Virus-induced Lymphoma Research Articles

Genetic mapping of a cellular DNA region involved in induction of thymic lymphomas (Mlvi-1) to mouse chromosome 15.

Mlvi-1 defines a genetic locus representing a common domain for proviral DNA integration in Moloney murine leukemia virus-induced rat thymic lymphomas. Cellular sequences homologous to Mlvi-1 are present in mouse DNA, and we have used hamster-mouse somatic cell hybrids to chromosomally map Mlvi-1 in the mouse genome. Results demonstrated that Mlvi-1 maps to mouse chromosome 15 and that it is distinct from the Mlvi-2 integration region and from the cellular oncogenes c-myc and c-sis, which also map to this chromosome. Therefore, Mlvi-1 may contain novel sequences involved in the establishment and maintenance of virus-induced murine tumors, many of which contain abnormalities of chromosome 15.

Existence of cytotoxic acitivity against BLV-transformed cells in lymphocytes from normal cattle and sheep

Peripheral blood lymphocytes (PBL) from normal cattle and sheep were tested for their cytotoxic activity against several target cells using a 20-hour 51Cr release assay. The following characteristics of the effector cells were observed; 1) PBL from animals showed cytotoxic activity against two sheep cell lines (FLK and SF-28) that were transformed with bovine leukemia virus. However, normal sheep and bovine cells and Molony leukemia virus-induced mouse lymphoma cell line (YAC-1) were not killed by these cells. 2) A time course study showed that the activity was first observed at 4 to 8 hours and reached a maximum at 20 to 30 hours after incubation. 3) Cytotoxic activity was observed in both adherent and nonadherent cell fractions when PBL were passed through a nylon-wool column. This indicated that the effector cells showed some degree of adherence. 4) Treatment of PBL with carrageenan did not change the cytotoxic activity against target cells, indicating that phagocytic capability is not perhaps necessary for cytotoxicity to take place. These results indicate that the effector cells participating in the cytotoxic reaction resembled natural killer cells or natural cytotoxic cells which are present in murine and human systems. However, analysis of the cell surface markers of the effector cells is yet to be done in future studies.

Transcription of three c-myc exons is enhanced in chicken bursal lymphoma cell lines.

The chicken c-myc gene, as defined by its homology to the v-myc gene of MC29 virus, is comprised of two exons. Using the techniques of runoff transcription, primer extension, and S1 nuclease protection, we demonstrate that there is a third c-myc exon of approximately equal to 345 base pairs (bp) located 0.7 kbp upstream of the 5' end of the v-myc homology. This first exon is transcribed and present in myc mRNA in normal chicken cells. We also examined RNA from five cell lines derived from avian leukosis virus-induced bursal lymphomas. In all these lines, the level of transcription of the 2.2- to 2.5-kbp myc mRNA is increased 30- to 60-fold over normal cells. The myc mRNA in four of these lines also contains increased levels of the first noncoding exon, and evidence is presented that the long terminal repeat (LTR) in the vicinity of c-myc is functioning as an enhancer of c-myc transcription rather than as a promoter in several of these cell lines. In two cell lines in which the viral LTR has integrated between the first and second exons in the proper orientation for downstream promotion of myc, the LTR does not exhibit promoter function. The pattern of c-myc transcription observed by others in a vast majority of avian leukosis virus-induced neoplasms is not observed in any of the five cell lines examined.

Chromosomal Localization of Protooncogenes

Publisher Summary This chapter discusses the concept of protooncogenes and describes the studies by which these genes have been located in a variety of species, with a marked emphasis on man. The chapter summarizes the chromosomal location of 22 protooncogenes in chicken, mouse, and human cells in tabulated form. It also lists the diseases associated with the homologous retrovirus oncogene and associations with naturally occurring tumors. The chicken protooncogenes were the first examined, mainly for determining the chromosomal association between endogenous retrovirus loci and protooncogenes. This examination, along with Southern blot analyses of diverse species, has revealed no correlation, and it is assumed that these protooncogenes are important growth and/or regulatory genes that infrequently act as nonspecific targets for exogenous retrovirus genomes. The localization of human protooncogenes has progressed at breakneck speed since the discovery that chicken c -myc was involved in avian leukosis virus-induced bursal lymphomas. The localization of c- myc and c- abl to the breakpoints of very consistent translocations in Burkitt's lymphoma and chronic myelogenous leukemia, respectively, support the importance of pursuing the localization of protooncogenes by linking specific genes with the disease state of human malignancies.

