Mesothelioma, asbestos, and reported history of cancer in first-degree relatives

BACKGROUND

Although malignant mesothelioma is known to be strongly related to asbestos exposure, its relationship to familial factors is unclear.

METHODS

We compared reported histories of cancer in first-degree relatives, obtained from telephone interviews with the next-of-kin of 196 patients who had a pathologic diagnosis of mesothelioma, and with those from 511 decreased controls.

RESULTS

Among men exposed to asbestos, we found a statistically significant twofold elevation in the risk of mesothelioma for patients reporting cancer in two or more first-degree relatives. We found no significant elevation in women or among the small number of men without asbestos exposure. The next-of-kin of three patients (but no controls) reported a possible mesothelioma in a first-degree relative; asbestos exposure could not be ruled out in those relatives. Associations of asbestos with pleural mesothelioma were stronger among men with a reported family history of cancer than men without, although no statistical evidence of an interaction was detected.

CONCLUSIONS

These results provide suggestive, but limited, evidence that a family history of cancer may be a risk factor for mesothelioma, or may indicate an increased susceptibility to mesothelioma given asbestos exposure.

Frequent involvement of chromosome 3p alterations in lung carcinogenesis: allelotypes of 215 established cell lines at six chromosome 3p loci

We have determined the allelotypes of 215 established lung cancer cell lines by PCR analysis at six loci on the short arm of chromosome 3 (3p): D3S3 (3p12-p13), D3S30 (3p13), D3S2 (3p14-p21.1), D3S32 (3p21), D3F15S2 (3p21), and THRB (3p24). Eighty-seven small cell lung cancer (SCLC), 93 non-small cell lung cancer (NSCLC), 6 extrapulmonary SCLC, 6 mesothelioma, and 23 normal B lymphocyte (BL) cell lines were analyzed. Low levels of heterozygosity at all six 3p loci were seen in both the SCLC and NSCLC cells. SCLC cell lines exhibited the lowest frequencies of heterozygosity at D3S3 (3%), D3S2 (3%), D3F15S2 (10%), and THRB (6%) when compared with frequencies of 8, 42, 48, and 34% at these same loci in the normal population. The lowest frequencies of heterozygosities among the NSCLC cell lines were seen at D3S3 (5%), DF15S2 (17%), and THRB (15%). Adenocarcinoma (Ad) was the only subtype of NSCLC that exhibited any heterozygosity (7%) at D3S3. In addition to D3S3, the lowest frequencies of heterozygosity were seen at D3F15S2 for Ad (9%), D3S2 for large cell carcinomas (8%), and THRB for adenosquamous (0%), bronchioloalveolar (0%), and large cell (8%) carcinomas. In summary, the 3p chromosome region near the D3S3 locus (3p12-p13) appears to be involved in all forms of lung cancer with additional involvement of regions close to the D3S2 (3p14-p21.1), D3F15S2 (3p21), and THRB (3p24) loci.

In vitro and in vivo studies of mesothelioma

Pleural mesothelioma is an asbestos-related malignancy characterized by progressive local growth, late metastases, and median survivals between 8 and 18 months. It is only recently that the in vitro and in vivo characteristics of the malignancy has been investigated. These investigations have been aided by the development of cell lines from patients with the disease, as well as lines developed from asbestos-exposed animals. Nude mouse models constructed with subcutaneous, intraabdominal, or intrathoracic innoculation of cultured cell lines or fresh tumor have been used for evaluating response to innovative therapies. Karyotyping has been performed on a number of cell lines and multiple abnormalities involving many chromosomes have been identified. Aneuploidy is commonly seen, along with reported non-random patterns of chromosomal aberrations. The role of tumor suppressor genes, including p53 is controversial. Multiple growth factors including PDGF are being investigated for a possible paracrine/autocrine loop, and PDGF receptors seem to be differentially expressed in mesothelioma cells compared to normal mesothelial cells. The role of cytokines in the pathophysiology of the disease, secreted either by the tumor cells themselves or by monocyte/macrophages in the local tumor environment, remains to be defined.

High frequency of inactivating mutations in the neurofibromatosis type 2 gene (NF2) in primary malignant mesotheliomas

Malignant mesotheliomas (MMs) are aggressive tumors that develop most frequently in the pleura of patients exposed to asbestos. In contrast to many other cancers, relatively few molecular alterations have been described in MMs. The most frequent numerical cytogenetic abnormality in MMs is loss of chromosome 22. The neurofibromatosis type 2 gene (NF2) is a tumor suppressor gene assigned to chromosome 22q which plays an important role in the development of familial and spontaneous tumors of neuroectodermal origin. Although MMs have a different histogenic derivation, the frequent abnormalities of chromosome 22 warranted an investigation of the NF2 gene in these tumors. Both cDNAs from 15 MM cell lines and genomic DNAs from 7 matched primary tumors were analyzed for mutations within the NF2 coding region. NF2 mutations predicting either interstitial in-frame deletions or truncation of the NF2-encoded protein (merlin) were detected in eight cell lines (53%), six of which were confirmed in primary tumor DNAs. In two samples that showed NF2 gene transcript alterations, no genomic DNA mutations were detected, suggesting that aberrant splicing may constitute an additional mechanism for merlin inactivation. These findings implicate NF2 in the oncogenesis of primary MMs and provide evidence that this gene can be involved in the development of tumors other than nervous system neoplasms characteristic of the NF2 disorder. In addition, unlike NF2-related tumors, MM derives from the mesoderm; malignancies of this origin have not previously been associated with frequent alterations of the NF2 gene.

