Tissue-specific expression of SV40 in tumors associated with the Li-Fraumeni syndrome

The SV40 virus enhancer functions as a somatic hypermutation-targeting element with potential oncogenic activity

Simian virus 40 (SV40) is a monkey virus associated with several types of human cancers. SV40 is most frequently detected in mesotheliomas, brain and bone tumors and lymphomas, but the mechanism for SV40 tumorigenesis in humans is not clear. SV40 relative Merkel cell polyomavirus (MCPyV) causes Merkel cell carcinoma (MCC) in humans by expressing truncated large tumor antigen (LT) caused by APOBEC cytidine deaminase family enzymes induced mutations. AID (activation-induced cytidine deaminase), a member of the APOBEC family, is the initiator of the antibody diversification process known as somatic hypermutation (SHM) and its aberrant expression and targeting is a frequent source of lymphomagenesis. In this study, we investigated whether AID-induced mutations could cause truncation of SV40 LT. We demonstrate that the SV40 enhancer has strong SHM targeting activity in several cell types and that AID-induced mutations accumulate to SV40 LT in B cells and kidney cells and cause truncated LT expression in B cells. Our results argue that the ability of the SV40 enhancer to target SHM to LT is a potential source of LT truncation events in various cell types that could contribute to carcinogenesis.

Pediatric Case of Li-Fraumeni Syndrome in Honduras

Li–Fraumeni syndrome is an inherited, autosomal dominant disease. It is categorized as a rare disease caused by mutations of the TP53 gene, which causes increased susceptibility of the patients and their children to many types of cancer. Choroid plexus tumor is rare, which occurs in 0.3 cases per 1,000,000 people, of which 40% turn out to be carcinomas. We present a 12-year-old boy with a history of worsening headaches of more than one month, gait disturbance, projectile vomiting, and right hemiparesis. An intraventricular tumor was identified in the occipital of the left lateral ventricle, which turned out to be a TP53-mutant choroidal plexus carcinoma.

Widely Metastatic Choroid Plexus Carcinoma Associated with Novel TP53 Somatic Mutation

BACKGROUND

Choroid plexus carcinoma (CPC) is a rare, malignant tumor occurring more commonly in children than adults. This case report describes the clinical course of a 3-year-old boy with a rare case of metastatic CPC with a novel TP53 mutation.

CASE DESCRIPTION

A 3-year-old boy presented with postconcussive symptoms after a fall. Computed tomography and magnetic resonance imaging revealed lesions in the suprasellar cistern, left lateral ventricle, and cauda equina. The tumor was diagnosed as choroid plexus carcinoma with a novel TP53 V216M somatic mutation. The patient underwent resection of the left lateral ventricle lesion.

CONCLUSION

We describe a case of CPC with highly metastatic characteristics and a novel TP53 mutation. Our report implicates TP53 in the pathogenesis of pediatric CPC, and we emphasize that CPC in children should prompt careful consideration of TP53 status to inform prognosis and clinical treatment.

Serum Antibodies Against Simian Virus 40 Large T Antigen, the Viral Oncoprotein, in Osteosarcoma Patients

Human osteosarcoma (OS) is a rare human cancer, mostly occurring in children and adolescents. Simian virus 40 (SV40 = Macaca mulatta polyomavirus 1) sequences have been detected in different human cancers, including osteosarcoma. SV40 is an oncogenic virus in vivo, whereas it transforms different kinds of mammalian cells, as well as distinct human cell types. SV40 injected in rodents induces tumors of different histotypes, such as bone and brain tumors. Herein, the association between OS and SV40 large T antigen (Tag) was studied by employing indirect ELISAs using synthetic peptides that mimic different epitopes of the SV40 Tag, the viral oncoprotein. Indirect ELISAs were used to detect serum IgG antibodies against this oncogenic virus in samples from OS patients. Controls were sera from healthy subjects (HS) and oncological patients affect by breast cancer (BC), which is not associated with SV40. It turned out that sera of OS patients had a higher prevalence of SV40 Tag antibodies, 35%, compared to HS, 20% and BC, 19%, respectively. The different prevalence of SV40 Tag antibodies revealed in OS vs. HS and vs. BC is statistically significant with P < 0.05 and P < 0.01, respectively. Our immunological data indicate a significantly higher prevalence of antibodies against SV40 Tag epitopes in serum samples from OS patients compared to HS and BC, the controls. These results suggest an association between OS and SV40 Tag, indicating that this oncogenic virus may be a cofactor in OS development.

Significant association between human osteosarcoma and simian virus 40

BACKGROUND

Simian virus 40 (SV40) has been considered to be an oncogenic viral agent in the development of osteosarcoma (OS), which to the authors' knowledge continues to be of unknown etiology.

METHODS

In the current study, serum samples from patients with OS were investigated with an indirect enzyme-linked immunoadsorbent assay (ELISA) to test for the presence of immunoglobulin G antibodies, which react with SV40 antigens. In ELISA, SV40 antigens were represented by 2 synthetic polypeptides that mimic epitopes of the viral capsid proteins 1 to 3. Additional sera from patients with breast cancer and undifferentiated nasopharyngeal carcinoma as well as healthy subjects were the controls.

RESULTS

Immunologic results suggested that antibodies that react with SV40 mimotopes were more prevalent (44%) in serum samples from patients with OS compared with healthy subjects (17%). The difference in prevalence between these cohorts was statistically significant (P<.001). It is interesting to note that in the patients with OS, significance indicated the difference between OS versus breast cancer (44% vs 15%; P<.001) and OS versus undifferentiated nasopharyngeal carcinoma (44% vs 25%; P<.05).

