Iliac crest bone graft: a 23-years hystory of infection at donor site in vertebral arthrodesis and a review of current bone substitutes

OBJECTIVE

This is an exemplary case report underlining a relevant morbidity which could be associated to the use of autologous iliac crest bone graft (ICBG) for spine fusion.

CASE REPORT

Starting from 1990, a 25-years-old woman underwent two subsequent surgical treatments for non-Hodgkin lymphoma vertebral localizations. In the second surgery, arthrodesis was obtained with autograft through right posterior iliac crest osteotomy. During the chemotherapy treatment following the surgery, the patient suffered from infection at posterior iliac crest scar, the site of previous graft, caused by methicillin-resistant Staphylococcus aureus. She was subjected to surgical debridement and specific antibiotic treatment with local healing and phlogosis index reduction. Chemotherapy protocol was concluded and the patient healed with definitive lymphoma remission. After 22 years the patient had a relapse of donor site infection, requiring a new antibiotic therapy and a new surgical debridement.

RESULTS

The relapsed infection at donor site lasted for a long period, more than one year, despite of specific care. It finally healed after another accurate surgical debridement and postoperative antibiotic therapy.

CONCLUSIONS

This case report underlines the possible consequences on the patient's quality of life of a long-term disease affecting the iliac crest bone graft donor site. Literature concerning alternatives to autograft for spine fusion is also reviewed.

Spinal Infection Multidisciplinary Management Project (SIMP): From Diagnosis to Treatment Guideline

Spine infections require a multidisciplinary approach to be treated and solved. A guide line to drive physicians in the deep complexity of such a disease is extremely helpful. SIMP suggests a flow-chart built up on clear concepts such as right and well managed antibiotic therapy, sound stability of the spine, correct and smart use of the standard and functional imaging techniques, such as f18 FDG PET/CT. In 16 months a total of 41 patients have been treated for spondylodiscitis, discitis and vertebral osteomyelitis by our team of physicians and 25 patients have been enrolled in a prospective study whose target is the assessment of the SIMP flow-chart and of every single aspect that characterize it.

Prevalence of liver tumours in HIV-1 tat-transgenic mice treated with urethane

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.

Cloning and characterization of a senescence inducing and class II tumor suppressor gene in ovarian carcinoma at chromosome region 6q27

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.

Patellar height after high tibial osteotomy

We analysed two series of patients affected by unicompartmental arthrosis or axial malalignment of the knee treated with two different techniques of high tibial osteotomy. Forty-seven knees were treated with a closing wedge osteotomy (CWO) and 40 with an opening wedge osteotomy (OWO). The two groups were comparable with respect to age, gender and deformity. For each patient the patellar height was measured by Caton's method before surgery, and at the latest assessment (at least 1 year after operation). The correction rate for the two series was analysed to assess any possible correlation between the variation of the patellar height and the degree of correction of the knee axis. We concluded that a high tibial osteotomy modifies the patellar height and that this depends on the technique employed. Patellar 'lowering' occurred more often with OWO than with CWO and the latter also produced a high degree of patellar elevation.

Enhancement of chemical hepatocarcinogenesis by the HIV-1 tat gene

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.

Alternative splicing, genomic structure, and fine chromosome localization of REV3L

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.

Cloning and characterization of two overlapping genes in a subregion at 6q21 involved in replicative senescence and schizophrenia

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.

Evaluation of radiolucency condition in total hip arthroplasty: a statistical comparison of the diagnostic capability of digitised image vs. conventional X-ray film

This work analyses the diagnostic capability of radiographic images taken from patients with total hip arthroplasty and visualised on monitor. Images were obtained with digital acquisition of conventional X-ray films. The investigated pathology is the absence of direct contact between bone and prosthesis (radiolucency). Three senior orthopaedists defined the diagnostic "truth" on well-defined regions of interest on 22 conventional X-ray films of total hip arthroplasty, obtaining a total of 110 reference ratings. Films were digitised by use of an X-ray scanner. Four readers evaluated the X-ray images, applying conventional and monitor visualisation. To show any difference between ratings on film and ratings on monitor a sensitivity, specificity and accuracy study jointly with a receiver operating characteristics (ROC) study were performed for each reader and for all combined readings. The intra-observer reproducibility of the radiographic protocol was equal to 87% and the inter-observer one was in the range 85-92%. The sensitivity, specificity and accuracy study together with the ROC analysis did not show significant differences between the two evaluation modes. The evaluation of radiolucency from digitised X-ray films visualised on a monitor resulted statistically comparable with the conventional evaluation on X-ray films.

Antiangiogenic, antitumoural and antimetastatic effects of two distamycin A derivatives with anti-HIV-1 Tat activity in a Kaposi's sarcoma-like murine model

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.

