Paul K. Pattengale

Single-step induction of mammary adenocarcinoma in transgenic mice bearing the activated c-neu oncogene

We have used transgenic mice that carry an activated c-neu oncogene driven by a mouse mammary tumor virus (MMTV) promoter to assess the stepwise progression of carcinogenesis in mammary epithelium. Unlike the stochastic occurrence of solitary mammary tumors in transgenic mice bearing the MMTV/c-myc or the MMTV/v-Ha-ras oncogenes, transgenic mice uniformly expressing the MMTV/c-neu gene develop mammary adenocarcinomas that involve the entire epithelium in each gland. Because these tumors arise synchronously and are polyclonal in origin, expression of the activated c-neu oncogene appears to be sufficient to induce malignant transformation in this tissue in a single step. In contrast, expression of the c-neu transgene in the parotid gland or epididymis leads to benign, bilateral epithelial hypertrophy and hyperplasia which does not progress to full malignant transformation during the observation period. These results indicate that the combination of activated oncogene and tissue context are major determinants of malignant progression and that expression of the activated form of c-neu in the mammary epithelium has particularly deleterious consequences.

Coexpression of MMTV/v-Ha-ras and MMTV/c-myc genes in transgenic mice: Synergistic action of oncogenes in vivo

We have derived and mated separate strains of transgenic mice that carry either the v-Ha-ras or the c-myc gene driven by the mouse mammary tumor virus (MMTV) promoter/enhancer. Mice carrying the MMTV/v-Ha-ras transgene manifest two distinct disturbances of cell growth. The first, a benign hyperplasia of the Harderian lacrimal gland, is diffuse, involves the entire gland, and likely requires only the abnormal action of the v-Ha-ras gene. The second involves the focal development of malignancies of mammary, salivary, and lymphoid tissue and likely requires additional somatic events. When the MMTV/v-Ha-ras and MMTV/c-myc strains are crossed to yield hybrid mice, their joint action results in a dramatic and synergistic acceleration of tumor formation. Since these tumors arise stochastically and are apparently monoclonal in origin, additional somatic events appear necessary for their full malignant progression, even in the presence of activated v-Ha-ras and c-myc transgenes.

Spontaneous mammary adenocarcinomas in transgenic mice that carry and express MTV/myc fusion genes

We have produced 13 strains of transgenic mice that carry an otherwise normal mouse myc gene in which increasingly larger portions of the myc promoter region have been replaced by a hormonally inducible mouse mammary tumor virus promoter. Although expression of the fusion genes varies among these animals, the female founders of two of these transgenic strains spontaneously developed mammary adenocarcinomas during one of their early pregnancies. Both the tumors and the breast tissue of these founder animals expressed RNA transcripts corresponding to the fusion gene. Furthermore, in the best studied strain, all the available F1 female progeny that inherited the MTV/myc gene also developed mammary adenocarcinomas during their second or third pregnancies. Thus, although it has no obvious effect on the early development of these mice, the constitutionally deregulated myc gene appears to act as a heritable, predisposing factor favoring the accelerated development of a tissue-specific adenocarcinoma.

Increased neutrophil respiratory burst in bcr-null mutants

Philadelphia (Ph)-positive leukemias invariably contain a chromosomal translocation fusing BCR to ABL. The BCR-ABL protein is responsible for leukemogenesis. Here we show that exposure of bcr-null mutant mice to gram-negative endotoxin led to severe septic shock and increased tissue injury by neutrophils. Neutrophils of bcr (-/-) mice showed a pronounced increase in reactive oxygen metabolite production upon activation and were more sensitive to priming stimuli. Activated (-/-) neutrophils displayed a 3-fold increased p21rac2 membrane translocation compared with (+/+) neutrophils. These results connect Bcr in vivo with the regulation of Rac-mediated superoxide production by the NADPH-oxidase system of leukocytes and suggest a link between Bcr function and the cell type affected in Ph-positive leukemia.

Epstein-Barr virus-induced diseases in boys with the X-linked lymphoproliferative syndrome (XLP): Update on studies of the registry

Analyses of 100 subjects with the X-linked lymphoproliferative syndrome (XLP) in 25 kindreds revealed four major interrelated phenotypes: infectious mononucleosis, malignant B-cell lymphoma, aplastic anemia, and hypogammaglobulinemia. Eighty-one of the patients died. Two male subjects were asymptomatic but showed immunodeficiency to Epstein-Barr virus (EBV). Seventy-five subjects had the infectious mononucleosis phenotype and concurrently, 17 subjects of this group had aplastic anemia. All subjects with aplastic anemia died within a week. Aplastic anemia did not accompany hypogammaglobulinemia or malignant lymphoma phenotypes. Hypogammaglobulinemia had been detected before infectious mononucleosis in three subjects, after infectious mononucleosis in five subjects, and was not associated with infectious mononucleosis in 11 boys with hypogammaglobulinemia. In nine subjects infectious mononucleosis appeared to have evolved into malignant lymphoma; however, the majority of patients with malignant lymphoma showed no obvious antecedent infectious mononucleosis. One subject had infectious mononucleosis following recurrent malignant lymphoma. Twenty-six of 35 lymphomas were in the terminal ileum. Results of immunologic and virologic studies of 15 survivors revealed combined variable immunodeficiency and deficient antibody responses to EBV-specific antigens. Mothers of boys with XLP exhibited abnormally elevated titers of antibodies of EBV. Subjects of both sexes with phenotypes of XLP should be investigated for immunodeficiency to EBV. Persons with inherited or acquired immunodeficiency may be vulnerable to life-threatening EBV-induced diseases.

