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Loss of menin, a tumor suppressor coded by the MEN1 gene, is a key factor in the pathogenesis of multiple endocrine neoplasia type I and in a percentage of sporadic endocrine tumors of the pancreas and parathyroid glands. This study investigated expression of the menin protein in the normal exocrine pancreas and in pancreatic ductal adenocarcinoma (PDAC), the most common pancreatic tumor. Immunofluorescence (IF) analyses showed that menin is expressed at high levels in normal acinar and duct cells. Examination of 24 clinical samples of PDAC revealed a pronounced decrease in menin expression in all tumors examined. To identify alterations underlying this defect, we searched for disruption and epigenetic silencing of the MEN1 gene. Analysis of nine laser-microdissected tumors revealed loss of heterozygosity of intragenic (one tumor) or adjacent (three tumors) MEN1 microsatellite markers. Methylation of CpG sites in the MEN1 promoter was documented in five of 24 tumors. IF analyses also revealed low to undetectable menin expression in the PDAC cell lines MiaPaCa-2 and Panc-1. Ectopic expression of menin in these cells resulted in a marked alteration of the cell cycle, with an increase in the G1/S+G2 ratio. These findings represent the first evidence that the MEN1 gene is a target of mutation and methylation in PDAC and that menin influences the cell cycle profile of duct cells.

Patterns of endemicity of human herpesvirus 8 (HHV8) are still undefined in some European populations, such as those from Western Balkan countries. Serum samples from 605 human immunodeficiency virus-seronegative subjects (299 Albanians and 306 Kosovars) were tested for the presence of HHV8 antibodies to a capsid-related open reading frame (ORF65)-encoded protein and a latency-associated nuclear antigen (LANA) to determine HHV8 seroprevalence in populations from Albania and from the Kosovo region of former Yugoslavia. Levels of co- circulation with hepatitis A (HAV) and hepatitis B (HBV) viruses were also determined. HHV8 antibodies to at least one of the two antigens were detected in 28.8% of Albanians and 18% of Kosovars. The seroprevalence of HHV8 was found to be 25.0 and 16.8% in Albanian and Kosovar children (

The seroprevalence of human herpesvirus 8 (HHV-8) in a group of HIV-1-infected pregnant women and in mother–child pairs from Southeastern Italy (Apulia) was determined. Blood was collected from 49 HIV-1-infected women during pregnancy or at delivery as well as from their children. Samples were analysed for the presence of antibodies to the latency-associated nuclear antigen and a structural antigen encoded by open reading frame 65. The presence of antibodies to hepatitis C virus (HCV) was also determined. Nineteen women (38.7%) were found to be positive for HHV-8 antibodies to at least one of the two antigens, and 21 (42.9%) for HCV antibodies. HHV-8 antibodies were more common in injecting drug users (56.3%) than in women infected through heterosexual intercourse (30.3%). HCV antibodies were significantly more prevalent in HHV-8-seropositive (66.7%) than HHV- 8-seronegative (29%) women. Thirteen children born to HIV-1/HHV-8 co-infected women were HHV-8-seroreactive, with a variable pattern of reactivity to the analysed antigens. Follow-up of children showed a prolonged persistence of antibodies, in two cases for more than 12 months. This study has provided serological evidence for a high rate of HHV-8 infection in HIV-1-infected women in the Apulia region, and has identified a possible association between HHV-8 infection, past use of injection drugs and HCV infection. Parenteral transmission may, therefore, be a mode of virus spread. J. Med. Virol. 72:656–660, 2004. © 2004 Wiley-Liss, Inc.

Deregulation of the apoptotic process can lead to pathophysiological changes that result in either degenerative diseases or cancer. Although the transactivator Tax has been established as an essential effector of human T-lymphotropic virus type-1 (HTLV-1)-mediated diseases, which include both a neurodegenerative pathology and leukemia/lymphoma, its exact role(s) in the pathogenesis remains to be clarified. Because the apoptotic potential of Tax is still being debated, we addressed this question by testing the susceptibility of Tax(-) and Tax(+) cells to apoptosis under conditions of growth factor withdrawal and Bax overexpression. Results showed that Tax(+) cells are protected from apoptosis triggered by depletion of growth factors. This protective effect seems to be the result of a block in the apoptotic program regulated by mitochondria. Furthermore, in an attempt to elucidate which transcriptional pathway activated by Tax is important in the observed Tax-induced resistance, we found that CREB/ATF activity plays a relevant role in protecting cells from apoptosis induced by Bax overexpression. All together, these data might suggest that the ability of Tax to inhibit certain apoptotic stimuli could be important in its role as a viral transforming protein.

