Induction of senescence and control of tumorigenicity in BK virus transformed mouse cells by human chromosome 6

Bilateral administration of autologous CD133+ cells in ambulatory patients with refractory critical limb ischemia: lessons learned from a pilot randomized, double-blind, placebo-controlled trial

BACKGROUND AIMS

CD133+ cells confer angiogenic potential and may be beneficial for the treatment of critical limb ischemia (CLI). However, patient selection, blinding methods and end points for clinical trials are challenging. We hypothesized that bilateral intramuscular administration of cytokine-mobilized CD133+ cells in ambulatory patients with refractory CLI would be feasible and safe.

METHODS

In this double-blind, randomized sham-controlled trial, subjects received subcutaneous injections of granulocyte colony-stimulating factor (10 μg/kg per day) for 5 days, followed by leukapheresis, and intramuscular administration of 50-400 million sorted CD133+ cells delivered into both legs. Control subjects received normal saline injections, sham leukapheresis and intramuscular injection of placebo buffered solution. Subjects were followed for 1 year. An aliquot of CD133+ cells was collected from each subject to test for genes associated with cell senescence.

RESULTS

Seventy subjects were screened, of whom 10 were eligible. Subject enrollment was suspended because of a high rate of mobilization failure in subjects randomly assigned to treatment. Of 10 subjects enrolled (7 randomly assigned to treatment, 3 randomly assigned to control), there were no differences in serious adverse events at 12 months, and blinding was preserved. There were non-significant trends toward improved amputation-free survival, 6-minute walk distance, walking impairment questionnaire and quality of life in subjects randomly assigned to treatment. Successful CD133+ mobilizers expressed fewer senescence-associated genes compared with poor mobilizers.

CONCLUSIONS

Bilateral administration of autologous CD133+ cells in ambulatory CLI subjects was safe, and blinding was preserved. However, poor mobilization efficiency combined with high CD133+ senescence suggests futility in this approach.

Characterization of genomic instability in ulcerative colitis neoplasia leads to discovery of putative tumor suppressor regions

Ulcerative colitis (UC) is an inflammatory disease of the colon that is associated with increased risk of colorectal cancer associated with genomic instability. We have previously demonstrated that genomic instability is present in UC patients with colonic neoplasia, and hypothesized that the chromosomal alterations may be taking place in regions that are susceptible to mutation or that provide a growth advantage to a cell undergoing neoplastic transformation. In this study, we used two polymerase chain reaction (PCR)-based DNA fingerprinting techniques (arbitrarily primed PCR and inter-simple-sequence-repeat PCR) to study the process of genomic instability. The two techniques of DNA fingerprinting cross-validate the instability observed in these studies. We analyzed the molecular basis of 10 commonly altered DNA bands obtained from DNA fingerprints of biopsies from various histologic grades of UC patients with dysplasia or cancer (UC Progressors). We determined that the band changes in the fingerprint truly represent changes in DNA sequence, and that the fingerprinting provides highly reproducible results. Furthermore, our investigation revealed that 40% of alterations involve repetitive sequences. Two frequently deleted sequences in 6q27 and 2q14 were studied further because they were frequently abnormal in the dysplastic and nondysplastic tissue of UC Progressors. The losses from 6q27 and 2q14 were confirmed by loss of heterozygosity and real-time PCR analysis. Both of these regions in chromosomes 6 and 2 are surrounded by highly repetitive and mobile LINE-1 elements, possibly making the region susceptible to mutational change. These regions were affected (lost) in UC Progressors but not in UC patients who were neoplasia free. Loss of heterozygosity at 6q27 has been described in ovarian and other cancers, while the 2q14 region has been implicated in prostate and sporadic colon cancers. Both regions are likely to contain tumor-suppressor genes. In conclusion, the genomic instability in UC Progressors can occur in regions that are susceptible to change and are locations of putative tumor-suppressor genes.