[Correlation between sensitivity of the cytogenetic and cytological analysis and thoracoscopic findings in the study of malignant pleural effusions]

We studied 104 patients with pleural effusion. All underwent thoracoscopic exploration to allow direct examination of any pleural lesions present. At the same time pleural biopsies for histopathologic study and samples of pleural fluid for cytopathologic and cytogenetic study were taken. The volume of fluid in pleural cavity was also measured. The aims of the study were: a) to evaluate the sensitivity of cytogenetic analysis and cytopathology, both separately and together, and b) to look for a correlation between the sensitivity of these cell studies and the following thoracoscopic findings: tissue biopsy of pleural neoplasms, volume of pleural effusion and extension of neoplastic lesions in the pleural cavity. Seventeen of the pleural liquids studied were benign and 87 were neoplastic. Cytopathology was sensitive in 55% of the neoplastic cases and cytogenetic study was sensitive in 49%. Sensitivity rose to 74% when both techniques were applied. Cytogenetic study yielded a higher percentage of correct diagnoses in the group with hematologic neoplasia, whereas cytopathology was correct more often in cases of solid tumors, though these differences were not statistically significant. Use of both techniques resulted in correct diagnosis in 92% of patients with mesotheliomas. The number or correct diagnoses achieved with cytopathology tended to increase with size of macroscopic pleural lesion whereas cytogenetic study was more sensitive in patients with minimal or incipient pleural involvement. There were no statistically significant differences in sensitivity of cytopathology and cytogenetic analysis with regard to volume of pleural effusion.

Role of Epstein-Barr virus in pleural lymphomagenesis

Longstanding inflammation in chronic pyothorax (CP) plays a role in the development of pleural lymphoma; therefore, in 1987, the term pyothorax-associated lymphoma (PAL) was proposed. A recent study showed in the tumor cells of a limited number of patients, the presence of the Epstein-Barr virus (EBV) genome together with the expression of latent infection genes in the tumor cells of PAL. The purpose of the present study is to evaluate an association of EBV with PAL in a large number of patients. In addition, the presence of the EBV genome was examined in cases with CP without PAL. Histologic, immunohistochemical studies, and analyses by polymerase chain reaction (PCR) and in situ hybridization method for EBV were performed on 34 PAL and 16 CP collected by nationwide study. Median age of the patients in both diseases was approximately 70 years with a marked preponderance in men. Mean duration of CP in patients with CP alone and with CP complicated with PAL was 33 and 37 years, respectively. Histologically all PAL were non-Hodgkin's lymphoma, with immunoblastic type being the most common. Immunohistochemistry revealed 28 of 34 PAL to be B-cell type. Combined PCR, in situ hybridization method, and immunohistochemistry showed that the EBV genome was detected in lymphoma cells in 85% of PAL with almost constant expression of latent membrane protein-1. The EBV genome was detected by PCR in only one of 16 CP.(ABSTRACT TRUNCATED AT 250 WORDS)

Pleural-based mesothelioma in immune competent rats: a model to study adenoviral gene transfer

BACKGROUND

Despite multimodality approaches, pleural-based malignant mesothelioma remains a disease with a very poor prognosis. Novel therapeutic strategies such as gene therapy clearly are needed to improve the survival of patients with this neoplasm. To aid in the evaluation of new treatment strategies, animal models that closely mimic human disease are required. This article describes the establishment of a pleural-based model of malignant mesothelioma in immune-competent Fischer rats.

METHODS

Via a modified left anterior lateral thorocotomy, a syngeneic malignant mesothelioma cell line, called II-45, was placed into the pleural cavity of Fischer rats.

RESULTS

Placement of II-45 cells into the pleural cavity of Fischer rats results in a model of pleural mesothelioma that closely resembles the disease seen in patients and is highly reproducible, with animals dying within 1 month. We also demonstrate the feasibility of adenoviral-mediated gene transfer to normal mesothelial cells lining the pleural cavity, as well as to malignant cells deep within the substance of pleural-based malignant mesothelioma.

CONCLUSIONS

The model described here offers the opportunity to study a variety of new treatment modalities, especially somatic gene transfer, against pleural-based malignant mesothelioma in an immune competent setting.

Malignant pleural mesothelioma: newer aspects of carcinogenesis, molecular genetics, and prospects for future therapies

Malignant pleural mesothelioma (MPM) is an asbestos-related disease which, although rare, is having a major social impact, and is, for the majority of cases, an incurable illness. There has been a surge of information regarding data on mesothelial transformation, mesothelioma molecular genetics and somatic gene therapy for this disease. This report summarizes the most recent investigations attempting to characterize the behaviour, on a cellular and molecular level, of MPM, with an emphasis on data from investigations performed at the National Cancer Institute with our collaborators.

Cytogenetic and DNA analysis of two neuroectodermal tumors without a simple t(11;22)

Cytogenetic analysis was conducted on tumor biopsy material from two pediatric, small, round, blue-cell tumors whose histology failed to give a clearcut diagnosis. The first case showed a complex composite karyotype within which there were two normal chromosomes 11 and one abnormal chromosome 22 present. The composite karyotype in the second case was similarly complex but this time included an abnormal chromosome 11 but no corresponding abnormal chromosome 22. Analysis of tumor mRNA from both cases using a Reverse Transcriptase PCR test with primers derived from a Ewing's sarcoma t(11;22)(q24;q12) breakpoint sequence showed both to have abnormal, chimeric transcribed messengers, each of different lengths. Further analysis of case 2 using chromosome painting and centromeric probing confirmed the abnormal chromosome 11 to be a der(11)t(11;22)(q24;q12) and also revealed two additional minor clones containing a der(22), which may be the karyotypic locations of the t(11;22) fusion sequences. Taken into consideration with clinical and histologic information, the results of these investigations indicated that both were neuroectodermal tumors (Ewing sarcomas of the chest wall/Askin tumors). The comparative values of both cytogenetic and molecular analysis in the diagnosis of neuroectodermal tumors and the detection of covert chromosome rearrangements are discussed.

