Reduction in disialyl-T antigen levels in mice deficient for both St6galnac3 and St6galnac4 results in blood filling of lymph nodes

Sialic acid (SA) is present at the terminal ends of carbohydrate chains in glycoproteins and glycolipids and is involved in various biological phenomena. The biological function of the disialyl-T (SAα2-3Galβ1-3(SAα2-6)GalNAcα1-O-Ser/Thr) structure is largely unknown. To elucidate the role of disialyl-T structure and determine the key enzyme from the N-acetylgalactosaminide α2,6-sialyltransferase (St6galnac) family involved in its in vivo synthesis, we generated St6galnac3- and St6galnac4-deficient mice. Both single-knockout mice developed normally without any prominent phenotypic abnormalities. However, the St6galnac3::St6galnact4 double knockout (DKO) mice showed spontaneous hemorrhage of the lymph nodes (LN). To identify the cause of bleeding in the LN, we examined podoplanin, which modifies the disialyl-T structures. The protein expression of podoplanin in the LN of DKO mice was similar to that in wild-type mice. However, the reactivity of MALII lectin, which recognizes disialyl-T, in podoplanin immunoprecipitated from DKO LN was completely abolished. Moreover, the expression of vascular endothelial cadherin was reduced on the cell surface of high endothelial venule (HEV) in the LN, suggesting that hemorrhage was caused by the structural disruption of HEV. These results suggest that podoplanin possesses disialyl-T structure in mice LN and that both St6galnac3 and St6galnac4 are required for disialyl-T synthesis.

JC virus T-antigen regulates glucose metabolic pathways in brain tumor cells

Recent studies have reported the detection of the human neurotropic virus, JCV, in a significant population of brain tumors, including medulloblastomas. Accordingly, expression of the JCV early protein, T-antigen, which has transforming activity in cell culture and in transgenic mice, results in the development of a broad range of tumors of neural crest and glial origin. Evidently, the association of T-antigen with a range of tumor-suppressor proteins, including p53 and pRb, and signaling molecules, such as β-catenin and IRS-1, plays a role in the oncogenic function of JCV T-antigen. We demonstrate that T-antigen expression is suppressed by glucose deprivation in medulloblastoma cells and in glioblastoma xenografts that both endogenously express T-antigen. Mechanistic studies indicate that glucose deprivation-mediated suppression of T-antigen is partly influenced by 5′-activated AMP kinase (AMPK), an important sensor of the AMP/ATP ratio in cells. In addition, glucose deprivation-induced cell cycle arrest in the G1 phase is blocked with AMPK inhibition, which also prevents T-antigen downregulation. Furthermore, T-antigen prevents G1 arrest and sustains cells in the G2 phase during glucose deprivation. On a functional level, T-antigen downregulation is partially dependent on reactive oxygen species (ROS) production during glucose deprivation, and T-antigen prevents ROS induction, loss of ATP production, and cytotoxicity induced by glucose deprivation. Additionally, we have found that T-antigen is downregulated by the glycolytic inhibitor, 2-deoxy-D-glucose (2-DG), and the pentose phosphate inhibitors, 6-aminonicotinamide and oxythiamine, and that T-antigen modulates expression of the glycolytic enzyme, hexokinase 2 (HK2), and the pentose phosphate enzyme, transaldolase-1 (TALDO1), indicating a potential link between T-antigen and metabolic regulation. These studies point to the possible involvement of JCV T-antigen in medulloblastoma proliferation and the metabolic phenotype and may enhance our understanding of the role of viral proteins in glycolytic tumor metabolism, thus providing useful targets for the treatment of virus-induced tumors.

A novel role of Rac1 GTPase in JCV T-antigen-mediated beta-catenin stabilization

Wnt signaling follows canonical and non-canonical pathways to regulate a variety of processes during cellular homeostasis and development. The large T-antigen (T-Ag) of the human neurotropic JC virus, has been shown to modulate the Wnt-signaling pathway via interaction with beta-catenin, one of the most important components of the canonical Wnt pathway. Here, we have identified an alternative non-canonical pathway that allows T-Ag to recruit Rac1 for stabilizing beta-catenin by inhibiting its ubiquitin-dependent proteasomal degradation. We demonstrate that inhibition of Rac1 by its dominant negative mutant, RacN17, abrogates T-Ag-mediated stabilization of beta-catenin yet exhibits no impact on the transcriptional activity of beta-catenin. Results from immunocytochemistry revealed that together with T-Ag, a pool of beta-catenin appears at the cell surface, particularly at the membrane ruffles where active Rac1 is positioned. Interestingly, cooperativity between T-Ag and beta-catenin leads to activation of Rac1, which in turn, stimulates its association with beta-catenin. These observations unravel the interplay between beta-catenin and Rac1 that is initiated by T-Ag and results in stabilization of beta-catenin and its presence in cell membrane ruffles.

Low frequency of BK virus in prostatic adenocarcinomas

BK virus (BKV) exhibits many oncogenic properties and has been associated with a variety of tumors in humans. BKV has not been well studied in the context of prostate neoplasia; however, an association of BKV with prostatic adenocarcinoma has been suggested based on the detection of viral DNA sequences and expression of viral proteins in clinical samples. To further investigate the reported association of BKV with prostatic adenocarcinoma and the potential role of the virus in prostate tumorigenesis, 30 cases of adenocarcinoma of the prostate were analyzed for evidence of BKV infection by in situ hybridization and immunohistochemistry. In situ hybridization analysis detected BKV DNA in 2 of 30 (7%) prostatic adenocarcinomas, with positive signals focally identified in less than 1% of the neoplastic cells in both cases. However, none of the tumors evaluated demonstrated evidence of BKV large tumor antigen expression by immunohistochemistry. Among prostatic adenocarcinomas that showed no evidence of BKV infection, BKV DNA was focally observed in the adjacent non-neoplastic prostate tissue in four cases by in situ hybridization in the absence of BKV large tumor antigen immunoreactivity. The findings of the present study indicate rare cases of prostatic adenocarcinoma may be associated with BKV infection. However, lack of localization of BKV to a large population of the neoplastic cells and absence of BKV large tumor antigen expression suggest that the virus does not play a role in the pathogenesis of prostate cancer.

Detection of polyomaviruses and herpesviruses in human adrenal tumors

The presence of polyomaviruses and herpesviruses in adrenal tumors and their role in adrenal tumorigenesis has never been investigated, even though the adrenal gland seems to be a preferential site of infection by these viruses and adrenal steroid hormones have been shown to activate their replication. We examined in a large series of normal adrenal gland tissues (n=20) and adrenal tumors (n=107) the presence of herpesviruses and polyomaviruses sequences and gene expression, which were detected in a high proportion of both normal and neoplastic adrenal samples (overall, viruses were found in 15% normal adrenals, 27.8% benign adrenal tumors and 35.3% malignant tumors). The polyomaviruses SV40 and BK virus were more frequently found in malignant adrenal tumors, whereas herpesviruses, especially Epstein-Barr virus and human cytomegalovirus, were more frequently detected in functioning benign adrenocortical tumors, often as coinfection. Moreover, tumors from patients with severe hypercortisolism frequently showed herpesvirus coinfections at high viral genome copy number. Our study suggests that the adrenal gland could be a reservoir of infection for these viruses and that hormone overproduction by the adrenal gland could represent a trigger for virus reactivation. On the other hand, these viruses could also contribute to adrenal cell proliferation and tumorigenesis.

