The Evi-1 proto-oncogene encodes a transcriptional repressor activity associated with transformation

The myeloid transforming gene Evi-1 encodes a protein with two zinc finger domains, designated ZF1 and ZF2, with distinct DNA binding specificities. For the first time we demonstrate that Evi-1 has transcriptional repressor activity which is directly proportional to the amount of Evi-1 protein in cells. Repression has been observed with two distinct promoters: the minimal HSV-1 tk promoter and a VP16 inducible adenovirus E1b minimal promoter. Optimal repression is DNA binding dependent and is mediated by either ZF1 or a heterologous GAL4 DNA binding domain (GAL4DBD) but is significantly less efficient through the ZF2 binding site. Both GAL4DBD/Evi-1 fusion and non-fusion proteins have been used to map the repressor activity to a proline-rich region located within amino acids 514-724 between the ZF1 and ZF2 domains. Constitutive expression of mutant proteins lacking the repressor domain are defective for transformation of Rat1 fibroblasts demonstrating that this region is required for the oncogenic activity of the Evi-1 protein. These studies show that the Evi-1 gene encodes a transcriptional repressor and has important implications for the mechanism of action of the Evi-1 protein both in development and in the progression of some myeloid leukaemias.

HIV infection--induced posttranslational modification of T cell signaling molecules associated with disease progression

In attempt to elucidate the mechanism of the HIV infection induced T cell unresponsiveness, we studied signal-transducing molecules proximal to the T cell receptor (TCR) in T lymphocytes of HIV-infected individuals. Total amounts of protein tyrosine kinases (PTKs) Lck, Fyn, and ZAP-70 and the zeta chain of the TCR were found significantly decreased in T cells of symptomatic/AIDS patients as well as in T cells of individuals in acute and early asymptomatic stages of HIV infection. Unexpectedly, the detection of Lck, Fyn, and ZAP-70 was reversed after the treatment of cell lysates with dithiothreitol. This suggests that PTKs Lck, Fyn, and ZAP-70 were modified by a mechanism altering the status of sulfhydryl groups. Moreover, this mechanism seems to affect selectively T cells of HIV infected patients since B cell PTKs Syk and Lyn were detected structurally and functionally intact. Interestingly, similar alterations of signaling molecules were not detected in T cells of HIV-infected long-term asymptomatic individuals. Modification of T cell PTKs may thus underlie the HIV-induced impairment of lymphocyte function and may potentially predict disease progression.

The international epidemiology of disseminated Mycobacterium avium complex infection in AIDS. International MAC Study Group

OBJECTIVE

To determine rates of disseminated Mycobacterium avium complex (MAC) infection among AIDS patients in developed and developing countries, and to determine whether different rates reflect differences in exposure or immunity, or both.

DESIGN

Prospective cohort study.

SETTING

University hospitals and outpatient AIDS programs.

METHODS

HIV-infected subjects with CD4 counts < 200 x 10(6)/l were interviewed and had CD4 lymphocyte counts, blood cultures for mycobacteria (baseline and at 6 months), and skin tests with purified protein derivative (PPD) and M. avium sensitin.

RESULTS

Among 566 study patients rates of disseminated MAC were 10.5-21.6% in New Hampshire, Boston and Finland compared to 2.4-2.6% in Trinidad and Kenya (P < 0.001). PPD skin test reactions > or = 5 mm were present in 20% of patients from Kenya compared to 1% at other sites (P < 0.001). Among patients from the United States and Finland, multiple logistic regression indicated that occupational exposure to soil and water was associated with a decreased risk of disseminated MAC, whereas the following were associated with an increased risk of disseminated MAC: low CD4 count, swimming in an indoor pool, history of bronchoscopy, regular consumption of raw or partially cooked fish/shellfish and treatment with granulocyte colony-stimulating factor.

CONCLUSIONS

Rates of disseminated MAC in AIDS are higher in developed than developing countries and are due to both differences in exposure and differences in immunity. These data provide a rationale for prevention of MAC through both active immunization and reduction in exposure to the organism.