Characteristics of nine newly derived mesothelioma cell lines

This report characterizes nine new cell lines derived from patients with malignant pleural mesothelioma. The lines were initiated between July 1990 and July 1992 from solid tumors (5 lines) or effusions (4 lines) and had proliferated for a period of at least 2 months without senescence. They were characterized by cell size, doubling time, immunohistochemical analyses, electron microscopy, and chromosomal karyotyping. Growth factor/cytokine elaboration was determined using enzyme-linked immunoassays. The established lines were similar in morphology to their parent tumor (ie, epithelial or sarcomatoid). Cell sizes ranged from 59 to 81 microns, and the doubling times varied from 31 to 65 hours. The lines stained with cytokeratin and showed expected negative staining for adenomarkers including B72.3 and carcinoembryonic antigen. All cell lines exhibited aneuploidy, with modal chromosome numbers between 40 and 81 and had multiple chromosomal aberrations. Significant production of granulocyte-monocyte colony-stimulating factor, leukemia inhibitory factor, platelet-derived growth factor, and interleukin-6 was seen. These new cell lines derived from human mesotheliomas can now be used to aid in the design of innovative treatment strategies.

Biological and immunological aspects of malignant mesothelioma

Malignant mesothelioma (MM) is an aggressive tumour, which is strongly associated with previous asbestos exposure and is resistant to all conventional anticancer therapies. An understanding of the biological properties of MM may provide insights into useful therapeutic strategies, and MM cell lines and animal models have been major contributors to our current knowledge of this tumour. Although karyotypic abnormalities are frequent, there is no clear evidence of a mesothelioma-specific chromosomal aberration. Similarly, there is no evidence of activation or over-expression of a known oncogene, or of the inactivation of currently identified tumour suppressor genes. A number of growth factors, including platelet derived growth factors A and B (PDGF-A and -B), insulin-like growth factor I and transforming growth factor-beta (TGF-beta), and some of their receptors, have been reported to be expressed by MM cells, and each has the potential to play a role as a growth stimulant for MM or to modify immune responses to the tumour. Some data support an autocrine role for PDGF-A. MM cell lines are susceptible to lysis by a variety of immune effector cells, and their growth can often be inhibited by cytokines. The possibility of stimulating an immune response to MM by genetic manipulation of the tumour cells has been investigated using a murine model. The data so far suggest that transfection of allogeneic class I major histocompatibility complex genes or syngeneic class II genes alone is unlikely to induce protective immunity.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of numerical chromosomal aberrations in paraffin-embedded malignant pleural mesothelioma by non-isotopic in situ hybridization

An in situ hybridization (ISH) study on paraffin sections of 13 malignant mesotheliomas was performed to detect numerical chromosomal aberrations with biotin-labelled DNA probes specific for the centromeric regions of chromosomes 1, 3, 6, 7, 11, and 17. All chromosomes contributed to numerical changes, which can be summarized as follows: first, a monosomy for chromosome 6 was found in one case; second, in five cases a trisomy for at least one chromosome was detected; and third, in seven cases a pentasomy or a higher polysomy was found for at least one chromosome. Although these data have to be confirmed on a larger group of patients, survival analysis of this group showed no significant difference between the first and second groups taken together and the third group. In this study no specific numerical chromosomal aberrations were identified. Nevertheless, numerical gains appear to be more frequent than has previously been shown by karyotype analysis.

Prognostic significance of DNA aneuploidy in diffuse malignant mesothelioma

DNA ploidy of pepsin digested preparations of 48 paraffin-embedded specimens from 19 patients with histologically confirmed malignant mesothelioma was determined by laser flow cytometry. Eight of the 19 tumors (42%) were diploid and 11 (58%) were aneuploid. Of the aneuploid tumors, only one showed multiploidy. The median survival time of the patients with diploid tumors was 19, 16, and 14 months from the onset of symptoms, diagnosis, and treatment, respectively. The median survival in patients with aneuploid tumors was 8, 7, and 7 months from the onset of first symptoms, diagnosis, and treatment. Thus, patients with diploid tumors lived longer than patients with aneuploid tumors. These results suggest that DNA ploidy analysis may be of prognostic value in malignant mesothelioma.

Epstein-Barr virus-associated primary malignant lymphomas of the pleural cavity occurring in longstanding pleural chronic inflammation

Primary pleural non-Hodgkin's lymphomas (NHLs) have been described mostly in Japan and occasionally in western countries. We report three cases occurring in nonimmunocompromised patients demonstrating close similarities to the Japanese cases. These lymphomas occurred more than 20 years after thoracoplasty for the treatment of pleural or pulmonary tuberculosis. They were all high grade lymphomas of B phenotype (two immunoblastic with plasmocytoid differentiation and one immunoblastic with anaplastic large cells). In situ hybridization (ISH) detected small nuclear RNAs encoded by Epstein-Barr virus (EBERs) in most lymphomatous cells in all cases. This suggests a link between primary pleural lymphoma and the longstanding chronic inflammation, which could favor a clonal evolution of Epstein-Barr virus (EBV)-infected B cells through the production of growth factors or immunosuppressive cytokines produced by inflammatory cells.

Biologic Charachterization of Pleural Metastases from Lung Adenocarcinoma: Description of the New DV90 Cell Line

Aims and background

The characterization of pleural metastases from lung adenocarcinoma is often limited to single biologic features.

Methods

The present paper describes the cellular kinetic parameters, as well as immunocytochemical, ultrastructural and genetic characteristics of the new DV90 cell line, established from the pleural effusion of a stage IV lung adenocarcinoma.

