SV40 and p53 as team players in childhood lymphoproliferative disorders.

Simian virus 40 (SV40) is known to be potently oncogenic and can induce several types of tumours, such as lymphoma. p53 was discovered as a cellular partner of the SV40 large T-antigen, the oncoprotein of this virus. There have not been many studies on SV40 and p53 in lymphomas and the ones that exist, are controversial. A comparison of these two components in lymphoma has not been reported previously. We examined 91 lymphomas [60 B-cell non-Hodgkin's lymphomas (B-NHLs), 19 B-cell acute lymphoblastic leukemias (B-ALLs), 7 B-cell precursor acute lymphoblastic leukemias and 5 T-cell acute lymphoblastic leukemias] for the presence of SV40. Overall, 40 samples from 12 B-NHL/19 B-ALL patients were additionally investigated for p53 mutation in the hot-spot exons 5 to 8. Overall, we found 62/91 lymphomas to be SV40-positive, among them 16/19 B-ALLs and 38/60 B-NHLs. SV40 was absent in 147 of the 149 blood control samples. We found 11 p53 mutations in 19 B-ALL patients: 5 in exon 5 (codons 132, 141, 143, 155 and 181), 4 in exon 7 (codons 236, 238 and 248), 2 in exon 8 (codon 273). In B-NHL patients we found p53-mutations in 9/12 samples: 6 of these in 3 lymph nodes (LNs). One LN harboured 3 different p53 mutations: Exon 5 (codon 132), exon 6 (codon 213) and exon 8 (codon 288). Another LN showed 2 different p53 mutations: Exon 6 (codon 213) and exon 8 (codon 285). Except for 1 nonsense mutation in an LN of a B-NHL patient, all 20 mutations were missense mutations, 2 were homozygous, both found in B-NHL-samples, and one of these (codon 175) is known to cause the global denaturation of p53. All occur in the DNA-binding domain of p53. All specimens showing a p53 mutation, were SV40-positive. p53 mutaions found in LNs of B-NHL patients harbour high SV40 copy numbers. Our data strongly support an important role for SV40, as well as a strong association of SV40 and p53 in childhood lympho-proliferative disorders.

Ongoing remission after intensive ALL-type chemotherapy in pediatric intestinal T-cell lymphoma.

A rare case of primary intestinal T-cell lymphoma (ITL) of an 8-year-old boy is reported. Medium- to large-sized tumor cells were betaF1+, CD3+, CD8+. TIA-1+, but CD4-, CD5-, CD30-, CD56-, CD20-, CD79a-, TdT-, consistent with an intraepithelial lymphocyte (IEL) origin. They showed monoclonal rearrangement of the T-cell receptor gamma-chain and no evidence of EBV infection. No clinical, histologic, laboratory, or genetic evidence of celiac disease was detected. In adults, ITL is often associated with enteropathy and has a very poor outcome. Our patient remains in first remission 30 months after finishing the acute lymphoblastic leukemia protocol COALL-07-03 high risk standard.

Second allogeneic stem cell transplantation in myeloid malignancies.

For patients with myeloid malignancies who relapse after allogeneic stem cell transplantation (allo-SCT), one salvage option is a second SCT. We retrospectively analyzed outcomes of the second allo-SCT in 25 patients who received at least 2 allografts from related/unrelated donors due to relapse of acute myeloid leukemia, myelodysplastic syndrome or myelofibrosis after the first SCT. A minority of the acute myeloid leukemia/myelodysplastic syndrome patients had reached complete hematological remission before the second SCT (6/25, 24%). Reduced conditioning strategies were performed in the majority (n = 23). Complete remission was achieved in all 21 cases with available data after the second SCT, but relapse was seen in 11/25 patients (44%). After a median follow-up of 18 months (range 6-47), 8/25 patients (32%) were still alive, and of those, 6 (24%) were in stable remission. In 9 cases mortality was associated to relapse and in 8 cases to transplant-related causes (treatment-related mortality; 8/25, 32%). In conclusion, a second SCT offers the chance of stable remission for some patients relapsing with a myeloid malignancy after a first allo-SCT, although high treatment-related mortality and relapse rates remain a problem. Efforts should concentrate on an optimization of conditioning strategies, immunosuppression and post-transplant surveillance for this specific situation.