Sequence analysis of human T cell lymphotropic virus type I (HTLV-I) Env genes amplified from central nervous system tissues of patients with HTLV-I-associated myelopathy or leukemia

Human T cell lymphotropic virus type I (HTLV-I) is a retrovirus that has been linked to HTLV-I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP), a chronic or inflammatory neurological disease with some resemblance to multiple sclerosis. We used the polymerase chain reaction to amplify viral env genes in foci of inflammation and demyelination in the nervous system to adduce additional evidence of the association of HTLV-I with the neuropathological changes in HAM/TSP, and document in this report such an association. We also sought evidence of a distinct viral species in the lesions by amplifying, cloning and sequencing the env genes from tissues sections in which there were pathological changes. We did not find changes in the env gene that correlated with HTLV-I-associated neurological disease vs adult T cell leukemia or with the nervous system vs peripheral blood and lymphoid organs. We did, however, find evidence of extensive mutation and possibly deletions in the env gene in HTLV-I-associated neurological disease. We interpret these findings of increased genetic diversity as a reflection of higher rates of viral replication in HTLV-I-associated myelopathy that support a model of pathogenesis in which increased viral replication activates immune cells that subsequently enter the nervous system and cause injury by immunopathological mechanisms.

Effect of human T-lymphotropic virus type I infection on non-Hodgkin's lymphoma incidence

BACKGROUND

We previously reported from a case-control analysis that T-cell non-Hodgkin's lymphoma (NHL) was strongly associated with human T-lymphotropic virus type I (HTLV-I) infection in Jamaica and Trinidad and that the relative risk for HTLV-I infection was very high in younger patients.

PURPOSE

The objective of this study was to estimate the age-specific incidence rates of NHL among HTLV-I-infected and HTLV-I-uninfected adults in Jamaica and Trinidad.

METHODS

Population rates of HTLV-I infection were calculated from available census reports and serosurvey data. Incidence rates for NHL were calculated from all incident cases in Jamaica during 1984-1987 (n = 135) and from all incident cases in Trinidad during 1986-1990 (n = 117). Using biopsy material, we determined whether the immunophenotype of the tumor cells was T cell, B cell, or other. NHL incidence rates were computed according to HTLV-I status, age, sex, and tumor phenotype for each country separately and for both countries combined by weighting to the relative population size of each country.

RESULTS

The age-standardized NHL incidence rate (mean +/- SE) in Jamaica was 1.9 +/- 0.2 per 100,000 person-years (PY). In Trinidad, the rate was 2.9 +/- 0.4 per 100,000 PY. Overall, the incidence of NHL increased with age and was higher in males than in females. In the HTLV-I-infected population, the incidence of NHL was inversely related to age, and age-specific rates were higher in males than in females. The NHL incidence in those estimated to have acquired HTLV-I infection in childhood, however, showed no sex difference, and one in 1300 such carriers (95% confidence interval: one in 1100 to one in 1600) per annum were estimated to be at such risk. For T-cell NHL, as proxy for adult T-cell lymphoma/leukemia, incidence was highest in those patients infected with HTLV-I early in life (perinatally or via breast milk), with high, sustained risk from early adulthood in both sexes.

CONCLUSIONS

While overall NHL incidence rates reveal that HTLV-I endemicity does not impose an exaggerated lymphoma burden on these populations, the risk for lymphoma among carriers who acquire infection early in life is dramatic and is consistent with the hypothesis that virus exposure early in life is most important for lymphoma-genesis.

IMPLICATIONS

Studies of HTLV-I carriers known to be infected in childhood may provide insight into markers intermediate in the lympho-magnetic process. Strategies to disrupt early-life transmission of HTLV-I, notably mother-infant transmission, may be critical in reducing the burden of lymphoreticular disease in these populations.

HIV-1 prevalence and risk factors among sexually transmitted disease clinic attenders in Trinidad

OBJECTIVES

To study trends in prevalence and to ascertain risk factors for HIV-1 among sexually transmitted disease (STD) clinic attenders in Trinidad.

DESIGN AND METHODS

Serial cross-sectional studies were conducted in 1987-1988 and 1990-1991 at a centralized STD clinic in Port of Spain. A case-control study was carried out to examine in greater detail the demographic and behavioral risk factors for HIV-1 among self-declared heterosexuals in this population.