Genetic progression in microsatellite instability high (MSI-H) colon cancers correlates with clinico-pathological parameters: A study of the TGRbetaRII, BAX, hMSH3, hMSH6, IGFIIR and BLM genes

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.

A human melanoma metastasis-suppressor locus maps to 6q16.3-q23

Loss, deletion or rearrangement along large portions of the long arm (q-arm) of chromosome 6 occurs in >80% of late-stage human melanomas, suggesting that genes controlling malignant characteristics are encoded there. Metastasis, but not tumorigenicity, was completely suppressed in the human melanoma cell line C8161 into which an additional intact chromosome 6 had been introduced by microcell-mediated chromosome transfer. Our objective was to refine the location of a putative metastasis suppressor gene. To do this, we transferred an intact (neo6) and a deletion variant [neo6qdel; neo6(del)(q16.3-q23)] of neomycin-tagged human chromosome 6 into metastatic C8161 subclone 9 (C8161.9) by MMCT. Single cell hybrid clones were selected in G-418 and isolated. Following verification that the hybrids retained the expected regions of chromosome 6 using a panel of polymorphic sequence-tagged sites, the hybrids were tested for tumorigenicity and metastasis in athymic mice. As reported previously, intact, normal chromosome 6 suppressed metastasis whether tumor cells were injected i.v. or into an orthotopic (i.e., intradermal) site. In contrast, metastasis was not suppressed in the neo6qdel hybrids. Tumorigenicity was unaffected in hybrids prepared with either chromosome 6 donor. These data strongly suggest that a human melanoma metastasis suppressor locus maps between 6q16.3-q23 ( approximately 40 cM).

A human melanoma metastasis-suppressor locus maps to 6q16.3-q23

Loss, deletion or rearrangement along large portions of the long arm (q-arm) of chromosome 6 occurs in >80% of late-stage human melanomas, suggesting that genes controlling malignant characteristics are encoded there. Metastasis, but not tumorigenicity, was completely suppressed in the human melanoma cell line C8161 into which an additional intact chromosome 6 had been introduced by microcell-mediated chromosome transfer. Our objective was to refine the location of a putative metastasis suppressor gene. To do this, we transferred an intact (neo6) and a deletion variant [neo6qdel; neo6(del)(q16.3-q23)] of neomycin-tagged human chromosome 6 into metastatic C8161 subclone 9 (C8161.9) by MMCT. Single cell hybrid clones were selected in G-418 and isolated. Following verification that the hybrids retained the expected regions of chromosome 6 using a panel of polymorphic sequence-tagged sites, the hybrids were tested for tumorigenicity and metastasis in athymic mice. As reported previously, intact, normal chromosome 6 suppressed metastasis whether tumor cells were injected i.v. or into an orthotopic (i.e., intradermal) site. In contrast, metastasis was not suppressed in the neo6qdel hybrids. Tumorigenicity was unaffected in hybrids prepared with either chromosome 6 donor. These data strongly suggest that a human melanoma metastasis suppressor locus maps between 6q16.3-q23 ( approximately 40 cM).

Gain of imprinting at chromosome 11p15: A pathogenetic mechanism identified in human hepatocarcinomas

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.

Abnormal RNA expression of 11p15 imprinted genes and kidney developmental genes in Wilms' tumor

Wilms' tumor (WT) is caused by abnormal development of embryonal kidney cells. WT cells are frequently affected by deletions or functional inactivation of maternal alleles at chromosome 11p15, which indicates that the loss of maternally expressed genes in this region plays an important role in WT pathogenesis. Maternally expressed genes indeed exist within an imprinted region at 11p15.5. Among these, BWR1C is highly expressed in fetal but not in adult kidney, which suggests that it may fulfil an important role in kidney development. Here, we demonstrate that the lack of BWR1C expression is common in WT. Its homology with the proapoptotic gene TDAG51 suggests that the loss of BWR1C expression may be relevant in WT development. In addition, the analysis of the expression of other 11p15 imprinted genes and kidney-developmentally regulated genes indicates that IGF2 overexpression, inappropriate coexpression of RET and GDNF and, in some cases, down-regulation of CDKN1C may also play an important role in the pathogenesis of WT. Our results add new elements to the understanding of the biological basis of WT, which may have implications for WT diagnosis and therapy.