Evaluation of SV40 in osteosarcoma and healthy population: a Hungarian-German study.

Simian virus 40 (SV40) has been linked to human cancer, as has osteosarcoma (OS). Although significant discrepancies exist in the frequency, evidence that the virus plays a causative role in some malignancies is mounting. The large-T-antigen and significant SV40 oncoprotein, bind and inactivate the tumour suppressor genes p53 and pRb, which play a key role in osteosarcoma development. We analysed 277 OS samples from two different European countries (154 OS samples from Hungary and 123 from Germany). To ascertain the prevalence of SV40 in the general population, additional blood samples from healthy volunteers from the two countries (166 Hungarian and 149 German) were analysed. To reach an appropriate detection level, we investigated a real-time quantitative PCR-based assay for the detection and quantification of SV40 <10 copies in 500 ng of genomic DNA. We detected SV40 in 52% (143/277) of the OS samples analysed. In detail, we saw differences in the distribution of SV40 between the two countries. Of the Hungarian OS samples, 74% (114/154) showed high amounts of SV40 (>100 copies), whereas only 22% (29/123) of the German OS samples harbour small amounts of SV40 ( approximately 10 copies). SV40 was detected in 8 of 60 German tumour samples (14%) and 21 of 63 German blood samples (33%) from OS patients. In the peripheral blood of healthy volunteers we found only weak SV40 positivity (<10 copies) in the two countries with a somewhat higher frequency in Hungarian 30/166 (18%) than in German blood samples 2/149 (1.3%). No sequence variations were found in SV40-positive samples from the two countries. Our data demonstrate significant differences in the prevalence and quantity of SV40 in OS of these different European geographical origins with a lower frequency in the blood samples of healthy volunteers from the two countries, underlining again the geographical differences previously described by other investigators.

Prognostic value of minimal residual disease quantification before allogeneic stem-cell transplantation in relapsed childhood acute lymphoblastic leukemia: the ALL-REZ BFM Study Group.

PURPOSE: Minimal residual disease (MRD) before allogeneic stem-cell transplantation was shown to predict outcome in children with relapsed acute lymphoblastic leukemia (ALL) in retrospective analysis. To verify this, the Acute Lymphoblastic Leukemia Relapse Berlin-Frankfurt-Münster (ALL-REZ BFM) Study Group conducted a prospective trial. PATIENTS AND METHODS: Between March 1999 and July 2005, 91 children with relapsed ALL treated according to the ALL-REZ BFM 96 or 2002 protocols and receiving stem-cell transplantation in >or= second remission were enrolled. MRD quantification was performed by real-time polymerase chain reaction using T-cell receptor and immunoglobulin gene rearrangements. RESULTS: Probability of event-free survival (pEFS) and cumulative incidence of relapse (CIR) in 45 patients with MRD >or= 10(-4) leukemic cells was 0.27 and 0.57 compared with 0.60 and 0.13 in 46 patients with MRD less than 10(-4) leukemic cells (EFS, P = .004; CIR, P < .001). Intermediate-risk patients (strategic group S1) with MRD >or= 10(-4) leukemic cells (n = 14) had a pEFS of 0.20 and CIR of 0.73, whereas patients with MRD less than 10(-4) leukemic cells (n = 21) had a pEFS of 0.68 and CIR of 0.09 (EFS, P = .020; CIR, P < .001). High-risk patients (S3/4, third complete remission) who received transplantation with an MRD load of less than 10(-4) leukemic cells (n = 25) showed a pEFS and CRI of 0.53 and 0.18, respectively. In contrast, pEFS and CRI were 0.30 and 0.50 in patients who received transplantation with an MRD load of >or= 10(-4) leukemic cells. Multivariate Cox regression analysis revealed MRD as the only independent parameter predictive for EFS (P = .006). CONCLUSION: MRD is an important predictor for post-transplantation outcome. As a result, new strategies with modified stem-cell transplantation procedures will be evaluated in ALL-BFM trials.