Lack of BK virus DNA sequences in most transitional-cell carcinomas of the bladder

BK virus (BKV), a common human polyomavirus infection latent in the kidneys, can reactivate with immunosuppression to cause renal disease. Some have suggested that BKV may contribute to the development of bladder cancer, and BKV sequences have been reported from bladder tumors. To further examine the role of BKV in human bladder cancer, a series of bladder tumors was investigated for BKV genomic sequences. Fresh-frozen specimens from 76 transitional cell carcinoma tissues and 46 paired adjacent normal urothelial tissues archived at the H. Lee Moffitt Cancer Center were studied. All tissues were histopathologically reviewed. DNA extracted from the tissues was tested by quantitative real-time polymerase chain reaction (QPCR) assays to detect BKV DNA sequences in the VP1 coding region. Amplification of ERV-3 was conducted separately to quantify cell copy number. Conventional PCR targeting the BKV T-antigen (T-Ag) coding region and immunohistochemistry for BKV T-Ag were also conducted on all tissues that tested positive for BKV by QPCR. Seventy-three bladder tumors yielded >/=3,000 copies of ERV-3, 4 (5.5%) of which tested positive for BKV with average copy numbers of 7.9, 15.8, 0.4 and 0.3 per 1,000 cells. Paired normal tissue was available for 2 of these BKV-positive tumors, 1 of which was BKV-positive (14.6 copies/1,000 cells). No other normal tissues were BKV-positive by QPCR. The 6 BKV-positive tissues by QPCR were also positive by conventional PCR, but all stained negative for BKV T-Ag by immunohistochemistry. BKV is unlikely to be involved in the etiology of most bladder tumors.

High JC virus load in gastric cancer and adjacent non-cancerous mucosa

The JC virus (JCV) infects a large proportion of the worldwide population and approximately 90% of adults are seropositive. Recent reports have described the possibility of its oncogenetic role in several malignancies. The aim of the present study was to assess the oncogenetic significance of JCV for gastric cancer. Twenty-two sample pairs of fresh tumor and adjacent non-cancerous tissue (ANCT) as well as 10 normal gastric mucosa specimens were investigated on the basis of nested polymerase chain reaction (PCR) followed by Southern blotting, DNA direct sequencing, real-time PCR, in situ PCR and immunohistochemistry. The T antigen sequence was detected in 86.4% of gastric cancers and ANCT, and in 100% of the normal mucosa samples, as for virus capsid protein, 54.1%, 68.1% and 70%, respectively. A generally low incidence was noted for agnoprotein. The JCV DNA load was approximately 10-fold higher in both gastric cancers and paired ANCT (4784 +/- 759 and 5394 +/- 1466 copies/microg DNA, respectively) than in normal gastric tissue (542.4 +/- 476.0 copies/microg DNA, P < 0.0001). In situ PCR revealed sporadic JCV genome-positive cancer cells and foveolar epithelial cells. T antigen protein expression assessed by immunohistochemistry was detected only in one case (1/22; 4.5%), probably because the half life of T antigen might be short. It was concluded that the gastric epithelium in most Japanese people is infected with JCV at a low rate but levels of infection are increased markedly in both cancer cells and ANCT, indicating that multiplication of JCV copies might be a risk factor and a background for gastric carcinogenesis.

Association of JC virus T-antigen expression with the methylator phenotype in sporadic colorectal cancers

BACKGROUND & AIMS

JC virus (JCV) is a polyomavirus that ubiquitously infects humans and has been implicated in various human cancers. JCV encodes a "transforming" gene, T-antigen (T-Ag), which is believed to mediate the oncogenic potential of the virus. We have previously shown that JCV DNA sequences are usually present in human colorectal cancers (CRCs), and we have provided in vitro evidence that JCV can induce chromosomal instability (CIN) in CRC cells. This study tests the hypothesis that JCV T-Ag expression correlates with one or more forms of genomic or epigenetic instability in sporadic CRCs.

METHODS

We characterized 100 sporadic CRCs for microsatellite instability (MSI) and CIN. PCR amplifications were performed for T-Ag sequences, and immunohistochemical (IHC) staining was performed to detect T-Ag expression. De novo methylation of the promoter regions of nine putative tumor suppressor genes thought to play a role in colorectal carcinogenesis was studied by methylation-specific PCR.

RESULTS

JCV T-Ag DNA sequences were found in 77% of the CRCs and 56% of these cancers (or 43% of the total) expressed T-Ag by IHC. Significant associations were observed between T-Ag expression and CIN in CRCs (P = .017) and between T-Ag expression and promoter methylation of multiple genes (P = .01).

CONCLUSIONS

The association between T-Ag expression and promoter methylation in CRC suggests that this viral oncogene may induce methylator phenotype and that JCV may be involved in CRC through multiple mechanisms of genetic and epigenetic instability.

Detection of JC virus DNA sequences in colorectal cancers in Japan

JC virus (JCV), a ubiquitous polyoma virus that commonly infects humans, was first identified as the etiologic agent for the fetal demyelinating disease, progressive multifocal leukoencephalopathy. Recently, a number of reports have documented detection of JCV in samples derived from several types of neural as well as non-neural human tumors. It has been suggested that oncogenicity of JCV depends on a T antigen having a strict structural homology to the T antigen of simian virus 40. To clarify whether JCV might have a potential role with regard to colorectal cancers, we investigated the presence of its genome in a series of cases along with colorectal adenomas and normal colonic mucosa, targeting T antigen, VP and agnoprotein by nested polymerase chain reaction and Southern blotting and T antigen by immunohistochemistry. While VP and agnoprotein were not found in any of the samples examined, T antigen was detected in 6 of 23 colorectal cancers (26.1%) and 1 of 21 adenomas (4.8%), but none of 20 samples of normal colonic mucosa. No clear and diffuse staining with anti-T-antigen antibodies (1:100) could be detected, and there was no correlation with CD20-positive cells, which might have indicated JCV latent infection of B lymphocytes. Presence of T antigen did not influence clinicopathological variables, including survival. In one colonic cancer case positive for T antigen together with lymph node metastasis, DNA extracted from cancer cells in the lymph node revealed no detection of T antigen. Our results are in the intermediate position between the high T antigen rate (81%) in one report and the lack of it (0%) in another focused on colon cancers. It was concluded that T antigen might be integrated in cancer cells in approximately one fourth of Japanese colon cancer cases without clear and diffuse expression of the protein, suggesting a possible role in oncogenesis which might involve a hit-and-run mechanism.

Detection of JC virus DNA sequences and expression of viral T antigen and agnoprotein in esophageal carcinoma

BACKGROUND

The human polyomavirus JC virus (JCV) causes progressive multifocal leukoencephalopathy. Subclinical infection with JCV occurs in 85-90% of the population worldwide. The virus usually remains latent but can reactivate under immunosuppressive conditions, resulting in progressive multifocal leukoencephalopathy. JCV is oncogenic in experimental animals and is associated with human brain tumors. JCV is found in normal mucosa of the gastrointestinal tract, and some colon carcinomas express the oncogenic JCV T-antigen protein. The objective of this study was to examine the presence of JCV DNA sequences and JCV protein expression in normal and malignant human esophageal tissues.

METHODS

The authors examined the presence of JCV DNA sequences and protein expression in normal and malignant human esophageal tissues. Seventy well characterized biopsy specimens from patients with a spectrum of esophageal disorders were studied by immunohistochemistry, and 18 specimens were analyzed further by polymerase chain reaction amplification.

RESULTS

JC viral DNA was isolated from 11 of 13 normal esophageal biopsy specimens (85%) and from 5 of 5 esophageal carcinomas (100%). Using immunohistochemistry, JCV T antigen was detected in 10 of 19 carcinomas (53%), agnoprotein was detected in 8 carcinomas (42%), p53 tumor suppressor was detected in 11 carcinomas (58%), and beta-catenin was detected in 4 carcinomas (21%). Zero of 51 normal, benign, and premalignant esophageal samples expressed viral proteins. Laser-capture microdissection verified the presence and specificity of JCV DNA sequences. beta-Catenin and p53 were colocalized with JCV T-antigen in the nuclei of neoplastic cells.

CONCLUSIONS

The results provide evidence for infection of gastrointestinal tract cells by JCV and suggest a potential role of JCV in the development of upper digestive tract carcinomas.