The progressive shortening of telomeres at each cell division is a key mechanism in controlling cell proliferative capacity. The activation of telomerase, a reverse transcriptase that extends telomere length, potentially leads to unlimited cell proliferation, and is believed to play a critical role in the neoplastic process. High levels of telomerase activity have been demonstrated in almost all solid tumours; however, little data is available concerning its expression in chronic B-cell neoplasms. By using a quantitative polymerase chain reaction-based method we quantified telomerase activity in normal B lymphocytes, and in various B-cell malignancies, including chronic lymphocytic leukaemia (CLL), mantle cell lymphoma (MCL) and hairy cell leukaemia (HCL). Compared to normal B cells, which expressed very low levels of telomerase activity, malignant cells from most of the patients showed a significant increase in telomerase activity, with highest values observed in HCL samples. Moreover, among the CLL and HCL cases, significantly higher levels of telomerase activity were found in patients with progressive disease at 1 year follow-up versus patients with stable disease. These data suggest that telomerase activity might correlate with disease progression.

To assess the prevalence of HTLV-I and HTLV-II infections in different groups at risk for HIV-I infection, a study on 867 subjects was carried out by means of serological and PCR analyses. Serum specimens were collected from 268 intravenous drug users (IVDU), 66 homosexual men, 248 subjects with sexually transmitted diseases (STD), 105 thalassemics and 180 hemophiliacs. Sera from 3 IVDU and a sample from an STD patient were confirmed as HTLV-II seropositive; a thalassemic patient was seropositive for HTLV-I; a homosexual man, though confirmed as HTLV-I/II-seroreactive, could not be typed by serological methods. No hemophiliac was found to be HTLV-I/II-reactive. All 3 HTLV-II-seroreactive IVDU and the HTLV-I-infected thalassemic were confirmed by PCR; an additional sample from an IVDU, indeterminate by Western blot, was confirmed to be positive for HTLV-II by PCR. Subtyping of HTLV-II samples indicated the presence of II/b subtype in all 4 cases. Up to now, the reservoir for HTLV-II infection in southeastern Italy is mainly represented by IVDU, while HTLV-I infection seems to be sporadic.

Intraperitoneal injection of lymphoid cells from EBV+ donors into SCID mice might provide a useful tool for studying the pathways of B-cell lymphomagenesis in man. Since previous studies showed that donor T cells greatly favor B-cell proliferation and tumor generation in this model, we addressed the host and donor factors involved in limiting or promoting lymphoma development. The number of EBV-infected B-cell precursors was crucial, since purified B lymphocytes, which alone were unable to generate tumors, underwent expansion and established tumor masses when the animals were inoculated with an EBV-containing supernatant. Host factors were critical in limiting tumor development; in vivo NK-cell removal allowed purified B cells to expand and proceed to tumors in the absence of T lymphocytes, whereas potentiation of mouse NK-cell activity prevented tumor generation in PBMC- and LCL-injected animals. The T-cell-derived factors that favor lymphomagenesis could not be identified; IL-2, IL-4, IL-6, and soluble CD23 were not able to promote B-cell expansion, and treatment of PBMC-injected mice with the relevant anti-cytokine anti-sera did not counteract lymphoma development. These experiments also showed that IL-6 plays a minor role, if any, in B-cell lymphoproliferation in this model. Our data indicate that reconstitution of SCID mice with PBMC from EBV+ donors may constitute a useful model for determining the events involved in lymphomagenesis in humans, provided that strict control of all the experimental variables is guaranteed.

