association in South American BL (51%) is also intermediate with respect to tumors from the United States (30%) and Africa (100%). No correlation with the breakpoint location on chromosome 8 was discernable. Surprisingly, only 54% of tumors with breakpoint outside c-myc were EBV positive. This is in contrast to endemic tumors and suggests that any pathogenetic contribution of EBV is not dependent on breakpoint location, but is more likely to complement additional pathogenetic elements that differ in different world regions.
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PMID:Molecular epidemiology of Burkitt's lymphoma from South America: differences in breakpoint location and Epstein-Barr virus association from tumors in other world regions. 131 26

To search for possible anti-tumor-promoters, fourteen flavones obtained from the root of Scutellaria baicalensis were examined for their inhibitory effects on the Epstein-Barr virus early antigen (EBV-EA) activation by a short-term in vitro assay. Among these flavones, 5,7,2'-trihydroxy- and 5,7,2',3'-tetrahydroxyflavone showed remarkable inhibitory effects on the EBV-EA activation, and the effect of the latter on Raji cell cycle was also examined by flow cytometer. These two flavones exhibited remarkable inhibitory effects on mouse skin tumor promotion in an in vivo two-stage carcinogenesis test.
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PMID:Studies on inhibitors of skin tumor promotion. XI. Inhibitory effects of flavonoids from Scutellaria baicalensis on Epstein-Barr virus activation and their anti-tumor-promoting activities. 131 92

We report a new and apparently unique human lymphoma cell line termed Deglis. The line was established from a polymorphic centroblastic lymphoma. The cell line and its source carry a dual B-cell and T-cell phenotype and Epstein-Barr virus (EBV) genomes. Simultaneous expression of B-cell (CD19+, CD20+, CD23+, CD37+) and T-cell (CD2+, CD3+/-, CD7+, CD43+) antigens, activation antigens (CD30+, CDw70+) as well as CD68+, a macrophage-associated antigen, was observed on the cell line and its source. Genotypic studies of the cell line showed dual gene rearrangements. JH (on both primary tumor and the cell line) and C kappa were rearranged without expression of cytoplasmic or surface immunoglobulins. T-cell receptor-alpha (TCR-alpha) and TCR-beta genes were rearranged, but TCR-delta and TCR-gamma genes were in germline configuration. Apparently, functional transcripts of TCR-alpha and truncated transcripts for TCR-beta and TCR-delta were observed. EBV-encoded proteins (LMP and EBNA2) were expressed by the parent tumor and the cell line. Southern blot analysis showed the same clonal EBV genomes in the primary tumor and the cell line. Karyotypic analysis of the cell line showed several chromosomal abnormalities but normal chromosomal number. The characteristics of this cell line suggest that neoplastic transformation has occurred in a precursor cell broadly committed to lymphoid lineage. Further studies on this cell line may help resolve some issues in the physiopathology of lymphoid tumors.
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PMID:A novel human lymphoma cell line (Deglis) with dual B/T phenotype and gene rearrangements and containing Epstein-Barr virus genomes. 131 35


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