Polyomaviruses and primary central nervous system lymphomas

The authors investigated the potential association of human primary CNS non-Hodgkin lymphoma (PCNSL) with polyomavirus in HIV-1 infected and uninfected individuals. Immunohistochemical analysis of CNS biopsies from 19 HIV-negative and 17 HIV-positive patients and PCR analysis of 12 HIV-negative and 14 HIV-positive patients revealed that the lymphomas were uniformly negative for polyomaviruses. The authors conclude that polyomaviruses are unlikely to be related to the pathogenesis of most PCNSL.

Evidence against a role for SV40 infection in human mesotheliomas and high risk of false-positive PCR results owing to presence of SV40 sequences in common laboratory plasmids

BACKGROUND

PCR-based evidence of infection by simian virus 40 (SV40) has been reported in varying proportions of pleural mesotheliomas and other tumours, but data are conflicting and reproducibility limited. During a study of SV40 in relation to homozygous deletion of CDKN2A in mesotheliomas, we became concerned by inconsistent results and therefore used several independent techniques to investigate SV40 in these tumours.

METHODS

High-quality DNA and RNA were extracted from 71 frozen mesothelioma samples. DNA PCR was done with four sets of primers for the SV40 T-antigen gene. RNA transcripts were examined by RT-PCR.

FINDINGS

The first two primer sets for DNA PCR gave positive results in proportions similar to those reported in positive studies (56-62%) but there were unusual reproducibility difficulties. These primers were in a region of the T-antigen gene (nucleotides 4100-4713) that is present in many common laboratory plasmids. In assays with PCR primers not included within that region, only four cases (6%) showed products but these were too faint to suggest clonal infection. Further PCR assays confirmed that the SV40 sequences in the tumour samples had a deletion found only in plasmids, not in native functional SV40. Review of previous studies showed a similar pattern of discrepancies between SV40 T-antigen DNA PCR results obtained with primers within and beyond the region 4100-4713. All 71 mesotheliomas were negative for T-antigen transcripts by RT-PCR, and lacked T-antigen-positive tumour cells by immunohistochemistry.

INTERPRETATION

Our data based on three independent experimental approaches do not support a significant role for SV40 in human mesotheliomas. The risk of false-positive results due to contamination by common laboratory plasmids containing SV40 sequences has been underestimated. Studies of SV40 based on PCR methods require careful primer design to reduce this risk.

RELEVANCE TO PRACTICE

This paper presents several lines of evidence against the proposed link between SV40 infection and human mesotheliomas. Studies reporting a high prevalence of SV40 DNA in human tumours have been based on molecular assays prone to false-positive results. Because SV40 appears unlikely to have a major role, if any, in human mesotheliomas, clinicians should continue to consider asbestos exposure as the most likely and most thoroughly established aetiological factor in individuals with this cancer.

Expression of the interferon-induced MxA protein in viral encephalitis

MxA protein accumulates cytoplasmically in response to interferon stimulation, and mediates resistance against several viruses. In order to test whether MxA may serve as a diagnostic tool for viral infections of the central nervous system (CNS), we performed MxA immunohistochemistry on biopsies and autopsies of 57 patients with neurological disorders of known viral and nonviral aetiology. MxA was detectable in all HIV patients with proven opportunistic viral encephalitis, in all patients suffering from isolated viral encephalitis, in one of three HIV patients with cerebral toxoplasmosis, and in one case of micronodular encephalitis. No MxA was detectable in HIV patients with isolated HIV encephalitis or HIV infection accompanied by an opportunistic nonviral disorder. We were unable to show MxA expression in a variety of nonviral inflammatory and noninflammatory disorders of the CNS. Several cases of Rasmussen's encephalitis and multiple sclerosis tested negative, arguing against their possible viral aetiology. Two-colour immunohistochemistry identified macrophages and activated microglia as MxA expressing cells. In all studied cases MxA expression was accompanied by a marked T-cell infiltrate. Therefore, the detection of MxA-protein is a sensitive adjuvant marker for those cases of viral encephalitis which are accompanied by pronounced lymphocytic infiltrates.

Lytic JC virus infection in the kidneys of AIDS subjects

Our objective was to investigate the role of the human polyomavirus JC virus as a possible cause of renal damage in AIDS subjects. Histology, immunohistochemistry, and molecular biology were used to evaluate the frequency of viral infection, genotypes, viral status, and the presence of rearrangements or point mutations in specific genomic regions of strains isolated from renal tissue. Formalin-fixed, paraffin-embedded sections of postmortem renal specimens obtained from 111 unselected AIDS patients were stained for routine histology and with anti-SV40 antibody. The immunohistochemically positive specimens were further investigated by means of nested polymerase chain reaction for different polyomavirus genomic regions (large T, transcriptional control region, and viral protein 1). Furthermore, the sequences of transcriptional control region and viral protein 1 were also analyzed. Immunohistochemistry was positive in seven cases (6.3%), four of which showed morphological evidence of viral replication (intranuclear inclusion bodies and/or intratubular cellular casts): in all seven cases, only epithelial tubular cells (with and without inclusion bodies) and cellular casts were stained. The JC virus genome was identified by polymerase chain reaction in five of the seven immunohistochemically positive cases; transcriptional control region and viral protein 1 were amplified in, respectively, three and four cases. Transcriptional control region sequence analysis revealed major rearrangements in all three cases, with duplications of all the transcriptional factor-binding sites, whereas no point mutations were found in the viral protein 1 region, which was characterized as Type 1A in all cases. For the first time in AIDS subjects, this study shows that although rarely, JC virus can replicate in renal tissue. Molecular biology revealed major rearrangements in the transcriptional control region that, together with other unknown factors, could justify the increased pathogenicity of this human polyomavirus.

Ultrastructural localization of binding sites for PNA and VVA-B(4) lectins in human breast cancer cell lines detected by confocal fluorescence microscopy

Three cancer cell lines (MCF-7, HBL-100, MDA-MB 231) and subnormal breast epithelial cell line MCF-10A were labeled with FITC-conjugated VVA-B4 lectin, specific for D-GalNAcalpha-O-ser/thr, matching the structure of Tn antigen sugar residues, and with RTIC-conjugated PNA lectin, specific for DGalbeta1-3GalNAc-O-ser/thr, corresponding to the structure of T antigen. Simultaneous expression of Tn and T antigens on the same cells (but in widely differing proportions) led to their large heterogeneity and occurrence of numerous cell subpopulations within each of the studied cell lines. This observation proved that the changes leading to the formation of Tn antigen are not caused by an irreversible genetic mutation of beta1-3-galactosyltransferase. Expression of Tn antigen on MCF-10A cells with normal (or subnormal) karyotype suggests that the process of malignant transformation of the cell begins with the changes in molecular structure of glycoconjugates.

Expression of JC virus agnoprotein in progressive multifocal leukoencephalopathy brain

To examine the function of JC virus (JCV) agnoprotein, we examined the brains of cases of progressive multifocal leukoencephalopathy (PML), which is caused by JCV infection, using a newly generated antibody. The antibody reacted with 8 kDa protein specific for JCV agnoprotein by Western blotting. In vitro analyses showed that JCV capsid protein VP1 and large T antigen (T-Ag) were localized in the nuclei, but that agnoprotein was mainly detected in the cytoplasm of JCV-infected cells with an occasional nuclear staining. In the PML brain, an immunoreactive signal for agnoprotein was distributed in the perinuclear areas and cytoplasmic processes with occasional punctate staining in demyelinating lesions as well as adjacent myelinated areas. Agnoprotein presented mostly in the infected oligodendrocytes and partly in the astrocytes. Using double immunostaining, agnoprotein was seen to be expressed in the cytoplasmic processes of the cells, the nuclei of which were labeled with VP1 and T-Ag, where virus particles existed. Thus, JCV agnoprotein was mostly expressed in the infected oligodendrocytes and mainly localized in the cytoplasmic processes apart from virus particles in the demyelinated lesions.