CONCLUSIONS

The data from the current study indicate an association between OS and SV40. These data could be transferred to clinical applications for innovative therapies to address SV40-positive OS.

Fanconi anemia patients are more susceptible to infection with tumor virus SV40

Fanconi anemia (FA) is a recessive DNA repair disease characterized by a high predisposition to developing neoplasms. DNA tumor polyomavirus simian virus 40 (SV40) transforms FA fibroblasts at high efficiency suggesting that FA patients could be highly susceptible to SV40 infection. To test this hypothesis, the large tumor (LT) antigen of SV40, BKV, JCV and Merkel Cell (MC) polyomaviruses were tested in blood samples from 89 FA patients and from 82 of their parents. Two control groups consisting of 47 no-FA patients affected by other genetic bone marrow failure diseases and 91 healthy subjects were also evaluated. Although JCV, BKV and MC were not found in any of the FA samples, the prevalence and viral load of SV40 were higher in FA patients (25%; mean viral load: 1.1×10² copies/10⁵cells) as compared with healthy individuals (4.3%; mean viral load: 0.8×10¹ copies/10⁵cells) and genetic controls (0%) (p<0.005). A marked age-dependent frequency of SV40 was found in FA with respect to healthy subjects suggesting that, although acquired early in life, the virus can widespread more easily in specific groups of population. From the analysis of family pedigrees, 60% of the parents of SV40-positive probands were positive for the virus compared to 2% of the parents of the SV40-negative probands (p<0.005). It is worthy of note that the relative frequency of SV40-positive relatives detected in this study was the highest ever reported, showing that asymptomatic FA carriers are also more susceptible to SV40. In conclusion, we favor the hypothesis that SV40 spread could be facilitated by individuals who are genetically more susceptible to infection, such as FA patients. The increased susceptibility to SV40 infection seems to be associated with a specific defect of the immune system which supports a potential interplay of SV40 with an underlying genetic alteration that increases the risk of malignancies.

Subgroup-specific prognostic implications of TP53 mutation in medulloblastoma

PURPOSE

Reports detailing the prognostic impact of TP53 mutations in medulloblastoma offer conflicting conclusions. We resolve this issue through the inclusion of molecular subgroup profiles.

PATIENTS AND METHODS

We determined subgroup affiliation, TP53 mutation status, and clinical outcome in a discovery cohort of 397 medulloblastomas. We subsequently validated our results on an independent cohort of 156 medulloblastomas.

RESULTS

TP53 mutations are enriched in wingless (WNT; 16%) and sonic hedgehog (SHH; 21%) medulloblastomas and are virtually absent in subgroups 3 and 4 tumors (P < .001). Patients with SHH/TP53 mutant tumors are almost exclusively between ages 5 and 18 years, dramatically different from the general SHH distribution (P < .001). Children with SHH/TP53 mutant tumors harbor 56% germline TP53 mutations, which are not observed in children with WNT/TP53 mutant tumors. Five-year overall survival (OS; ± SE) was 41% ± 9% and 81% ± 5% for patients with SHH medulloblastomas with and without TP53 mutations, respectively (P < .001). Furthermore, TP53 mutations accounted for 72% of deaths in children older than 5 years with SHH medulloblastomas. In contrast, 5-year OS rates were 90% ± 9% and 97% ± 3% for patients with WNT tumors with and without TP53 mutations (P = .21). Multivariate analysis revealed that TP53 status was the most important risk factor for SHH medulloblastoma. Survival rates in the validation cohort mimicked the discovery results, revealing that poor survival of TP53 mutations is restricted to patients with SHH medulloblastomas (P = .012) and not WNT tumors.

CONCLUSION

Subgroup-specific analysis reconciles prior conflicting publications and confirms that TP53 mutations are enriched among SHH medulloblastomas, in which they portend poor outcome and account for a large proportion of treatment failures in these patients.

Rhabdomyosarcomas: an overview on the experimental animal models

Rhabdomyosarcomas (RMS) are aggressive childhood soft-tissue malignancies deriving from mesenchymal progenitors that are committed to muscle-specific lineages. Despite the histopathological signatures associated with three main histological variants, termed embryonal, alveolar and pleomorphic, a plethora of genetic and molecular changes are recognized in RMS. Over the years, exposure to carcinogens or ionizing radiations and gene-targeting approaches in vivo have greatly contributed to disclose some of the mechanisms underlying RMS onset. In this review, we describe the principal distinct features associated with RMS variants and focus on the current available experimental animal models to point out the molecular determinants cooperating with RMS development and progression.

Simian virus 40 transformation, malignant mesothelioma and brain tumors

Simian virus 40 (SV40) is a DNA virus isolated in 1960 from contaminated polio vaccines, that induces mesotheliomas, lymphomas, brain and bone tumors, and sarcomas, including osteosarcomas, in hamsters. These same tumor types have been found to contain SV40 DNA and proteins in humans. Mesotheliomas and brain tumors are the two tumor types that have been most consistently associated with SV40, and the range of positivity has varied about from 6 to 60%, although a few reported 100% of positivity and a few reported 0%. It appears unlikely that SV40 infection alone is sufficient to cause human malignancy, as we did not observe an epidemic of cancers following the administration of SV40-contaminated vaccines. However, it seems possible that SV40 may act as a cofactor in the pathogenesis of some tumors. In vitro and animal experiments showing cocarcinogenicity between SV40 and asbestos support this hypothesis.

