Faculty Bibliography

Malignant mesothelioma, a tumor of the pleura, pericardium, and peritoneum, is presently a worldwide problem. Current therapy is ineffective in slowing the course of the disease, and median survival from the time of diagnosis is rarely greater than 1 year. While the tumor was almost unknown prior to the second half of the twentieth century, it is presently responsible for more than 2000 deaths per year in the US alone. Mesothelioma is frequently associated with exposure to asbestos, but the incidence of cases involving individuals with low levels of asbestos exposure is increasing. For this reason, there has been much interest in studying whether there are alternative factors that act alone or in conjunction with asbestos in producing this malignancy. In the last decade, simian virus 40 (SV40) has become the most notable suspected agent

Many of these deaths could be prevented if there were better screening methods to uncover the disease when it is limited and most responsive to intervention. Novel biomarkers of early-stage disease are therefore needed. By applying the principle of 'oncology recapitulates ontogeny', we have discovered three homeobox (HOX) genes that are inappropriately expressed in the majority of lung tumors. Understanding the role of these inappropriately expressed genes in lung epithelial cell carcinogenesis may not only augment early detection, but may also offer new avenues of treatment of this disease

Mesothelioma, a malignancy associated with asbestos, has been recently linked to simian virus 40 (SV40). We found that infection of human mesothelial cells by SV40 is very different from the semipermissive infection thought to be characteristic of human cells. Mesothelial cells are uniformly infected but not lysed by SV40, a mechanism related to p53, and undergo cell transformation at an extremely high rate. Exposure of mesothelial cells to asbestos complemented SV40 mutants in transformation. Our data provide a mechanistic explanation for the ability of SV40 to transform mesothelial cells preferentially and indicate that asbestos and SV40 may be cocarcinogens

Accumulating data demonstrate overexpression of both inducible NO synthase (NOS2) and cyclooxygenase-2 (COX2) in many epithelial neoplasias. In addition, cyclooxygenase inhibitors have been shown to have antineoplastic and prophylactic efficacy against human colon cancer and in mouse models of this disease. Mesothelioma arises in a context of asbestos exposure and chronic inflammation, which would be expected to enhance the expression of these inducible enzymes. This study demonstrates that both inducible enzymes were expressed in 30 human mesothelioma tissues but were not detectable in nonreactive mesothelial tissues from the same individuals. In contrast, areas of reactive mesothelial cells stained positively for these enzymes. In vitro exposure of human mesothelioma cell lines to the COX2 inhibitor, NS398, revealed dose- and time-dependent antiproliferative activity, whereas the NOS2 inhibitor, 1400W, had no detectable inhibitory effect. Surprisingly, nonmalignant human mesothelial isolates expressed both NOS2 and COX2 in vitro at the same level as mesothelioma cell lines but were less sensitive to NS398 inhibition. This finding indicates that these nonmalignant isolates may retain properties of reactive mesothelial cells and suggests that targets in addition to COX2 may be involved in the antiproliferative response of mesothelioma cell lines. These results have clinical significance because of the selective activity of the drug coupled with the therapeutic resistance and poor prognosis of mesothelioma. The findings presented here suggest that further preclinical studies of these inhibitors in animal models of mesothelioma would be of great interest

Mesotheliomas are malignancies of the pleural, pericardial, and peritoneal surfaces with a mean survival of less than 1 year from the time of diagnosis (1). While mesotheliomas were extremely rare in the first half of this century, the incidence of these tumors has increased enormously in the last several decades. Presently, 2-3 thousand people in the US develop and die of mesothelioma each year (1). It is estimated that approximately 80% of mesotheliomas develop in people with a history of occupational asbestos exposure or in individuals with family member(s) professionally exposed to asbestos that brought home fibers on their clothing (1). Although conventional wisdom dictates that asbestos is the most commonly associated 'environmental' factor with mesothelioma, asbestos does not transform human mesothelioma cells in tissue culture (2). This suggests that additional carcinogens act in concert with asbestos to cause mesothelioma. Recent evidence indicated that Simian Virus 40 (SV40) preferentially causes mesotheliomas in hamsters, and that SV40 is present in up to 80% of human mesotheliomas in the US and in Europe (reviewed in ref. 3 and 4)

BACKGROUND: PCR amplification of target molecules involves sequence specific primers that flank the region to be amplified. While this technique is generally routine, its applicability may not be sufficient to generate a desired target molecule from two separate regions involving intron /exon boundaries. For these situations, the generation of full-length complementary DNAs from two partial genomic clones becomes necessary for the family of low abundance genes. RESULTS: The first approach we used for the isolation of full-length cDNA from two known genomic clones of Hox genes was based on fusion PCR. Here we describe a simple and efficient method of amplification for homeobox D13 (HOXD13) full length cDNA from two partial genomic clones. Specific 5' and 3' untranslated region (UTR) primer pairs and website program (primer3_www.cgv0.2) were key steps involved in this process. CONCLUSIONS: We have devised a simple, rapid and easy method for generating cDNA clone from genomic sequences. The full length HOXD13 clone (1.1 kb) generated with this technique was confirmed by sequence analysis. This simple approach can be utilized to generate full-length cDNA clones from available partial genomic sequences

Simian virus 40 (SV40) causes mesotheliomas, osteosarcomas, ependymomas, choroid plexus tumors, and lymphomas in hamsters. In humans, SV40 has been detected in tumors of the first four types. Using the polymerase chain reaction (PCR), we tested 29 non-Hodgkin's lymphomas (intermediate and high-grade), 25 posttransplant lymphoproliferative disorders, and 5 AIDS lymphomas for SV40 DNA. PCR analysis revealed that 3 of 29 lymphomas, 6 of 25 posttransplant lymphoproliferative disorders, and 2 of 5 AIDS lymphomas contained SV40 sequences corresponding to the retinoblastoma (RB)-pocket binding domain of SV40 tumor antigen (Tag). However, among positive samples, only one posttransplant lymphoproliferative disorder and one AIDS lymphoma contained the SV40 regulatory region, which suggest a higher viral load in these patients. In parallel experiments, 8 of 12 mesotheliomas tested positive for SV40 for both the RB-pocket binding domain of Tag and the SV40 regulatory region. These data confirm the presence of SV40 in most United States mesotheliomas and indicate that in human non-Hodgkin's lymphomas, the prevalence of SV40 is low