Results

The cell line has a diploid DNA content, a doubling time of 24 h and 7% cloning efficiency, it is tumorigenic in nude mice. Ultrastructural investigation revealed the typical features of lung adenocarcinoma; the diagnosis was confirmed by its immunohistochemical reactivity with a panel of monoclonal antibodies specifically capable of identifying adenocarcinoma cells. Genetic analysis revealed a 46 X, –Y, +8, der (6)t(6?)(q27;?) karyotype and hyperexpression of the protein codified by genes Her2/Neu and p53.

Conclusion

The importance of multidisciplinary biologic characterization in identifying the origin and biological behavior of pleural metastases deriving from lung adenocarcinoma is discussed.

Cytogenetic analysis of effusions from malignant mesothelioma. A diagnostic adjunct to cytology

Most patients with malignant mesothelioma (MM) present with an effusion, but distinguishing malignant from reactive mesothelial cells by conventional cytology may be difficult. We investigated the possibility of identifying clonal cytogenetic aberrations in pleural or peritoneal fluid from 10 patients with a clinical suspicion of MM. Direct metaphase harvests and short-term cultures were performed on fresh fluid. Clonal cytogenetic aberrations indicative of malignancy, with findings previously reported in association with mesothelioma, were found in all patients; these included del(1p), del(3p) and del(22q). Cytologic examination of the effusions showed malignant cells consistent with MM in 5 patients and atypical mesothelial cells suggestive of MM in 4. In one case the cytology of several samples of pleural fluid was within normal limits. Subsequent histology confirmed the diagnosis of MM in 9 of the 10 patients; medical complications precluded tissue biopsy in the 10th. We conclude that the cytogenetic analysis of effusions may be a useful and reliable adjunct to cytology in the diagnosis of MM.

Contemporary approaches in the investigation and treatment of malignant pleural mesothelioma

The cellular and molecular biology of mesothelioma is a complicated, multifactorial, incompletely understood process of carcinogenesis. Normal mesothelial cells can be transformed into a malignant phenotype by multiple factors, usually asbestos. Several tumor suppressor genes may be lost, and several oncogenes can be activated. A local environment of inflammation with associated release of cytokines may promote deregulated cell growth. The release of immunosuppressive substances such as nitric oxide may contribute to this process. The interaction of asbestos and viral DNA incorporation is unclear but warrants further investigation. In the majority of mesothelioma patients, present standard therapies have little effect on survival. Clinical trials studying a variety of innovative treatment strategies are being performed at centers with a significant referral base for the disease. Future treatments, however, must be based on understanding of the biology of mesothelioma.

Successful adenovirus-mediated gene transfer in an in vivo model of human malignant mesothelioma

Malignant mesothelioma remains a frustrating clinical problem with uniformly poor responses to current therapeutic regimens. However, the localized nature of the disease, the potential accessibility of the tumor, and the relative lack of distant metastases make it a particularly attractive candidate for somatic gene therapy. The purpose of this study was to evaluate the ability of an adenoviral vector system to transfer genetic material to human mesothelioma cells in vitro and in vivo. Using a replication-deficient recombinant adenovirus carrying the Escherichia coli lacZ marker gene, we found that human mesothelioma cell lines were susceptible to adenovirus infection. Furthermore, surprisingly effective gene transfer was accomplished within tumor implants of human mesothelioma growing within the peritoneal cavity of immunodeficient mice after intraperitoneal administration of virus. These studies demonstrate that adenoviral vectors hold promise as vehicles to deliver gene therapy in human malignant mesothelioma.

Localized fibrous tumor of the pleura: immunohistochemical and flow-cytometric DNA study

This report describes three cases of localized fibrous tumor of the pleura (LFTP) with clinical and pathological differences. Case 1 presented with symptoms; the tumor size was 6.5 cm and it was attached to the lung and chest wall; histologically it was composed of spindle cells with pleomorphism, mitoses, hemorrhage and necrosis. Cases 2 and 3 were casual findings and consisted of well-circumscribed tumors of 3 and 8.5 cm, respectively; histologically both showed hypocellularity. All cases exhibited positive stains for vimentin and negative for keratin. These results, added to histological features, suggested a mesenchymal origin. Flow cytometry quantitation of DNA disclosed a diploid pattern in all three cases with a small "near diploid" cell population additionally in Case 1; the S-phase fraction was low in all cases. These findings, that could be considered favourable prognostic signs, and the complete tumoral resection performed in the three tumors, could explain the absence of recurrences after 32, 27 and 19 months, respectively.

Recurrent deletions of specific chromosomal sites in 1p, 3p, 6q, and 9p in human malignant mesothelioma

Detailed cytogenetic analyses were carried out on primary tumor specimens and cell lines from 23 patients with pleural malignant mesothelioma (MM). Clonal abnormalities were identified in 20 of 23 MM. In 3 cases, karyotypic data were compiled from harvests of both short-term cultures (1-3 days), and primary cultures grown on murine feeder layers for several weeks. The karyotypes obtained with these 2 different culture methods were very similar, although polyploid versions of abnormal clones were found only in the long-term cultures. In addition, while short-term cultures from 9 tumor biopsies usually exhibited near-diploid clones, cell lines derived from 11 tumors tended to have higher ploidies. Each of the cytogenetically abnormal MM displayed multiple clonal alterations. The 2 most frequent changes were chromosomal losses of specific regions in 1p (17 cases) and 9p (16 cases). The shortest regions of overlap of these losses were at 1p21-p22 and 9p21-p22, respectively. Other common abnormalities included losses of 3p21 (13 cases) and 6q15-q21 (9 cases), and numerical losses of chromosomes 14, 16, 18, and 22 (each observed in 10-13 tumors). In many of the MM examined, most or all of these recurrent changes occurred in combination, suggesting the involvement of a pathogenetic cascade in this cancer. The pattern of recurrent chromosomal losses suggests that these regions represent the locations of tumor suppressor genes whose loss/inactivation may have a pivotal role in MM tumorigenesis.