Thymic lymphoproliferative disease after successful correction of CD40 ligand deficiency by gene transfer in mice.

Inherited deficiency of the CD40 ligand (X-linked hyper-IgM syndrome) is characterized by failure of immunoglobulin isotype switching and severe defects of cell-mediated immunity. To test the potential for gene transfer therapy to correct this disorder, we transduced murine bone marrow or thymic cells with a retroviral vector containing the cDNA for the murine CD40 ligand (CD40L) and injected them into CD40L–/– mice. Even low-level, constitutive expression of the transgene stimulated humoral and cellular immune functions in these mice. With extended follow-up, however, 12 of 19 treated mice developed T-lymphoproliferative disorders, ranging from polyclonal increases of lymphoblasts to overt monoclonal T-Lymphoblastic lymphomalymphomas that involved multiple organs. Our findings show that constitutive (rather than tightly regulated), low-level expression of CD40L can produce abnormal proliferative responses in developing T lymphocytes, apparently through aberrant interaction between CD40L+ and TCRαβ+CD40+ thymocytes. Current methods of gene therapy may prove inappropriate for disorders involving highly regulated genes in essential positions in proliferative cascades.

Convoluted lymphocytic lymphoma in adults: a clinicopathologic entity.

Twelve adults had a distinct clinicopathologic type of malignant lymphoma that closely resembles the mediastinal lymphomas of childhood. Nine patients presented with mediastinal masses, and seven had symptoms related to intrathoracic compression. Seven patients presented with or developed leukemia, and in four of these patients the central nervous system (CNS) became involved. Structurally, the tumor cells had a distinctive stippled chromatin pattern, in addition to the characteristic nuclear convolutions. Tumor cells from five patients were studied immunologically, and, in each case, the tumor cells formed rosettes with sheep erythrocytes. The response to combination chemotherapy was rapid and dramatic, but usually transient, with relapse in the CNS or previously involved sites. The above data strongly suggest that these cases represent a distinct clinicopathologic entity that should be treated similarly to childhood leukemia and lymphoma, with intensive multiple agent induction, CNS prophylaxis, possibly radiation therapy to initially involved sites, and prolonged maintenance.

Atypical lymphocytes in acute infectious mononucleosis. Identification by multiple T and B lymphocyte markers.

Abstract Atypical lymphocytes from four patients with acute infectious mononucleosis were tested for the presence of five separate markers of thymic-derived (T) and bone-marrow-derived (B) lymphocytes. This test was done to rule out the possibility that the previously described sheep erythrocyte rosetting capacity (a normal T-cell marker) of atypical lymphocytes in infectious mononucleosis was due to passive adsorption or production of heterophil (anti-sheep erythrocyte) antibody on the surface of B lymphocytes and was therefore a false-positive reaction. The vast majority of atypical lymphocytes had sheep erythrocyte receptors as well as human T-lymphocyte specific antigens and lacked three reliable B-cell markers (complement receptors, surface immunoglobulin, and human B lymphocyte specific antigens). Since Epstein-Barr virus, the etiologic agent of infectious mononucleosis, has recently been shown to infect only B lymphocytes, the finding that the atypical lymphocytes are indeed T cells suggests that t...

Human bcr-abl gene has a lethal effect on embryogenesis.

The chimaericbcr-abl oncogene is thought to have a crucial role in the development or maintenance of chronic nyelogenous leukaemia. To study this oncogene in a more direct way, thebcr-abl gene encoding the P210 protein under control of thebcr gene promoter was introduced into fertilized one-cell embryos, which were then re-implanted into foster mothers. Our data, obtained after several experiments, demonstrate that no live transgenic progeny could be obtained using thisbcr-abl construct. Thebcr gene is expressed in the course of embryogenesis and thebcr-abl gene product appears to have a pleiotropic lethal effect during this period of development. In concordance, several gross abnormalities were observed while no evidence of neoplastic formation was found. These results suggest that thebcr-abl encoded protein severely affects the process of normal embryogenesis.

Combination of CD80 and Granulocyte-Macrophage Colony-Stimulating Factor Coexpression by a Leukemia Cell Vaccine: Preclinical Studies in a Murine Model Recapitulating Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia

Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) is a highly aggressive malignancy caused by the bcr-abl translocation oncogene. To explore alternative treatments for Ph+ ALL we tested gene-modified cell vaccines in the BALB/c-derived BM185 leukemia model. We compared the efficacy of BM185 cell vaccine expressing CD80 alone or in combination with IL-2 or GM-CSF. Mice injected with viable BM185 leukemia cells modified to express CD80 and GM-CSF (BM185/CD80+GM-CSF) showed the highest leukemia rejection rates. Cell vaccines consisting of irradiated BM185/CD80+GM-CSF cells administered subcutaneously stimulated a potent cytotoxic T lymphocyte (CTL) response against parental BM185. Histological examination of the vaccination site showed a large concentration of immune cells. Administration of the BM185/CD80+GM-CSF cell vaccine before intravenous challenge with parental cells caused strong inhibition of leukemia development. Vaccination after subcutaneous challenge with BM185 cells caused efficient elimination of leukemia promoting 40-60% long-term survival rates. The immunization efficacy of the BM185/CD80+ GM-CSF cell vaccine was directly correlated with the percentage of cells expressing the transgenes. In all, this preclinical study shows that leukemia cell vaccines coexpressing CD80 and GM-CSF can potentially be explored for immunotherapy in Ph+ ALL patients.