Low frequency of alterations of the alpha (PPP2R1A) and beta (PPP2R1B) isoforms of the subunit A of the serine-threonine phosphatase 2A in human neoplasms

The phosphatase 2A (PP2A) is one of the major cellular serine-threonine phosphatases. It was recently shown that the gene encoding for the beta isoform of its subunit A, PPP2R1B, is altered in human lung and colorectal carcinomas, suggesting a role in human tumorigenesis. Here, we report the detection of mutations in breast, lung carcinomas and melanomas in the genes of both alpha (PPP2R1A) and beta isoforms. Mutations affecting PPP2R1B were found in four breast carcinomas, while mutations in PPP2R1A were found in carcinomas of the breast and of the lung and in one melanoma. Most of the mutations affecting PPP2R1B were exons deletions, suggesting abnormal splicing. These splicing abnormalities were detected in tumor samples in the absence of the normal splicing product, and were not found in several normal controls. In one case, a homozygous deletion present in tumor DNA, and not in the matched normal control was demonstrated. Mutations affecting the PPP2R1A gene were nucleotide substitutions changing highly conserved amino acids and one frame-shift. Although the frequency of alterations is low, the inclusion of both isoforms of subunit A in the genes mutated in human cancer and the addition of breast cancer to the list of neoplasms in which PPP2R1B is altered, strengthen the potential role of PP2A in human tumorogenesis.

HIV-1 Tat mutants in the cysteine-rich region downregulate HLA class II expression in T lymphocytic and macrophage cell lines

Human macrophage and T cell lines were stably transfected with HIV-1 wild-type Tat or Tat mutants in the cysteine-rich region displaying trans-dominant negative effects on HIV-1 life cycle. The expression of HLA class I and class II molecules was not affected by wild-type Tat. Tat mutants, instead, profoundly down-regulated in a dose-dependent fashion the expression of class II, but not of class I, in both cell types by acting at the transcriptional level. Down-regulation was manifested on constitutive and IFN-gamma-induced class II gene expression and did not correlate with reduced transcription of the AIR-1 gene product CIITA, the major transcriptional activator of class II genes, indicating that Tat mutants did not act by inhibiting AIR-1 gene expression. Class II down-modulation had important functional implications in macrophages, as both antigen processing and presenting capacity were inhibited. These results represent the first evidence that a modified HIV-1 Tat product can act as a potent immunosuppressor by inhibiting the HLA class II expression necessary for triggering both cellular and humoral responses against pathogens. The use of these HIV-1 Tat mutants also discloses new opportunities to investigate the molecular mechanisms underlying the coordinate HLA class II gene transcription.

Transcriptional map of chromosome region 6q16-->q21

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.

Exon structure and promoter identification of STIM1 (alias GOK), a human gene causing growth arrest of the human tumor cell lines G401 and RD

The stromal interaction molecular 1 gene (STIM1) encodes a type I trans-membrane protein of unknown function, which induces growth arrest and degeneration of the human tumor cell lines G401 and RD but not HBL100 and CaLu-6, suggesting a role in the pathogenesis of rhabdomyosarcomas and rhabdoid tumors. Here, we describe the STIM1 genomic organization including the identification of the promoter region. The gene consists of 12 exons that span a region larger than 250 kb between the genes RRM1 and NUP98. Nucleotide sequences of all exon-intron boundaries were determined and oligonucleotide primers for the amplification of individual exons were designed. The promoter region was identified within a 1.8-kb SacI fragment at the 5' end of the gene. In vitro CpG methylation of the promoter region indicated that transcription can be downregulated by this mechanism. The genetic tools developed in the present work will help to determine whether pathogenetic mechanisms that associate STIM1 with tumorigenesis involve mutations in coding sequences and/or promoter, and whether methylation could determine STIM1 transcriptional down-regulation in tumor samples.

Detailed genetic and physical mapping of tumor suppressor loci on chromosome 3p in ovarian cancer

Hemizygosity and homozygosity mapping studies show that many common sporadic cancers including lung, breast, kidney, cervical, ovarian, and head and neck cancer display deletions on the short arm of chromosome 3. For ovarian cancer, monochromosomal transfer suppression studies have identified three candidate regions for chromosome 3p ovarian cancer tumor suppressor genes (OCTSGs). To accurately map OCTSG candidate regions, we analyzed 70 ovarian tumors for loss of heterozygosity (LOH) at 20 loci on chromosome 3p that were selected to target those regions proposed to contain tumor suppressor genes for common sporadic cancers. All samples were informative for at least five markers. In 33 (52%) tumors without microsatellite instability, LOH was observed for at least one 3p marker. Analysis of 27 ovarian tumors demonstrating both loss and retention of 3p markers enabled us to define four nonoverlapping minimal deletion regions (OCLOHRs): (a) OCLOHR-1 mapped distal to D3S3591 at 3p25-26; (b) OCLOHR-2 mapped between D3S1317 and D3S1259 at 3p24-25; (c) OCLOHR-3 mapped between D3S1300 and D3S1284, an area that includes the FHIT locus at 3p14.2; and (d) OCLOHR-4 mapped between D3S1284 and D3S1274 at 3p12-13, a region known to contain overlapping homozygous deletions in lung and breast tumor cell lines. However, microsatellite markers from the chromosome 3p21.3 interval homozygously deleted in lung cancer cell lines did not identify a distinct OCLOHR. The frequency and extent of 3p LOH correlated with tumor stage such that LOH at two or more OCLOHRs was present in 53% (16 of 30) of stage III tumors but only 26% (5 of 19) of stage I/II tumors (P = 0.08). To determine the relationship between the OCLOHRs and the three candidate ovarian cancer suppression regions (OCSRs) identified previously by monochromosome transfer studies, we performed detailed genetic and physical mapping studies to define the extent of the three candidate OCSRs and to establish YAC contigs covering each region. OCSR-A at 3p25-26 and OCSR-B at 3p24 were shown to overlap with OCLOHR-1 and OCLOHR-2, respectively, providing further evidence for OCTSGs in these regions. We also show that OCSR-C overlaps with a locus at 3p21.3 previously implicated in lung and breast cancer.