Gap junctional intercellular communication of primary and asbestos-associated malignant human mesothelial cells

We examined gap junctional intercellular communication (GJIC) of primary human mesothelial cells and cell lines of asbestos-associated human pleural mesotheliomas, and the effect of asbestos and other mineral fibres on these cells. In homologous cultures, the GJIC capacity of six out of seven tumour cell lines was markedly less than for primary mesothelial cells. This defect in GJIC appeared not to be at the expression level of mRNA and protein of the gene encoding the 43 kDa gap junction protein. In heterologous cocultures of tumour cells and primary mesothelial cells, however, 80-90% of the tumour cell/normal cell contacts were functional. Exposure of primary mesothelial cells to TPA, a phorbol ester tumour promoter, resulted in marked inhibition of GJIC, being an action common to numerous tumour promoters. Such an effect though was not observed with the carcinogenic mesothelioma-inducing mineral fibres chrysotile and amosite, neither with glass wool. These results suggest that a permanent defect in GJIC capacity is a common feature of human mesothelioma cells, but how mineral fibres are involved in the process of mesotheliomagenesis is still unclear.

SV40 induces mesotheliomas in hamsters

In the course of studies to elucidate the relative contribution of simian virus 40 (SV40) large T and small t proteins during oncogenesis, we observed the appearance of pericardial and pleural tumors in 100% of Syrian hamsters injected in the pleural space with wild type SV40. When SV40 was injected via the intracardiac or intraperitoneal routes, more than 50% of hamsters developed mesothelial tumors. Macroscopic, microscopic, ultramicroscopic, and histochemical characteristics identify these neoplasms and derived cell lines as mesotheliomas and mesothelioma-derived cell lines. The SV40 genome was integrated and expressed in the mesotheliomas and derived cell lines. The absence of mesotheliomas in hamsters injected with SV40 small t deletion mutants indicates that the small t protein plays an important role in the development of SV40-induced mesotheliomas. To the best of our knowledge, this is the first definitive report of virus-induced mesotheliomas in mammals.

Familial cystic nephroma and pleuropulmonary blastoma

BACKGROUND

Cystic nephroma (CN) and pleuropulmonary blastoma (PPB) are rare tumors without any previously recognized familial association.

METHODS

Two cases of CN and one case of PPB in three siblings are reported.

RESULTS

A 27-month-old girl and a 31-month-old boy underwent nephrectomy for CN and are free of disease in the contralateral kidney 16 and 14 years later, respectively. Their 28-month-old sister underwent pleuropneumonectomy with postoperative chemotherapy for PPB and died of recurrent disease 9 months later.

CONCLUSION

To the knowledge of the authors, these cases represent the first reported familial occurrence of CN and the second of CN and PPB among siblings. The inheritance of a germline mutation predisposing to the development of these tumors is postulated.

Expression of mdr1 gene in human breast primary tumors and metastases

Expression of mdr1 gene has been evaluated in 34 tumor samples obtained from breast cancer patients who were classified according to their treatment, and clinical follow-up. No gene amplification was found. mdr1-RNA was never detected in 29 primary breast tumors including 5 samples from patients previously treated by 6 courses of 5-fluorouracil, epirubicin, cyclophosphamide (FEC). On the other hand, mdr1-RNA expression was detected in 1 local recurrence and 2 out of 3 metastases, all of them being treated and exhibiting a poor evolution. A second, untreated local recurrence remained negative. Clinical follow-up for 7 to 48 months in patients receiving chemotherapy showed that absence of mdr1-RNA could not be an accurate factor of satisfactory response to chemotherapy. But, all the patients with detectable mdr1-RNA exhibited a poor evolution and response to treatment. In conclusion, evaluation of mdr1-RNA seemed to be of little interest in primary breast tumors. However, the concomitant presence of an mdr1-RNA and a metastatic phenotype could give a new insight into the relationship between invasive and resistance properties of cancer cells. Such situations would need to be analyzed very carefully for a better utilization of chemotherapy.

DNA ploidy analysis of pleural mesotheliomas: its usefulness for their distinction from lung adenocarcinomas

The distinction of malignant mesotheliomas from adenocarcinomas with pleural involvement is often difficult, even with electron microscopic and state-of-the-art histochemical and immunologic studies. We evaluated the DNA ploidy and cell cycle of 45 clinically, morphologically, and immunohistochemically well-characterized malignant mesotheliomas to establish their ploidy profile and compared it with that of 41 pulmonary adenocarcinomas. All the cases were mucin negative and had been immunophenotyped with the following monoclonal antibodies: anti-keratin, anti-CEA, anti-Vimentin, anti-HMFG2, Leu M1 (CD15) and B72.3. Single cell suspensions from the paraffin blocks were prepared following Hedley's technique and were analyzed with a Coulter EPICS V flow cytometer. The resulting histograms were interpreted with the Multicycle software program. Five cases were excluded due to their high coefficients of variation. DNA aneuploidy was defined by the presence of more than one G0/G1 peak on the histograms obtained exclusively from the tumor sample. With this criterion, there is a possibility of missing aneuploid cases with a single aneuploid cycling population; however, fixatives and time of fixation produce such a remarkable variation in the fluorochrome uptake that any control, other than normal tissue present in the sample, was rendered unreliable. Five (14%) cases were DNA aneuploid with DNA indexes ranging from 1.2 to 1.9 (mean = 1.5). Three cases had increased S + G2/M values. Of the aneuploid cases, four were epithelial and one sarcomatous. In comparison, aneuploidy was found in 31 (75%) of the lung adenocarcinomas studied (p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Interphase cytogenetics on paraffin sections of malignant pleural mesothelioma. A comparison to conventional karyotyping and flow cytometric studies