Termination of lifespan of SV40-transformed human fibroblasts in crisis is due to apoptosis

Normal human fibroblasts in culture have a limited lifespan, ending in replicative senescence. Introduction of SV40 sequences encoding large T antigen and small t antigen into pre-senescent cells results in an extension of lifespan for an additional 20-30 population doublings. Rare clones of SV40-transformed cells are capable of indefinite growth and are described as immortal; however, the great majority of SV40-transformed cells terminate this extended lifespan in cell death, termed "crisis." We have examined the properties of cells in crisis to obtain further insights into mechanism of cell death and immortalization. Populations at the terminal cell passage show a balance between cell replication and cell death over a period of several weeks, with a progressive increase in cells undergoing cell death. During this period, there is less than a 3-fold increase in attached cell number, with two stages being identifiable on the basis of the focal pattern of cell survival. We also demonstrate that cells in crisis are undergoing apoptosis based on TUNEL assay, subG1 DNA content, annexin V reactivity, and activation of caspases 3 and 8. We suggest a model whereby SV40-transformed cells acquire increased sensitivity to apoptosis based on changes in properties which activate caspase 8 in addition to changes previously described involving shortening of telomeric sequences. While only telomere stabilization could be clearly shown to be essential for survival of cells through crisis, the extended period of cell replication and altered gene expression observed in SV40-transformed cells during crisis are compatible with other genetic alterations in immortal cells.

Involvement of Wnt signaling pathway in murine medulloblastoma induced by human neurotropic JC virus

By using the early genome of the human neurotropic polyomavirus, JCV, we have created transgenic animals that develop cerebellar primitive neuroectodermal tumors which model human medulloblastoma. Expression of T-antigen was found in some, but not all, tumor cells, and examination of the clonal cell lines derived from the tumor population showed enhanced tumorigenicity of cells expressing T-antigen in comparison to T-antigen negative cells. Considering the earlier notion on the potential involvement of beta-catenin with human medulloblastoma, we investigated various components of the Wnt signaling pathway including beta-catenin, its partner transcription factor, LEF-1, and their downstream target gene c-myc in these two cell populations. Immunohistochemical staining of the cells revealed enhanced nuclear appearance of beta-catenin in T-antigen positive cells. Results from Western blot showed higher levels of beta-catenin and LEF-1 in T-antigen positive cells in comparison to those in T-antigen negative cells. The enhanced level of LEF-1 expression correlated with the increase in DNA binding activity of this protein in nuclear extracts of T-antigen positive cells. Results from Northern and Western blot analyses revealed that the level of c-myc expression is augmented both at the RNA and protein levels in T-antigen positive cells. These observations corroborated results from transfection studies indicating the ability of JCV T-antigen to stimulate c-myc promoter activity. Further, co-transfection experiments revealed that the amount of c-myc and T-antigen protein in tumor cells may dictate the activity of JCV early promoter in these cells. These observations are interesting in light of recent discoveries on the association of JCV with human medulloblastoma and suggest that communication between JCV and the Wnt pathway may be an important event in the genesis of these tumors.

The immunoexpression of Tn, sialyl-Tn and T antigens in chronic active gastritis in relation to Helicobacter pylori infection

The simple mucin-type carbohydrate antigens Tn, sialyl-Tn and T represent the mucin core oligosaccharide structures that are produced in the initial steps of mucin biosynthetic pathway. Utilising monoclonal antibodies anti-Tn antigen, anti-sialyl-Tn antigen and anti-T antigen, we have investigated the expression of the simple mucin-type carbohydrate antigens in 47 biopsy specimens of antral mucosa with chronic active gastritis, 25 of which had Helicobacter pylori infection. The Tn immunoreactivity, localised at the supranuclear region of surface and glandular mucous cells, was observed in all samples, independently from H. pylori status. The sialyl-Tn antigen, mainly localised in the cytoplasm of glandular mucous cells and in goblet cells vacuoles, was seen in 56% of the cases with H. pylori infection and in 41% of the cases in the H. pylori-negative group. In addition, the T antigen was found in the cytoplasm of surface and glandular mucous cells in 16% of the H. pylori-positive group, whereas the percentage of positive cases was reduced to 5% in H. pylori-negative patients, with an exclusive localisation in the cytoplasm of glandular mucous cells; after neuraminidase treatment, the percentage of T antigen-positive cases was increased to 28% in H. pylori-positive cases and to 27% in negative cases. No significant relationships between H. pylori infection and Tn, sialyl-Tn or T antigen immunoexpression were encountered in our cases. Therefore, we maintain that the inflammatory infiltrate may itself play an important role in the expression of simple mucin-type carbohydrate antigens in chronic active antral gastritis.

Expression of Tn, sialosyl-Tn and T antigens in human foetal large intestine

Tn, sialosyl-Tn and T antigens are simple mucin-type carbohydrate antigens that may be expressed in human neoplasies due to alteration of the glycoprotein biosynthetic pathway. Utilising specific monoclonal antibodies (HB-Tn1, HB-STn1 and HB-T1), we have investigated the expression of these simple mucin-type carbohydrate antigens in large intestine of 8 human foetuses at early gestational age (9-10 weeks), obtained after therapeutic abortion. In all cases the expression of Tn antigen was mainly localised as a thin rim at the cell membrane and occasionally in the supranuclear region of epithelial cells, while sialosyl-Tn antigen was documented in some goblet cell vacuoles and occasionally in the cytoplasm of columnar cells. T antigen was not expressed in any case. These results indicate that Tn and sialosyl-Tn antigens are expressed as early as nine weeks of gestation, further supporting the notion that they may be considered as oncodevelopmental cancer-associated antigens in the large intestine.

Typing of Streptococcus pyogenes strains isolated from throat infections in the region of Aachen, Germany

BACKGROUND

Changes in the epidemiology of Streptococcus pyogenes infections may be associated with the introduction and reappearance of individual serotypes within a population.

MATERIALS AND METHODS

Typing of 216 consecutive isolates of S. pyogenes from patients with pharyngitis in the region of Aachen, Germany, was performed by sequencing the emm gene, slide-agglutination of the T-antigen and determining the serum opacity reaction (SOR).

RESULTS

All 216 isolates were unequivocally emm-typable. emm1 was most common (18.5%), foLlowed by emm12 (15.7%), emm3 (14.4%) and emm28 (13.9%). Only four isolates contained newly validated emm types: emm89 or emm94 were harbored by two isolates each. In one isolate, the sequence type s104 was found.

CONCLUSION

Despite an anticipated selective pressure, the prevalence of emm1 among isolates from throat infections in northwestern Germany remains high, but does not reflect the predominance of emm1 among invasive isolates in Germany.

Conditionally immortalized retinal capillary endothelial cell lines (TR-iBRB) expressing differentiated endothelial cell functions derived from a transgenic rat

The objective of this study was to establish and characterize a retinal capillary endothelial cell line (TR-iBRB) from a newly developed transgenic rat harboring the temperature-sensitive simian virus 40 (SV 40) large T-antigen gene (Tg rat). Retinal capillary endothelial cells were isolated from a Tg rat and cultured in collagen-coated dishes at 37 degrees C for a period of 48 hr. Cells were subsequently cultured at 33 degrees C to activate the large T-antigen. At the third passage, cells were cloned by colony formation and isolated from other cells. Nine immortalized cell lines of retinal capillary endothelial cells (TR-iBRB1 approximately 9) were obtained from a Tg rat. These cell lines had a spindle-fiber shape morphology, expressed the typical endothelial marker, von Willebrand factor, and internalized acetylated-low density lipoprotein. Moreover, vascular endothelial growth factor (VEGF) receptor-2 was expressed in TR-iBRBs. TR-iBRBs expressed a large T-antigen and grew well at 33 degrees C with a doubling time of 19-21 hr. In contrast, cells did not grow at 37 and 39 degrees C due to the reduced expression of large T-antigen, supporting temperature-dependent cell growth. TR-iBRBs expressed GLUT1 and exhibited 3- O -methyl- D -glucose (3-OMG) uptake activity. This 3-OMG uptake was saturable with a Michaelis-Menten constant of 5.56 +/- 0.51 m M and a maximum uptake rate of 45.3 +/- 2.6 nmol min(-1) mg protein(-1). P-Glycoprotein, with a molecular weight of approximately 180 KDa, was expressed in TR-iBRBs. In addition, mdr 1a, mdr 1b and mdr 2 were detected in TR-iBRB2 using RT-PCR. In conclusion, conditionally immortalized retinal capillary endothelial cell lines were established from a transgenic rat harboring the temperature-sensitive SV 40 large T-antigen gene and these lines were shown to exhibit the properties of retinal capillary endothelial cells.