Formation of a transformed follicle is necessary but not sufficient for development of an avian leukosis virus-induced lymphoma.

Avian leukosis virus (ALV) infection of susceptible chickens induces bursal lymphomas after a latent period of several months. The clonal development of these B-cell tumors is believed to be a multistep process. Histopathological changes, referred to as transformed follicles, occur within the target organ soon after virus infection and may represent a proximal stage of lymphomagenesis. To establish further the significance of this lesion and its relationship to the subsequent development of lymphomas, we have compared the incidence of transformed follicles observed in animals susceptible or resistant to ALV-induced tumor development. During the 8 weeks following ALV infection, transformed follicles were detected in 82% of the susceptible animals and in 11% of the resistant animals. These results indicate that the incidence of transformed follicles in these animals correlates with their susceptibility to lymphoma development. Furthermore, each transformed follicle does not develop into a tumor. These observations suggest that the formation of a transformed follicle is necessary but not sufficient for lymphoma development.

Integration of type B retroviral DNA in virus-induced primary murine thymic lymphomas.

In previous studies we described the isolation and characterization of a highly leukemogenic virus, DMBA-LV, isolated from a transplanted, chemical carcinogen-induced thymic lymphoma. The virus is composed of a mixture of two unrelated retroviral genomes, one highly related to type B milk-borne mouse mammary tumor virus isolates and the other partially related to type C viral genomes. In the present study, primary thymic lymphomas induced by DMBA-LV in CFW/D, NIH Swiss, C3H/Bi/Ka, and C57BL/Ka mice were assessed for the presence of newly integrated type B retroviral DNA. All 46 primary thymic lymphomas examined contained one to four newly acquired murine mammary tumor virus proviruses. Based on the sizes of provirus-cell DNA junction fragments, the integration of newly acquired murine mammary tumor virus proviruses did not appear to be random.

Characterization of cellular sequences flanking an integrated bovine leukemia virus genome.

We cloned a 20.2-kilobase fragment, including the unique proviral integration site, from the tumor tissue DNA of a bovine leukemia virus-induced lymphoma (tumor 1351). This clone contained 5.5 kilobases of flanking sequences at either side of the full-length integrated viral genome. Hybridization analysis of both 3' and 5' cellular flanking regions provided no evidence for rearrangements at this locus in other tumors, RNA transcription from either flanking region, or homology to eight known onc genes.

Nucleotide sequence 5′ of the chicken c- myc coding region: Localization of a noncoding exon that is absent from myc transcripts in most avian leukosis virus-induced lymphomas

Nucleotide sequence 5′ of the chicken c- <i>myc</i> coding region: Localization of a noncoding exon that is absent from <i>myc</i> transcripts in most avian leukosis virus-induced lymphomas

Ecotropic and dualtropic mink cell focus-inducing murine leukemia viruses can induce a wide spectrum of H-2 controlled lymphoma types

Neonatal infection of C57BL and BALB/c mice by cloned ecotropic and dualtropic mink cell focus-inducing (MCF) murine leukemia viruses (MuLV) induces a wide spectrum of different lymphomas of T, B, and non-T/non-B cell types. Oncogenic dualtropic MCF viruses and poorly oncogenic ecotropic MuLV act synergistically in lymphomagenesis. Within one mouse strain virus-induced T-cell lymphomas arise earlier than B-cell lymphomas after neonatal inoculation of a single-cloned MuLV. The host genetic constitution, notably the H-2 complex has a marked influence on lymphoma type. This H-2 influence can be explained by an H-2-linked difference in penetration of the thymus early in life by oncogenic thymotropic MuLV, which in turn is correlated with, but not necessarily due to the magnitude of the anti-MuLV antibody response.

Mechanisms of oncogenesis by subgroup F avian leukosis viruses.

Subgroup F avian leukosis viruses, such as RAV-61 and ring-necked pheasant virus, are recombinants between exogenous chicken retroviruses and endogenous pheasant viruses and contain new envelope (env) genes. Chickens infected as 10-day-old embryos with subgroup F viruses develop fibrosarcomas, nephroblastomas, osteopetrosis, B-cell lymphomas, and a high incidence of a proliferative disorder involving the lung. Fibrosarcomas, nephroblastomas, and lymphomas appear after long latent periods (3 to 12 months). They contain discrete virus-cell junction fragments and are therefore clonal outgrowths of a single infected cell. Two ring-necked pheasant virus-induced B-cell lymphomas and an adenocarcinoma of the abdomen contained proviruses integrated at the c-myc locus and elevated levels of myc mRNA. At least four of the fibrosarcomas appeared to contain proviruses integrated at a common site, suggesting that a specific cellular gene may be involved in these tumors. The host gene has not been identified, however; 16 different oncogene probes failed to hybridize to fibrosarcoma junction fragments. In contrast to these neoplasms, lung lesions appeared rapidly (4 to 5 weeks), showed no evidence of clonality, and lacked long terminal repeat-initiated transcripts other than viral 35S and 21S mRNA. We conclude, therefore, that subgroup F retroviruses induce the proliferative disorder of the lung by a different mechanism.