RESULTS

HIV-1 prevalence increased from 3.0% [95% confidence interval (CI), 2.3-3.9] in 1987-1988 to 13.6% (95% CI, 11.8-15.6) in 1990-1991. Age > or = 40 years [odds ratio (OR), 2.0; 95% CI, 1.4-2.8], urban residence (OR, 2.2; 95% CI, 1.6-3.0), and human T-lymphotropic virus-I seropositivity (OR, 3.1; 95% CI, 1.6-6.0) were significant risk factors for HIV-1 in 1990-1991. In the case-control analysis, significant independent risk factors for men included current genital ulcer disease (OR, 5.2; 95% CI, 2.2-12.5), current genital warts (OR, 3.9; 95% CI, 1.2-12.0), having ever had syphilis (OR, 3.2; 95% CI 1.6-6.1), and use of crack cocaine in the preceding 6 months (OR, 6.2; 95% CI, 2.7-14.2). Corresponding risk factors for women were commercial sex work (OR, 5.7; 95% CI, 1.3-25.7), initiation of sexual activity before age 14 years (OR, 4.8; 95% CI, 1.5-16.0), and past non-gonococcal cervicitis (OR, 4.1; 95% CI, 1.3-13.1).

CONCLUSIONS

HIV-1 in this setting is primarily heterosexually transmitted in a milieu of unprotected sexual activity fuelled by a crack cocaine epidemic. Targeted interventions to prevent, detect and treat STD and crack cocaine addiction, as well as disrupt their adverse synergism, may substantially reduce HIV-1 transmission in this population.

Perinephric abscess mimicking fulminant hepatic failure

We describe a female diabetic patient who presented with features suggestive of hepatobiliary disease and who exhibited clinical signs of fulminant hepatic failure. Identification and drainage of a right perinephric abscess resulted in prompt resolution of both the physical signs and biochemical indices of liver disease. Infection remote from the hepatobiliary tree can mimic fulminant hepatic failure, and recognition of this unusual presentation of infection is important if dangerous delay in diagnosis and treatment is to be avoided.

Induction of two alternatively spliced evi-1 proto-oncogene transcripts by cAMP in kidney cells

The evi-1 proto-oncogene is normally predominantly expressed in the kidney. We report here that evi-1 transcripts are also abundant in foetal kidney and expression is retained in primary kidney cell cultures. However available kidney cell lines express low or no evi-1 mRNA. In the human renal cell carcinoma cell line, A704, evi-1 is inducible approximately 16-fold by elevating intra-cellular cAMP levels with either forskolin or dibutyryl cAMP. TPA down-regulates evi-1 mRNA production and blocks forskolin mediated induction. Similar effects are seen in NIH3T3 cells and primary kidney cell cultures. Induction of evi-1 gene expression by forskolin does not alter the ratio of full length and an alternatively spliced transcript which encodes a protein lacking two repeats of the zinc finger motif. Potential regulation of evi-1 expression in kidney by hormones which modulate intra-cellular cAMP levels suggest that it can respond to environmental cues which might be important to the normal physiological role of this protein in kidney differentiation, development and function.

Role of HTLV-I in development of non-Hodgkin lymphoma in Jamaica and Trinidad and Tobago. The HTLV Lymphoma Study Group

Human T-cell lymphotropic virus type I (HTLV-I) has been implicated in the aetiology of adult T-cell leukaemia/lymphoma in Japan and elsewhere, particularly the Caribbean. We have carried out parallel case-control studies in Jamaica and in Trinidad and Tobago to quantify the role of HTLV-I in the development of non-Hodgkin lymphoma (NHL). 135 cases of NHL were enrolled in Jamaica and 104 in Trinidad and Tobago. Controls were selected from patients treated in the same wards or clinics at the same time as the cases. Overall, patients with NHL were 10 times more likely than were controls to be seropositive for HTLV-I (Jamaica odds ratio 10.3 [95% CI 6.0-18.0], Trinidad and Tobago 14.4 [7.6-27.2]). In both countries the association between NHL and HTLV-I was greatest for T-cell lymphomas (18.3 [9.5-35.6] and 63.3 [25-167]). Among T-cell lymphomas especially, there was no significant difference between men and women in the association between NHL and HTLV-I, but there was a significant inverse relation between age and likelihood of HTLV-I seropositivity. B-cell lymphomas were predominant in the older age groups and were not associated with HTLV-I seropositivity. These findings are consistent with the hypothesis that early life exposure to HTLV-I is important for risk of subsequent ATL. Prevention of vertical transmission of HTLV-I could reduce by 70-80% cases of NHL in people under 60 years in this region.