Inhibitory effects of antisense oligonucleotides on the expression of procollagen type III gene in mouse hepatic stellate cells transformed by simian virus 40

The effects of phosphorothioate antisense oligonucleotides (ASO), complementary to the AUG start region, the junctional region of the intron and exon, and to exon of the procollagen type III gene, were investigated in a mouse hepatic stellate cell (HSC) line transformed by the simian virus 40 gene, SV68c-IS cells. ASO were transfected by lipofection. Immunohistochemistry, western and northern blotting showed inhibitory effects on procollagen type III gene expression by ASO that were complementary to the AUG start region and the junctional region of the intron and exon 2. However, ASO complementary to the exon 2 and 3, junctional region of the intron and exon 3, and sense oligonucleotides complementary to each ASO did not show any inhibitory effects. The effects of ASO complementary to the AUG start region were greater than those of ASO complementary to the junctional region. The effects of ASO were transient and a large amount of ASO was required to induce inhibitory effects without lipofection. ASO were effective in inhibiting the expression of the procollagen type III gene in the HSC which is well known to play a critical role in liver fibrosis.

Simian virus (SV) 40 like sequences in cell lines and tumour biopsies from Australian malignant mesotheliomas

BACKGROUND

Simian virus (SV) 40 sequences have been found in some, but not all studies of mesotheliomas. This virus is known to cause tumours in rodents but its role in human oncogenesis remains controversial.

AIMS

The aim of this study therefore was to determine whether SV40 is associated with the development of mesotheliomas in Australia. The absence of the virus or its gene products in tissue derived from mesotheliomas would detract from this possibility.

METHODS

We used polymerase chain reaction from three pairs of primers to amplify different regions of the large T antigen from DNA from cell lines and cDNA from both cell lines and an independent set of tumour biopsies from patients with mesothelioma.

RESULTS

We examined five human mesothelioma cell lines that were established in our laboratories. In addition, we examined several tumour biopsies from seven different patients. SV40 like sequences were present in all the cell lines and in at least one sample from each of the patients examined.

CONCLUSIONS

The large T antigen of SV40 or an SV40 like virus is expressed in Australian mesotheliomas and therefore could be aetiologically-associated with tumourigenesis. Alternatively, these sequences could be expressed subsequent to the development of the disease.

Presence and expression of the simian virus-40 genome in human giant cell tumors of bone

SV40 DNA sequences have been found in human tumors, such as mesotheliomas, ependymomas, and bone tumors, suggesting that SV40 may be involved in their etiology. The FOS oncogene could play an important role in bone development because SV40 is able to induce FOS in cell culture. In this study, the presence of SV40 sequences, large T antigen (Tag), and FOS protein expression were investigated in 120 giant cell tumors (GCTs), moderately benign bone tumors that in some cases can progress to a malignant phenotype. Polymerase chain reaction (PCR), using primers that amplify the RB1 pocket binding domain and the intron of Tag, was used to analyze GCT for the presence of SV40 DNA. Tag and FOS protein expression was evaluated by immunohistochemistry. SV40 sequences were found in 30/107 GCTs, and of these, 22/30 samples expressed Tag protein (73%) and 15/30 overexpressed the FOS oncogene (50%). FOS was undetectable in 77 SV40-negative GCTs. Sequence analysis of the amplified DNAs confirmed that the amplified sequences corresponded to SV40 DNA. The correlation between FOS overexpression and SV40-positive GCTs was highly statistically significant (P < 0.001). These results show that SV40 DNA sequences and SV40 Tag are present in GCTs and might induce FOS activity. These data suggest that SV40 might play a role in the development and progression of some GCTs.

Molecular quantification of cell cycle-related gene expression at the protein level

BACKGROUND

Immunofluorescence cytometry of antigen and DNA content provides relative measurements of the cell cycle phase distribution of a specific epitope. Measurement of correlated expression of epitopes on signaling and regulatory proteins will be useful in the study of the complex pathways involved in cell cycle regulation and carcinogenesis. However, to formulate regulatory pathway models, measurements of molecules per cell would be more useful than relative measurements of intensity. Here, we report on a system in which the relationship between molecules and fluorescence is determined for a reference set of cell lines that are then used to directly calculate the number of molecules for unknowns. To demonstrate the process, we calculated the cell cycle phase distribution of SV40 large T antigen (Tag) in the reference cells.

METHODS

A set of cell line clones expressing different levels of Tag were isolated. Quantitative Western blots of these cells and purified, recombinant Tag were performed. Cells from the same sample were stained and analyzed by flow cytometry for Tag and DNA. The relationship between molecules and fluorescence was established and calculations were performed for the phase distributions of Tag.

RESULTS

The five cell lines had 0.11, 0.27, 1.06, 2.44, and 2.63 x 10(6) molecules of Tag per cell, determined by Western blot. The average coefficient of variation was 10.6%. The relationship of molecules to fluorescence fit a linear equation (r(2) = 0.96) over the range, 0.11 - 2.63 x 10(6) molecules, however, the same equation did not fit the relationship between 0 molecules, defined by isotype staining controls, and the lowest expressing cell line. To calculate the phase distributions of molecules in the lowest cell line, a second linear equation from 0 to 110,000 molecules was used.

CONCLUSIONS

This work describes a system where fixed cells expressing various levels of a target antigen quantified by Western blots can be used to standardize flow cytometric measurements of gene expression in absolute terms.

Heterotopic endochondrial ossification with mixed tumor formation in C3(1)/Tag transgenic mice is associated with elevated TGF-beta1 and BMP-2 expression

Transgenic mice which express the simian virus 40 large T-antigen (Tag) under the regulatory control of the hormone responsive rat C3(1) gene develop unusual lesions of heterotopic bone growth associated with mixed tumor formation arising from eccrine sweat glands found only in the foot pads of mice, ischiocavernosus muscle adjacent to bulbourethral glands and occasionally the salivary and mammary glands. These lesions are very similar to mixed tumors arising in several types of human cancers. Based upon electron microscopic examination and immunocytochemical analyses of cellular differentiation markers, the mixed proliferative lesions in this transgenic mouse model begin with the Tag-induced proliferation of epithelial and myoepithelial cells. The proliferation of these two types of cells results in hyperplasia and adenomatous transformation of the epithelial component, whereas the proliferating myoepithelial cells undergo metaplasia to form chondrocytes which deposit extracellular matrix, including collagen fibers. Cartilage develops focally between areas of epithelial proliferation and subsequently ossifies through a process of endochondrial bone formation. The metaplasia of myoepithelial cells to chondrocytes appears to require the inductive interaction of factors produced by the closely associated proliferating epithelial cells, including members of the TGF-beta superfamily. We demonstrate that TGF-beta1 protein accumulates in the extracellular matrix of the lesions, whereas RNA in situ hybridization reveals that BMP-2, another strong inducer of heterotopic bone formation, is overexpressed by the proliferating epithelial cells during the development of ectopic bone. The formation of sarcomatous tumors within the mixed tumors appears to be androgen-dependent and more frequent in mice lacking a normal allele of p53. This process of cartilage and bone induction may mimic epithelial-mesenchymal interactions which occur during embryonic bone formation. These transgenic mice may provide new insights into the processes of ectopic endochondrial bone formation associated with mixed tumor formation and serve as a useful model for human heterotopic bone disease.