Transiently transfected and stably integrated HIV-1 LTR responds differentially to the silencing activity of the Krüppel-associated box (KRAB) transcriptional repressor domain

It has been demonstrated previously that the transcriptional repressor domain called the Krüppel-associated box (KRAB), conserved in a large number of Krüppel-type zinc finger proteins, fused to Tat transdominant negative mutants, is able to silence HIV-1 long terminal repeat (LTR)-driven gene expression in transient transfection assays. In the present study chimeric Tat mutant-KRAB retroviral expression vectors were used to control HIV-1 replication in acutely infected cells. It was found that while transient and stable expression of Tat mutant-KRAB chimeric proteins represses HIV-1 LTR-driven gene transcription in transient assays, stable expression of Tat mutant-KRAB chimeric molecules does not confer resistance to HIV-1 infection in Jurkat T lymphocytic cell lines. The results provide further evidence that transient transfection may underestimate the role of chromosomal structure in transcriptional regulation and highlight the caveat of direct extrapolation of transient results for designing gene therapy strategies for efficient control of HIV-1 infection.

DNA immunization with HIV-1 tat mutated in the trans activation domain induces humoral and cellular immune responses against wild-type Tat

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.

Morphological, histochemical, immunohistochemical, and ultrastructural characterization of tumors and dysplastic and non-neoplastic lesions arising in BK virus/tat transgenic mice

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.

Refinement of the LOH region 1 at 11q23.1 deleted in human breast carcinomas and sublocalization of 11 expressed sequence tags within the refined region

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.

Relationship between P-glycoprotein expression and p53 status in high-grade osteosarcoma

The transcription of MDR1 gene may be increased by mutation or loss of function of p53 gene. In this study, we investigated whether in osteosarcoma, the p53 status is correlated with overexpression of the MDR1 gene product P-glycoprotein. The relationship between P-glycoprotein expression and p53 status was analyzed by immunohistochemistry in 64 primary and 11 metastatic high-grade osteosarcomas. In the same series, we also assessed the nuclear accumulation of MDM2 protein, whose binding to p53 protein provides an alternative mechanism of p53 inactivation. No association was found between mutant-p53 and MDM2 nuclear accumulation either with P-glycoprotein expression or with clinical course. Only increased expression of P-glycoprotein in tumor cells was significantly associated with a poor outcome, further supporting the adverse prognostic value of this marker in osteosarcoma.

Characterization of the effects of two polysulfonated distamycin A derivatives, PNU145156E and PNU153429, on HIV type 1 Tat protein

We examined whether two sulfonated distamycin A derivatives, PNU145156E and PNU153529, inhibit the trans-activating and angiogenic effects of HIV-1 Tat protein. The study was carried out by analyzing the activity of the two drugs on: (1) extracellular and intracellular Tat protein, introduced into HL3T1 cells containing an integrated HIV-1 LTR/CAT plasmid; (2) binding of Tat to 3H-labeled heparin and to 14C-labeled PNU145156E; and (3) the angiogenic response induced in vivo by culture medium conditioned by T53c14 cells, which release extracellular Tat. PNU145156E and PNU153429 interacted with extracellular Tat in the culture medium and physically bound the Tat protein, most likely sequestering it in the extracellular space. As a consequence, the two drugs inhibited trans-activation of the HIV-1 LTR on addition of the free Tat protein to HL3T1 cells. However, the two compounds inhibited the activity of intracellular Tat when they were introduced into the cells by lipofection. In vivo experiments showed that the two drugs blocked the neoangiogenesis induced by Tat released in the conditioned medium of T53c14 cells. Owing to the critical role of intracellular and extracellular Tat in HIV-1 replication, these drugs show promise as a means to control the progression of HIV-1 infection as well as the neoplastic and angiogenic effects induced by Tat in the course of AIDS.