Evidence of previous infection with Mycobacterium avium-Mycobacterium intracellulare complex among healthy subjects: an international study of dominant mycobacterial skin test reactions

Skin tests with 0.1 mL of intermediate-strength Mycobacterium tuberculosis purified protein derivative (PPD) and 0.1 mL of Mycobacterium avium sensitin were conducted on 484 healthy subjects from diverse geographic sites. Reactions of > or = 5 mm to one antigen that exceeded the reaction to the other by > or = 3 mm were considered M. avium- or PPD-dominant. PPD-dominant reactions were more frequent at sites where routine Bacille Calmette-Guérin immunization is done or where there are high rates of tuberculosis: New Hampshire, 2%; Boston, 7%; Finland, 14%; Trinidad, 26%; and Kenya, 28%. However, rates of M. avium-dominant reactions ranged from 7% to 12% at all sites. Analysis of dominant reactions based on a more stringent 10-mm minimum reaction size showed similar trends. These data suggest that exposure to MAC is similar in developed and developing countries but that broad mycobacterial immunity is greater in developing countries and may contribute to the lower rates of disseminated MAC infections in AIDS in these areas.

Cushing's syndrome from topical glucocorticoids

A case of Cushing's syndrome is described in a woman who self-treated psoriasis with a variety of potent topical glucocorticoids over 15 years. She was successfully weaned off corticosteroids and was treated with alternative anti-psoriatic drugs. The disappearance, nine months later, of most features of Cushing's syndrome, and the normal suppression of cortisol in response to dexamethasone, excluded endogenous hypercorticolism. The apparent widespread availability across the counter of potent corticosteroids is a cause for concern.

Transactivation of the c-myc promoter by human T cell leukemia virus type 1 tax is mediated by NF kappa B

Human T cell leukemia virus type 1 is the causative agent of adult T cell leukemia. The virus encodes a 40-kDa protein, tax, that is important for the immortalization of T cells. Expression of tax activates several cellular transcription factors, including NF kappa B. We have previously identified two functional NF kappa B binding sites within the murine c-myc gene: upstream regulatory element (URE) and internal regulatory element (IRE). Using transient cotransfection analysis of Jurkat or HeLa cells, we report that tax can transactivate chimeric TK-CAT constructs containing multiple copies of wild-type URE or IRE, but not constructs with mutated versions of these elements. Furthermore, tax induced transcriptional activity of murine and human c-myc promoter-CAT hybrid genes in Jurkat and HeLa cells. A mutated tax expression vector, which fails to activate NF kappa B, was unable to induce either murine or human c-myc-CAT or URE/IRE-TK-CAT constructs. Mutant c-myc gene-CAT constructs, in which the URE and IRE were mutated either singly or in combination by site directed mutagenesis, displayed significantly reduced CAT activation upon cotransfection with a tax expression vector. These results suggest that tax can transactivate the c-myc gene through NF kappa B. The tax-induced stimulation of this oncogene may play a role in T cell immortalization.

An approach for the analysis of relapse and marrow reconstitution after autologous marrow transplantation using retrovirus-mediated gene transfer

