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The association between undifferentiated nasopharyngeal carcinoma (NPC) and Epstein-Barr virus (EBV) is well established. Nevertheless, available evidence suggests that other cofactors are required for the development of undifferentiated NPC. Several investigations reported simian virus 40 (SV40) footprints in human tumors of different histotypes. Serum samples from patients with undifferentiated NPC (n = 64) and healthy subjects (n = 130) were analyzed by an indirect enzyme-linked immunosorbent assay (ELISA) with SV40 synthetic peptides to detect antibodies against viral peptide (VP) capsid proteins VP1, 2, and 3. Immunologic data indicate that in sera from patients with undifferentiated NPC, the prevalence of SV40 antibodies was 25%, whereas in controls it was 16%. This difference is not statistically significant (p > .05). A similar prevalence of SV40 antibodies was detected in undifferentiated NPC and healthy subjects. Our serologic data suggest no association between undifferentiated NPC and SV40 infection. This investigation may stimulate further studies aimed at determining the possible contribution of other risk factors in the pathogenesis of undifferentiated NPC.

BACKGROUND Non-Hodgkin lymphoma (NHL), the most common cancer of the lymphatic system, is of unknown etiology. The identification of etiologic factors in the onset of NHL is a key event that could facilitate the prevention and cure of this malignancy. Simian virus 40 (SV40) has been considered an oncogenic agent in the onset/progression of NHL. METHODS In this study, an indirect enzyme-linked immunosorbent assay with 2 synthetic peptides that mimic SV40 antigens of viral capsid proteins 1 to 3 was employed to detect specific antibodies against SV40. Serum samples were taken from 2 distinct cohorts of NHL-affected patients (NHL1 [n = 89] and NHL2 [n = 61]) along with controls represented by oncologic patients affected by breast cancer (BC; n = 78) and undifferentiated nasopharyngeal carcinoma (UNPC; n = 64) and 3 different cohorts of healthy subjects (HSs; HS1 [n = 130], HS2 [n = 83], and HS3 [n = 87]). RESULTS Immunologic data indicated that in serum samples from NHL patients, antibodies against SV40 mimotopes were detectable with a prevalence of 40% in NHL1 patients and with a prevalence of 43% in NHL2 patients. In HSs of the same median age as NHL patients, the prevalence was 16% for the HS1 group (57 years) and 14% for the HS2 group (65 years). The difference was statistically significant (P

BACKGROUND Simian virus 40 (SV40) has been considered to be an oncogenic viral agent in the development of osteosarcoma (OS), which to the authors' knowledge continues to be of unknown etiology. METHODS In the current study, serum samples from patients with OS were investigated with an indirect enzyme-linked immunoadsorbent assay (ELISA) to test for the presence of immunoglobulin G antibodies, which react with SV40 antigens. In ELISA, SV40 antigens were represented by 2 synthetic polypeptides that mimic epitopes of the viral capsid proteins 1 to 3. Additional sera from patients with breast cancer and undifferentiated nasopharyngeal carcinoma as well as healthy subjects were the controls. RESULTS Immunologic results suggested that antibodies that react with SV40 mimotopes were more prevalent (44%) in serum samples from patients with OS compared with healthy subjects (17%). The difference in prevalence between these cohorts was statistically significant (P

Simian Virus 40, experimentally assayed in vitro in different animal and human cells and in vivo in rodents, was classified as a small DNA tumor virus. In previous studies, many groups identified Simian Virus 40 sequences in healthy individuals and cancer patients using PCR techniques, whereas others failed to detect the viral sequences in human specimens. These conflicting results prompted us to develop a novel indirect ELISA with synthetic peptides, mimicking Simian Virus 40 capsid viral protein antigens, named mimotopes. This immunologic assay allowed us to investigate the presence of serum antibodies against Simian Virus 40 and to verify whether Simian Virus 40 is circulating in humans. In this investigation two mimotopes from Simian Virus 40 large T antigen, the viral replication protein and oncoprotein, were employed to analyze for specific reactions to human sera antibodies. This indirect ELISA with synthetic peptides from Simian Virus 40 large T antigen was used to assay a new collection of serum samples from healthy subjects. This novel assay revealed that serum antibodies against Simian Virus 40 large T antigen mimotopes are detectable, at low titer, in healthy subjects aged from 18-65 years old. The overall prevalence of reactivity with the two Simian Virus 40 large T antigen peptides was 20%. This new ELISA with two mimotopes of the early viral regions is able to detect in a specific manner Simian Virus 40 large T antigen-antibody responses.

BK virus (BKV), a human polyomavirus closely related to JC virus and Simian Virus 40, is ubiquitous in human populations worldwide. After primary infection, BKV establishes a lifelong latent infection in many organs. BKV transforms rodent cells to the neoplastic phenotype and is highly oncogenic in rodents. This review considers the oncogenic potential of BKV in humans and its possible involvement in human tumors. BKV sequences and T antigen (Tag) are detected in several types of human neoplasms, although the viral load is generally low, with less than one copy of the viral genome per cell. The possible causative role of BKV in human oncogenesis rests on the ability of BKV Tag to inactivate the functions of tumor suppressor proteins p53 and pRB family as well as on its ability to induce chromosomal aberrations in human cells. A 'hit and run' mechanism and secretion of paracrine growth factors by BKV Tag-positive cells, recruiting into proliferation neighboring and distant cells, are discussed as possible BKV pathogenic elements in human oncogenesis.