[SV40 as a possible cofactor in the etiopathogenesis of mesothelioma and other human tumors]

Simian virus 40 (SV40) has been introduced into the human population with contaminated polio vaccines between 1955 and 1963. Previous research conducted by southern blot hybridization and recent analysis by PCR have shown the presence of SW0 sequences in human brain tumors, mesotheliomas and osteosarcomas as well as in normal tissues such as blood and sperm fluids. SV40 RNA and T antigen were detected in the same tissues. All the samples were coinfected by BK Virus (BKV), suggesting that BKV may have a helper function for SV40 replication in human cells. The presence of SV40 in human tumors suggests that the virus may be a cofactor in the etiopathogenesis of human neoplasia. In addition, blood and semen may represent the vectors for transmission of SV40 by horizontal infection in the human population.

Molecular cloning and characterization of ZNF202: a new gene at 11q23.3 encoding testis-specific zinc finger proteins

Two distinct regions of loss of heterozygosity (LOH) in breast carcinomas were previously identified at chromosome 11q23. With the aim of identifying a tumor suppressor gene, we undertook the isolation and characterization of genes within LOH region 2, defined between loci D11S1345 and D11S1316, which spans an area of about 1 Mb. Here, we describe the cloning and characterization of a new gene, ZNF202. The gene, which spans a genomic area of approximately 10 kb, is almost exclusively expressed in testis as a 4-kb mRNA. The predicted amino acid sequence of the protein product revealed significant homologies with zinc finger proteins, indicating that the ANF202 protein may function as a transcription factor. The presence of multiple CK2 and PKC phosphorylation sites suggests that its activity may be regulated by phosphorylation. The gene is also expressed in breast carcinoma cell lines. However, mutation analysis of 39 breast cancer samples revealed no evidence of mutations, indicating that ZNF202 is unlikely to be involved in the pathogenesis of this neoplasm. Nevertheless, a role for ZNF202 in the tumorigenic process of other tissues cannot be excluded.

The coding region of the Bloom syndrome BLM gene and of the CBL proto-oncogene is mutated in genetically unstable sporadic gastrointestinal tumors

Microsatellite instability (MSI) characterizes the hereditary nonpolyposis colorectal cancer syndrome but is also found in sporadic tumors. Frameshifts in microsatellites found in the coding regions (CDRs) of the TGFbeta1-RII, IGFIIR, hMSH3, hMSH6, and BAX genes indicate that MSI is involved in tumorigenesis by targeting genes that are directly implicated in the tumorigenic process. To identify additional genes targeted for MSI, we performed an analysis of the GenBank database that revealed 21 microsatellite repeats located in the CDR of 18 genes (12% of the analyzed sequences) whose function could be potentially associated with the tumorigenic process. Mutational studies of 57 sporadic gastrointestinal tumor DNAs revealed the presence of length variations in three of them: (a) BLM; (b) CBL; and (c) HOXA1. In the BLM gene, we found a frameshift mutation in a polyadenine repeat, whereas in the CBL proto-oncogene, an expansion of a trinucleotide repeat was detected with no translation shift. These alterations were present in 18 and 9%, respectively, of the genetically unstable sporadic gastrointestinal tumors analyzed, but in none of the cancers without the mutator phenotype. These changes were present in the DNA from the tumor but not in that from normal cells of the same patient. The HOXA1 retraction of a trinucleotide repeat was as frequent in both types of cancers and was also found in some normal paired tissues, therefore behaving as a neutral polymorphism. Our data extend the spectrum of unstable microsatellites located in gene CDRs and suggest that BLM and possibly CBL are involved in gastrointestinal tumorigenesis. Based on its proposed function, the BLM gene could represent a link between MSI and chromosomal instability pathways, because MSI targeting of the BLM gene could generate hypermutability and/or chromosomal instability.

Chromosomal aberrations induced by BK virus T antigen in human fibroblasts

Human fibroblasts, transfected with a recombinant DNA containing the neo gene and BK virus (BKV) early region, which expresses BPV large T antigen (TAg), show cytogenetic alterations characterized by dicentric chromosomes and other structural aberrations such as deletions, duplications, translocations, and ring chromosomes. Such alterations were absent or significantly less frequent in human fibroblasts transfected with a plasmid expressing only the neo gene. The chromosome damage in BKV-transfected cells was evident before the appearance of the morphologically transformed phenotype and therefore seems to be a primary effect of TAg expression in human cells. The specific pattern of chromosome aberrations suggests the prevalence of an indirect clastogenic effect, determined by the inhibition of p53 regulatory functions on genome stability by BKV TAg. Due to the widespread distribution of BKV in the human population and to the latent state of BKV DNA in many human organs, the clastogenic activity of BKV TAg may potentially participate in an oncogenic process involving BKV latently infected cells.