Anti-thymocyte globulin overcomes the negative impact of HLA mismatching in transplantation from unrelated donors.

OBJECTIVE: About one third of patients requiring allogeneic hematopoetic stem cell transplantation (HSCT) would not find a matched sibling or alternative donor. Allogeneic HSCT from matched unrelated and mismatched donors carries an increased risk of graft-vs-host disease (GVHD) and transplant-related mortality (TRM). MATERIALS AND METHODS: We used anti-thymocyte globulin (ATG-Fresenius) at a median dose of 90 mg/kg body weight as part of a total body irradiation or busulfan-based conditioning regimen for prevention of serious GVHD. All patients received cyclosporine A and short-course methotrexate. We compared outcomes of 65 recipients of human leukocyte antigen (HLA)-mismatched unrelated grafts and 194 recipients of HLA-matched unrelated grafts. Mismatches involved one or two loci. Both groups were comparable in age, graft source, diagnosis, stage of disease, and conditioning regimen, and differed only in dose of ATG administered. RESULTS: For matched and mismatched transplants, respectively, there was no significant difference in graft failure (0.5% vs 3%; p = 0.16), in the cumulative incidence of grade II to IV acute GVHD (45% vs 35%; p = 0.14) and no difference in overall chronic GVHD (42% vs 40%; p = 0.68). Estimated overall survival (OS) and disease-free survival (DFS) at 5 years were 55% vs 50% (p = 0.99) and 47% vs 47% (p = 1.0), respectively. The cumulative incidence of relapse and TRM at 5 years were 24% vs 25% (p = 0.63), and 29% vs 27% (p = 0.59), respectively. CONCLUSION: Inclusion of ATG-Fresenius in the conditioning regimen permits HSCT from mismatched unrelated donors without excess TRM and GVHD, resulting in identical OS and DFS of recipients of HLA-matched and HLA-mismatched grafts.

Determination of the prognostic value of loss of heterozygosity at the retinoblastoma gene in osteosarcoma.

The retinoblastoma (RB) tumour suppressor gene is implicated in the development of several malignancies including osteosarcoma. Recent studies postulated its loss of heterozygosity (LOH) to be a poor prognostic factor at diagnosis of osteosarcoma (OS). It remains unclear whether LOH of the RB gene is suitable as a prognostic factor at diagnosis in patients with osteosarcoma. In this study we aimed to determine the early prognostic value of RB-LOH as well as the ability of denaturating high performance liquid chromatography (DHPLC) to detect LOH at this gene locus in comparison to classical PAGE. We therefore analysed 41 samples of OS on restriction fragment length polymorphisms in introns 1, 17 and 25, and variable numbers of tandem repeats (VNTRs) in intron 20. PCR fragments were separated on 1.5% agarose gel electrophoresis. VNTRs with length differentiation of only a few base pairs were analysed by 8% PAA/Spreadex gels and additionally by DHPLC. One-hundred percent concordance was observed between the results obtained by classical PAGE and DHPLC. The latter improved intron 20 analysis as a sensitive and high throughput method for detecting LOH. Overall we found 16 RB-LOH in 41 OS (39%). Three tumours exhibited additional microsatellite instability. There was no significant correlation of the event-free- and overall-survival rate or response to chemotherapy with RB-LOH found in our study. LOH positivity was associated with a significantly younger age at diagnosis. In conclusion RB-LOH could not be verified as a poor prognostic factor for osteosarcoma in the present study.

Mutation spectrum in children with primary hemophagocytic lymphohistiocytosis: molecular and functional analyses of PRF1, UNC13D, STX11, and RAB27A.