Allelic loss of chromosome 6q in gastric carcinoma

Loss of the long arm of chromosome 6 (6q) has frequently been reported in gastric carcinoma, and most gastric cancer patients have evidence of intestinal metaplasia in the stomach. However, the relationship between loss of chromosome 6q and intestinal metaplasia has not been studied. In the first part of the study, we define the critical deletion region of chromosome 6q using loss of heterozygosity technique (LOH). Seventeen microsatellite markers were used to detect loss of heterozygosity (LOH) in 37 microdissected gastric tumors. We also examined intestinal metaplasia (IM) foci of the stomach in the same cancer patient (17 cases). Losses on chromosome 6q were detected in high frequency (51%) by LOH. Two distinct regions of common allelic loss were identified: one centered on the marker D6S300 (at 6q16.1) and the second on D6S446 (at 6q27), with LOH frequency of 36% and 31.3%, respectively. The deletions fall into 2 discrete regions, suggesting the existence of at least 2 tumor suppressor genes in 6q. The losses at 6q27 were confirmed by fluorescence in situ hybridization study (FISH). In the cases with LOH in the tumor, no LOH were detected in the autologous IM areas, but losses were detected by FISH. In some cases, these genetic changes may be acquired in the transition from normal gastric mucosa to intestinal metaplasia.

Parkin, a gene implicated in autosomal recessive juvenile parkinsonism, is a candidate tumor suppressor gene on chromosome 6q25-q27

In an effort to identify tumor suppressor gene(s) associated with the frequent loss of heterozygosity observed on chromosome 6q25-q27, we constructed a contig derived from the sequences of bacterial artificial chromosomeP1 bacteriophage artificial chromosome clones defined by the genetic interval D6S1581-D6S1579-D6S305-D6S1599-D6S1008. Sequence analysis of this contig found it to contain eight known genes, including the complete genomic structure of the Parkin gene. Loss of heterozygosity (LOH) analysis of 40 malignant breast and ovarian tumors identified a common minimal region of loss, including the markers D6S305 (50%) and D6S1599 (32%). Both loci exhibited the highest frequencies of LOH in this study and are each located within the Parkin genomic structure. Whereas mutation analysis revealed no missense substitutions, expression of the Parkin gene appeared to be down-regulated or absent in the tumor biopsies and tumor cell lines examined. In addition, the identification of two truncating deletions in 3 of 20 ovarian tumor samples, as well as homozygous deletion of exon 2 in the lung adenocarcinoma cell lines Calu-3 and H-1573, supports the hypothesis that hemizygous or homozygous deletions are responsible for the abnormal expression of Parkin in these samples. These data suggest that the LOH observed at chromosome 6q25-q26 may contribute to the initiation andor progression of cancer by inactivating or reducing the expression of the Parkin gene. Because Parkin maps to FRA6E, one of the most active common fragile sites in the human genome, it represents another example of a large tumor suppressor gene, like FHIT and WWOX, located at a common fragile site.

KISS1 metastasis suppression and emergent pathways

Metastatic disease is the most critical impediment to cancer patient survival. However, comparatively little is known concerning the intricate pathways which govern the complex phenotypes associated with metastasis. The KISS1 metastasis suppressor gene inhibits metastasis in both in vivo melanoma and breast carcinoma models. Despite its clear physiological activity, the mechanism of KISS1 remains unclear. Recent identification of a 54 amino acid peptide of KISS1, termed metastin or kisspeptin-54, and its cognate G-protein coupled receptor (hOT7T175, AXOR12, GPR54) have provided additional clues and avenues of research. While studies have attributed KISS1 with modulation of NFkappaB regulation, experiments with metastin and its receptor implicate MAP kinase pathways and also suggest the potential of autocrine, paracrine and endocrine roles. Impacts on motility, chemotaxis, adhesion and invasion have each been documented in disparate cell lines and conflicting observations require resolution. Nevertheless, mounting clinical evidence, particularly the loss of KISS1 in metastases, correlates KISS1 and metastin receptor expression with human tumor progression. Together, the data substantiate roles for these molecules in metastasis regulation.

Cloning and characterization of the common fragile site FRA6F harboring a replicative senescence gene and frequently deleted in human tumors

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.

Chromosome studies of in vitro senescent lymphocytes: nonrandom trisomy 2

Chromosome studies were carried out in long-term (142 and 184 d) human lymphocyte in vitro cultures in order to investigate the cytogenetic status of aging lymphocytes. The female donors were subdivided into three subgroups according to their age: 20-40 year-old (three individuals), 70-90 year-old (five persons), and centenarians (three persons). Besides some aneuploidy and structural abnormalities, telomere fusions were detected in all donor cells, and associations of acrocentric chromosomes were found in six persons in the three age-groups. Clonal trisomy 2 was present in three individuals (two from the 70-90 year-group and one centenarian with a clone +2, +8). While telomeric fusions and acrocentric associations seem to be more related to in vitro aging, trisomy 2 also appears dependent on the age of the cell donors.