SV40 virus transformation down-regulates endothelin receptor

Simian virus 40 (SV40) is an oncogenic DNA virus that induces malignant transformation. Endothelin (ET), a 21 amino acid peptide with mitogenic and anti-apoptotic effects, binds to G-protein coupled ETA and ETB receptors. This report examines the effect of SV40 transformation on the expression of ET receptors. Results from receptor binding and reverse transcription (RT)-polymerase chain reaction (PCR) studies show that human lung fibroblasts IMR90 and WI38 express both ETA and ETB receptors, and that the expression of both receptors is significantly down-regulated in IMR90-SV40 and WI38-SV40, cell lines derived from IMR90 and WI38 with SV40 virus transformation. Receptor binding and RT-PCR analysis of 3A(tPA-30-1), a cell line derived from human placenta that expresses a higher level of SV40 large T-antigen at the permissive temperature (33 degrees C) than at the restrictive temperature (40 degrees C), further demonstrates that there is an inverse correlation between the expression of SV40 T-antigen and the expression of ET receptor. ET-1 and fetal bovine serum stimulate DNA synthesis in non-transformed cells; however, proliferation of transformed cells is independent of either fetal bovine serum or ET-1. We conclude that SV40 transformation down-regulates the expression of ET receptors, and that expression of ET receptors is inversely correlated with expression of SV40 large T-antigen.

A possible contributory role of BK virus infection in neuroblastoma development

The tumor suppressor protein p53 is aberrantly localized to the cytoplasm of neuroblastoma cells, compromising the suppressor function of this protein. Such tumors are experimentally induced in transgenic mice expressing the large tumor (T) antigen of polyomaviruses. The oncogenic mechanisms of T antigen include complex formation with, and inactivation of, the tumor suppressor protein p53. Samples from 18 human neuroblastomas and five normal human adrenal glands were examined. BK virus DNA was detected in all neuroblastomas and none of five normal adrenal glands by PCR. Using DNA in situ hybridization, polyomaviral DNA was found in the tumor cells of 17 of 18 neuroblastomas, but in none of five adrenal medullas. Expression of the large T antigen was detected in the tumor cells of 16 of 18 neuroblastomas, but in none of the five adrenal medullas. By double immunostaining BK virus T antigen and p53 was colocalized to the cytoplasm of the tumor cells. Immunoprecipitation revealed binding between the two proteins. The presence and expression of BK virus in neuroblastomas, but not in normal adrenal medulla, and colocalization and binding to p53, suggest that this virus may play a contributory role in the development of this neoplasm.

Reappraisal of progressive multifocal leukoencephalopathy due to simian virus 40

Several cases of progressive multifocal leukoencephalopathy (PML) have been associated with simian virus 40 (SV40), rather than with JC virus (JCV), the polyomavirus originally isolated from PML tissue. PML has, therefore, been defined as a demyelinating syndrome with possible multiple viral etiologies. Tissues from three of the cases thought to be associated with SV40 were available for reexamination. Monoclonal antibodies specific for SV40 capsid antigen VPI, virus-specific biotinylated DNA probes for in situ hybridization, and virus-specific primers in the polymerase chain reaction (PCR) were used. Macaque PML brain served as a positive control tissue for SV40 brain infection. Monoclonal antibodies to SV40 VPI failed to recognize viral antigen in lesions from all three human PML cases. The biotinylated DNA probe, which reacted with SV40 in macaque PML, failed to detect SV40 in human PML. However, JCV could be detected by in situ hybridization with a JCV-specific DNA probe. Moreover, JCV DNA sequences were amplified by PCR from the human PML tissues, whereas SV40 DNA sequences were amplified only from the macaque brain. Thus, we could not confirm the original reports that the demyelinating agent in these three cases of PML was SV40, rather than JCV. We conclude that SV40 infection of the central nervous system need not be ruled out in the differential diagnosis of PML.

Simultaneous detection of antigens and specific DNA sequences of human papillomavirus in uterine cervical biopsy specimens. Description of a double-labelling technique

We studied 70 uterine cervical biopsy specimens with a histological diagnosis compatible with human papillomavirus (HPV) infection. We carried out immunohistochemical and in situ hybridization techniques and selected 22 specimens that had given a positive result with both techniques. We then used a double-labelling technique (a combination of immunohisto-chemistry and in situ hybridization) to detect simultaneously viral antigens and specific gene sequences of HPV. With this technique we found three different cell types in the tissue: (1) cells with black nuclei, positive by immunohisto-chemistry and in situ hybridization; (2) cells with red nuclei, negative by immunohistochemistry and positive by in situ hybridization; and (3) cells with light blue nuclei, negative by both techniques. In this study we describe this technique; and we believe that the simultaneous detection of viral antigens and specific gene sequences of HPV may be very useful in the study of the virus-cell interaction.

[Expression of T and Tn antigens in breast cancers]

Expression of carcinoembryonic Tn antigen studied with VVA-B4 and GSI-A4 lectins with the monoclonal antibody 83D4 and of T antigen with LDL and PNA lectins with the monoclonal antibody ZCMO4, were examined in 54 malignant or benign human breast tumors and for MCF-7, T47D and MCF-10A cell lines of human breast tumors origin. For breast tissues, positive membrane labelling with D-GalNAc alpha-O-ser/thr (Tn-antigen) specific lectins and 83D4 MAb occurred in benign cases indicating that modification of glycoconjugates may precede the cytologic anomalies. In fibroadenoma, fibrocystic dystrophy, ductal hyperplasia and grade I invasive ductal carcinomas, the binding sites for lectins and 83D4 MAb were essentially on the cell membrane with labelling of both apical and basolateral compartments. In grade II and III, the labelling involved the cytoplasma, and cell heterogeneity appeared. The disappearance of reactivity observed for a large proportion of cells at grade III may be due either to the loss of glycosyltransferase, or to the lack of synthesis of the protein back-bone. Invasive lobular carcinomas showed labelling both on apical membrane and the outermost part of the cytoplasm with a distinct cell polarity. Lectin receptors are present at the surface of metastatic cells, possibly related to their involvement in adhesion. In all cases, T or sialosyl-T antigens are present at the surface of tumors cells. All cell lines from breast tumors cultured in vitro were labelled with lectins and monoclonal antibodies. The simultaneous presence of Tn and T antigens on the cells, indicates that the expression of Tn antigen is due to a partial but non total deficiency in the beta-1- > 3 galactosyltransferase involved in T-antigen synthesis.

Detection of Tn, sialosyl-Tn and T antigens in hereditary nonpolyposis colorectal cancer

The simple mucin-type carbohydrate antigens Tn, sialosyl-Tn, T and the 'cryptic' sialylated variant of the last represent the mucin core oligosaccharide structures that are produced in the initial steps of the mucin biosynthetic pathway. Utilizing monoclonal antibodies anti-Tn antigen (HB-Tn1), anti-sialosyl-Tn antigen (HB-STn1), anti-T antigen (HB-T1) and the biotinylated Amaranthus caudatus agglutinin (ACA), we have investigated the expression of the simple mucin-type carbohydrate antigens in hereditary nonpolyposis colorectal cancer (HNPCC; 15 cases) compared with sporadic colorectal cancer (CRC; 60 cases) and normal colonic mucosa (30 cases). A variable positivity of Tn, sialosyl-Tn, T and the cryptic sialylated form of this latter antigen was encountered in both HNPCC and sporadic CRC cases; in addition, in normal colonic mucosa a constant reactivity was encountered only for Tn and the cryptic sialylated form of T, while negative results were always obtained for sialosyl-Tn and T antigens. Statistical analysis, performed using a Chi-square test, showed significantly lower (P = 0.037) expression of sialosyl-Tn and higher (P = 0.022) expression of T in HNPCC than in sporadic CRC, suggesting a greater presence of beta 1,3 galactosyltransferase activity in HNPCC than in sporadic CRC. We were unable to identify a peculiar phenotype for HNPCC with simultaneous evaluation of reactivity for HB-Tn1, HB-STn1, HB-T1 and ACA; the biological significance of the preferential expression of T antigen in HNPCC remains to be investigated.