Nucleotide sequence 5' of the chicken c-myc coding region: localization of a noncoding exon that is absent from myc transcripts in most avian leukosis virus-induced lymphomas.

We have determined the nucleotide sequence of the 2.2-kilobase-pair region upstream of the chicken c-myc coding exons. Using RNA blot analysis, we have localized a noncoding exon to a region that is separated from the c-myc coding sequences by an intron of 700-800 base pairs. In most avian leukosis virus-induced lymphomas proviral integration has occurred within, or downstream of, the first exon, thus presumably displacing the regulatory sequences that normally control c-myc expression. More than 70% of the integration sites were clustered in a 250-base-pair region in the first intron, immediately preceding the coding sequences. Sequences from the upstream noncoding exon were absent from the myc transcripts in these lymphomas; RNA transcripts from the normal c-myc allele were not expressed at detectable levels.

Epstein-barr virus-induced lymphoma in a cardiac transplant recipient

A monoclonal diffuse histiocytic lymphoma developed during the course of a serologically documented primary Epstein-Barr virus infection in a 22-year-old cardiac transplant recipient taking cyclosporine and prednisone. Throat washings revealed the virus at tumor presentation, and the tumor was shown to contain EpsteinBarr nuclear antigen-positive cells and the viral genome. Prolonged inversion of the T cell helper/suppressor ratio was demonstrated. A brief course of acyclovir appeared to halt viral shedding in the throat but had no apparent effect on the tumor.

Cellular DNA region involved in induction of thymic lymphomas (Mlvi-2) maps to mouse chromosome 15.

Two cellular DNA regions representing common domains for proviral DNA integration ( Mlvi -1 and Mlvi -2) have been identified in Moloney murine leukemia virus-induced rat thymic lymphomas. Cellular sequences which were free of repeated DNA derived from a clone that defines the Mlvi -2 integration domain (lambda Cl228 ) were found to be highly conserved in a variety of vertebrate species that we examined, including mice, hamsters, cats, and humans. In this study, we identified the chromosomal map location of the Mlvi -2 homologous sequences in mice by using hamster-mouse somatic cell hybrids. The results show that Mlvi -2 is present on mouse chromosome 15 but is unrelated to the c-myc and c-sis proto-oncogenes, which map on the same chromosome. Since aberrations on chromosome 15 have been observed reproducibly in mouse thymomas, our data suggest that Mlvi -2 may define a novel sequence involved in the induction or progression of murine thymic lymphomas.

Cellular DNA region involved in induction of thymic lymphomas (Mlvi-2) maps to mouse chromosome 15.

Two cellular DNA regions representing common domains for proviral DNA integration ( Mlvi -1 and Mlvi -2) have been identified in Moloney murine leukemia virus-induced rat thymic lymphomas. Cellular sequences which were free of repeated DNA derived from a clone that defines the Mlvi -2 integration domain (lambda Cl228 ) were found to be highly conserved in a variety of vertebrate species that we examined, including mice, hamsters, cats, and humans. In this study, we identified the chromosomal map location of the Mlvi -2 homologous sequences in mice by using hamster-mouse somatic cell hybrids. The results show that Mlvi -2 is present on mouse chromosome 15 but is unrelated to the c-myc and c-sis proto-oncogenes, which map on the same chromosome. Since aberrations on chromosome 15 have been observed reproducibly in mouse thymomas, our data suggest that Mlvi -2 may define a novel sequence involved in the induction or progression of murine thymic lymphomas.

Proviruses are adjacent to c-myc in some murine leukemia virus-induced lymphomas.

Sixty-one murine leukemia virus-induced lymphomas were examined for evidence of proviral insertions adjacent to known oncogenes. Five of these lymphomas were found to have alterations adjacent to c-myc. Two of the lymphomas with altered c-myc sequences were examined in detail. Evidence was obtained showing that the alterations in the c-myc sequences in these two lymphomas were the result of proviral integrations. This result suggests that lymphomagenesis by murine leukemia viruses can result from insertional mutagenesis of cellular oncogenes.