Analysis of chromosome 6q deletion in EBV-associated NK cell leukaemia/lymphoma

Deletions involving chromosome 6q have been reported in a number of human cancers such as ovarian and breast tumours as well as haematopoietic malignancies. It seems that this region might contain tumour-suppressor genes. Putative natural killer cell lymphomas/leukaemias (NKLL) represent a group of recently characterized haematolymphoid malignancies sharing an immunophenotype of CD3/Leu4- CD3epsilon+ CD56+, a genotype of germline T-cell receptor genes, and have a close association with Epstein-Barr virus (EBV). Deletion at 6q21-q25 was demonstrated in three recently reported cases of NKLL. Here we investigated the possible involvement of 6q deletions in the pathogenesis, and especially the tumorigenesis of NKLL. The regions of D6S1574 (6p25), DS276 (6p12), D6S257 (6q11), D6S434 (6q14), D6S287 (6q15), D6S292 (6q21), D6S308 (6q22), D6S264 (6q25), and D6S446 (6q26) were analysed by PCR in 25 cases of NKLL, including seven cases with chronic NK leukaemia, six with acute NK leukaemia and 12 with NK lymphoma. 6q deletions, especially 6q15-25, were frequently detected, but 6p deletions were not detected in any cases. Analysis of 6q21 showed possible deletion in two of seven cases (29%) with chronic NK leukaemia, three of six (50%) with acute leukaemia, and 12 of 12 (100%) with NK lymphoma. The frequency of deletion increased in clinical phases. In three cases with lymphoma, fluorescence in situ hybridisation was performed, which confirmed 6q21 deletion in two cases, although 6q telomeric and centromeric regions were preserved. The other case failed to show deletion. Our results suggest that 6q deletion, especially 6q21-25, might be involved in NKLL tumorigenesis, and support the presence of the tumour suppressor genes associated with the development of NKLL.

A novel homozygous deletion at chromosomal band 6q27 in an ovarian cancer cell line delineates the position of a putative tumor suppressor gene

Chromosomal band 6q27 is believed to contain a tumor suppressor gene important in the development of several cancer types, including ovarian cancer. However, repeated efforts to identify a tumor suppressor gene in this region have been unsuccessful. Because homozygous deletions have been useful in the positional cloning of a number of tumor suppressor genes, we initiated a systematic search for such deletions in ovarian cancer cell lines using 6q microsatellite markers. One of the cell lines, OV167, was found to contain an 80 kb homozygous deletion encompassing marker D6S193 at 6q27 but excluding nearby marker D6S297. No known genes were present in the deleted region. Because the homozygous deletion might affect the expression of nearby genes, we analyzed the expression of the two closest known genes flanking the deletion, RNASE6PL and RSK-3. The expression of these genes were unaffected by the homozygous deletion, suggesting that the functional target of the deletion is located between these two genes. A search of the region against expressed sequence tag (EST) databases revealed that it contained four sets of expressed sequences. The first expressed sequences were derived from a LINE repetitive element and were considered unlikely to represent a tumor suppressor gene. The other expressed sequence tags identified did not show homology to known genes and are currently being investigated. This data may significantly reduce the magnitude of the search for the 6q tumor suppressor gene as it suggests a small area as a prime target for investigation.

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.

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.

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).

Identification of a gene at 16q24.3 that restores cellular senescence in immortal mammary tumor cells

We have mapped a cellular senescence gene, SEN16, within a genetic distance of 3 - 7 cM, at 16q24.3. Microcell mediated transfer of a normal human chromosome 16, 16q22-qter or 16q23-qter restored cellular senescence in four immortal cell lines, derived from human and rat mammary tumors. The resumption of indefinite cell proliferation, concordant with the segregation of the donor chromosome, confirmed the presence of a senescence gene at 16q23-qter. While microcell hybrids were maintained in selection medium to retain the donor chromosome, sporadic immortal revertant clones arose among senescent cells. Reversion to immortal growth could occur due to inactivation of the senescence gene either by a mutation or a deletion. The analysis for chromosome 16 specific DNA markers, in revertant clones of senescent microcell hybrids, revealed a consensus deletion, spanning a genetic interval of approximately 3 - 7 cM at 16q24.3.