Autologous bone marrow transplantation (ABMT) is widely used as treatment for malignant disease. Although the major cause of treatment failure is relapse, it is unknown if this arises entirely because of residual disease in the patient or whether contaminating cells in the rescuing marrow contribute. Attempts to purge marrow of its putative residual malignant cells may delay hematopoietic reconstitution and are of uncertain efficacy. We now describe how retrovirus-mediated gene transfer may be used to elucidate the source of relapse after ABMT for acute myeloid leukemia and to evaluate the efficacy of purging. Clonogenic myeloid leukemic blast cells in patient marrow can be transduced with the NeoR gene-containing helper-free retrovirus, LNL6, with an efficacy of 0% to 23.5% (mean, 10.5%). Transduced colonies grow in selective media and the presence of the marker gene can be confirmed in individual malignant colonies by polymerase chain reaction. If such malignant cells remain in harvested "remission" marrow, they will therefore be marked after exposure to LNL6. Detection of the marker gene in the malignant cells present at any later relapse would be firm evidence that residual disease contributed to disease recurrence, and would permit rapid subsequent evaluation of purging techniques. The technique also marks normal marrow progenitors from patients with acute myeloblastic leukemia. These colony-forming cells can be detected in long-term marrow cultures at a frequency of 1% to 18% for up to 10 weeks after exposure to the vector. Animal models and analysis of probability tables both suggest that these levels of marking in vitro are sufficient to provide information about the mechanisms of relapse and the biology of marrow regeneration in vivo. These preclinical data form part of the basis for current clinical studies of gene transfer into marrow before ABMT.

Retrovirus-mediated gene transfer as an approach to analyze neuroblastoma relapse after autologous bone marrow transplantation

Disseminated neuroblastoma is a malignancy of children often treated by intensive chemotherapy/radiotherapy followed by autologous bone marrow transplantation (ABMT). A high proportion of those treated subsequently relapse. It is unknown if relapse is a consequence of residual disease in the patient or of contaminating malignant cells remaining in the infused marrow, which, of necessity, is harvested and stored prior to ablative chemotherapy/radiotherapy. The assumption that residual cells in the infused marrow contribute to relapse has lead to the adoption of marrow purging prior to reinfusion. However, neither the necessity nor the efficacy of the procedure have been established. We now show how retroviral-mediated gene transfer using the LNL6 vector may resolve this issue. Clonogenic neuroblastoma cells in patient marrow can be transduced and the NEOR gene detected by observing individual neuroblastoma cell colony growth in G418, and by polymerase chain reaction (PCR) of individual colonies. Efficiency of transduction is between 0 and 13.5%. If marrow is exposed to LNL6 prior to infusion and marked cells are detected at the time of relapse, this would demonstrate that infused marrow contributed to disease recurrence. The technique could then be used to analyze the efficacy of marrow purging techniques. Since normal progenitor cells from these patients are also marked, the technique can be used to study factors that modify reconstitution and transducibility of infused marrow. Clinical studies using this approach have now begun.

His-1 and His-2: identification and chromosomal mapping of two commonly rearranged sites of viral integration in a myeloid leukemia

To identify genes that contribute to myeloid leukemogenesis we have cloned viral integration sites from a CasBrM-MuLV-induced interleukin 3-independent myeloid leukemia cell line. Genomic probes derived from cellular sequences flanking two integrated proviruses were used to screen restriction digests of DNAs from a panel of 52 hematopoietic cell lines, 30 of which were established from CasBrM-MuLV- or MoMuLV-induced mouse leukemias. Probes from one integration site (His-1) defined a region that was rearranged in 3/52 cell lines, and probes from a second integration site (His-2) identified a rearrangement in 2/52 cell lines. Both cases of His-2 rearrangements occurred in concert with viral insertions in the His-1 locus. Genetic mapping of these loci using interspecific backcross analysis assigned the His-1 locus to mouse chromosome 2 and the His-2 locus to mouse chromosome 19. In situ hybridization with a probe from the human homologous region mapped the His-1 locus to human chromosome 2q14-q21. No recombinants were observed between His-2 and Gin-1, a common site of provirus integration in Gross passage A MuLV-induced T-cell leukemias, in 131 backcross animals, suggesting that these loci are tightly linked. The His-1 locus maps to mouse chromosome 2 distinct from any known oncogene or common site of integration but near the proximal breakpoint for a deletion that is observed in over 90% of radiation-induced leukemias.