Glioblastoma multiforme (GBM) is the most severe form of cancer among gliomas. Indeed, GBM is a World Health Organization grade IV tumor of the CNS, with a mean survival time of 0.5 years.1 Its incidence is ∼1/100 000, which represents 30% of all CNS malignancies.2 According to the recent Eurocare 3 report,3 the mean age of patients affected by glioblastoma is 66 years. The extremely grim prognosis of GBM patients probably explains why such a rare tumor accounts for 2% of all cancer-related deaths in both Europe and the United States.4 GBM is characterized by high genotypic and phenotypic heterogeneities, but it is invariably and homogeneously resistant to conventional chemo/radiotherapy.1 The vast majority (95%) of GBM is represented by primary de novo glioblastomas.5 GBM is considered, like other tumors, a genetic disease of the somatic cell due to an impressive series of alterations of the cellular genome, such as point mutations, gene amplifications, translocations, and deletions, as well as epigenetic modifications, including methylation of specific genes. A limited percentage (5%) of GBM is linked to genetic predispositions, which are mainly associated with rare hereditary syndromes, such as Li–Fraumeni syndrome, Turcot syndrome, Peutz–Jegher syndrome, and neurofibromatosis 1 and 2.2 Exposure to chemical and physical carcinogenic agents, the genetic predisposition, and/or infections by oncogenic viruses, including simian virus 40 (SV40), have been repeatedly advocated in the literature.6,7 SV40 is a nonenveloped small DNA virus of ∼5.2 kb in size. SV40 was recognized in the 1960s as a contaminant of both inactivated (Salk) and live attenuated (Sabin) antipoliomyelitis vaccines. As a consequence, SV40 was inadvertently administered to human populations worldwide mainly by antipoliomyelitis vaccines, produced in SV40 naturally infected monkey kidney cells. Soon after its isolation, SV40 was characterized as a transforming and tumorigenic viral agent.6,7 Cell transformation and tumorigenesis by SV40 is induced by 2 oncoproteins, the large T antigen (Tag) and the small t antigen (tag), which target key cellular proteins, such as the tumor suppressor p53 and retinoblastoma family proteins, inactivating their functions.6,8 This small DNA tumor virus was found to be associated with some human cancers, including GBM. SV40 footprints were detected at high prevalence in GBM specimens, but SV40 sequences have also been revealed, although at lower prevalence, in blood specimens from healthy donors.9–11 In this context it is worth recalling that other investigations did not find SV40 footprints in human brain tumor specimens12,13 or higher SV40 antibodies in serum samples from brain tumor patients than in normal individuals.14 It has been reported that SV40-negative data on human tumor samples obtained by some groups were affected by technical flaws that invalidate the conclusions.15–17 A considerable debate, because of these contrasting reports, has developed in the scientific community.6,7 SV40 antibody detection had been performed in most cases using serologic methods with SV40 virus-like particles, but due to the high protein homology among the 3 main polyomaviruses—SV40, BKV, and JCV—final results were always influenced by some cross-reactivity.18–24 Altogether these reports prompted us to use an indirect ELISA with synthetic peptides employed as specific mimotopes, mimicking SV40 viral capsid antigens. Indeed, recent investigations have reported on the development of a specific and sensitive serologic test for SV40. The test is based on an indirect ELISA employing synthetic peptides as mimotopes/antigens of SV40 viral capsid proteins (VPs), without cross-reactivity with other closely related human polyomaviruses, such as BKV and JCV.25–28 This immunologic assay was used to detect specific serum antibodies against SV40 VPs in normal individuals of different ages and oncologic patients affected by malignant pleural mesothelioma and breast cancer (BC).25–28 In this investigation, serum samples from GBM patients were comparatively analyzed for the presence and titer of antibodies against SV40 infection, with serum samples from healthy individuals and from other reliable controls. No other slow virus infections were investigated.

Colon carcinomas with microsatellite mutator phenotype exhibit specific genetic and clinico-pathological features. This report describes the analysis of 63 "microsatellite instability-high" (MSI-H) tumors for the presence of mutations in microsatellites located in the coding regions (CDRs) of 6 genes: TGFbetaRII, BAX, hMSH3, hMSH6, IGFIIR, and BLM. The following frequencies of mutations were detected: TGFbetaRII (70%), BAX (54%), hMSH3 (36.5%), IGFIIR (22%), hMSH6 (17.5%), and BLM (16%). The overall picture revealed combinations of mutations suggestive of a progressive order of accumulation, with mutations of TGFbetaRII and BAX first, followed by frameshifts in hMSH3, hMSH6, IGFIIR, and BLM. Correlations with 12 clinico-pathological parameters revealed that tumors with frameshifts in 1 or 2 CDRs were significantly better differentiated than tumors with frameshifts in more than 2 CDRs. We also found that mutations in the hMSH3 gene were significantly associated with decreased wall invasiveness and aneuploidy, and frameshifts in the BLM gene were significantly associated with the mucinous histotype. A trend toward an association between hMSH3 and IGFIIR with the medullary and conventional adenocarcinoma histotypes, respectively, was seen. Our results strengthen the concept that mutations in target genes have a role in the tumorigenic process of MSI-H tumors, and indicate that frameshifts in microsatellites located in CDRs occur in a limited number of combinations that could determine distinct clinico-pathological traits.