Familial hemophagocytic lymphohistiocytosis (FHL) is an autosomal-recessive disease that affects young children. It presents as a severe hyperinflammatory syndrome with activated macrophages and T lymphocytes. Mutations in the perforin 1 gene (PRF1) were found in FHL-2 in 15-50% of all cases. Defective granule exocytosis caused by mutations in the hMunc13-4 gene (UNC13D) has been described in FHL-3. FHL-4 patients have mutations in STX11, a t-SNARE involved in intracellular trafficking. We analyzed a large group of 63 unrelated patients with FHL of different geographic origins (Turkey:32; Germany:23; others:8) for mutations in STX11, PRF1, and UNC13D. We identified mutations in 38 samples (20 in PRF1, 12 in UNC13D, and six in STX11). Of 32 patients from Turkey, 14 had mutations in PRF1, six had mutations in UNC13D, and six had mutations in STX11. The mutation Trp374X in PRF1 was found in 12 patients from Turkey and was associated with a very early onset of the disease below the age of 3 months in all cases. In contrast, three of 23 and four of 23 patients from Germany, and three of eight and two of eight from other origins showed mutations in PRF1 and UNC13D, respectively, but none in STX11. Thus, FHL-2, FHL-3, and FHL-4 account for 80% of the HLH cases of Turkish origin, and for 30% of German patients. Furthermore, we identified mutations in RAB27A in three patients with FHL-related Griscelli syndrome type 2. In functional studies using a mammalian two-hybrid system we found that missense mutations Ala87Pro in Rab27a and Leu403Pro in hMunc13-4 each prevented the formation of a stable hMunc13-4/Rab27a complex in vitro. Our findings demonstrate extensive genetic and allelic heterogeneity in FHL and delineate an approach for functionally characterizing missense mutations in RAB27A and UNC13D.

Amsacrine combined with etoposide and high-dose methylprednisolone as salvage therapy in acute lymphoblastic leukemia in children.

In a retrospective analysis of 24 children with refractory or multiply relapsed acute lymphoblastic leukemia (ALL), a salvage regimen comprising amsacrine, etoposide, and high-dose methylprednisolone AEP achieved a significant treatment response in 11 of 19 evaluable patients (8 complete and 3 partial remissions). Five of 9 AEP-responsive patients who underwent subsequent stem cell transplantation are alive (median follow-up: 43 months; range 10 to 91). The load of minimal residual disease prior to transplantation appears to be predictive for outcome in this very poor-prognosis subgroup of ALL.

DHPLC based fraction collection of TCR-gamma rearrangements in childhood ALL: direct sequencing of products amplified by a single or a multiplex PCR approach.

Clonal T-cell receptor gamma (TCR-gamma) rearrangements are frequently used for detection of minimal residual disease (MRD) in childhood acute lymphoblastic leukemia. In approximately 70-80% of cases PCR amplified clonal rearrangements can be sequenced directly. The remaining 20-30% are rearranged on both alleles for the same target and disables direct sequencing. Here we describe a novel HPLC based method for identification and characterisation of TCR-gamma rearrangements either by a single or a multiplex PCR approach. The latter one amplifies several Vgamma segments in two distinct reactions either with a Jgamma1.3/2.3 or a Jgamma1.1/2.1 specific primer. The clonality status was evaluated on a high resolution micropellicular DNASep matrix (WAVE, Transgenomic) at different temperatures. From 331 samples analysed, 151 samples were positive for VgammaI-Jgamma1.3/2.3 including 51 biclonal rearrangements. For characterisation of these biclonal products or for products generated by multiplex-PCR, a second HPLC run was performed utilising a tandem arranged fraction collector. From clearly separated biclonal/biallelic products, several collected fractions were air-dried and afterwards sequenced directly with the appropriate Jgamma primer. We conclude from our results that HPLC is a fast and reliable method for identification of TCR-gamma rearrangements. The fraction collection simplifies the characterisation of single alleles within biclonal or biallelic rearrangements or within multiplex PCR products. The target identification process prior to routine MRD analysis will be shortened due to a simplified screening and sequencing strategy.

Osteosarcoma of the hand and forearm: experience of the Cooperative Osteosarcoma Study Group.