Tissue Tropism of SV40 Transformation of Human Cells: Role of the Viral Regulatory Region and of Cellular Oncogenes

SV40 has been detected prevalently in a limited panel of human tumors: mesothelioma, bone and brain tumors, and lymphoma. These are the same tumor types that are specifically induced by SV40 when injected into hamsters, a finding that has raised concerns about the possible pathogenic role of SV40 in humans. Two different SV40 isolates differing in the number of 72-bp elements in the virus regulatory region, archetypal SV40 (1ESV40), which contains one 72 bp, and nonarchetypal SV40 (wtSV40), which contains two 72 bp, have been detected in human tumors. 1ESV40 has been prevalently detected in brain tumors, with wtSV40 prevalently in mesothelioma. The apparent different cell tropism could be related to the virus (i.e., possibly to the number of 72-bp elements) and to different expression of cellular genes, known to play a critical role in SV40-mediated transformation of human cells, such as Notch-1 and c-Met. To test for possible differences in tissue tropism, we infected primary human mesothelial cells (HM) and primary human astrocytes (Ast) with 1ESV40 and with wtSV40 from 2 different SV40 strains, 776 and Baylor. All viruses transformed astrocytes; only wtSV40 transformed HM. Intracellular signaling of c-Met and Notch-1 was differently induced by these 2 viruses in HM and Ast. Differences in Notch-1 expression and signaling (i.e., downstream effectors, c-Myc, HEY-1, HES-1, and HEY-L) appeared to influence SV40-mediated transformation of primary astrocytes and mesothelial cells. Our results provide a biological rationale to the observation that 1ESV40 is prevalently detected in brain tumors and wtSV40 in mesotheliomas.

Evidence for an unanticipated relationship between undifferentiated pleomorphic sarcoma and embryonal rhabdomyosarcoma

Embryonal rhabdomyosarcoma (eRMS) shows the most myodifferentiation among sarcomas, yet the precise cell of origin remains undefined. Using Ptch1, p53 and/or Rb1 conditional mouse models and controlling prenatal or postnatal myogenic cell of origin, we demonstrate that eRMS and undifferentiated pleomorphic sarcoma (UPS) lie in a continuum, with satellite cells predisposed to giving rise to UPS. Conversely, p53 loss in maturing myoblasts gives rise to eRMS, which have the highest myodifferentiation potential. Regardless of origin, Rb1 loss modifies tumor phenotype to mimic UPS. In human sarcomas that lack pathognomic chromosomal translocations, p53 loss of function is prevalent, whereas Shh or Rb1 alterations likely act primarily as modifiers. Thus, sarcoma phenotype is strongly influenced by cell of origin and mutational profile.

Simultaneous choroid plexus carcinoma and pilocytic astrocytoma in a pediatric patient

Simultaneous primary brain tumors in pediatric patients without prior chemotherapy or radiotherapy, phacomatosis, or known familial history are a rare occurrence. The authors report the case of a 4-year-old boy with simultaneous choroid plexus carcinoma and pilocytic astrocytoma with features of oligodendroglioma. Magnetic resonance imaging studies revealed diffuse heterogeneously enhancing left intraventricular and posterior fossa tumors initially believed most consistent with multicentric choroid plexus carcinomas. A multiple staged resection was carried out for each tumor and gross-total resection was achieved. Upon gross inspection intraoperatively as well as postoperative histological analysis, 2 distinct simultaneous tumors were identified: choroid plexus carcinoma and pilocytic astrocytoma. To the authors' knowledge this is the first case report published identifying 2 distinct tumor types with similar radiological appearances in a pediatric patient with no prior history of radiotherapy, chemotherapy, or phacomatosis.

Viral regulatory region effects on vertical transmission of polyomavirus SV40 in hamsters

Viral strain differences influence the oncogenic potential of polyomavirus simian virus 40 (SV40). We hypothesized that viral strain differences might also affect vertical transmission of SV40 in susceptible hosts. Pregnant Syrian golden hamsters were inoculated intraperitoneally with 10(7) plaque-forming units of SV40 and offspring were sacrificed post-delivery (1-21 days, 6 months). Organ extracts were analyzed for SV40 DNA by polymerase chain reaction assay. Transmission of SV40 from mother to offspring was detected in over half of litters. Most placentas were virus-positive. Mothers inoculated with SV40 strains containing complex regulatory regions transmitted virus more frequently than those infected with simple enhancer viruses (p<0.001). Virus was detected more often in progeny brain than in spleen (p<0.05). Several progeny were virus-positive at 6 months of age, suggesting viral persistence. Maternal animals retained virus in several tissues through day 21 and developed T-antigen antibodies. These results indicate that SV40 replicates in hamsters, vertical transmission of SV40 can occur, and the viral regulatory region influences transmission.

Histone acetylation resulting in resistance to methotrexate in choroid plexus cells

Choroid plexus carcinomas are rare tumors that typically occur in young children. Prognosis is poor, and very little information is available to optimize treatment protocols. We used a cell culture model to evaluate whether combining chemotherapeutic agents such as methotrexate with histone deacetylase inhibitors (HDACI) such as valproic acid and MS-275 could improve efficacy. Valproic acid increased the cytotoxicity of radiation and of all the chemotherapeutic agents in Z310 and SV11 mouse choroid plexus cell lines, with the exception of methotrexate. Both HDACIs made choroid plexus cells resistant to this folate antagonist. Searching for a molecular explanation, we found that thymidylate synthase was up regulated when the cells were incubated with HDACI. We also confirmed this finding in human choroid plexus carcinoma cells. Methotrexate should not be combined with HDACI in the treatment of choroid plexus carcinoma.

Risk stratification in cancer predisposition syndromes: lessons learned from novel molecular developments in Li-Fraumeni syndrome

Germ-line mutations in specific genes predispose family members to cancer. Prediction of the exact tumor type and timing of cancer initiation is fundamental to the development of management strategies for these individuals. Recent advances in our understanding of the general processes that control cancer initiation may enable us to tailor more precise risk stratification. This, in turn, will lead to more effective early detection strategies, which would result in more favorable clinical outcomes. In this review, we highlight the steps and methods used to reach this futuristic model.