We performed in situ hybridization (ISH) studies of malignant pleural mesotheliomas to detect numerical aberrations of chromosomes 1 and 7 in interphase nuclei of paraffin sections of 13 cases that had been analyzed previously by conventional karyotyping and flow cytometry. The hybridizations were performed with the biotin-labeled probes recognizing repetitive DNA sequences in the (peri)centromeric regions of chromosomes 1 (1q12) and 7(7cen). Application of histologic sections allowed us to analyze the tumor cells only. Comparison of the karyotype and ISH studies showed that the same chromosome copy numbers were detectable by both methods in 13 (chromosome 1) and in 12 (chromosome 7) cases evaluable by ISH. DNA indexes determined in the paraffin-embedded tumor material corresponded with the ISH findings. As compared with karyotype analysis, ISH showed a larger heterogeneity in chromosome copy numbers. The results can be divided into three groups: 1) Monosomy or disomy of chromosomes 1 and 7 was detected by both methods in two cases; 2) in four cases, disomy of both chromosome 1 and 7 was observed in most of the cells by ISH analysis, and karyotype analysis had shown clear polyploidization in three of these cases; 3) in seven cases, supernumerary copies of chromosomes 1 and/or 7 were present in an evident fraction (27-80%) of the cells analyzed by ISH, and karyotype analysis confirmed the aberrant copy numbers in five of these cases. On the other hand, ISH showed copy numbers not detected by karyotype analysis in six of the seven cases. Thus, by combining karyotype and interphase cytogenetic studies, complementary information about chromosomal aberrations in mesothelioma is obtained.

Chromosome number correlates with survival in patients with malignant pleural mesothelioma

Modal (MO) and mean (ME) chromosome numbers determined by cytogenetic analysis were compared with survival in 34 patients with diffuse malignant pleural mesothelioma. The patients with normal chromosome number and no clonal abnormalities (MO = 46) survived longer (median survival 17 months) than patients with clonal abnormalities. MO greater than 46 correlated with shorter survival (median 12 months) (p = 0.0186). The correlation was more clear between mean chromosome number (ME) and survival: the median survival of patients with ME greater than 46 was 13 months whereas that of the patients with ME less than 46 was 26 months and ME = 46 (normal chromosome number and no clonal abnormalities) 31 months (p = 0.0007). Furthermore, there was a tendency of an association between ME = 46, ME less than 46 and epithelial subtype reported to be associated with a favorable prognosis in mesothelioma. The addition of chromosome material may present a mechanism to enhance expression of genes important in the pathogenesis of mesothelioma and lead to more aggressive behavior of the tumor.

CD7 expression in malignant pleural mesothelioma

CD7 antigen was found to be expressed on malignant mesothelioma arising from the right pleura in a 15-year-old girl not only by immunostaining using monoclonal antibodies, but also by Northern blot analysis. The level of expression in this tumor was comparable to those in T-cell lines, Jurkat and CCRF-CEM. Cytogenetic analysis of the tumor showed hypodiploidy (n = 43). CD7 has been regarded as one of the hematopoietic cell markers selectively expressed on the majority of T cells and multipotential stem cells. To our knowledge, this is the first report of a non-hematopoietic tumor expressing CD7.

Abnormalities of chromosomes 7 and 22 in human malignant pleural mesothelioma: Correlation between southern blot and cytogenetic analyses

Southern blot hybridization studies were performed on 23 mesothelioma primary tumor specimens to detect chromosome 1-, 7-, and 22-specific numerical changes, gene amplifications, and gene rearrangements. The molecular findings were compared with previous cytogenetic findings. No gene rearrangements or amplifications were detected. A numerical abnormality of chromosome 7 was detected by Southern blot analysis in two cases in which no numerical abnormality had been detected by the previous chromosome study. A numerical aberration of chromosome 22 was detected in five cases, which was compatible with the cytogenetic finding of monosomy 22 in these cases. The Southern blot results for the copy numbers of chromosomes 7 and 22 were concordant with the cytogenetic findings in 65%-80% of the cases.

del(6q) as a possible primary change in malignant mesothelioma

Detailed cytogenetic and fluorescence in situ hybridization analysis of an untreated pleural malignant mesothelioma revealed two clonal cell populations, both with a single abnormality affecting chromosome 6. The majority of cells had a deletion together with an inversion of the long arm of chromosome 6, while a smaller population showed loss of this chromosome. The normal 6 was retained. Most reports show that mesotheliomas are characterized by complex karyotypes, involving numerous chromosomes. Abnormalities of chromosome 6 (particularly deletions of the long arm) are among the consistent changes. Our case apparently is the first report of a mesothelioma with a single change involving chromosome 6, which could be the primary cytogenetic change.

Malignant mesothelioma: clinical characteristics, asbestos mineralogy and chromosomal abnormalities of 41 patients

The clinical characteristics and the results of mineral fibre and cytogenetic analyses were coordinated prospectively for 41 patients with confirmed malignant pleural mesothelioma. A correlation was found between high total fibre concentration, and partial or total loss of chromosomes 1, 4 and 9 and chromosomal rearrangements involving a breakpoint at 1p11-p22. There was also a correlation between crocidolite/amosite as the main fibre type and partial or total loss of chromosomes 1, 3 and 4 and chromosomal rearrangements involving del (3p). Positive prognostic factors were female gender, low total fibre concentration (less than 10(6) fibres per g dried lung tissue), anthophyllite as the main fibre type and normal chromosome 7. In addition, we found 4 patients with malignant mesothelioma who had been exposed mainly to anthophyllite fibres (total lung fibre concentrations of 1.2, 0.4, 0.2 and 0.1 x 10(6) fibres per g dried lung tissue). This would seem to indicate that there may be a carcinogenic role for anthophyllite.