International Symposium on Retroviruses and Human Pathology

Introduction: The Role of Retroviruses.- Opening Remarks.- Retroviruses in Neoplasia Yesterday, Today, and Tomorrow.- The Role of Retroviruses in Nature.- W. P. Rowe Memorial Lecture.- Changing Dogmas in Retrovirology.- Section 1 Retroviruses and the Murine Model System.- The Biology of Endogenous Leukemia Viruses: A Study of the DBA/2 Mouse.- Murine Xenotropic Retroviruses in the Computer Age.- Viral and Nonviral Mammary Tumorigenesis.- The Proviral Genome of Radiation Leukemia Virus: Molecular Cloning, Nucleotide Sequence of Its Long Terminal Repeat, and Integration in Lymphoma Cell DNA.- Metastatic Potential of Friend Leukemia Cells: Fibronectin Induces Specific Arrest, Survival, and Growth of FLC in Liver of DBA/2 Mice.- The Envelope Gene of Mammalian Retroviruses: Analysis of Its Structure Reveals Specific Recombination Signals.- The Major Histocompatibility Complex (H-2) of the Mouse Influences the Phenotype of Murine Leukemia Virus-Induced Lymphomas.- Mouse Mammary Tumor Virus (MMTV) Morphology in the Gastrointestinal Lumen of Suckling Mice.- Murine Retroviruses: An Alternative Screening Approach for Antiviral Drug Research.- Section 2 Retroviruses and the Vertebrate Model System.- Retroviruses and Oncogenes in Rats.- Target Cells for Avian Leukemia Viruses Revisited.- Feline Retroviruses.- Bovine Leukemia Virus, A Distinguished Member of the Human TLymphotropic Viruses Family.- Association of Ultraviolet-Induced Retrovirus Expression with Anchorage-Independent Survival in Rat Embryo Cells.- Participation of 7S L RNA in Reverse Transcription by an Avian Retrovirus.- Different Retroviruses Show Different Susceptibilities to 2-Deoxy-D-glucose.- A Comparative Study of Bovine Leukemia Virus (BLV) Detection Methods.- Structural and Functional Heterogeneity among Type D Retroviruses.- Retroviruses and Oncogenes in the Rat Sarcoma Galliera: An old Tumor as a Unique Model System.- Section 3. Retroviruses and Human Pathology.- Molecular Biology of Viruses of the HTLV Family.- Activation of Retroviral Genes in Human Reproductive Tissues and Tumors.- Retrovirus and AIDS.- Human T-Cell Leukemia (Lymphotropic) Retroviruses: The HTLV Family and Their Role in Leukemias, Lymphomas, and AIDS.- The Organization of Mouse Mammary Tumor Virus-Related Sequences in Human Cellular DNA.- Close Structural Similarities Between the LTRs of Bovine Leukemia and Human T-Cell Leukemia Viruses.- Analysis and Immunological Properties of Lymphadenopathy- Associated Virus (LAV) Structural Proteins.- RNA Viruses and Lymphocyte Immune Functions.- Anti HTLV-III and Anti T-Cell Antibodies in AIDS and ARC Patients.- Seroepidemiological Study of Lymphadenopathy-Associated Virus, by ELISA, in Acquired Immunodeficiency Syndrome.- IgG Antibodies to SAIDS-D Virus Associated Antigens in Patients with AIDS and at Risk for AIDS.- Is a Retrovirus-Like Particle Expressed at a Specific Stage During Human Oocyte Maturation?.- Psoriasis - A Retrovirus Disease?.- Purification and Characterization of a High Molecular Weight Human Milk Ribonuclease: Its Potential use for Diagnosis and Prognosis of Human Mammary Neoplasia.- The Role of Retroviruses in AIDS and Slow Infections.- Section 4. Retroviruses and Oncogenes.- Retroviruses with Two Oncogenes.- Molecular Assays for Detection Of ras Oncogenes in Human and Animal Tumors.- The raf Oncogene.- Role of Retroviral Oncogenes in the Attachment of Cells to Natural Substrata.- Amplification of Cellular Oncogenes in Colon and Lung Cancer Cells.- The Nucleotide Sequence of the erbA Gene of Avian Erythroblastosis Virus Appears Unrelated to Other Known Oncogenes.- Characterization of a Human Osteosarcome Oncogene.- Coordinated Regulation of the c-myc Gene and a Tumor-related Multigenic Set in Human Neoplastic Cells Treated with Differentiation Inducers Including Tumor Promoters.- Transcripts of c-fes Oncogene are Present at Detectable Levels in Total Cellular RNA of Human Myeloid but not Lymphoid Normal and Neoplastic Cells.- Heterogeneity of Human Normal and Leukemic Cells of Lymphoid and Myeloid Lineage in Respect to the Expression Of c-myc and c-myb Mrna Transcripts.- Detection Of c-myc, c-myb and c-fes Oncogene Transcripts in Human Myeloid and Lymphoid Normal and Leukemic Cells by In Situ Hybridization.