BACKGROUND: Osteosarcoma is extremely rare in the hand and forearm. Therefore, only limited data are available for planning treatment or predicting the outcome and prognosis of osteosarcoma in the peripheral upper extremity. METHODS: Epidemiological, clinical, and histopathologic data were analyzed in 39 patients with osteosarcoma of the forearm or hand who were enrolled in studies of the Cooperative German-Austrian-Swiss Osteosarcoma Study Group from 1977 to December 2000. In patients with high-grade osteosarcoma, the treatment entailed surgical resection in combination with chemotherapy, whereas patients with low-grade osteosarcoma underwent only surgery. RESULTS: The 5-year overall survival rate among the 33 patients with high-grade central osteosarcoma of the distal upper extremity was 86.2% +/- 6.4%. The 5-year event-free survival rate was 65.4% +/- 9.6%. Five of the eight patients with secondary metastases were in remission at the time of analysis. Four patients died of their disease, and two patients died of chemotherapy-related complications. The mean overall survival rate was 88.0% +/- 6.5% in patients treated by wide or radical tumor resection and was 75.0% +/- 21.7% in patients with nonwide margins of resection. Whether amputation or local resection was performed had no significant influence on the prognosis. All six patients whose osteosarcoma was not classified as high-grade central osteosarcoma were in remission at the time of analysis. CONCLUSIONS: The results demonstrate a remarkably high survival rate for patients with high-grade osteosarcoma of the hand and forearm and confirm that multiagent chemotherapy in combination with wide excision is a highly effective treatment for this malignant tumor.

Linkage of familial hemophagocytic lymphohistiocytosis (FHL) type-4 to chromosome 6q24 and identification of mutations in syntaxin 11.

Familial hemophagocytic lymphohistiocytosis (FHL) is a rare autosomal recessive disorder characterized by hyperactive phagocytes and defects in natural killer cell function. It has been shown previously that mutations in the perforin 1 gene (PRF1) and in UNC13D are associated with FHL2 and FHL3, respectively, indicating genetic heterogeneity. We performed genome-wide homozygosity mapping in a large consanguineous Kurdish kindred with five children affected with FHL. Linkage to a 10 cM region on chromosome 6q24 between D6S1569 and D6S960 defined a novel FHL locus. By screening positional candidate genes, we identified a homozygous deletion of 5 bp in the syntaxin 11 gene (STX11) in this family. We could demonstrate that syntaxin 11 protein was absent in the mononuclear cell fraction of patients with the homozygous 5 bp deletion. In addition to this family, we found homozygous mutations in STX11 in five consanguineous Turkish/Kurdish FHL kindreds including two families with the 5 bp deletion, one family with a large 19.2 kb genomic deletion spanning the entire coding region of STX11 (exon 2) and two families with a nonsense mutation that leads to a premature stop codon in the C-terminal end of the protein. As both STX11 and UNC13D are involved in vesicle trafficking and membrane fusion, we conclude that, besides mutations in perforin 1, defects in the endocytotic or the exocytotic pathway may be a common mechanism in FHL.

Standardized detection of Simian virus 40 by real-time quantitative polymerase chain reaction in pediatric malignancies.

BACKGROUND AND OBJECTIVES: Recent studies have detected Simian virus 40 (SV40) DNA in specific human tumors albeit with significant discrepancies in frequency. Possible inefficiency of DNA isolation and different detection methods do not allow comparable and precise quantification of SV40 in human samples. A standardized and common detection method is, therefore, essential for further routine SV40 analysis. DESIGN AND METHODS: We established a real time quantitative (RQ-) polymerase chain reaction (PCR) based TaqMan assay on the LightCycler system for reproducible detection and quantification of SV40 DNA. We used 500 ng of the COS-1 cell line, containing one single integrated copy of SV40 DNA, as the quantification standard. Amplification of b-globin served as the quality control for DNA integrity. For the extraction of the episomal form of SV40 we compared a column and a precipitation-based DNA extraction method. DNA samples from 149 healthy controls, from 26 fresh frozen childhood cases of acute lymphoblastic leukemia (ALL) (B-, BCP- and T-ALL) and from 12 paraffin-embedded osteosarcomas were investigated. RESULTS: The RQ-PCR assay had a linear amplification rate from 10 to 100,000 copies of SV40 in 500 ng genomic DNA. Very low copy numbers of SV40 DNA were detectable in 2/149 (1,3%) blood samples from healthy German controls. Various amounts of SV40 were detectable in 20/26 (77%) childhood ALL samples of German origin and, in part, high amounts were visible in 11/12 (92%) paraffin embedded Hungarian osteosarcomas. The column-based DNA isolation method allowed the detection of both, the integrated and the episomal forms of SV40. INTERPRETATION AND CONCLUSIONS: Our assay provides a standardized and reproducible quantification of SV40 DNA in a wide spectrum of specimens. Exact quantification strongly depends on the source, as well as on the quality, of the DNA used. Quantification of paraffin-embedded DNA generally leads to lower sensitivity of SV40 DNA detection. We strongly recommend this RQ-PCR assay for standardized detection of SV40.