Characterization and application of polyclonal antibodies that specifically recognize JC virus large T antigen

Polyomavirus JC virus (JCV) is the causative agent of progressive multifocal leukoencephalopathy, a fatal demyelinating disease of the central nervous system. Similar to other polyomaviruses, such as simian vacuolating virus 40 (SV40) and BK virus (BKV), JCV is also associated with human tumours. The Polyomavirus early protein large T antigen (TAg) plays a crucial role in tumour pathogenesis. An antibody to SV40 TAg (PAb416), which cross-reacts with TAgs of both JCV and BKV, has been used widely for the detection of JCV and BKV TAgs. As a consequence, it is difficult to discriminate between the TAgs of SV40, BKV and JCV by immunohistochemical analyses. In the present study, we generated JCV TAg-specific polyclonal antibodies (JCT629 and JCT652) by immunization of New Zealand white rabbits with synthetic peptides reproducing the JCV TAg carboxyl-terminal region as immunogens. Immunoblotting analyses indicated that the new antibodies bind specifically to JCV TAg, and not to those of SV40 or BKV. We also demonstrated that these antibodies can be used for immunoprecipitation, immunocytochemical analyses and immunohistochemical staining of routinely processed specimens. In conclusion, the newly generated JCV-specific TAg antibodies may be useful both in the investigation of the pathophysiological function of JCV TAg and in discriminating between Polyomavirus-related clinical samples.

Genetics of choroid plexus tumors

Choroid plexus tumors consist of papillomas and carcinomas. A variety of germline and somatic genetic changes have been demonstrated for each of these subtypes. In this paper, the authors summarize the current knowledge of the genetic bases of these tumors.

Cancer Survivorship—Genetic Susceptibility and Second Primary Cancers: Research Strategies and Recommendations

Cancer survivors constitute 3.5% of the United States population, but second primary malignancies among this high-risk group now account for 16% of all cancer incidence. Although few data currently exist regarding the molecular mechanisms for second primary cancers and other late outcomes after cancer treatment, the careful measurement and documentation of potentially carcinogenic treatments (chemotherapy and radiotherapy) provide a unique platform for in vivo research on gene-environment interactions in human carcinogenesis. We review research priorities identified during a National Cancer Institute (NCI)-sponsored workshop entitled "Cancer Survivorship--Genetic Susceptibility and Second Primary Cancers." These priorities include 1) development of a national research infrastructure for studies of cancer survivorship; 2) creation of a coordinated system for biospecimen collection; 3) development of new technology, bioinformatics, and biomarkers; 4) design of new epidemiologic methods; and 5) development of evidence-based clinical practice guidelines. Many of the infrastructure resources and design strategies that would facilitate research in this area also provide a foundation for the study of other important nonneoplastic late effects of treatment and psychosocial concerns among cancer survivors. These research areas warrant high priority to promote NCI's goal of eliminating pain and suffering related to cancer.

Simian virus 40 tumor antigen expression and immunophenotypic profile of AIDS-related non-Hodgkin's lymphoma

Simian virus 40 (SV40) is associated with some systemic non-Hodgkin's lymphomas (NHL) among HIV-positive patients, based on assays for viral DNA sequences. To investigate the possible production of the viral transforming protein, we examined age-matched case-control specimens from patients with HIV/AIDS for the expression of SV40 large tumor antigen (T-ag). Masked specimens initially examined by polymerase chain reaction (PCR) for polyomavirus and herpesvirus DNA sequences were assessed for the expression of SV40 T-ag and phenotypic lymphocyte markers by immunohistochemistry (IHC). Fifty-five systemic NHL and 25 nonmalignant lymphoid and malignant nonlymphoid tissue control cases from two HIV community programs in Texas and New Jersey were scored for IHC positivity without knowledge of the PCR results. IHC showed expression of SV40 T-ag among B-cell lymphomas, whereas none of the control tissue samples were positive for T-ag (12/55, 22% vs. 0/25, 0%; P = 0.01). SV40 T-ag expression was detected only in B-cell lymphoma specimens that contained SV40 DNA sequences. Not all lymphoma cells in a positive specimen stained for T-ag, and the reaction was lower intensity than observed in SV40 hamster tumors. SV40 T-ag was demonstrated in both primary and recurrent tumors from one patient. A germinal center B-cell-like (GCB) profile was more frequently expressed by SV40-positive tumors than in Epstein-Barr virus (EBV)-related lymphomas (10/12, 83% vs. 6/13, 46%; P = 0.05), whereas a non-GCB phenotype was more frequent in EBV-positive than in SV40-positive lymphomas (7/13, 54% vs. 2/12, 17%; P = 0.05). This study shows that SV40 gene expression occurs in a fraction of cells in some B-cell lymphomas among patients with HIV/AIDS.

Identification of five new families strengthens the link between childhood choroid plexus carcinoma and germline TP53 mutations

We present five families of paediatric patients suffering from choroid plexus carcinoma in which we found germline TP53 mutations. Only one of the families conformed to the criteria of Li-Fraumeni syndrome and only three (including the Li-Fraumeni syndrome family) met the Chompret criteria for germline TP53 mutation testing. In the remaining two families no family history of cancer was identified and/or the parents of the patient were shown not to carry the mutation. Our results give further support to the notion that the occurrence of this rare paediatric tumour, especially in combination with a positive family history of cancer, but possibly also without any family history, may be an indicator of a germline TP53 mutation. The identification of this genetic defect has important consequences for cancer prevention and treatment in affected families.