Epithelioid pleural mesotheliomas and pulmonary adenocarcinomas: a comparative DNA flow cytometric study

The DNA flow cytometric characteristics of 23 immunohistochemically and ultrastructurally proven pleural epithelioid mesotheliomas were compared with those of 41 primary pulmonary adenocarcinomas. Multiple, separate tissue blocks were analyzed from each neoplasm to assess DNA heterogeneity. All of the pleural mesotheliomas and 80% of the pulmonary adenocarcinomas manifested a homogeneous DNA ploidy (DNA stability). A significant statistical difference in the ploidy pattern between pleural mesotheliomas and pulmonary adenocarcinomas was noted (P < .001). Mesotheliomas were mostly diploid (78%) and adenocarcinomas were preponderantly aneuploid (88%). The proliferative rate and DNA indexes of the aneuploid adenocarcinomas were significantly higher than those of pleural mesotheliomas (P < .001). There was no statistical significance between the proliferative rates of diploid mesotheliomas and those of adenocarcinomas. We conclude that the DNA flow cytometric characteristics of mesotheliomas are significantly different from those of pulmonary adenocarcinomas. The clinical implications of these findings are discussed.

A new non-Hodgkin's B-cell line (DoHH2) with a chromosomal translocation t(14;18)(q32;q21)

A spontaneously growing EBV-negative B-cell line (DoHH2) was established from the pleural fluid cells of a 60-year-old man with centroblastic/centrocytic non-Hodgkin's lymphoma, that had transformed into an immunoblastic lymphoma. The pleural fluid cells and the DoHH2 cells expressed IgG lambda, were reactive with CD10 and CD19 monoclonal antibodies, and showed by cytogenetic analysis 48,XY, +7, +del(12)(q24), t(14;18)(q32;q21). Southern blot analysis of mini-satellite DNA patterns, and of rearrangements of the immunoglobulin genes and bcl-2, confirmed that the cell line was derived from the patient's clonal lymphoma cells. Direct nucleotide sequence analysis on polymerase chain reaction (PCR) products of the t(14;18) junction revealed an identical sequence for the JH-bcl-2 junction at JH6 and in the major breakpoint region of bcl-2 in both the original tumor cells and the DoHH2 cell line. The cell line was valuable as a standard quantification control for PCR analysis of the t(14;18) breakpoint. Titration experiments demonstrated the detection of up to one tumor cell in 10(5) normal blood lymphocytes.

Diploid predominance and prognostic significance of S-phase cells in malignant mesothelioma

70 histologically verified, malignant mesotheliomas were analysed by flow cytometry for DNA content and S-phase fraction (SPF) of tumour cells. 60% (42/70) were DNA diploid. 18 of the 28 aneuploid tumours were near-diploid with DNA indices of 1.3 or less. SPF could be calculated in 51 cases. SPF was significantly higher in aneuploid (median 16.0%) than in diploid tumours (median 5.6%). DNA ploidy was not a prognostic determinant; survival was the same for both aneuploid and diploid tumours. SPF, however, was significantly correlated (P = 0.039) with prognosis. Patients who had tumours with a low SPF survived almost twice as long as those with a high SPF. Thus malignant mesothelioma has a peculiar DNA ploidy pattern compared with many other solid tumours, with a predominance of diploid or near-diploid type cells. As in many other tumours, SPF may be used as a clinically relevant prognostic indicator.

[Massive exposure to asbestos and malignant mesothelioma, familial accumulation]

In a family with a remarkable aggregation of malignant mesothelioma the father, mother, and a son all died of the condition, whereas two other sons and a daughter were unaffected. From 1944 to 1961 the family produced a material that was used to fix screws in drilled holes and consisted of amosite, gypsum, and sand. This was produced in the basement of their villa and was described as being a dusty job. The father died in 1984 aged 74, the son in 1985 aged 45, and the mother in 1987 aged 79. It is concluded that there is a high risk of malignant mesothelioma after massive exposure to amosite and the risk and latency period are independent of age during the exposure.

[The mesothelial cells]

Mesothelial cells are described in situ at the surface of the pleura. Their functions are discussed, in relation with the inflammatory response to different agents (infectious agents, mineral fibres...) and with the carcinogenic transformation, particularly in relation to asbestos exposure. The mechanisms of fibrogenesis, either symphysis or pleural plaques, are not clearly understood. The numerous studies now in progress on the different steps and mechanisms of mesothelial transformation and mesothelioma genesis are summarized focusing on the most recent cytogenetic and molecular biology findings.

DNA analysis by flow cytometry in malignant pleural mesothelioma: relationship to histology and survival

In a retrospective study of 70 patients with malignant pleural mesothelioma, 168 formalin-fixed, paraffin-embedded tumour specimens were examined for DNA content by flow cytometry. In 20 patients where two or more blocks of the same tumour were available, there was considerable agreement between ploidy status and S-phase percentage in the different specimens. There were no significant differences for survival for patients who had been exposed to asbestos and those in whom no exposure could be elicited, nor for aneuploid and diploid tumours. The S-phase content was examined for different areas of the same tumour and the percentages were largely in agreement. However, those patients who had tumours with an S-phase percentage greater than the median (6 per cent) had a significantly shorter survival than those with tumours of lower S-phase percentage. Differences in DNA content and other cell cycle parameters were not associated with the histological subtypes.