The human homologue of the Drosophila tailless gene (TLX): characterization and mapping to a region of common deletion in human lymphoid leukemia on chromosome 6q21

Deletion of the long arm of chromosome 6 (6q) is one of the most common chromosomal abnormalities in human hematological malignancies. Two distinct regions of minimal deletion have been identified by loss of heterozygosity studies at 6q25 to 6q27 (RMD-1) and at 6q21 to 6q23 (RMD-2), suggesting the presence of one or more tumor suppressor genes. We have cloned sequences within RMD-2 and screened for novel genes using a combination of direct sequencing, cDNA library screening, and exon trapping. Sequences generated from a cosmid fragment, mapping within RMD-2, showed homology to the Drosophila tailless gene (tll). The human homologue of the Drosophila tailless gene (human tlx; MGMW-approved symbol, TLX) was subsequently cloned from a fetal brain cDNA library. The gene is a member of the steroid nuclear receptor superfamily and is homologous to tll genes from other species that are involved in brain development. TLX is predominately expressed in the brain and maps to RMD-2 at 6q21 between DNA markers FYN and D6S447, in a YAC clone that also contains marker D6S246. The contributions of this gene to human B-cell leukemia and to brain development are unknown at present.

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.

Linkage analysis of familial melanoma and chromosome 6 in 14 Australian kindreds

CDKN2A (9p21) and CDK4 (12q13) have been identified as melanoma susceptibility genes in certain familial melanoma (FM) kindreds. There remain other FM families, however, for which there is little or no evidence for linkage of melanoma to these loci. Other loci may be involved in susceptibility to this malignancy. Chromosome 6 is deleted or rearranged in 66% of melanomas and has been targeted by several studies in an attempt to identify chromosomal regions associated with initiation or progression of melanoma. Previous studies of familial melanoma and chromosome arm 6p reported evidence suggestive of linkage for markers flanking the HLA complex. We have carried out genetic linkage analysis in 14 Australian familial melanoma kindreds using 16 short tandem repeat polymorphism (STRP) markers spanning 6p23-6q27. Analysis by maximum likelihood and non-parametric (affected pedigree member) techniques showed no evidence of linkage of melanoma in this family set to chromosome 6 (two-point Zmax = 0.5 at theta = 0.2 for D6S285). Lod scores > 1.0 were obtained for the loci D6S285, D6S105, D6S265, D6S292, and D6S311 in three individual kindreds but these were insufficiently strong for formal heterogeneity testing to confirm that a chromosome 6-linked subset of families exists. These data imply little or no role for a major chromosome 6 melanoma susceptibility locus; however the possibility of such a locus remains open and warrants further investigation.

Identification of highly expressed genes in metastasis-suppressed chromosome 6/human malignant melanoma hybrid cells using subtractive hybridization and differential display

Microcell-mediated transfer of chromosome 6 into human melanoma cell lines C8161 and MelJuSo suppresses metastasis by at least 95% without affecting tumorigenicity. Subtractive hybridization and differential display were used to identify the molecule(s) responsible for suppressing metastasis in neo6/melanoma (neo6/C8161 and neo6/MelJuSo) hybrids. Seven cDNA clones exhibiting quantitatively or qualitatively higher expression in neo6/melanoma hybrids were obtained. These genes fell into 2 categories: 1) transcription-related genes (AP-2A, HMG-I(Y) and a novel isoform of nucleophosmin B23), which have previously been shown to regulate metastasis-associated genes; and 2) novel genes. One of the novel genes, designated KiSS-1, significantly suppressed metastasis of the human malignant melanoma cell lines MelJuSo and a highly metastatic subclone of C8161, C8161cl.9, following transfection and constitutive expression. Our results illustrate the power of subtractive hybridization and differential display to identify functional metastasis-controlling genes in human melanoma.