Human polyomaviruses and brain tumors

Polyomaviruses are DNA tumor viruses with small circular genomes. Three polyomaviruses have captured attention with regard to their potential role in the development of human brain tumors: JC virus (JCV), BK virus (BKV), and simian vacuolating virus 40 (SV40). JCV is a neurotropic polyomavirus that is the etiologic agent of progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease of the central nervous system occurring mainly in AIDS patients. BKV is the causative agent of polyomavirus-associated nephropathy (PVN) which occurs after renal transplantation when BKV reactivates from a latent state during immunosuppressive therapy to cause allograft failure. SV40, originating in rhesus monkeys, gained notoriety when it entered the human population via contaminated polio vaccines. All three viruses are highly oncogenic when injected into the brain of experimental animals. Reports indicate that these viruses, especially JCV, are associated with brain tumors and other cancers in humans as evidenced from the analysis of clinical samples for the presence of viral DNA sequences and expression of viral proteins. Human polyomaviruses encode three non-capsid regulatory proteins: large T-antigen, small t-antigen, and agnoprotein. These proteins interact with a number of cellular target proteins to exert effects that dysregulate pathways involved in the control of various host cell functions including the cell cycle, DNA repair, and others. In this review, we describe the three polyomaviruses, their abilities to cause brain and other tumors in experimental animals, the evidence for an association with human brain tumors, and the latest findings on the molecular mechanisms of their actions.

Immunodetection of SV40 large T antigen in human central nervous system tumours

BACKGROUND/AIMS

DNA sequences from Simian virus 40 (SV40) have been previously isolated from various human tumours of the central nervous system (CNS). This study aimed to investigate a series of tumours of the CNS for the expression of the SV40 large T antigen (Tag), which is an oncogenic protein of the virus.

METHODS

A French series of 82 CNS tumours was investigated for Tag expression using a monoclonal antibody and immunohistochemistry. A Tag positive hepatocellular carcinoma cell line from transgenic mice and a kidney biopsy from a patient infected by SV40 were used as positive controls.

RESULTS

None of the tumours (20 ependymomas, 20 glioblastomas, 12 oligodendrogliomas, three plexus choroid adenomas, two plexus choroid carcinomas, 15 meningiomas, and 10 medulloblastomas) contained SV40 Tag positive cells.

CONCLUSIONS

The lack of SV40 Tag in 82 CNS tumours of various types is at variance with previous studies from different countries, and suggests that the virus may not be an important factor in CNS tumorigenesis, at least in French cases.

INI1 Protein Expression Distinguishes Atypical Teratoid/Rhabdoid Tumor from Choroid Plexus Carcinoma

Central nervous system atypical teratoid/rhabdoid tumor (AT/RT) and choroid plexus carcinoma (CPC) are rare, highly malignant tumors that predominantly arise in infants and young children. Overlapping clinical, histologic, ultrastructural, or immunophenotypic features may obscure the diagnosis in some cases. AT/RT is characterized by deletions and/or mutations of the INI1 tumor-suppressor gene on chromosome band 22q11.2. We have recently developed an INI1 immunohistochemical staining assay. Negative staining of tumor cells resulting from inactivation of the INI1 gene is a consistent feature of AT/RT. Mutations of INI1 in some CPCs have been reported. The purpose of the present study was to determine if immunohistochemical staining with an INI1 antibody would provide a sensitive means of distinguishing between CPC and AT/RT. We examined 28 tumors with a submitted diagnosis of CPC. Twenty-one CPCs showed retained expression of INI1 and seven tumors showed loss of INI1 expression. Cytogenetic, FISH, and/or INI1 mutation results were also available for 13 tumors. In three of the seven cases, monosomy 22 was the only cytogenetic abnormality, suggestive of AT/RT. However, monosomy 22 was also identified in 3 tumors with complex karyotypes that retained INI1 expression. The 7 tumors that were immunonegative for INI1 had features that were consistent with AT/RT. Immunostaining for INI1 protein is retained in the majority of CPC and is lost in AT/RT. This expression pattern seems to better define the 2 groups of tumors than does light or electron microscopy, routine immunohistochemistry, or cytogenetic analysis alone.

Mutational analysis of hSNF5/INI1 and TP53 genes in choroid plexus carcinomas

We report here the mutational analysis of hSNF5/INI1 and TP53 genes performed on 11 specimens of choroid plexus carcinomas (CPC) in which a large number of abnormalities has been detected by molecular biology techniques. Loss of heterozygosity (LOH) analysis performed on six tumors revealed losses on chromosomes 1, 3, 5, 9, 10, 13, 16, 18, and 22. However, there were no abnormalities on 17p and mutations of the TP53 gene have been observed for two tumors comprising exons 5 and 7, respectively. Exon 4 of hSNF5/INI1 was mutated in one tumor with LOH restricted to the hSNF5/INI1 locus. There was no coexistence of mutations in both analyzed genes. Our analysis confirms the presence of the hSNF5/INI1 mutations and proves involvement of TP53 mutations in sporadic cases of CPC.

TP53 mutations and outcome in osteosarcoma: a prospective, multicenter study

PURPOSE

Mutations of the TP53 gene have been associated with resistance to chemotherapy as well as poor prognosis in many different malignancies. This is the first prospective study of the prognostic value of somatic TP53 mutations in patients with newly diagnosed extremity osteosarcoma.

PATIENTS AND METHODS

One hundred ninety-six patients with high-grade, nonmetastatic osteosarcoma of the extremities were enrolled from seven tertiary care institutions and observed prospectively for tumor recurrence (median follow-up duration, 44 months). All patients received neoadjuvant or adjuvant chemotherapy and surgery. Tumors were analyzed for the presence of TP53 mutations by polymerase chain reaction single-strand conformation polymorphism analysis and direct DNA sequencing. The association of the status of the TP53 gene with the risk of systemic recurrence was examined using survival analyses with traditional and histologic markers as prognostic factors.