Osteosarcoma relapse after combined modality therapy: an analysis of unselected patients in the Cooperative Osteosarcoma Study Group (COSS).

PURPOSE: To evaluate the impact of patient, tumor, and treatment-related factors on outcome in unselected patients with recurrent osteosarcoma. PATIENTS AND METHODS: Five hundred seventy-six consecutive patients who had achieved a first complete surgical remission (CR) during combined-modality therapy on neoadjuvant Cooperative Osteosarcoma Study Group (COSS) protocols and then developed recurrent osteosarcoma were analyzed (median time from biopsy to relapse, 1.6 years; range, 0.1 to 14.3 years). There were 501 patients with metastases, 44 with local recurrences, and 31 with both. Metastases involved lungs (469 patients), bones (90 patients), and/or other sites (54 patients). RESULTS: After a median follow-up of 1.2 years for all patients and 4.2 years for survivors, actuarial overall survival (OS) rates at 2, 5, and 10 years were 0.38, 0.23, and 0.18, respectively. Five-year OS was 0.39 for 339 patients with and 0.00 for 229 patients without a second surgical CR (P < .0001). A long time to relapse, a solitary lesion, and, in the case of pulmonary metastases, unilateral disease and the absence of pleural disruption, were of positive prognostic value in uni- and multivariate analyses, as were a second surgical CR and the use of second-line chemotherapy. Radiotherapy was associated with moderately prolonged survival in patients without a second CR. The very limited prognostic differences associated with the use of second-line chemotherapy appeared to be more pronounced with polychemotherapy. CONCLUSION: Time to relapse and tumor burden correlate with postrelapse outcome in osteosarcoma. Complete surgery is an essential component of curative second-line therapy. Chemotherapy, particularly chemotherapy with more than one agent, may contribute to limited improvements in outcome.

Hematopoietic stem cell transplantation (HSCT) in children with juvenile myelomonocytic leukemia (JMML): results of the EWOG-MDS/EBMT trial.

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only proven curative therapy for juvenile myelomonocytic leukemia (JMML). We, the European Working Group on Childhood MDS (EWOG-MDS) and the European Blood and Marrow Transplantation (EBMT) Group, report the outcome of 100 children (67 boys and 33 girls) with JMML given unmanipulated HSCT after a preparative regimen including busulfan, cyclophosphamide, and melphalan. Forty-eight and 52 children received transplants from an HLA-identical relative or an unrelated donor (UD), respectively. The source of hematopoietic stem cells was bone marrow, peripheral blood, and cord blood in 79, 14, and 7 children, respectively. Splenectomy had been performed before HSCT in 24 children. The 5-year cumulative incidence of transplantation-related mortality and leukemia recurrence was 13% and 35%, respectively. Age older than 4 years predicted an increased risk of disease recurrence. The 5-year probability of event-free survival for children given HSCT from either a relative or a UD was 55% and 49%, respectively (P = NS), with median observation time of patients alive being 40 months (range, 6 to 144). In multivariate analysis, age older than 4 years and female sex predicted poorer outcome. Results of this study compare favorably with previously published reports. Disease recurrence remains the major cause of treatment failure. Outcome of UD-HSCT recipients is comparable to that of children receiving transplants from an HLA-identical sibling.

Osteosarcoma cell lines display variable individual reactions on wildtype p53 and Rb tumour-suppressor transgenes.