Intramuscular immunization of mice with plasmids encoding two transdominant negative mutants of the HIV-1 Tat protein (Tat22 and Tat22/37) elicited a humoral response to wild-type Tat that is comparable to that induced by inoculation of wild-type tat DNA or Tat protein. The percentage of the responders and the Ab titers continued to increase after three additional DNA boosts and pretreatment with bupivacaine at the site of inoculation, without a significant difference (p > 0.05) among the three groups of mice immunized with mutant and wild-type tat genes. By utilizing synthetic peptides representing the amino acid sequence of Tat, one major B cell epitope was defined within the cysteine-rich domain of Tat. Anti-Tat IgG Abs directed against this epitope were found in mice immunized with all tat DNA constructs, whereas different Tat epitopes were detected in mice immunized with the Tat protein. Similarly, IgG2a was the predominant isotype in DNA-immunized mice, with both mutants and wild-type tat genes, as compared with protein immunization, which induced mostly IgG1 and IgG3. Sera from most immunized mice neutralized the effect of extracellular Tat in activating HIV-1 replication. A cellular response was also elicited as indicated by the proliferation of splenocytes when stimulated with wild-type Tat. These results indicate that the wild-type Tat Ag is recognized by Abs and T cells induced by DNA immunization with mutated tat genes, suggesting the possible use of these Tat transdominant mutants, lacking viral trans activation activity and capable of blocking wild-type Tat activity, in the development of an anti-HIV-1 vaccine.

To study the role in AIDS pathogenesis of the human immunodeficiency virus type 1 (HIV-1) Tat protein, a transactivator of viral and cellular genes, we generated transgenic mice with a recombinant DNA containing BK virus (BKV) early region and the HIV-1 tat gene, directed by its own promoter-enhancer. DNA hybridization revealed that the transgene is stably maintained in all organs of transgenic mice as a tandem insertion in a number of copies ranging from 5 to 20 per cell. In addition, tat and BKV RNA were expressed in all tissues. Transgenic mice developed three types of lesions: 1) tumors, 2) hyperplastic and dysplastic lesions, and 3) non-neoplastic lesions. Tumors of different histotypes, such as lymphomas, adenocarcinomas of skin glands, leiomyosarcomas, skin squamous cell carcinomas, hepatomas, hepatocarcinomas, and cavernous liver hemangiomas, developed in 29% of transgenic animals. The majority of tumors were malignant, invasive, and producing metastases. Conversely, tumors of only two histotypes (lymphomas and adenocarcinomas of skin glands) appeared in control mice. Hyperplastic and dysplastic lesions were more frequent in transgenic than in control mice and involved the skin or its adnexes, the liver and the rectum, indicating multiple targets for the activity of the transgene. Pyelonephritis, frequently complicated with hydronephrosis, inflammatory eye lesions, and amyloid depositions represented the most frequent non-neoplastic lesions detected in transgenic mice. Many of the pathological findings observed in this animal model are comparable to similar lesions appearing in AIDS patients, suggesting a relevant role for Tat in the pathogenesis of such lesions during the course of AIDS.

Loss of constitutive heterozygosity at 11q23 has been detected in various human solid tumors. Here, we described the analysis of a series of normal and tumor pairs from 110 breast carcinomas for the presence of loss of heterozygosity at 11q23 loci. The overall frequency of LOH was 48%, confirming the importance of deletions at 11q23 in breast tumorigenesis. Previously, we have identified two independent regions of LOH at 11q23, the LOH region 1 at 11q23.1 and the LOH region 2 at 11q23.3. The most telomeric region was recently refined between loci D11S1345 and D11S1316, a region of about 1 Mb. However, the LOH region 1, most centromeric, was still not finely refined: the boundaries were defined by loci D11S2000 and D11S897, separated by about 8 Mb. Here, we refined its boundaries between loci D11S1347 and D11S927, a region of about 2 Mb. We have mapped 11 expressed sequence tags (ESTs) within this region and excluded another 20. This study represents a further step toward the identification of the putative tumor suppressor gene found within the LOH region 1 at 11q23.1.

The antiangiogenic, antitumoural and antimetastatic effects of two novel sulphonic derivatives of distamycin A, PNU145156E and PNU153429, were studied in a Kaposi’s sarcoma-like tumour model obtained by injecting nude mice with cells releasing extracellular HIV-Tat protein, derived from a tumour which developed in a BK virus/tat transgenic mouse. Both PNU145156E and PNU153429 were administered intraperitoneally every fourth day for three weeks at doses of 100 or 50 mg/kg of body weight respectively, starting one day after injecting the tumour cells. Both drugs delayed tumour growth in nude mice, preventing neovascularization induced by the Tat protein. PNU153429 also significantly reduced the number and size of spontaneous tumour metastases. Both effects on tumour growth and metastases were augmented by treating simultaneously nude mice with 7.5 mg/kg of body weight of minocycline given per os daily for four weeks starting four days after injecting the tumour cells. Neither acute nor chronic toxic side-effects were observed during the life span of treated nude mice. Due to their antiangiogenic and anti-Tat effects, these drugs are promising for the treatment of Kaposi’s sarcoma in AIDS patients.

We present the transcription map of chromosome region 6q16→q21 by mapping fifteen known genes within this region. Five genes lay in the subregion containing a tumor suppressor gene, eight genes are located in the subregion harboring a senescence gene, and two genes are distal to the latter region. The precise location of the genes was obtained using a previously described translocation and deletion mouse/human hybrid panel. An even more accurate definition was possible for the genes spanning the senescence gene region, since a previously described YAC contig with its restriction map was available. From this transcription map it is possible to derive a large region of synteny with mouse chromosome 10.