RESULTS

Patient age was the only factor that varied with TP53 gene status (P = .05). No relationship was identified between TP53 status and systemic relapse (relative risk, 1.24; P = .41). Analyses based on missense or nonsense mutations gave similar results (P > .10). In multivariate analysis, large (> 9 cm) tumor size (relative risk, 1.9; P = .006) and poor histologic response (< or = 90% necrosis) to chemotherapy (relative risk, 2.14; P = .02) were the only significant independent predictors of systemic outcome.

CONCLUSION

We found no evidence that TP53 mutations predict for development of metastases in patients with high-grade osteosarcoma. Identification of other genes that influence chemotherapy response and clinical outcome in osteosarcoma is needed to facilitate further improvements in patient outcomes.

Investigation of human brain tumors for the presence of polyomavirus genome sequences by two independent laboratories

JC virus (JCV), BK virus (BKV) and simian virus 40 (SV40) may be associated with human brain tumors. These polyomaviruses have been shown to induce brain tumors in experimentally infected animals. Several studies have found polyomavirus genomic sequences in human brain tumor tissues by using polymerase chain reaction (PCR), while others have not. Inconsistencies in previous findings may be due in part to small sample sizes and differences in underlying patient populations, laboratory techniques and quality control measures. To assess the role of polyomaviruses in human brain tumors and address inconsistencies of previous reports, we investigated the prevalence of viral sequences in a series of 225 brain tumor tissue specimens in 2 independent laboratories. PCR followed by Southern hybridization was performed at the National Institute of Neurological Disorders and Stroke (NINDS). Real-time quantitative PCR was performed on the same tissues at Johns Hopkins University (JHU). Only those tumors with amplifiable DNA were tested further for polyomavirus sequences. Positive and negative control tissues were included, and all specimens were masked. Amplifiable DNA was detected in 225/225 (100%) tumors at NINDS, 9 (4%) of which contained polyomavirus sequences (3 JCV-positive, 3 BKV-positive and 3 SV40-positive). The JHU laboratory amplified DNA from 165/225 (73%) tumors, of which 1 tumor tested positive (for SV40). No tumors tested positive in both laboratories. Results for masked quality control tissues were concordant between laboratories. Nucleotide sequences for JCV, BKV and SV40 are rarely present in a large series of adult and pediatric brain tumors.

Successful treatment of an unresectable choroid plexus carcinoma in a patient with Li-Fraumeni syndrome

Choroid plexus carcinoma (CPC) is an uncommon central nervous system tumor requiring complete surgical excision for favorable outcome. The authors report the successful treatment of a 2-year-old patient with widely disseminated CPC and Li-Fraumeni syndrome. Following a partial resection of the tumor the patient received chemotherapy consisting of cyclophosphamide, etoposide, and carboplatin. There were no additional surgical procedures and radiation was not administered. Remarkably, the patient remains without evidence of active disease more than 3 years from the completion of therapy. Additional studies are necessary to determine whether this treatment plan can be beneficial to other patients with CPC and whether the patient's p53 mutation had an effect on outcome.

Differential ability of two simian virus 40 strains to induce malignancies in weanling hamsters

Different strains of simian virus 40 (SV40) exist and are associated with some human malignancies, but it is not known if SV40 strains differ in biological potential in vivo. In two long-term experiments, Syrian golden hamsters 21 days of age were inoculated by the intraperitoneal route with two different strains of SV40 (10(7) plaque-forming units/animal) and were followed for 8 or 12 months. In vivo responses to strain VA45-54, isolated originally from monkey kidney cells, and to strain SVCPC, recovered from human cancers, were compared. Control animals of the same age were inoculated intraperitoneally with cell culture media. Malignancies developed only in animals infected with SV40 and not in controls. The rate of tumor development was more frequent among animals infected with strain SVCPC than with VA45-54, both in experiments held for 8 months (11/22, 50% vs. 4/20, 20%) and for 12 months (7/15, 47% vs. 3/13, 23%). Histologically, the tumors resembled mesotheliomas, osteosarcoma, and poorly differentiated sarcomas. Metastases to lung and lymph nodes occurred with both viral strains. T-antigen expression was detected in most tumor cells by immunohistochemistry. Anti-T-antigen antibodies were produced by almost all tumor-bearing animals and by about two-thirds of those that did not develop tumors after virus inoculation. SV40 viral neutralizing antibodies were detected in all tumor-bearing animals and in 92% and 38% of those inoculated with SVCPC and VA45-54, respectively, that failed to develop tumors. Antibody titers were usually higher in animals with tumors than in those without. Control animals did not develop viral antibodies. Infectious virus was recovered from 2 of 15 tumors tested. This study showed that there are biological differences between these two SV40 strains that influence the outcome of infections in normal hosts, including the development of malignancies and neutralizing antibody, and proved the principle that SV40 strains from different clades can vary in biological properties in vivo.

Emergent human pathogen simian virus 40 and its role in cancer

The polyomavirus simian virus 40 (SV40) is a known oncogenic DNA virus which induces primary brain and bone cancers, malignant mesothelioma, and lymphomas in laboratory animals. Persuasive evidence now indicates that SV40 is causing infections in humans today and represents an emerging pathogen. A meta-analysis of molecular, pathological, and clinical data from 1,793 cancer patients indicates that there is a significant excess risk of SV40 associated with human primary brain cancers, primary bone cancers, malignant mesothelioma, and non-Hodgkin's lymphoma. Experimental data strongly suggest that SV40 may be functionally important in the development of some of those human malignancies. Therefore, the major types of tumors induced by SV40 in laboratory animals are the same as those human malignancies found to contain SV40 markers. The Institute of Medicine recently concluded that "the biological evidence is of moderate strength that SV40 exposure could lead to cancer in humans under natural conditions." This review analyzes the accumulating data that indicate that SV40 is a pathogen which has a possible etiologic role in human malignancies. Future research directions are considered.

