Faculty Bibliography

Normal human mesothelial cells from individual donors were studied for susceptibility to asbestos-induction of apoptosis and generation of an extended lifespan population. Such populations were generated after death of the majority of cells and arose from a subset of mesothelial cultures (4/16) whereas fibroblastic cells (5/5) did not develop extended lifespan populations after asbestos exposure. All mesothelial cultures were examined for the presence of SV40 T antigen to obtain information on (i) the presence of SV40 T antigen expression in normal human mesothelial cells and (ii) the relationship between generation of an extended lifespan population and expression of SV40 T antigen. Immunostaining for SV40 T antigen was positive in 2/38 normal human mesothelial cultures. These cultures also had elevated p53 expression. However, the two isolates expressing SV40 T antigen did not exhibit enhanced proliferative potential or develop an extended lifespan population. Asbestos-generated extended lifespan populations were specifically resistant to asbestos-mediated but not to alpha-Fas-induced apoptosis. Deletion of p16Ink4a was shown in 70% of tumor samples. All mesothelioma cell lines examined showed homozygous deletion of this locus which extended to exon 1beta. Extended lifespan cultures were examined for expression of p16Ink4a to establish whether deletion was an early response to asbestos exposure. During their rapid growth phase, extended lifespan cultures showed decreased expression of p16Ink4a relative to untreated cultures, but methylation was not observed, and p16Ink4a expression became elevated when cells entered culture crisis. These data extend the earlier observation that asbestos can generate extended lifespan populations, providing data on frequency and cell type specificity. In addition, this report shows that generation of such populations does not require expression of SV40 T antigen. Extended lifespan cells could represent a population expressing early changes critical for mesothelioma development. Further study of these populations could identify such changes

In this report we examine the ability of a recombinant tumor antigen preparation to prevent the establishment of experimental pulmonary metastasis. Baculovirus-derived recombinant simian virus 40 (SV40) large tumor antigen (T-Ag) was injected into BALB/c mice followed by challenge with an intravenous injection of syngeneic SV40-transformed tumorigenic cells. The experimental murine pulmonary metastasis model allows for the accurate measurement of metastatic lessions in the lungs at various times after the challenge, using computer-assisted video image analysis. Following challenge, lung metastasis and survival data for the groups of mice were obtained. Animals immunized with recombinant SV40 T-Ag showed no detectable sign of lung metastasis and survived for more than 120 days after challenge. Antibodies specific for SV40 T-Ag were detected in the serum of immunized mice by enzyme-linked immunosorbent assay. Splenocytes obtained from mice immunized with recombinant SV40 T-Ag did not lyse syngeneic tumor cells, indicating that no cytotoxic T lymphocyte response was induced. Control mice developed extensive lung metastasis and succumbed to lethal tumor within 4 weeks after challenge. These data indicate that immunization with the recombinant SV40 T-Ag induces protective, T-Ag-specific immunity in an experimental pulmonary tumor metastasis model

The International Registry of Lung Metastases was established in 1991 to asses the long-term results of pulmonary metastasectomy. The Registry has accrued 5206 cases of lung metastasectomy, from 18 departments of thoracic surgery in Europe (n = 13), USA (n = 4) and Canada (n = 1). Of these patients 4572 (88%) underwent complete surgical resection. The primary tumor was epithelial in 2260 (43%), sarcoma in 2173 (42%), germ cell in 363 (7%), and melanoma in 328 (6%) patients. The disease-free interval was 0 to 11 months in 1729 (33%) cases, 12 to 35 months in 1857 (36%) and more than 36 months in 1620 (31%). Single metastases accounted for 2383 (46%) cases and multiple lesions for 2726 (52%). Mean follow up was 46 months. Analysis was performed by Kaplan-Meier estimates of survival, relative risk of death and multivariate Cox model. The actuarial survival after complete metastasectomy was 36% at 5 years, 26% at 10 years and 22% at 15 years (median 35 months); the corresponding values for incomplete resection were 13% at 5 years and 7% at 10 years (median 15 months). Among complete resections, the 5-year survival was 33% for patients with a disease free-interval of 0 to 11 months and 45% for those with a disease-free interval of more than 36 months; 43% for single lesions and 27 for four or more lesions. Multivariate analysis showed a better prognosis for patients with germ cell tumors, disease-free interval of 36 months and more and single metastases. These results confirm that lung metastasectomy is a safe and potentially curative procedure

BACKGROUND: A cohort (20%) of patients with mesothelioma will not have an exposure to asbestos. Recently, a DNA tumor virus (simian virus 40) has been shown to cause hamster mesotheliomas; we previously described simian virus 40-like DNA amino terminus sequences in 29 of 48 mesotheliomas. We analyzed an additional 42 mesotheliomas to determine (1) whether our initial observations were durable and (2) the extent to which the simian virus 40 genome is present in mesotheliomas. METHODS: Genomic DNA was extracted from snap frozen mesothelioma tumor samples and from the simian virus 40-induced hamster mesothelioma tumor H9A. Polymerase chain reaction primers were used to amplify various simian virus 40 large T-antigen regions including a 105-base pair amino terminus fragment, a 281-base pair carboxyl terminus fragment, and a 310-base pair fragment of the enhancer promoter region. Endonuclease digestions and Southern blotting were used to verify the expected product. RESULTS: Thirty of the 42 (71%) samples amplified T-antigen amino sequences, and specificity was verified by Southern hybridization. Sixteen of 42 samples (38%) amplified the appropriate size fragment for the carboxyl terminus, and digestion with BsaB1 matched that of H9A. Twenty-two of 42 samples (52%) amplified simian virus 40 regulatory sequences and Fok1 digestion matched that of the hamster control tumor. Sequence analysis (4 patients) revealed 100% homology with the regulatory region of simian virus 40 strain 776. CONCLUSIONS: These data suggest an association between the simian virus 40 virus and human mesothelioma that could be exploited for diagnostic/therapeutic options including early detection and potential vaccination strategies