BACKGROUND: One of the most widely studied gene therapeutic strategies for cancer is the introduction of tumour-suppressor genes-generally p53-into the target cells. As the genes of p53 and/or retinoblastoma (Rb) are mutated in the major part of osteosarcomas (OS), we aimed to study the effect of p53 and Rb transgenes on a panel of five different osteosarcoma cell lines. METHODS: OS cell lines were transduced by adenoviral vectors delivering the transcription units of the wildtype p53 and the Rb gene. Effects of the transgenes alone and at additional cytostatic stress were studied by proliferation, alive/dead and cell cycle assays. RESULTS: The individual cells lines displayed divergent reactions to p53- or Rb-transgene delivery reaching from cell death (SaOs-2, U2OS at p53 transduction) over stopped or lowered cell division (MG-63, K-HOS, SJSA-1 at p53 and Rb transduction) to nearly unhindered cell growth (U2OS at Rb transduction). In those OS cell lines reacting with lowered cell division to p53 or Rb delivery, cytostatics only moderately intensified the transgene effects. Surprisingly, these reactions were apparently not dependent on the functional status of the cellular p53 and/or Rb genes or on differences in the infectability of the cell lines by the adenoviral vectors. Most interestingly, the respective effects of the p53 or Rb transgenes were not multiplied by simultaneous transduction of both tumour-suppressor genes. CONCLUSIONS: The application of wildtype tumour-suppressor gene therapy on genetically variable osteosarcomas may be efficient only in yet not identified genetic subgroups of this tumour entity. Hyperactive tumour-suppressor transgenes could be an alternative.

Limited specificity of promoter constructs for gene therapy in osteosarcoma.

Osteosarcoma (OS), a malignant bone neoplasia in childhood, has poor prognosis if metastases appear in the lung. A novel therapeutic approach could consist in a gene therapeutic treatment of OS metastases. However, if promiscuous viral vectors are applied for the delivery of potentially toxic transgenes, their misdelivery into normal tissues could cause severe complications. This problem could be circumvented by application of OS-specific promoters for transgene expression control. We analysed the function of promoters described to be tumour-, osteosarcoma- or osteoblast-specific. Expression rates driven by osteoblast- specific fragments from the collagen1A1-promoter, the human Osteocalcin-promoter, the bone-sialoprotein promoter and the beta-catenin promoter depending on vitamin supplementation were analysed in five OS cell lines, in normal lung fibroblasts and in a non-osteoblastic prostate cancer cell line (LNCaP) by dual luciferase assays. In addition, an unspecific but doxycyclin-repressible promoter construct (pAd.3r-luc) was examined. We found that all constructs were active in OS cell lines to varying extents. The complete human Osteocalcin promoter and the bone-sialoprotein promoter were partially induced by vitamin D3 or C respectively while the pAd.3r-luc activity could be shut down by doxycyclin. In contrast, the human Osteocalcin-promoter was not activated by vitamin D3 in LNCaP cells; its action remained relatively low. Interestingly, excepting the beta-catenin promoter, we measured strong activities of all promoters in lung fibroblast cells. Our study demonstrates that promoter activity should be evaluated not only for the target cells of the gene therapeutic approaches, but also for neighbouring normal tissues. Unspecific but repressible promoters could represent an alternative.

Absence of simian virus 40 DNA sequences in primary central nervous system lymphoma in HIV-negative patients.

Simian virus 40 (SV40) is known to induce primary brain tumors and lymphomas in animal models. Recently, it was also associated with the pathogenesis of human non-Hodgkin's lymphomas. In the present study, we investigated primary central nervous system lymphomas (PCNSL), a defined subgroup of diffuse large B-cell lymphoma confined to the central nervous system, for the presence of SV40 DNA. Frozen tissue samples of 23 PCNSL derived from human immunodeficiency virus-negative patients were analyzed by two different, fully nested polymerase chain reaction protocols. SV40 DNA sequences could not be detected in any of these samples. Thus, SV40 can be added to the list of viruses that have already been excluded as pathogenetically relevant cofactors in PCNSL.