Analysis of chromosome 6 deletions in lymphoid malignancies provides evidence for a region of minimal deletion within a 2-megabase segment of 6q21

Fluorescence in situ hybridization has been used to define deletion breakpoints within chromosome bands 6q16-21 in cases of lymphoid malignancy. Previous evidence suggested that the region might contain a tumour-suppressor gene. Six yeast artificial chromosome probes, each selected using a single marker, were localized to 6q16-21 and the following order was confirmed; D6S330-D6S283-D6S301-D6S447-D6S246-FYN+ ++. Of 32 cases of lymphoid malignancy, 30 showed deletion of D6S246 and, in the two cases in which D6S246 was retained, the adjacent marker, D6S447, was deleted. These observations imply that a region of minimal deletion is located within a 2-megabase segment of 6q21, between D6S447 and D6S246, providing a candidate region for the location of a tumour-suppressor gene.

Neurodegeneration, myocardial injury, and perinatal death in mitochondrial superoxide dismutase-deficient mice

Manganese superoxide dismutase (SOD2) converts superoxide to oxygen plus hydrogen peroxide and serves as the primary defense against mitochondrial superoxide. Impaired SOD2 activity in humans has been associated with several chronic diseases, including ovarian cancer and type I diabetes, and SOD2 overexpression appears to suppress malignancy in cultured cells. We have produced a line of SOD2 knockout mice (SOD2m1BCM/SOD2m1BCM) that survive up to 3 weeks of age and exhibit several novel pathologic phenotypes including severe anemia, degeneration of neurons in the basal ganglia and brainstem, and progressive motor disturbances characterized by weakness, rapid fatigue, and circling behavior. In addition, SOD2m1BCM/SOD2m1BCM mice older than 7 days exhibit extensive mitochondrial injury within degenerating neurons and cardiac myocytes. Approximately 10% of SOD2m1BCM/SOD2m1BCM mice exhibit markedly enlarged and dilated hearts. These observations indicate that SOD2 deficiency causes increased susceptibility to oxidative mitochondrial injury in central nervous system neurons, cardiac myocytes, and other metabolically active tissues after postnatal exposure to ambient oxygen concentrations. Our SOD2-deficient mice differ from a recently described model in which homozygotes die within the first 5 days of life with severe cardiomyopathy and do not exhibit motor disturbances, central nervous system injury, or ultrastructural evidence of mitochondrial injury.

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.

Identification of two distinct regions of deletion at 6q in gastric carcinoma

Loss of heterozygosity (LOH) affecting the long arm of chromosome 6 has been found repeatedly in human cancers. Recently, our group reported that del(6)(q21-22-->qter) was the most consistent structural cytogenetic abnormality in gastric carcinomas. To determine more precisely the deleted region, we studied 51 tumors with 9 polymorphic markers on this chromosome arm. LOH of one or more markers was found in 39% of the tumors. LOH at region 6q22.3 was detected in 50% of informative tumors and at 6q26-q27 in 37% of informative tumors. By comparative analysis of LOH regions, we identified two separate regions of overlapped deletions at 6q, one between 6q16.3-q21 and 6q22.3-q23.1, another distal to 6q23-q24. A comparison of clinicopathologic features of gastric carcinomas with and without LOH at 6q revealed statistically significant or suggestive differences between LOH and young age of the patients and proximal location of the tumors. The two informative early gastric carcinomas both showed LOH at 6q. The occurrence of LOH at 6q was similar in all histological types. We conclude that two distinct regions at 6q appear to be involved in the early stages of gastric carcinogenesis.

High incidence of BK virus large-T-antigen-coding sequences in normal human tissues and tumors of different histotypes

T-antigen (TAg) coding sequences specific for BK virus (BKV) were detected, by PCR amplification followed by Southern-blot hybridization, in a high percentage of human tumors and tumor-cell lines, as well as in normal tissues, by analysis of 189 specimens. Specifically, the BKV early region was detected in 85% of brain tumors and in all normal brain tissues, in 78% of osteosarcomas, in 38% of Ewing's tumors, in 40% of normal bone specimens and in 71% of normal peripheral blood cell samples. Wilms' tumor tissues used as a control were all negative for BKV sequences. RT-PCR analysis indicated that TAg coding sequences were expressed in specimens carrying BKV early region, ranging from 64% of the osteosarcomas to 100% of glioblastomas, Ewing's tumors, peripheral blood cells and normal bone. Moreover, DNA sequencing performed in 12 different positive samples revealed that the amplified PCR products are identical to the early-region sequence of wild-type BKV. The role of BKV TAg and its possible mechanism of action in human tumorigenesis are discussed.