A series of retroviral vectors with potential anti-tat and anti- constructs inhibited virus replication at a high multiplicity of rev activity was developed. Vectors containing a tat trans- infection (MOI). At a low MOI, two cell clones containing dominant negative mutant (tat22/37) and an RRE decoy in tat22/37 and the RRE decoy in 3′ position showed a long different positions, directed by the same promoter or by lasting protection against virus replication, in comparison different promoters, were generated. Retroviral vectors to control cultures expressing tat22/37 or RRE alone. Combicontaining tat 22/37 and the RevM10 transdominant negative nation of tat and rev mutants was ineffective in inhibiting mutant were also constructed. Jurkat cells were trans- HIV-1 replication at both low and high MOIs. At a low MOI, duced with the recombinant retroviruses to produce mono- HIV-1 replication was efficiently blocked in two cell clones clonal and polyclonal cultures. In these cell lines the expressing the RevM10 mutant alone. These results show recombinant proviruses were correctly integrated and a synergic effect of anti-tat and anti-rev molecules when expression of the inserted genes was detected by Northern the RRE sequence is cloned 3′ to tat22/37, suggesting the blot or RT-PCR analysis. However, infection of these cell possibility of using this vector design to control HIV-1 lines with HIV-1 showed that none of these recombinant replication.

Twenty-one expressed sequence tags (ESTs) belonging to unidentified transcripts were mapped to 9 intervals at 11p 15.5-p15.3. Thirteen were mapped to a region of an estimated size of 7 Mb with the help of a YAC contig. The remaining eight were mapped outside this region, and the centromeric or telomeric position of the ESTs relative to the YAC contig was defined with the help of a cellular hybrid containing a derivative chromosome 11 with a break-point within the region covered by the contig. The average size of the intervals, where the ESTs were mapped, was estimated to be 0.3-0.4 Mb. The refinement of the chromosomal location of these ESTs could be of great help in the identification of potential candidate genes for disease locus mapping at 11p15.

HIV-1 associated neurocognitive disorders (HAND) are a major complication of HIV-1 infection. The mechanism(s) underlying HAND are not completely understood but, based on in vitro studies, the HIV-1 Tat protein may play an important role. In this study, the effect of prolonged exposure to endogenously produced Tat in the brain was investigated using a tat-transgenic (TT) mouse model constitutively expressing the HIV-1 tat gene. We found that stimulus-evoked glutamate exocytosis in the hippocampus and cortex was significantly increased in TT as compared with wild-type control (CC) mice, while GABA exocytosis was unchanged in the hippocampus and decreased in the cortex. This suggests that Tat generates a latent hyper-excitability state, which favors the detrimental effects of neurotoxic and/or excitotoxic agents. To challenge this idea, TT mice were tested for susceptibility to kainate-induced seizures and neurodegeneration, and found to exhibit significantly greater responses to the convulsant agent than CC mice. These results support the concept that constitutive expression of tat in the brain generates a latent excitatory state, which may increase the negative effects of damaging insults. These events may play a key role in the development of HAND.

We have analyzed by PCR skin lesions from classic, endemic and AIDS-related Kaposi's sarcoma (KS), as well as from KS-derived cell lines, the presence of ubiquitous transforming viruses. BK virus (BKV), a transforming human papovavirus which has been associated with human tumors, was detected in 100% of KS skin lesions and 75% of KS cell lines. KS specimens contained a full-length, intact BKV early region, but minor rearrangements were observed in some tumors. BKV was also detected with a high prevalence (57-67%) in genital tissues and sperm, thus fulfilling the role of a sexually transmitted agent in KS. The closely related JC virus (JCV), which has never been associated with human malignancies, was present in 11-20% of KS specimens and was detected with a low prevalence (0-21%) in genital tissues and sperm. Simian virus 40 (SV40) was not detected in any KS lesions. Herpes simplex virus (HSV) DNA sequences were detected in 20-25% of KS lesions. Malignant human papillomavirus (HPV) types 16 and 18 and benign HPV types 6 and 11 were detected in KS specimens with a similar prevalence of 11-83%, suggesting that the presence of HPV-transforming sequences is not a specific trait of HPV interaction with KS tissue. Furthermore, JCV, SV40, HSV and HPV DNA sequences were not detected in KS cell lines, suggesting that these viruses are not associated to KS neoplastic cells in KS tissue. KS cell lines were also negative for DNA sequences of KS-HV, the novel herpesvirus detected in primary KS lesions. The constant association of BKV DNA with KS lesions and KS cell lines suggests that BKV-transforming functions may participate in the development of KS.

Wild-type P16/CDKN2 (p16INK4A, MTS1) cDNA, directed by the cytomegalovirus (CMV) immediate early promoter, was transfected into RT4 and RT112 bladder-carcinoma cell lines bearing a mutated endogenous P16/CDKN2 gene and lacking endogenous P16/CDKN2 respectively. In both cases, only transfected clones with rearranged exogenous P16/CDKN2 cDNA could be grown and propagated in cell culture. This result is reminiscent of transfection of wild-type p53 into cells with a deleted or mutated endogenous gene and suggests that P16/CDKN2, over-expressed under control of the strong CMV promoter, induces growth arrest in RT4 and RT112 cells. Transfer of human chromosome 9 to RT4 cells produced RT4/H9 hybrid clones retaining the P16/CDKN2 gene, since in RT4/H9 cell clones P16/CDKN2-gene expression is modulated by the physiological control of chromosomal regulatory sequence. All the RT4/H9 clones lost the entire chromosome 9, except clone 4 and clone 5, which maintained a deleted and an intact chromosome 9 respectively. Loss of several loci in 9p21, including P16/CDKN2, in tumors induced in nude mice by clone 4 and clone 5 suggests that P16/CDKN2 or other genes in 9p21 suppress tumorigenicity in bladder-carcinoma cells. Tumors induced by clone 4 and clone 5 show loss of markers in 9q. The regions 9q22.3, 9q32-33 and 9q34.2, which were maintained in the 2 clones and lost in their derived tumors, may contain tumor-suppressor genes relevant in bladder carcinoma. The results of this study suggest that the P16/CDKN2 gene controls growth of bladder-carcinoma cells when it is over-expressed, and may be involved in the development of bladder carcinoma, but other genes in 9p21 and 9q may participate in bladder-cancer progression.