Polyomaviruses and human cancer: molecular mechanisms underlying patterns of tumorigenesis

Polyomaviruses are DNA tumor viruses with small circular genomes encoding only six proteins including three structural capsid proteins. Despite this simplicity, our understanding of the mechanisms of polyomavirus-mediated tumorigenesis is far from complete. The archetypal primate polyomavirus, SV40, was isolated more than 40 years ago and has been used extensively as a model system for the study of basic eukaryotic cellular processes such as DNA replication and transcription. Two human polyomaviruses have been isolated from clinical samples: JC virus (JCV) and BK virus (BKV). In this review, SV40, JCV, and BKV will be compared based on what is known about their molecular biology from experiments performed in vitro, in cell culture and in laboratory animals. The association of these viruses with clinical tumors is discussed along with the possible roles of these polyomaviruses in the etiology of human malignant disease.

Incidence of malignant disease by morphological type, in young persons aged 12–24 years in England, 1979–1997

Cancer incidence data are generally presented in terms of primary site, but this method is inappropriate for cancers in young persons. We have used a morphology-based classification system to produce national incidence rates for cancers in persons aged 12-24 years by detailed diagnostic sub-type. The overall incidence rates for malignant disease in young persons aged 12-14, 15-19 and 20-24 years were 10.1, 14.4 and 22.6 per 100000 population, respectively. The three most frequent cancer types in 12-14-year-olds were leukaemias, lymphomas and central nervous system (CNS) tumours. In 15-19-year-olds, lymphomas were most frequent and leukaemias second with carcinomas third. In 20-24-year-olds, lymphomas were again most frequent, but carcinomas and germ cell tumours were second and third. There was also variation with age in the ratios of rates in males and females. These changing incidence patterns have aetiological implications and provide clues for future hypothesis-based research.

SV40 Tag DNA sequences, present in a small proportion of human hepatocellular carcinomas, are associated with reduced survival

AIMS

To study the association between simian virus 40 (SV40) and human hepatocarcinogenesis.

METHODS

Polymerase chain reaction (PCR) to detect SV40 large T antigen (Tag) DNA was performed on: 50 human hepatocellular carcinoma (HCCs) diagnosed between 1978 and 1989 (cohort A); 20 cases of alcoholic liver cirrhosis from the same period; and 20 HCCs diagnosed after 1997 (cohort B). PCR to detect SV40 regulatory sequence and SV40 Tag immunohistochemistry were performed on selected cases from cohorts A and B. Amplified products were directly sequenced. Immunohistochemistry for p53 and pRb and clinicopathological analyses were performed on selected cases from cohorts A and B. Complete survival data were collected for cohort A.

RESULT

SV40 Tag DNA was found in five cohort A HCCs but not in alcoholic liver cirrhosis cases or cohort B HCCs. Neither SV40 regulatory sequence nor SV40 Tag protein were demonstrated in Tag DNA positive HCCs. No clinicopathological differences existed between Tag DNA positive and negative HCCs, but the presence of Tag DNA was associated with reduced disease specific survival. Relatively fewer Tag DNA positive than negative HCCs expressed p53, but loss of pRb expression was similar in the two groups. Patients with Tag DNA positive HCCs were unlikely to have received SV40 contaminated poliovirus vaccine.

CONCLUSIONS

SV40 Tag DNA is present in a small proportion of historical HCCs and may contribute to their pathogenesis and influence their outcome. The source of the virus is uncertain and more recent HCCs show no evidence of SV40.

Simian virus 40 and its association with human lymphomas

Simian virus 40 (SV40) is a potent DNA tumor virus that is known to induce cancer in laboratory animals. The neoplasias induced by SV40 in animal models are brain cancers, mesothelioma, bone cancers, and systemic lymphomas. SV40 oncogenesis is mediated primarily by the viral large tumor antigen, which inactivates the tumor suppressor proteins p53 and pRb family members. Evidence indicates that SV40 is an emergent human pathogen and that a significant excess risk of SV40 is associated with primary human brain cancers, malignant mesothelioma, bone cancers, and non-Hodgkin's lymphoma. Therefore, the major types of tumors induced by SV40 in laboratory animals are the same as those human malignancies found to contain SV40 markers. Experimental and clinical data indicate that SV40 may be functionally important in the development of some of those malignancies. Recently, the Institute of Medicine of the National Academies concluded that SV40 infections could lead to cancer in humans under natural conditions (based on moderate strength biologic evidence). This review examines the data implicating SV40 in the pathogenesis of human lymphomas and discusses future directions to define the causative role for SV40 in these malignancies.

SV40 in human brain cancers and non-Hodgkin's lymphoma

Simian virus 40 (SV40) is a potent DNA tumor virus that is known to induce primary brain cancers and lymphomas in laboratory animals. SV40 oncogenesis is mediated by the viral large tumor antigen (T-ag), which inactivates the tumor-suppressor proteins p53 and pRb family members. During the last decade, independent studies using different molecular biology techniques have shown the presence of SV40 DNA, T-ag, or other viral markers in primary human brain cancers, and a systematic assessment of the data indicates that the virus is significantly associated with this group of human tumors. In addition, recent large independent studies showed that SV40 T-ag DNA is significantly associated with human non-Hodgkin's lymphoma (NHL). Although the prevalence of SV40 infections in humans is not known, numerous observations suggest that SV40 is a pathogen in the human population today. This review examines the molecular biology, pathology, and clinical data implicating SV40 in the pathogenesis of primary human brain cancers and NHL and discusses future research directions needed to define a possible etiologic role for SV40 in these malignancies.