Mapping of 22 new ESTs around a tumor suppressor gene and a senescence gene at 6q16-->q21

Twenty two expressed sequence tags (ESTs) have been mapped at the border of 6q16-->q21 and at the proximal end of 6q21, a candidate for two tumor suppressor genes and a senescence gene. Use of a translocation and deletion hybrid panel together with a 4-Mb YAC contig allowed us to precisely define the position of the ESTs. Thirteen ESTs were placed within the 4-Mb interval at the proximal portion of 6q21 using a restriction map of the YAC contig, seven ESTs span a 2-Mb region on the 6q16-->q21 border, and two are distal to the contig. Refinement of the localization of these ESTs will provide substantial assistance in identifying new genes within the region 6q16-->q21.

Transcriptional map of 170-kb region at chromosome 11p15.5: identification and mutational analysis of the BWR1A gene reveals the presence of mutations in tumor samples

Chromosome region 11p15.5 harbors unidentified genes involved in neoplasms and in the genetic disease Beckwith-Wiedemann syndrome. The genetic analysis of a 170-kb region at 11p15.5 between loci D11S601 and D11S679 resulted in the identification of six transcriptional units. Three genes, hNAP2, CDKN1C, and KVLQT1, are well characterized, whereas three genes are novel. The three additional genes were designated BWR1A, BWR1B, and BWR1C. Full-length cDNAs for these three genes were cloned and nucleotide sequences were determined. While our work was in progress, BWR1C cDNA was described as IPL [Qian, N., Franck, D., O'Keefe, D., Dao, D. , Zhao, L., Yuan, L., Wang, Q., Keating, M., Walsh, C. & Tycko, B. (1997) Hum. Mol. Genet. 6, 2021-2029]. The cloning and mapping of these genes together with the fine mapping of the three known genes indicates that the transcriptional map of this region is likely to be complete. Because this region frequently is altered in neoplasms and in the genetic disease Beckwith-Wiedemann syndrome, we carried out a mutational analysis in tumor cell lines and Beckwith-Wiedemann syndrome samples that resulted in the identification of genetic alterations in the BWR1A gene: an insertion that introduced a stop codon in the breast cancer cell line BT549 and a point mutation in the rhabdomyosarcoma cell line TE125-T. These results indicate that BWR1A may play a role in tumorigenesis.

Simian virus 40 footprints in normal human tissues, brain and bone tumours of different histotypes

SV40 footprints were investigated by PCR in normal human tissues and tumours of different histotypes, followed by Southern blot hybridization with a specific internal oligoprobe for SV40 DNA. Specific SV40 amplification products were detected at high prevalence in primary human brain tumours: 83% of choroid plexus papillomas, 75% ependymomas, 47% astrocytomas and 37% glioblastomas. SV40 footprints were also revealed in primary bone tumours: 35% osteosarcomas and Ewing's tumours. Positive normal tissue samples ranged from 45% of sperm fluids to 8% of brain tissue. Normal bone tissue specimens were SV40 negative. These results indicate that SV40 is associated with human brain and bone neoplasms, whereas normal bone and brain tissues were either SV40 negative or positive at low grade. SV40 footprints were found in other normal samples such as PBC, B- and T-lymphocytes and sperm fluids, indicating that SV40 is latent in these cells. Therefore, these cells may be vectors of SV40 in other host tissues and may spread SV40 infection by blood transfusion and sexual transmission in the human population.

Inhibition of HIV-1 replication by a Tat transdominant negative mutant in human peripheral blood lymphocytes from healthy donors and HIV-1-infected patients

It was previously shown that a tat mutant (tat22) where cysteine 22 is substituted by glycine behaves as a transdominant negative mutant in Jurkat T cells lytically or latently infected by HIV-1. In this study we demonstrate that tat22 controls HIV-1 replication in primary cells. This effect was observed both after in vitro infection of peripheral blood mononuclear cells (PBMCs) from normal donors and after reactivation of the latent infection in PBMCs from seropositive patients. The antiviral effect of tat22 was limited to conditions of low virus production. The use of tat22 may be promising for a gene therapy approach to AIDS during the asymptomatic phase of the disease allowing control of virus replication in infected cells and inhibition of virus spread to uninfected cells.