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.

Metastatic prostate cancer in a transgenic mouse

We have previously reported the development of a transgenic mouse model for prostate cancer derived from PB-Tag transgenic line 8247, henceforth designated the TRAMP (transgenic adenocarcinoma mouse prostate) model. We now describe the temporal and spatial consequences of transgene expression and report the identification and characterization of metastatic disease in the TRAMP model. TRAMP mice characteristically express the T antigen oncoprotein by 8 weeks of age and develop distinct pathology in the epithelium of the dorsolateral prostate by 10 weeks of age. Distant site metastases can be detected as early as 12 weeks of age. The common sites of metastases are the periaortic lymph nodes and lungs, with occasional metastases to the kidney, adrenal gland, and bone. By 28 weeks of age, 100% harbor metastatic prostate cancer in the lymph nodes or lungs. We have also demonstrated the loss of normal E-cadherin expression, as observed in human prostate cancer, as primary tumors become less differentiated and metastasize. The TRAMP model provides a consistent source of primary and metastatic tumors for histopathobiological and molecular analysis to further define the earliest molecular events involved in the genesis, progression, and metastasis of prostate cancer.

Expression of mucin antigens and Lewis X-related antigens in carcinomas and dysplasia of the pharynx and larynx

Recent studies have identified that mucin antigens and Lewis X (Lex)-related antigens behave like oncodevelopmental tumor-associated antigens in several human adenocarcinomas. However, the expression of these antigens in pharyngeal and laryngeal squamous cell carcinomas (SCC) and in the precursor lesion is not fully elucidated yet. In the present study, the expression of mucin core protein antigens associated with the MUC1 gene product (DF3 antigen, mammary-type apomucin) and the MUC2 gene product (intestinal-MRP antigen, intestinal-type apomucin) mucin carbohydrate antigens that are associated with the earliest steps in mucin glycosylation (Tn, sialyl-Tn and T), and Lex-related antigens (Lex, Ley and sialyl Lex-i) in biopsy or resected specimens from 26 normal squamous epithelia (NSE), 49 dysplastic squamous epithelia (DSE) and 51 SCC were examined. The DF3 antigen was not expressed in NSE (0%), whereas it was expressed in 20 DSE (41%) and in 31 SCC (61%). The intestinal-MRP antigen showed no expression in NSE, DSE or SCC. The Tn antigen showed no expression in NSE, but showed low expression rates in DSE (14%) and in SCC (16%). The sialyl-Tn and T antigens were expressed in NSE, as well as in DSE and SCC. The T antigen expression increased with progression from NSE to DSE to SCC, while the sialyl-Tn antigen did not show such a tendency. Any of the three Lex-related antigens showed no characteristic expression in DSE and SCC. In the eight antigens examined, only DF3 antigen was an effective marker for DSE and SCC in the pharyngeal and laryngeal region. Cytoplasmic expression of DF3 and sialyl-Tn antigens were more frequently seen in SCC than in DSE, and might be useful to differentiate SCC from DSE.

Detection of JC virus DNA sequence and expression of the viral oncoprotein, tumor antigen, in brain of immunocompetent patient with oligoastrocytoma

We describe molecular and clinical findings in an immunocompetent patient with an oligoastrocytoma and the concomitant presence of the human papovavirus, JC virus (JCV), which is the etiologic agent of the subacute, debilitating demyelinating disease, progressive multifocal leukoencephalopathy. Histologic review revealed a glial neoplasm consisting primarily of a moderately cellular oligodendroglioma with distinct areas of a fibrillary astrocytoma. Immunohistochemical analysis revealed nuclear staining of tumor cells with antibodies against the viral oncoprotein [tumor antigen (T antigen)], the proliferation marker (Ki67), and the cellular proliferation regulator (p53). Using primers specific to the JCV control region, PCR yielded amplified DNA that was identical to the control region of the Mad-4 strain of the virus. PCR analysis demonstrated the presence of the genome for the viral oncoprotein, T antigen, and results from primer extension studies revealed synthesis of the viral early RNA for T antigen in the tumor tissues. The presence of viral T antigen in the tumor tissue was further demonstrated by immunoblot assay. To our knowledge, this is the first report of the presence of JCV DNA, RNA, and T antigen in tissue in which viral T antigen is localized to tumor cell nuclei and suggests the possible association of JCV with some glial neoplasms.

Antibodies to butyrate-inducible antigens of Kaposi's sarcoma-associated herpesvirus in patients with HIV-1 infection

BACKGROUND

The recent identification in patients with Kaposi's sarcoma of DNA sequences with homology to gammaherpesviruses has led to the hypothesis that a newly identified virus, Kaposi's sarcoma-associated herpeslike virus (KSHV), has a role in the pathogenesis of Kaposi's sarcoma. We developed serologic markers for KSHV infection.

METHODS

KSHV antigens were prepared from a cell line (BC-1) that contains the genomes of both KSHV and the Epstein-Barr virus (EBV). We used immunoblot and immunofluorescence assays to examine serum samples from 102 patients with human immunodeficiency virus type 1 (HIV-1) infection for antibodies to KSHV-associated proteins and to distinguish these antibodies from antibodies to EBV antigens. A positive serologic response was defined by the recognition of an antigenic polypeptide, p40, in n-butyrate-treated BC-1 cells and by the absence of p40 recognition in untreated BC-1 cells or EBV-infected, KSHV-negative cells. The detection by the immunofluorescence assay of 10 to 20 times more antigen-positive cells in n-butyrate-treated BC-1 cells than in untreated cells was considered a positive response.

RESULTS

Antibodies to the p40 antigen expressed by chemically treated BC-1 cells were identified in 32 of 48 HIV-1-infected patients with Kaposi's sarcoma (67 percent), as compared with only 7 of 54 HIV-1-infected patients without Kaposi's sarcoma (13 percent). These results were confirmed by an immunofluorescence assay. The positive predictive value of the serologic tests for Kaposi's sarcoma was 82 percent, and the negative predictive value 75 percent.

CONCLUSIONS

The presence of antibodies to a KSHV antigenic peptide correlates with the presence of Kaposi's sarcoma in a high-risk population and provides further evidence of an etiologic role for KSHV.

Quantitative flow cytometry reveals a hierarchy of glucocorticoid effect on cell surface mouse mammary tumor virus gp52

A flow cytometry protocol with CM mouse mammary tumor cells (Mm5mt/C1) was utilized to provide a fluorescence measurement of hormone-mediated changes in mouse mammary tumor virus (MMTV) cell surface envelope glycoprotein (gp52 CSA). Standards permitted gp52-specific fluorescence intensity to be measured as molecules of equivalent soluble fluorescein (MESF). The feasibility of using MESF determinations to reflect hormone-modulated changes in continuously infected cells was tested. A panel of five glucocorticoids having differing affinity for the glucocorticoid receptor were tested in 60 h treatments at dosages ranging from 10(-6) M to 10(-8) M. Determinations of MESF, as a measure of gp52 CSA, were highest with 10(-6) M treatments (36.7-44.5 x 10(-6) MESF). At lower dosages, MESF determinations were lower but showed a clear hierarchy of glucocorticoid effect. At 10(-8) M treatments, determinations of MESF x 10(-6) demonstrated the following glucocorticoid hierarchy: triamcinolone acetonide (TA) (33.7 +/- 1.6) > dexamethasone (DEX) (26.1 +/- 1.7) > prednisolone (8.0 +/- 0.3) > triamcinolone (6.6 +/- 0.4) > hydrocortisone (6.4 +/- 0.4) > control (2.4 +/- 0.1). The MESF-derived respective fold increases over control for this hierarchy were: 13.87, 10.74, 3.31, 2.71, and 2.65. The ability of TA to enhance gp52 CSA was 1.3-fold greater than DEX. 10-fold higher levels of steroid controls did not significantly elevate MESF levels. Findings argue that dosage, duration of treatment and relative affinity of glucocorticoids for receptor are reflected in MESF determinations of changing gp52 levels. Therefore, this new measure of effect may be useful in studying hormonal influence on viral and cellular regulatory systems in chronically infected cells.