Retroviral insertions 90 kilobases proximal to the Evi-1 myeloid transforming gene activate transcription from the normal promoter

The inappropriate production of the Evi-1 zinc finger protein occurs in retrovirus-induced murine myeloid leukemias and human acute myelogenous leukemias. In murine leukemias, expression of the Evi-1 gene is associated with retroviral insertions either in the Evi-1 locus, which is immediately 5' of the coding region of the gene, or in the genetically linked Cb-1/fim-3 locus. In these studies, we demonstrate by chromosomal walking and pulse field electrophoresis that the Cb-1/fim-3 locus is located 90 kb 5' of the Evi-1 locus. Primary structure analysis of Evi-1 cDNA clones from a Cb-1/fim-3 rearranged cell line (DA-3) demonstrates that transcription initiates 5' of the Evi-1 locus and that the first noncoding exon of the gene is 681 bp larger than previously defined. S1 nuclease protection studies reveal multiple transcription initiation sites within this region. Comparable transcriptional initiation sites were identified in RNA from kidney and ovary, in which the gene is normally expressed, suggesting that retroviral insertions in the Cb-1/fim-3 locus activate transcription from the normal promoter. In one myeloid cell line (DA-3), a single long terminal repeat (LTR) is present in the Cb-1/fim-3 locus. No stable transcripts were detectable from this LTR. In cells with retroviral insertions in the Cb-1/fim-3 locus, one allele of the Evi-1 locus becomes hypermethylated in the 5' region of the gene. Together, these results are most consistent with an LTR-mediated, long-range cis activation of Evi-1 gene expression.

Phenotypes and mechanisms in the transformation of hematopoietic cells

Interleukin 3 (IL-3) is a growth factor that supports the proliferation of early hematopoietic stem cells, as well as cells that are committed to a variety of the myeloid lineages. The mechanisms by which IL-3 functions have been studied through the use of a series of IL-3-dependent cell lines isolated from myeloid leukemias or long-term bone marrow cultures. A variety of studies have implicated tyrosine phosphorylation in IL-3 signal transduction. One of the substrates of phosphorylation is a 140 kDa, IL-3-binding protein that is speculated to be the biologically relevant IL-3 receptor. IL-3, through tyrosine phosphorylation, supports viability and growth through the regulation of transcription of a series of genes including c-myc and c-pim-1. The c-myc gene contributes to viability, in part, by regulating the transcription of the ornithine decarboxylase gene. The role of growth factors in differentiation is less clear. By studying IL-3-dependent myeloid leukemia cell lines, two genes have been identified whose altered expression is associated with blocking the ability of the cells to differentiate. The c-myb gene is a nuclear DNA binding protein that has been implicated in myeloid transformation in a number of systems. The Evi-1 gene is a novel gene of the zinc finger family of transcriptional activators. Possible mechanisms by which these genes interfere with normal differentiation are discussed.

William Hillary and sprue in the Caribbean: 230 years later

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Identification of a functional allele of a human interferon-alpha gene previously characterized as a pseudogene

Three recombinant phage lambda L47 clones containing 4 alpha interferon (IFN) genes have been isolated from a newly constructed human genomic library. Each gene is an allele of a previously described IFN gene, three being only minor variants. The fourth gene SMTIII.1A is a functional allele of the psi LeIF-L gene which previously has been described only as a pseudogene. Therefore, it appears likely that other variant alleles may remain to be described and that the IFN system may be able to tolerate some degeneracy as a consequence of the large number of members of the family.

Retroviral insertions in the CB-1/Fim-3 common site of integration activate expression of the Evi-1 gene

A common retroviral integration site (CB-1) was identified in two IL-3-dependent myeloid leukemia cell lines (DA-3, DA-34). The CB-1 locus was mapped to murine chromosome 3 and was shown to be closely linked to another myeloid common site of viral integrations in myeloid leukemias, Evi-1. A comparison of the CB-1 restriction map with published restriction maps for other common integration sites demonstrated that it was nearly identical to the restriction map of a common site of Friend MuLV integration in myeloid tumors termed Fim-3 (Bordereaux et al. 1987). Genomic clones representing approximately 110 kb of the CB-1 locus and 80 kb of the 5' region of the Evi-1 locus demonstrate no physical overlap of these viral integration sites. Previous studies (Morishita et al. 1988) have shown that retroviral insertions in the Evi-1 locus activate the expression of a gene potentially encoding a 120 kd zinc finger protein. Evi-1 expression is also activated in cell lines with viral integrations in the CB-1 locus. These results demonstrate that the CB-1/Fim-3 and Evi-1 loci constitute a large genomic region in which viral integrations activate the transcription of a new potential myeloid transforming gene.