A BK virus (BKV) episomal vector (pRPneoCMV) was constructed for expression of cDNAs under control of the cytomegalovirus (CMV) immediate-early promoter. Transfection of pRPneoCMV for expression of the chloramphenicol acetyltransferase (CAT) gene in several human cell lines showed that the CMV promoter is more efficient than the HIV-1 and RSV LTRs in directing gene expression from episomal vectors. In 293 human cells pRPneoCMV/CAT is twenty times more active in CAT expression than the well known pSV2CAT vector in COS7 cells. Stable expression of the gene of the herpes simplex virus type 1 and type 2 glycoprotein G, cloned into pRPneoCMV, was obtained in 293 cells. This vector will allow direct cloning of newly synthesized cDNAs whose expression can be monitored in human cells.

Bio-engineered scaffolds used in orthopedic clinical applications induce different tissue responses after implantation. In this study, non-stoichiometric Mg2+ ions and stoichiometric apatites, which are used in orthopedic surgery as bone substitutes, have been assayed in vitro with human adult mesenchymal stem cells (hMSC) to evaluate cytocompatibility and osteoconductivity. hMSCs from the bone marrow aspirates of orthopedic patients were isolated and analyzed by flow cytometry for the surface markers Stro1, CD29, CD44, CD71, CD73, CD90, CD105 (positive) and CD45, CD235 (negative). The hMSC were analyzed for self-renewal capacity and for differentiation potential. The hMSC, which were grown on different biomaterials, were analyzed for (i) cytotoxicity by AlamarBlue metabolic assay, (ii) osteoconductivity by ELISA for activated focal adhesion kinase, (iii) cytoskeleton organization by fluorescence microscopy, and (iv) cell morphology which was investigated by scan electron microscopy (SEM). Results indicate that isolated cell populations agree with minimal criteria for defining hMSC cultures. Non-stoichiometric Mg2+ and stoichiometric apatites, in granular form, represent a more favorable environment for mesenchymal stem cell adhesion and growth compared to the non-stoichiometric Mg2+ apatite, in nano-structured paste form. This study indicates that different forms of biomaterials modulate osteoconductivity and cellular growth by differential activation focal adhesion kinase. J. Cell. Physiol. 228: 1229–1237, 2013. © 2012 Wiley Periodicals, Inc.

Human malignant pleural mesothelioma (MPM) is considered a rare tumor, but recent estimations indicate that one-quarter million people will die of this neoplasm in Europe in the next three decades. The mineral asbestos is considered the main causative agent of this neoplasm. MPM is largely unresponsive to conventional chemotherapy/radiotherapy. In addition to asbestos exposure, genetic predisposition to asbestos carcinogenesis and to simian virus (SV)40 infection has also been suggested. SV40 is a DNA tumor virus found in some studies to be associated at high prevalence with MPM. SV40 sequences have also been detected, although at a lower prevalence than in MPM, in blood specimens from healthy donors. However, some studies have failed to reveal SV40 footprints in MPM and its association with this neoplasm. These conflicting results indicate the need for further investigations with new approaches. We report on the presence of antibodies in serum samples from patients affected by MPM that specifically react with two different SV40 mimotopes. The two SV40 peptides used in indirect ELISAs correspond to viral capsid proteins. ELISA with the two SV40 mimotopes gave overlapping results. Our data indicate that in serum samples from MPM-affected patients ( n = 97), the prevalence of antibodies against SV40 viral capsid protein antigens is significantly higher (26%, P = 0.043) than in the control group (15%) represented by healthy subjects ( n = 168) with the same median age (66 y) and sex. Our results suggest that SV40 is associated with a subset of MPM and circulates in humans.

Simian virus 40 (SV40), a small DNA tumor virus, was inadvertently administered to human populations with the use of contaminated vaccines. SV40 sequences have mainly been detected in healthy individuals and cancer patients using polymerase chain reaction techniques. However, some studies have failed to reveal the presence of SV40 in human specimens. These conflicting results indicate the need for new research to verify whether SV40 is circulating in humans. Mimotopes from SV40 structural peptides were tested to investigate for specific reactions to human sera antibodies. An indirect enzyme-linked immunosorbent assay with synthetic peptides from SV40 viral capsid proteins 1-2-3 (VPs 1-2-3) was set up and employed to test 855 serum samples from healthy blood donors. Data from immunologic assays indicate that serum antibodies against SV40 VP mimotopes are detectable, although with a low titer, in blood donors 18 to 65 years old. The overall prevalence of serum samples that reacted with the 2 SV40 VP peptides was 18%. The strong points for this novel method include the simplicity of its approach and the potential to discriminate between SV40-specific antibody responses and to draw correlations between responses to the 2 independent SV40 peptides. These data suggest that SV40, or a yet undetected closely related polyomavirus, is circulating in human populations, but with lower prevalence than that of the ubiquitous BK and JC human polyomaviruses.