Simian virus 40 in human cancers

BACKGROUND

Many studies have reported the presence of simian virus 40 (SV40) deoxyribonucleic acid (DNA) or protein in human brain tumors and bone cancers, malignant mesothelioma, and non-Hodgkin's lymphoma. However, the small samples and lack of control groups in some reports have made it difficult to assess their reliability.

METHODS

Studies were included in this analysis if they met the following criteria: original studies of patients with primary brain tumors and bone cancers, malignant mesothelioma, or non-Hodgkin's lymphoma; the investigation of SV40 was performed on primary cancer specimens; the analysis included a control group; and the same technique was used for cases and controls. Included reports were published from 1975 to 2002.

RESULTS

Thirteen studies fulfilled the criteria for the investigation of primary brain cancers (661 tumors and 482 control samples). Specimens from patients with brain tumors were almost four times more likely to have evidence of SV40 infection than were those from controls (odds ratio [OR] = 3.9; 95% confidence interval [CI]: 2.6 to 5.8). The association was even stronger for mesothelioma (OR = 17; 95% CI: 10 to 28; based on 15 studies with 528 mesothelioma samples and 468 control samples) and for bone cancer (OR = 25; 95% CI: 6.8 to 88; based on four studies with 303 cancers and 121 control samples). SV40 DNA was also more frequent in samples from patients with non-Hodgkin's lymphoma (OR = 5.4; 95% CI: 3.1 to 9.3; based on three studies with 301 cases and 578 control samples) than from controls.

CONCLUSION

These results establish that SV40 is associated significantly with brain tumors, bone cancers, malignant mesothelioma, and non-Hodgkin's lymphoma. Studies are needed to assess current prevalence of SV40 infections.

Brain tumors and polyomaviruses

Polyomaviruses, including JC virus (JCV), BK virus (BKV), and simian virus 40 (SV40) have attracted much attention in the past decade due to their repeated isolation from various human tumors, including those originating from the central nervous system (CNS). JCV and BKV are considered to be ubiquitous human pathogens that become reactivated under impaired physiological conditions such as immunosuppression. Productive replication of JCV and BKV induces diseases such as progressive multifocal leukoencephalopathy in the brain and hemorrhagic or nonhemorrhagic cystitis and nephritis in the kidney. JCV DNA sequences have been isolated from a number of human CNS tumors, including medulloblastoma, ependymoma, and a broad range of glial-origin neoplasms. SV40, once believed to be a monkey virus, has now been isolated from a variety of human cancer cells, including mesothelioma, ependymoma, and non-Hodgkin's lymphoma. In this mini-review, the authors focused their attention on the possible involvement of polyomaviruses, such as JCV, BKV, and SV40, with human brain tumors.

Conventional epidemiology and the link between SV40 and human cancers

Simian virus 40 (SV40) is known to cause tumourigenesis. The main types of tumour induced by SV40 in laboratory animals mirror the human cancers that have been found to contain SV40 DNA or the viral oncoprotein. Increasing amounts of data support the notion that SV40 may be an aetiological factor in the development of human cancers. Retrospective birth cohort studies have been used in attempts to refute the alleged causal link between SV40 and human cancers. However, these observational studies are affected by several important confounding factors, which mean that firm conclusions cannot be drawn. In this essay, we consider the unique features of SV40 infection in humans and examine the limitations of conventional studies that seek to disprove the aetiological link with human cancer.

Pediatric genitourinary tumors

Each year advances are made in the clinical evaluation and treatment of genitourinary tumors in children. Understanding of cellular, molecular, and genetic processes in tumorigenesis is evolving rapidly. In addition, information is accumulating about the long-term outcome and complications associated with treatment modalities. This article reviews the 2001 literature on pediatric Wilms tumor, other renal tumors, rhabdomyosarcoma of the pelvis, paratesticular rhabdomyosarcoma, and testicular tumors. The emphasis in molecular biology is to identify molecular or genetic markers that predict outcome. The National Wilms' Tumor Study Group reported on the complications of surgery and the decreased complication rate when these procedures are performed by pediatric surgical specialists. Long-term complications of treatment are also discussed, including short stature and leukemia. The Intergroup Rhabdomyosarcoma Study Group reported on the results of treatment for nonmetastatic disease and the goals of the upcoming Study V, reduction of chemotherapy and radiotherapy. They also presented data from Study IV and discussed the findings on improved prognosis.

The Li-Fraumeni syndrome

Li-Fraumeni syndrome (LFS) has been the most common terminology used for the syndrome. It is a rare familial dominantly inherited cancer syndrome characterized by a wide spectrum of neoplasms occurring in children and young adults. The canonical definition of LFS includes a proband diagnosed with sarcoma before 45 years of age, a first-degree relative with cancer before this same age and another first- or second-degree relative in the lineage with any cancer before this age or sarcoma at any age. Multiple studies have reported p53 germline mutations in LFS families in various parts of the world. As in sporadic tumors, loss of heterozygosity leading to the inactivation of the wild-type allele by deletion or mutation is observed in LFS tumors. Cancer-risk in mutation carriers has been estimated to be 73% in males and nearly 100% in females, the difference almost entirely explained by breast cancer. The identification of germline p53 mutations in rare cancer-prone families has given rise to the medical, counseling, psychological and ethical problems.