GOK: a gene at 11p15 involved in rhabdomyosarcoma and rhabdoid tumor development

The expression of GOK, a gene recently identified at 11p15.5, was studied in breast cancer, rhabdomyosarcoma, and rhabdoid tumor cell lines. In these neoplasms, deletions at 11p15 and suppression of tumorigenicity induced by a normal human chromosome 11 were previously demonstrated. Whereas breast cancer cell lines express readily detectable levels of GOK mRNA, expression is absent in rhabdomyosarcoma and rhabdoid tumor cell lines. This is in contrast with the high expression of GOK in skeletal muscle, the normal tissue of origin of rhabdomyosarcomas, suggesting that down-regulation of GOK expression could be involved in tumor development. In agreement with this hypothesis, transfection of GOK cDNA into G401 derived from a rhabdoid tumor and RD cells derived from a rhabdomyosarcoma that do not express detectable levels of GOK mRNA, induced cell death. Because GOK expression is not compatible with growth of these tumor cells, these results support the hypothesis that loss of GOK expression plays a role in tumor establishment or progression and suggest that GOK may act as a recessive tumor suppressor gene in rhabdomyosarcomas and rhabdoid tumors. On the contrary, transfection of GOK cDNA into the breast cancer cell line HBL100 produced no detectable effects, indicating that the growth-suppressive effect of GOK in RD and G401 cells was specific. Because rhabdomyosarcomas have been observed in cases of Beckwith-Wiedemann syndrome, a genetic disorder linked to 11p15, a role of GOK in this disease cannot be excluded.

Characterization of a 4-Mb region at chromosome 6q21 harboring a replicative senescence gene

A 4-Mb region containing a senescence gene was defined at 6q21 by fluorescence in situ hybridization and deletion mapping after transfer of a normal human chromosome 6 to a BK virus-transformed mouse cell line. By screening three different yeast artificial chromosome (YAC) libraries, a YAC contig was constructed that covers the deleted region at 6q21. The contig is composed of 18 overlapping YACs with a size of 250-1800 kb and contains 3 CpG islands and 10 expressed sequence tags. By sequencing YACs and P1 artificial chromosomes, nine new sequence tagged sites and three new expressed sequence tags were detected that enrich the genetic resources of the region. The contig may also contain a fragile site, FRA6F, located close to a CpG island, which could be a landmark to localize the senescence gene. This YAC contig will be used to detect expressed sequences to clone and characterize the senescence gene at 6q21.

Refined subchromosomal location of 21 expressed sequence tags from unknown genes at region 11p15

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.

Upregulation of urokinase-type plasminogen activator by endogenous and exogenous HIV-1 Tat protein in tumour cell lines derived from BK virus/tat-transgenic mice

OBJECTIVE

To demonstrate that Tat modulates the plasminogen-dependent proteolytic activity of tumour cell lines derived from BK virus (BKV)/tat-transgenic mice by affecting the production of plasminogen activators (PA) and the PA inhibitor (PAI)-1 and to demonstrate that this occurs through mechanism(s) that are distinct from those responsible for transactivating activity of extracellular Tat.

DESIGN AND METHODS

To assess whether endogenous Tat is responsible for PA activity in T53 adenocarcinoma cells, cell cultures were transfected with antisense Tat cDNA and evaluated for cell-associated PA activity by a plasmin chromogenic assay. The assay was also used to evaluate PA activity in T53 cells and T111 leiomyosarcoma cells stimulated by extracellular Tat. The type(s) of PA produced were identified by sodium dodecyl sulphate-polyacrylamide gel electrophoresis zymography. The levels of PAI-1 were evaluated by Western blotting. Tat transactivating activity was measured by a chloramphenicol acetyltransferase (CAT) enzyme-linked immunosorbent assay in HL3T1 cells containing integrated copies of an HIV-1 long terminal repeat (LTR)-CAT plasmid.

RESULTS

Transfection of T53 cells with antisense Tat cDNA results in the decrease of Tat production and PA activity. Exogenously added Tat increases PA levels in T53 and in T111 cells. PA activity was identified as urokinase-type PA (uPA). Tat also increases the production of PAI-1 in T111 but not in T53 cells. Chloroquine and heparin have different affects on the LTR-CAT-transactivating and the PA-inducing activities of Tat. The fusion protein glutathione-S-transferase-Tat and the mutant Tat-1e, lacking the second Tat exon, cause LTR-CAT transactivation without stimulating uPA upregulation.

CONCLUSIONS

Tat affects the fibrinolytic activity of tumour cell lines derived from BKV/tat-transgenic mice by modulating the production of both uPA and PAI-1 via autocrine and paracrine mechanisms of action. The capacity of Tat to modulate the plasminogen-dependent proteolytic activity of these tumour cell lines may contribute to their metastatic potential. The uPA-inducing activity of Tat depends upon specific biological and structural features of the Tat protein that are distinct from those responsible for its LTR-CAT-transactivating activity, suggesting distinct mechanisms of induction for the two biological responses.