Infection of Moloney mouse sarcoma virus (M-MSV) in adult mice of several inbred strains revealed that all strains except AKR are highly susceptible to M-MSV tumor development. F1 hybrids between AKR and CBA, DBA/2 or NIH mice are as resistant (93%) as the parental AKR strain, which indicates that resistance is transmitted as a dominant character. First backcross mice to the susceptible parent show a 3:1 ratio of resistant to susceptible mice. This is the expected ratio for two segregating loci which independently confer resistance. The incidence of resistant F2 mice is somewhat lower than expected. Further support for the two-gene hypothesis was obtained in second backcross mice. None of the major genes affecting MuLV infection (Fv-2 and H-2) seems to play any role in this system and no linkage was found with Thy. 1 and albino, dilute, agouti and brown markers.

We have shown in the preceding paper that AKR mice are highly resistant to M-MSV tumor development, and that resistance is transmitted as a dominant character. In the present studies the tumor-response pattern of F1 hybrids between resistant AKR and susceptible strains (C57Bl/6, BALB/c and B10BR) following injection with Moloney mouse sarcoma virus (M-MSV) resembles that of the non-AKR parent. Segregation is observed in first backcross (Bc1) and F2 mice, and the segregation ratios up to Bc3 mice fit a one-gene model. The data of triple cross hybrids suggests that this dominant susceptibility gene inhibits the phenotypic expression of M-MSV tumor resistance in some susceptible Fv1bb strains as well as in their hybrids with AKR. Neither Fv-1 nor H-2 exerts any significant influence on this complex system.

Summary The H-2 restriction phenomenon was evaluated with regard to the immune response to Moloney sarcoma virus (M-MSV)-induced tumours in the mouse. Using an in vitro51Cr release assay the lytic activity of lymphocytes from M-MSV immune strains of mice, including several H-2 recombinant strains, was determined on leukaemic cell lines originally induced in mice of different strains by neconatal infection with Moloney leukaemia virus. In analogy with other experimental models, it was observed that a compatibility between effector and target cells at the K and/or D regions is generally necessary and sufficient to obtain the cytotoxic effect. However, for the H-2d and H-2b haplotypes, identity at the K or D region respectively was not sufficient for lysis to occur. Attempts to demonstrate that this lack of activity might be associated with the absence of H-2-linked Ir responder genes, were not successful.

Bone marrow megakaryocytes from mice injected with Graffi or Passage A Gross viruses were studied by electron microscopy in order to establish a possible correlation between the presence of virus particles and the susceptibility of mice to leukemia induction. An appreciable number of virus particles were found in megakaryocytes from C57BL mice injected with Graffi virus at birth. In these animals there was a high incidence of leukemia. Negative results on the presence of virus particles as well as leukemia induction were obtained in mice of the same strain injected with the virus at adult age. Similarly, with Gross Passage A virus injected at birth into both C3Hf/Gs and C57BL mice, virus particles were found in megakaryocytes from mice of the C3Hf/Gs strain which is susceptible to leukemia induction. Virus particles were not found in megakaryocytes from C57BL mice which are resistant to the leukemogenic action of this virus. PRESENCE DE PARTICULES VIRALES DANS LES MEGACARYOCYTES DE LA MOELLE OSSEUSE ET SENSIBILITE DES SOURIS A LA LEUCEMIE INDUITE PAR DES VIRUS Nous avons etudie au microscope electronique des megacaryocytes de moelle osseuse provenant de souris inoculees avec le virus de Graffi ou le virus de Gross au passage A, afin de voir s'il y avait une correlation possible entre la presence des particules virales et la sensibilite des souris a la leucemie provoquee. Nous avons trouve un nombre appreciable de particules virales dans les megacaryocytes de souris C57BL inoculees avec le virus de Graffi a la naissance. On a observe chez ces animaux une incidence elevee de la leucemie. Chez les souris de la měme souche ayant recu le virus a l'ǎge adulte, les resultats ont ete negatifs tant en ce qui concerne la presence de particules virales que l'induction d'une leucemie. De měme, apres injection de virus de Gross au passage A chez des souris C3Hf/Gs et C57BL a la naissance, on a trouve des particules virales dans les megacaryocytes des souris de la souche C3Hf/Gs qui est sensible a la leucemie provoquee. En revanche, on n'en a pas trouve avec la souche C57BL qui est resistante a l'action leucemogene de ce virus.