T-cell-dependent hybrid resistance against a natural killer-resistant moloney virus-induced lymphoma (YWA): In vitro generation of cytotoxic lymphocytes

A Moloney leukemia virus-induced lymphoma of the A.SW strain, YWA, was used to generate cytotoxic cells in vitro. Cocultivation of spleen cells from in vivo primed syngeneic and semisyngeneic mice with X-irradiated YWA tumor cells for 5 days resulted in a strong killing activity against YWA. The cytotoxicity was H-2 restricted and mediated by Thy-1.2-positive lymphocytes. f 1 hybrids with variable degrees of natural resistance to the YWA tumor in vivo all generated cytotoxic cells after secondary stimulation in vitro but showed differences in optimal responder:stimulator requirements.

Natural resistance if mice pretreated with 5-(3,3′-dimethyl-1-triazeno)-imidazole-4-carboxamide (DTIC) + cyclophosphamide (Cy) against virus-induced lymphoma cells

Virus-induced leukemia was inoculated into histocompatible or allogeneic hosts pretreated with 5-(3,3′-dimethyl-1-triazeno)-imidazole-4-carboxamide (DTIC) + Cyclophosphamide (Cy), which abrogate endogemous cell proliferation and T-dependent graft responses, but not selected “natural resistance” (NR) activities. Marked impairment of lymphoma cell growth occurred mainly in the spleen of allogeneic mice with respect to that of histocompatible controls. Tumor inhibition was still present when lymphoma challenge was performed on day +3 after Cy administration. Parallel studies on “natural killer” (NK) activity in vitro or in vivo showed that complete abrogation of the NK function was detectable on day +3 or +6 after Cy treatment. It was concluded that in vivo inhibition of lymphoma growth in mice pretreated with DTIC+Cy could be a drug-resistant NR at least in part distinguishable from the NK function.

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The combined effects of nonspecific immunostimulation with Candida albicans (CA) and chemotherapy were studied in (BALB/cCr X DBA/2Cr)F1 and (C57BL/6Cr X DBA/2Cr)F1 mice bearing virus-induced LSTRA lymphomas. Paradoxically, animals treated with a relatively high number of tumor cells responded better to therapy with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) than those challenged with a low number of tumor cells. However, the majority of mice subjected to low initial tumor load were cured when they were treated with chemotherapy or chemotherapy plus booster injection of CA at a relatively "late" stage of the disease, i.e., when high tumor load was present in tumor-bearing hosts. It has been shown that this phenomenon, provisionally called high tumor load protection, occurs when the animals are challenged ip but not when they are challenged iv with the tumor and is abolished by total-body gamma-irradiation. Moreover, marked host protection can be attained when immunostimulated mice, inoculated iv with lymphoma cells, are subjected to simultaneous challenge with high inocula of the same tumor ip, followed by BCNU administration. These data stress the importance of the peritoneal cavity for successful CA plus drug treatment and suggest that optimal tumor "antigen load" should be present at the time of CA and/or BCNU administration.

Altered thymic epithelial cells may be decisive for Moloney virus-induced lymphoma development

Infection of newborn mice with Moloney leukemia virus (M-MuLV) causes a T-cell differentiation block in the thymic cortex accompanied by proliferation and accumulation of prethymic lymphoblasts in the thymus and subsequent spreading of these cells to generate systemic lymphoma. Current evidence shows that thymic reticular epithelial cells (REC) provide a microenvironment necessary for the maturation of prethymic lymphoblasts to mature T-lymphocytes by secretion of various thymic factors. A change in that environment due to infection of REC by virus could be decisive for the failure of lymphoblasts to mature and thus contribute to lymphoma development.We have studied the morphology and distribution of the major thymic cell populations at different stages of tumorigenesis in Balb/c mice infected when newborn with 0.2ml M-MuLV suspension, 6.8 log FFU/ml. Thymic tissue taken at 1-2 weekly intervals up to tumor development was processed for light and electron microscopy, using glutaraldehyde-OsO4fixation and Epon-Araldite embedding.