BACKGROUND: The role for reoperative pulmonary metastasectomy in patients with 'pediatric sarcomas' (osteosarcoma, nonrhabdomyosarcoma-soft tissue sarcoma, and Ewing's sarcoma) is undefined. METHODS: We reviewed our results for patients with these histologic presentations (median age, 17.5 years; range, 6 to 32 years) having two (70), three (27), or four (10) metastasectomies between January 1965 and March 1995 to define postresection survival and potential prognostic factors. Simple wedges (88 thoracotomies, 84%) were performed more frequently than anatomic (17 thoracotomies, 16%) resections. RESULTS: With a median potential follow-up of 12.7 years, median survival was 2.25, 3.60, and 0.96 years from the second, third, and fourth explorations, respectively. Primary tumor site, sex, histology, age, maximal metastasis size, and systemic chemotherapy did not influence survival. Resectability was the most important prognostic factor (5.6 versus 0.7 years, 5.2 versus 2.5 years, 2.2 versus 0.2 years, resectable versus unresectable, median survival from second, third, and fourth thoracotomy, respectively). Unresectability, disease-free interval less than 6 months between initial (ie, first) pulmonary resection and the second thoracotomy, and two or more preoperative nodules noted on the right were simultaneously negatively associated with survival from the second thoracotomy. Unresectability or finding two or more metastases negatively affected survival from the third thoracotomy. CONCLUSIONS: These data imply that repeat metastasectomy can salvage a subset of patients with sarcomatous pediatric histologic presentations who retain favorable prognostic determinants

Simian virus 40 (SV40) is an oncogenic virus which induces tumors in hamsters and transforms human cells in tissue culture. Between 1955 and 1963, polio vaccines and adenovaccines were contaminated with SV40; therefore, millions of people were exposed to this oncogenic virus. The SV40 proteins responsible for in vivo oncogenesis and in vitro cell transformation are encoded by the early region of the virus. These proteins are called T (tumor) antigens (Tags), because animals with tumors induced by SV40 have antibodies against these viral proteins. Recently, we and other research laboratories have found SV40 in specific types of human tumors: mesothelioma, ependymoma and choroid plexus tumors, osteosarcoma and sarcoma. The same tumor types will develop in hamsters which have been injected systemically with SV40. SV40 causes cell transformation in tissue culture and tumors in animals, because SV40 Tag binds and inactivates the cellular tumor suppressor gene products, Rb and p53. We found that SV40 Tag binds p53 and Rb in human mesotheliomas, possibly contributing to the malignant phenotype

Simian virus (SV) 40 is a deoxyribonucleic acid (DNA) virus that induces mesotheliomas, ependymomas, bone tumors, and lymphomas in hamsters. In recent years SV40 sequences have been detected in approximately 60% of mesotheliomas and ependymomas, in 33% of bone tumors and sarcomas, and in 13% of lymphomas. Because the amount of human specimens available for molecular studies is usually minimal, the method most commonly used to demonstrate SV40 in human specimens is the polymerase chain reaction (PCR). PCR is a highly sensitive and useful technique. In the PCR reaction, different sets of primers are used for targeting different regions of DNA. The regions of the SV40 genome targeted by PCR include the large T-antigen, the small t-antigen, the origin of replication, and viral protein-1 capsid protein. The use of these different sets of primers to test human tumor specimens for SV40 produce a different percentage of positive results. This is because these experiments revealed that some primers are more specific than others which may also detect sequences belonging to other DNA papovaviruses. Therefore, the combined use of different sets of primers is recommended when it is important to distinguish SV40 from other related papovaviruses such as BK and JC, which can also be occasionally present in human cells. Furthermore, these experiments demonstrated that polymerase chain reaction analyses for simian virus 40 can be performed better and easier when using deoxyribonucleic acid extracted from fresh and/or frozen tissue. Deoxyribonucleic acid from paraffin embedded specimens should not be used routinely for simian virus 40 testing because of the high risk of obtaining false negative results. However, these paraffin derived deoxyribonucleic acids can be used reliably in molecular laboratories specialized in these type of analyses. This paper describes the methods that we have developed to test simian virus 40 in human specimens

The management of pulmonary metastases remains controversial. More information is available, however, on outcomes in larger series of patients undergoing metastasectomy as well as the indications for the procedure. The role of video-assisted thoracic surgery for the diagnosis and management of these patients is being scrutinized carefully. Isolated perfusion techniques for treating patients with unresectable pulmonary metastases have been applied in phase I and II trials at selected institutions. More data regarding clinical outcomes are necessary, however, before widespread adaptation of this experimental form of treatment is accepted as standard practice