[Suitability of monoclonal reagents for antigen determination in T-antigen activation]

BACKGROUND

The lack of additional antibodies--for example anti-T--which can be contained in test sera of human origin has been pointed out as an advantage of monoclonal reagents in blood group serology. It was the aim of our study to examine whether the reactions of monoclonal reagents are nevertheless disturbed by T activation of red blood cells or not.

MATERIALS AND METHODS

Monoclonal reagents of several manufacturers of the specificities anti-A, -B, -AB, -A1, -H, -C, -c, -D, -E, -e, -K, -Jka, -Jkb, -Lea, -Leb, -M, and -N were tested. For this study we examined sialidase-treated and not treated red blood cells with and without the tested blood group antigen by the reagent using the tube centrifugation method.

RESULTS

We found no significant disturbances for the monoclonal reagents of the AB0-system, A subgroups, Rhesus system, Kidd system, Kell antigen, and Leb antigen. Monoclonal anti-M and anti-N showed missing reactivity with sialidase-treated erythrocytes, which is already known from polyclonal test sera. Most of the monoclonal anti-Lea reagents showed strong false-positive reactions with T-positive Le(a-) erythrocytes. After several absorptions of one of the monoclonal anti-Lea reagents with T-activated Le(a-b-) red blood cells, the reactivity of the reagent with the Lea antigen and the T antigen had disappeared.

CONCLUSIONS

In contrast to the other monoclonal reagents for most of the monoclonal anti-Lea reagents the lack of additional anti-T antibodies does not indicate the lack of false-positive reactions. This cross-reactivity might be caused by the fact that the type 1 chain antigen Lea and the type 3 chain antigen T have the same terminal saccharide (galactose) in beta 1-->3 connection to the preterminal saccharide of their peripheral core structure.

Bispecific antibodies retarget murine T cell cytotoxicity against syngeneic breast cancer in vitro and in vivo

Bispecific antibodies with specificity for CD3 and a tumor antigen can redirect cytolytic T cells to kill tumor targets, regardless of their natural specificity. To assess the clinical potential of bispecific antibodies for treatment of human cancers we have, in the present study, adapted a totally synergeic mouse model to the targeting of mouse T cells against mouse tumors in immunocompetent mice. We show that gp52 of the mouse mammary tumor virus (MTV) can serve as a tumor-specific antigen for redirected cellular cytotoxicity. Chemically crosslinked and genetically engineered bispecific antibodies with specificities for gp52 and murine CD3 epsilon-chain induced activated mouse T cells to specifically lyse mouse mammary tumor cells from cultured lines and primary tumors from C3H-MTV+ mice. Retargeted T cells also blocked the growth of mammary tumors in vitro as well as their growth in syngeneic mice. These findings identify murine MTV-induced mammary adenocarcinomas as a solid-tumor, animal model for retargeting T cells with bispecific antibodies against syngeneic breast cancer.

[A study on the complementary scheme of mass screening for colorectal cancer in an asymptomatic population]

Both SPA immunological fecal occult blood test (SPA FOBT test) and detection of T-antigen in rectal mucus (Shams' test) were used as screening tests in asymptomatic mass screening to evaluate the complementary effect of both tests for detection of colorectal cancers. SPA FOBT test showed a positive rate of 11.1% and shams' test 8.9% among 7,740 subjects. In 498 cases with positive screening test, 11 cases of carcinomas and 88 adenomas were found with colonoscopy. Only 9 cancers and 55 adenomas showed positive result in SPA FOBT test and 8 cancers and 51 adenomas in Shams' test. Both tests combined could enhance the detective rate of cancer in asymptomatic mass screening from 81.8% with SPA FOBT test or 72.7% with Shams' test to 90.9%. This complementary effect was more obvious in adenoma detection. It is suggested that there were some shortcomings in sequential FOBT test for cancer detection, the combined use of the two different screening tests for detection of colorectal cancer could decrease the rate of missed detection.

Simple mucins (T, sialosyl-T, Tn and sialosyl-Tn) are not diagnostic for malignant breast lesions

Immunohistochemical study of the distribution of carbohydrate core-structures on O-linked glycoproteins (T, sialosyl-T, Tn and sialosyl-Tn) was performed using specific monoclonal antibodies on 148 primary breast lesions, including 10 normal breast tissues, 16 benign lesions and 122 invasive carcinomas (79 localized and 43 metastatic lesions). T antigen, not observed in normal breast tissue, was present in 31% of the benign lesions and in some cases of morphologically normal epithelium adjacent to tumor cells, compatible with altered glycosylation being an early event. Sialosyl-T (s-T) antigen was present in all cases of normal epithelium and in 81% of the benign lesions. Both Tn and sialosyl-Tn (s-Tn) antigen were present in normal breast lesions. Both Tn and sialosyl-Tn (s-Tn) antigen were present in normal breast tissue (30%) and benign lesions (31% and 19%). In the malignant lesions, 20% were positive for T antigen, 82% for s-T antigen, 66% for Tn antigen and 22% for s-Tn antigen. The staining pattern was nearly identical for carcinomas with and without lymph node metastases. In conclusion, immunostaining for simple mucins does not permit a clear distinction between benign and malignant breast lesions.

Correlation of mitotic abnormalities and the presence of human papillomavirus antigens in squamous cell carcinomas of the oral cavity

To determine the association of human papillomavirus (HPV) with oral cancer lesions containing abnormal mitoses, we analysed 54 of them by immunohistochemical techniques for the presence of HPV structural antigens and correlated the results with their histology. Sixteen out of 19 lesions with abnormal mitotic figures (MFs) and 15 of the 25 lesions with normal MFs contained the HPV antigen. However, 9 of the 11 koilocytotic lesions with abnormal MFs and 13 of the 17 lesions with normal MFs were HPV antigen-positive. The nature of mitosis was not influenced by the grades of koilocytosis. No correlation of HPV antigen positivity and severity of the oral carcinomas was observed.

A cytoplasmically anchored nuclear protein interferes specifically with the import of nuclear proteins but not U1 snRNA

A cytoplasmically anchored mutant SV40 T antigen, FS T antigen, was shown previously to interfere specifically with the nuclear import of a heterologous nuclear protein, adenovirus 5 fiber protein, in cultured monkey cells (Schneider, J., C. Schindewolf, K. van Zee, and E. Fanning. 1988. Cell. 54:117-125; van Zee, K., F. Appel, and E. Fanning. 1991. Mol. Cell. Biol. 11:5137-5146). In this report, we demonstrate that FS T antigen also interferes with the nuclear import of adenovirus E1A and a peptide-albumin conjugate bearing multiple copies of the T antigen nuclear localization signal, but not with the import of U1 snRNA. A kinetic analysis indicates that nuclear import of the albumin-peptide conjugate is inhibited only when high intracellular concentrations of FS T antigen are reached. After microinjection into the cytoplasm of cultured cells, purified FS T antigen protein does not accumulate at the nuclear periphery, but rather is distributed in a punctate pattern throughout the cytoplasm. These data support a model in which cytoplasmic anchoring of FS T antigen enables the mutant protein to sequester and titrate out a cellular factor which is required for nuclear protein but not U1 snRNA import.