BK virus (BKV), JC virus (JCV) and Simian Virus 40 (SV40) are polyomaviruses, highly homologous at the DNA and protein levels. While the human polyomaviruses BKV and JCV are ubiquitous in humans, SV40 is a simian virus which was introduced in the human population, between 1955 and 1963, by contaminated poliovaccines produced in SV40-infected monkey cells. Alternatively, SV40 or an SV40-like virus may have entered the human population before anti-poliovirus vaccination. Epidemiological evidence suggests that SV40 is now contagiously transmitted in the human population by horizontal infection, independently from the earlier contaminated poliovaccines. All three polyomaviruses transform rodent and human cells and are oncogenic in rodents. JCV induces tumors also in experimentally inoculated monkeys. Transformation and oncogenicity induced by BKV, JCV and SV40 are due to the two viral oncoproteins, the large T antigen (Tag) and the small t antigen (tag), encoded in the early region of the viral genome. Both proteins display several functions. The large Tag acts mainly by blocking the functions of p53 and pRB family tumor suppressor proteins and by inducing in host cells chromosomal aberrations and instability. The principal effect of small tag is to bind the catalytic and regulatory subunits of the protein phosphatase PP2A, thereby constitutively activating the β-catenin pathway which drives cells into proliferation. All three polyomaviruses are associated with specific human tumor types which correspond to the tumors induced by experimental inoculation of the three viruses in rodents and to the neoplasms arising in mice transgenic for the polyomavirus early region gene directed by the native viral early promoter-enhancer. Human tumors associated with BKV. JCV and SV40 contain viral DNA, generally episomic, express viral RNA and are positive for large Tag by immunohistochemistry. The low copy number of viral genomes in human tumors suggests that polyomaviruses may transform human cells by a “hit and run” mechanism. An autocrine-paracrine effect, involving secretion of growth factors by cells expressing polyomavirus Tag, may be responsible for recruiting to proliferation Tag-negative cells in polyomavirus-associated human tumors.

We have localized a human homolog, REV3L, of the Saccharomyces cerevisiae REV3 gene on chromosome region 6q21. The full-length cDNA consists of 10,919 nucleotides, with a putative open reading frame of 9,159 bp for a predicted protein of 3,053 amino acids. The gene contains 33 exons in about 200 kb of genomic DNA. In contrast to the previously reported sequence, an additional exon and an alternative splicing site are demonstrated.

The region 6q27 from human chromosome 6 has been reported to contain one or more tumor suppressor genes on the basis of cytogenetic, molecular and functional studies. We have recently carried out a detailed analysis of a candidate gene from 6q27 to evaluate its putative role as a tumor suppressor gene involved in ovarian cancer pathogenesis. The RNASET2 gene was shown to behave as a class II tumor suppressor and abolish the tumorigenic potential of an ovarian cancer-derived cell line. In this study, we have started the cellular and biochemical characterization of RNASET2 and showed that it is a secreted glycoprotein. Moreover, we have extended our previous studies by evaluating the effect of RNASET2 on the metastatic behavior of the highly-invasive ovarian cancer cell line HEY3MET2. From such analysis, RNASET2 was found to significantly decrease the metastatic potential of this cell line in vivo. Moreover, RNASET2-mediated suppression of tumorigenesis and metastasis was not affected by a double point mutation targeted to the putative ribonuclease catalytic sites, suggesting that tumor suppression by RNASET2 is not mediated by its ribonuclease activity. The potential biological implications of this unexpected finding are discussed in relation to the current evolutionary models.

In this study, 82 DNA samples of simian virus 40 (SV40)-positive human tumors and normal tissues were transfected into SV40-permissive monkey cells. SV40 wild-type strain 776 was reactivated from two DNA samples, derived from peripheral blood mononuclear cells (PBMCs) of a blood donor and from a vulvar tissue. SV40 reactivation was confirmed by obtaining rescue of SV40 from the DNA of the vulvar tissue in a second transfection experiment. This investigation indicates that infectious SV40 is present in normal human tissues and suggests that (i) PBMCs are probably vectors of SV40 to different tissues of the host and (ii) blood and sexual transmission may be routes of SV40 infection in humans, leading to (iii) virus spread in the human population.

The human immunodeficiency virus type 1 (HIV-1) Tat protein stimulates cell proliferation, inhibits apoptosis, displays angiogenic functions and is believed to be involved in the pathogenesis of Kaposi's sarcoma (KS) and other tumours arising in AIDS patients. Tat-transgenic (TT) mice, which constitutively express Tat in all tissues and organs, may therefore be predisposed to tumorigenesis. To test this hypothesis, we treated TT mice with urethane, a general carcinogen inducing tumours of various organs. The results indicate that, after injection of urethane, the incidence of lung tumours and lymphomas is not significantly different in the TT and control (CC) mice, whereas liver preneoplastic lesions and tumours show a significantly greater incidence in TT than in CC mice. This remarkable carcinogenic effect of urethane for the liver may be due to a tat-induced predisposition, manifested as a liver cell dysplasia (LCD), spontaneously affecting most of the TT mice. LCD may exert a promoting effect by stimulating proliferation of cell clones initiated by the mutagenic effect of urethane. In addition, LCD, which is associated with aneuploidy and chromosome instability, may enhance the progression to malignancy of the preneoplastic lesions induced by urethane. Interestingly, a significantly greater incidence of vascular ectasias and haemangiomas was detected in the liver of urethane-treated TT mice, most likely due to the marked angiogenic properties of Tat. This study suggests a role for Tat in the promotion and progression of tumours initiated by exogenous and endogenous carcinogens in HIV-1-infected patients, thereby contributing to the tumorigenesis in the course of AIDS.

Cancer is considered the genetic disease with the most complex pathogenetic mechanism. Contrary to normal human tissues, which function in a highly ordered and uniform manner, tumor tissues were considered to develop chaos. Here we propose that analysis of human neoplasia according to the concepts of chaos and antichaos allowed to distinguish two main types of cancers: the hematopoietic cancers, characterized by the orderly antichaos and solid cancers governed by a disordered complex of genetic and molecular events characteristic of a chaotic pattern. Genetic chaos and antichaos have generated rules that can be applied to the diagnosis and therapy of human tumors.