Studies on the effect of the combined expression of anti-tat and anti-rev genes on HIV-1 replication

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

SV40 early region and large T antigen in human brain tumors, peripheral blood cells, and sperm fluids from healthy individuals

SV40 T antigen (Tag) coding sequences were detected by PCR amplification followed by Southern blot hybridization in human brain tumors and tumor cell lines, as well as in peripheral blood cells and sperm fluids of healthy donors. SV40 early region sequences were found in 83% of choroid plexus papillomas, 73% of ependymomas, 47% of astrocytomas, 33% of glioblastoma multiforme cases, 14% of meningiomas, 50% of glioblastoma cell lines, and 33% of astrocytoma cell lines and in 23% of peripheral blood cell samples and 45% of sperm fluids from normal individuals. None of the 13 normal brain tissues were positive for SV40 DNA, nor were seven oligodendrogliomas, two spongioblastomas, one neuroblastoma, one meningioma, or four neuroblastoma cell lines. Expression of SV40 early region was found by reverse transcription PCR, and SV40-specific Tag was detected by indirect immunofluorescence in glioblastoma cell lines. DNA sequence analysis, performed in four positive samples, confirmed that the amplified PCR products belong to the SV40 early region. Sixty-one % of the neoplastic patients positive for SV40 sequences had an age excluding exposure to SV40-contaminated polio vaccines, suggesting a contagious transmission of SV40. The possible role of SV40 Tag in the etiopathogenesis of human brain tumors and the spread of SV40 by horizontal infection in the human population are discussed.

Latent BK virus infection and Kaposi's sarcoma pathogenesis

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.

Latent BK virus infection and Kaposi's sarcoma pathogenesis

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.

Promotion of tumour metastases and induction of angiogenesis by native HIV-1 Tat protein from BK virus/tat transgenic mice

OBJECTIVE

To characterize the T53 cell line and its clones derived from an adenocarcinoma of BK virus (BKV)/tat transgenic mice and to establish the role of native Tat in tumorigenicity, induction of metastases and angiogenesis.

DESIGN AND METHODS

Tat was quantified by flow cytometry and chloramphenicol acetyltransferase (CAT) assays. Tumorigenicity and metastatic ability of cell lines were assayed in nude mice. Production of proteases was evaluated by a plasmin chromogenic assay and gelatinase zymography. The angiogenic effect was studied in vivo with conditioned medium from tumour cell lines.

RESULTS

Tat protein was detected in tumour cell lines in amounts from 600-7000 molecules/cell. Conditioned medium from tumour cell lines was able to transactivate an LTR-CAT in HL3T1 cells, indicating release of extracellular Tat. Tumour cell lines, inoculated into nude mice induced angiogenic tumours with remarkable recruitment of host endothelial cells. Metastases were detected in lymph nodes, lungs, kidneys, and heart. Cell lines produced relevant amounts of proteases. Conditioned medium implanted in mice with matrigel induced an angiogenic response, enhanced by addition of heparin. Preincubation with an anti-Tat antibody abolished the angiogenic effect.

CONCLUSIONS

Tat from cells from BKV/tat transgenic mice promotes tumorigenesis and formation of metastases and induces angiogenic activity. Angiogenesis occurs at physiological concentrations of Tat lower than 20 ng/ml. The effects of Tat on induction of metastases and angiogenesis appear to be mediated by activation of proteases.

Growth arrest and suppression of tumorigenicity of bladder-carcinoma cell lines induced by the P16/CDKN2 (p16INK4A, MTS1) gene and other loci on human chromosome 9

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.

Inhibition of HIV-1 replication and reactivation from latency by tat transdominant negative mutants in the cysteine rich region

Tat mutants (tat22, tat37 and tat22/37) were constructed in the transactivation domain, where cysteines at positions 22 or/and 37 were substituted with glycine and serine, respectively. These mutants were expressed either in a BK virus episomal vector or in the retroviral vector LXSN. Constitutive production of tat22 by Jurkat T cells in the context of both vectors blocked HIV-1 replication during lytic infection. Conversely, the tat37 mutant did not show any inhibitory activity and tat22/37 displayed a mild effect on HIV-1 infection only when expressed by the recombinant retrovirus. However, constitutive production of tat22/37 by the BK virus vector in Jurkat T cells chronically infected by HIV-1 was effective in blocking reactivation of viral replication induced by tumor necrosis factor-alpha or human herpesvirus-6. These results suggest that mutants in the transactivation domain of tat may be considered in designing alternative strategies to control HIV-1 replication and reactivation from latency during different phases of infection.