Several sexually transmitted viruses have been associated with the development of Kaposi's sarcoma (KS), a highly vascularized multi-focal neoplasm, characterized by the presence of spindle-shaped and endothelial cells, fibroblasts and macrophages. As BK virus (BKV) sequences were found in 100% of primary KS and 75% of KS cell lines, we established an experimental model to test whether BKV may be involved in the pathogenesis of KS. For this purpose, we transformed primary and spontaneously immortalized murine endothelial cells with BKV or with a plasmid containing BKV early region, which encodes BKV T antigen. Murine endothelial cells lost endothelial markers after transformation by BKV and, when inoculated s.c. in nude mice, induced tumors which regressed 7-30 days after onset, whereas spontaneously immortalized murine endothelial MHE cells induced progressing tumors, which brought the animals to death. Histologic examination showed an initial formation of vessels around the tumors, followed by the appearance of a dense population of fibroblasts and mononuclear cells in the peritumoral tissue. Subsequently, tumors appeared to be infiltrated by mononuclear cells and surrounded by a thick fibrous wall with scattered fibroblasts and without vessels. Areas of necrosis developed in the tumor mass and finally the neoplastic tissue completely degenerated. The medium conditioned by BKV-transformed cells induced proliferation and migration of human fibroblasts and NIH3T3 cells. These effects were inhibited by an anti-transforming growth factor-beta1 (TGF-beta1) antibody. Northern blot analysis revealed that BKV-transformed cells express a greater amount of TGF-beta1 RNA than normal murine endothelial cells. Besides, TGF-beta1 was not expressed in progressing tumors induced by spontaneously immortalized endothelial MHE cells, whereas it was highly expressed during the regression of tumors induced by BKV-transformed MHE and primary endothelial cells. Over-expression of TGF-beta1 may be responsible for the mononuclear cell infiltration, inhibition of angiogenesis and formation of the fibrotic wall around tumors, inducing tumor regression through tumor cell necrosis and nutritional starvation. These results prompt us to test whether production of TGF-beta1 is associated with spontaneous KS regression in human patients. In this case, KS regression could be induced or accelerated by any means that enhances TGF-beta1 production at the tumor site.

BACKGROUND Many studies found only a small fragment of the large T-antigen coding sequences in human tumors, raising doubts on authenticity of SV40 sequences detected in these samples. METHODS Five different regions of SV40 DNA were investigated in 106 fresh human tumor biopsies (25 brain, 69 bone, 12 Wilms' tumors), 71 tumor-derived cell cultures (38 from brain and 33 from bone tumors) and normal tissues (5 fresh bone biopsies and 38 buffy coats) by polymerase chain reaction (PCR) techniques and filter hybridization with specific oligoprobes. Expression of SV40 Tag sequences was analyzed in human tumor specimens by RT-PCR. RESULTS SV40 large T-antigen sequences were detected at high prevalence, in human biopsies of primary brain (37–44%) and bone (21–37%) tumors, in cell cultures derived from brain (30–54%) and bone (53–80%) tumors. SV40 Tag sequences were detected in 29% of buffy coats of blood donors. However, only four brain tumor cell lines showed all the five regions of the SV40 genome investigated. Expression of SV40 Tag sequences was found in 11 of 27 (41%) human tumor samples. DNA sequence analysis indicated that the PCR-amplified products belong to the SV40 wild type. Polymerase chain reaction products of Tag middle portion from 20 of 78 (26%) samples showed a 97% homology with telomeric sequences of human chromosomes 10 and 11. CONCLUSIONS Authentic SV40 sequences were detected in human samples. The expression of SV40 Tag sequences indicates that SV40 could play a role, as a cofactor, in the onset/progression of specific human cancers. The inability to detect some regions of the virus genome may suggest that those regions are not required for tumor persistence or growth and have been lost or, alternatively, may be the result of assay conditions that were unable to PCR-amplify those regions in the tumors. Cancer 2002;94:1037–48. © 2002 American Cancer Society. DOI 10.1002/cncr.10272

Chromosome 11p15 deletion is frequent in human tumors, suggesting the presence of at least one tumor suppressor gene within this region. While mutation analyses of local genes revealed only rare mutations, we have previously described a mechanism, gain of imprinting, that leads to loss of expression of genes located on the maternal 11p15 chromosome in human hepatocarcinomas. Loss of expression was often associated with loss of maternal-specific methylation at the KvDMR1 locus. Here, we show that loss of the maternal KvDMR1 methylation is common, ranging from 30 to 50%, to a variety of adult neoplasms, including liver, breast, cervical and gastric carcinomas. We found that other 11p15.5 loci were concomitantly hypomethylated, indicating that loss of KvDMR1 methylation occurred in the context of a common mechanism affecting the methylation of a large 11p15 subchromosomal domain. These epigenetic abnormalities were not detected in any normal somatic tissue. Therefore, it seems possible that, contrary to the repression of promoter activity caused by hypermethylation, loss of gene expression at 11p15.5 may result from the activation, by hypomethylation, of one or more negative regulatory elements.

The common fragile site FRA6F, located at 6q21, is an extended region of about 1200 kb, with two hot spots of breakage each spanning about 200 kb. Transcription mapping of the FRA6F region identified 19 known genes, 10 within the FRA6F interval and nine in a proximal or distal position. The nucleotide sequence of FRA6F is rich in repetitive elements (LINE1 and LINE2, Alu, MIR, MER and endogenous retroviral sequences) as well as in matrix attachment regions (MARs), and shows several DNA segments with increased helix flexibility. We found that tight clusters of stem-loop structures were localized exclusively in the two regions with greater frequency of breakage. Chromosomal instability at FRA6F probably depends on a complex interaction of different factors, involving regions of greater DNA flexibility and MARs. We propose an additional mechanism of fragility at FRA6F, based on stem-loop structures which may cause delay or arrest in DNA replication. A senescence gene likely maps within FRA6F, as suggested by detection of deletion and translocation breakpoints involving this fragile site in immortal human-mouse cell hybrids and in SV40-immortalized human fibroblasts containing a human chromosome 6 deleted at q21. Deletion breakpoints within FRA6F are common in several types of human leukemias and solid tumors, suggesting the presence of a tumor suppressor gene in the region. Moreover, a gene associated to hereditary schizophrenia maps within FRA6F. Therefore, FRA6F may represent a landmark for the identification and cloning of genes involved in senescence, leukemia, cancer and schizophrenia.

Cytogenetic, molecular and functional analysis has shown that chromosome region 6q27 harbors a senescence inducing gene and a tumor suppressor gene involved in several solid and hematologic malignancies. We have cloned at 6q27 and characterized the RNASE6PL gene which belongs to a family of cytoplasmic RNases highly conserved from plants, to man. Analysis of 55 primary ovarian tumors and several ovarian tumor cell lines indicated that the RNASE6PL gene is not mutated in tumor tissues, but its expression is significantly reduced in 30% of primary ovarian tumors and in 75% of ovarian tumor cell lines. The promoter region of the gene was unaffected in tumors cell lines. Transfection of RNASE6PL cDNA into HEY4 and SG10G ovarian tumor cell lines suppressed tumorigenicity in nude mice. When tumors were induced by RNASE6PL-transfected cells, they completely lacked expression of RNASE6PL cDNA. Tumorigenicity was suppressed also in RNASE6PL-transfected pRPcT1/H6cl2T cells, derived from a human/mouse monochromosomic hybrid carrying a human chromosome 6 deleted at 6q27. Moreover, 63.6% of HEY4 clones and 42.8% of the clones of XP12ROSV, a Xeroderma pigmentosum SV40-immortalized cell line, transfected with RNASE6PL cDNA, developed a marked senescence process during in vitro growth. We therefore propose that RNASE6PL may be a candidate for the 6q27 senescence inducing and class II tumor suppressor gene in ovarian cancer.

The human immunodeficiency virus-1 Tat protein is suspected to be involved in the neoplastic pathology arising in AIDS patients. tat-transgenic (TT) mice, which constitutively express Tat in the liver, develop liver cell dysplasia (LCD) that may represent a preneoplastic lesion. To test if TT mice are predisposed to liver carcinogenesis, we treated them with diethylnitrosamine, a hepatotropic carcinogen. Diethylnitrosamine-treated TT mice developed both preneoplastic and neoplastic lesions in the liver. They showed an enhancement of LCD and developed basophilic liver cell nodules (BLCN), hepatocellular adenomas (HA), and hepatocellular carcinomas (HC). Both preneoplastic (LCD and BLCN) and neoplastic (HA and HC) lesions were significantly more frequent in TT than in control mice: 29.7% versus 12.7% for LCD, 57.9% versus 23.3% for BLCN, 40.6% versus 10.0% for HA, and 50.0% versus 12.7% for HC. These results indicate that Tat expression in the liver predisposes to both initiation of hepatocarcinogenesis and to malignant progression of liver tumors. This study supports a role for Tat in enhancing the effect of endogenous and exogenous carcinogens in human immunodeficiency virus-1-infected patients, thereby contributing to tumorigenesis in the course of AIDS.

Two new genes were cloned from region 6q21 and characterized. One gene, C6orf4-6, expresses three mRNA isoforms diverging at the 5' and 3' ends, and encodes two protein isoforms that differ by nine amino acids at their amino terminus. The second gene, C6UAS, is transcribed in the antisense orientation from the complementary strand of C6orf4-6. C6UAS overlaps the second exon of C6orf4, where the start codon of protein isoform 1 is located. C6UAS has no apparent ORF and most likely represents a structural RNA gene that is transcribed but not translated. This feature and the antisense polarity of transcription suggest that C6UAS could play a regulatory role on the expression of C6orf4, as indicated by a significant decrease of endogenous C6orf4 expression after transfection of C6UAS cDNA in human fibroblasts. Neither C6UAS nor C6orf4-6 genes show any homology with known human genes. The two genes were cloned from a subregion at 6q21 containing a replicative senescence gene, a tumor suppressor gene and a gene involved in hereditary schizophrenia. In addition, the common fragile site FRA6F was mapped in the same region. Cloning and characterization of C6orf4-6 and C6UAS may help to clarify the structure and the functional role of this important region.

Genomic imprinting is a reversible condition that causes parental-specific silencing of maternally or paternally inherited genes. Analysis of DNA and RNA from 52 human hepatocarcinoma samples revealed abnormal imprinting of genes located at chromosome 11p15 in 51% of 37 informative samples. The most frequently detected abnormality was gain of imprinting, which led to loss of expression of genes present on the maternal chromosome. As compared with matched normal liver tissue, hepatocellular carcinomas showed extinction or significant reduction of expression of one of the alleles of the CDKN1C , SLC22A1L , and IGF2 genes. Loss of maternal-specific methylation at the KvDMR1 locus in hepatocarcinoma correlated with abnormal expression of CDKN1C and IGF2 , suggesting a function for KvDMR1 as a long-range imprinting center active in adult tissues. These results point to the role of epigenetic mechanisms leading to loss of expression of imprinted genes at chromosome region 11p15 in human tumors.