Cytogenetic analysis of malignant mesothelioma

Cytogenetic analyses of 40 confirmed malignant mesotheliomas (MMs) are reported. Pleural effusion cells were studied in 90% of the cases by direct method or after culture or both. Biopsy and ascites fluid were also analyzed in some patients. A normal karyotype was found in nine cases, and complex karyotypic abnormalities were observed in 30 cases. In one case, analyzable metaphases were not obtained. The chromosomal changes were all complex and heterogeneous; no consistent presumably specific abnormality was detected. Nevertheless, two main patterns of nonrandom abnormalities were observed: 1) loss of chromosomes 4 and 22, 9p, and 3p in the most of the abnormal cases and corresponding to a hypodiploid and/or hypotetraploid modal chromosome number; and 2) gain of chromosomes 7, 5, and 20 with deletion or rearrangement of 3p as well in the hyperdiploid cases, which were a minority in our series. These findings are discussed in view of other reported cytogenetic studies of MM, asbestos exposure, and possible mechanisms of malignant transformation.

Asbestos-related malignant mesothelioma: growth, cytology, tumorigenicity and consistent chromosome findings in cell lines from five patients

Seven mesothelioma cell lines were established from clinical specimens from five patients with asbestos-related malignant pleural mesothelioma. The cells in culture show either epithelial or mixed epithelial/fibrosarcomatous growth with an average doubling time of 30 h. Giant multinucleated cells are common in all the cell lines, as well as long thin microvilli on the cell surfaces. All cell lines were cytokeratin positive and they stained negatively for monocyte-macrophage markers. All seven cell lines and one long-term tissue culture from a sixth mesothelioma patient were characterized cytogenetically. Karyotype analyses revealed complex structural and numerical abnormalities, primarily involving chromosome 1, 4, 5, 6, 7, 8, 9, 11, 12, 13 and 22. An excess of chromosome material of the short arm of chromosome 5 was seen consistently in six cell lines and in the long-term culture. In cell lines from four patients, changes in chromosome 13, mainly monosomy 13, were observed. The marker chromosomes observed in the early passages were conserved and few additional changes appeared in later passages. Six of the cell lines tested for tumorigenicity in athymic nude mice were weakly positive.

Serum-dependent growth patterns of two, newly established human mesothelioma cell lines

Two cell lines with different in vitro growth patterns were established from the pleural fluid of a patient with malignant epithelial pleural mesothelioma. The cell line established in RPMI 1640 supplemented with human AB serum had an epithelial morphology, while the cell line established in fetal calf serum-supplemented medium had a fibroblast-like morphology. Exposure of the fibroblast-like cell line to human AB serum-containing medium resulted in a nearly complete transformation of the morphology to the epithelial-like phenotype, and the epithelial-like cell line changed its phenotype to fibroblast-like upon exposure to fetal calf serum-supplemented medium. Both cell lines formed colonies in soft agarose and secreted hyaluronic acid into the culture medium. In both cell lines all the metaphases studied lacked chromosomes 5 and 9, demonstrating the same clonal origin. However, one marker and a missing chromosome 11 were found only in the fibroblast-like cell line. We conclude that human AB serum supplement can be used for the establishment of human tumor cell lines, and that the choice of serum can affect the in vitro morphology of the established mesothelioma cell lines. The mechanisms behind the different growth patterns seem to be a selective stimulation of different subpopulations of malignant cells as well as induction of changes in the morphology of individual cells.

Recurring loss involving chromosomes 1, 3, and 22 in malignant mesothelioma: possible sites of tumor suppressor genes

Cytogenetic analysis was performed on short-term cultures of primary tumor tissue obtained from five patients with pleural malignant mesothelioma. Clonal karyotypic abnormalities were detected in four patients, none of whom had received cytotoxic therapy prior to karyotypic evaluation. Recurring chromosomal changes included partial deletions of 1p and 3p, and monosomy of 18, 19, and 22. We also reviewed data on 24 previously reported pretreatment patients and determined that alterations of chromosomes 1, 3, and 22 are frequently associated with malignant mesothelioma. Partial loss of chromosome 1 due to deletions or other rearrangements most frequently involve bands 1p11-pter with the shortest region of overlap (SRO) occurring at 1p21-p22 in our patients. Deletions and other structural changes of chromosome 3 usually involve the region 3p14-p25. The SRO of 3p deletions appeared to be at band 3p21. Monosomy 22 represents the most consistent specific whole chromosome loss seen in malignant mesothelioma, being observed in 11 of 28 cases summarized. In addition, structural changes of 22q have been observed in three patients, and a breakpoint at 22q11 was reported in each case. Taken collectively, these data suggest that a cascade of events involving alterations of genes on more than one specific chromosome may play a critical role in the development of malignant mesothelioma. The pattern of recurring chromosomal loss, particularly of 1p, 3p, and 22q, indicates that these regions should be targeted for future molecular investigations into the possible involvement of suppressor genes in this malignancy.

Characterization of three human malignant mesothelioma cell lines

Three human malignant mesothelioma cell lines, designated Mero-14, Mero-25, and Mero-41, have been isolated from effusions and from autopsy material of confirmed cases of malignant mesothelioma. Light and electron microscopy, cytogenetics, growth requirements, and intermediate filament expression of these cell lines were studied and, where possible, compared with the original tumor material of the patient. Cytologic and ultrastructural morphology was consistent with the mesothelial nature of the cells. All cell lines displayed a hyperdiploid karyotype similar to that of the tumor cells obtained directly from the patient. All three malignant mesothelioma cell lines had marker chromosomes 1, 3, 9, and 22, as well as other markers that were occasionally present in these cell lines and in other malignant mesotheliomas studied. Growth kinetic studies in medium supplemented with epidermal growth factor (EGF) showed increased proliferation and a decreased proliferation in medium supplemented with hydrocortisone (HC) or EGF plus HC. The three malignant mesothelioma cell lines were positive for the cytokeratins 7, 8, 18, and 19 based on immunofluorescence and immunoblotting tests with chain-specific monoclonal antibodies. The characteristics of these cell lines support the assumption that Mero-14, Mero-25 and Mero-41 are derived from malignant mesotheliomas and have retained their original character.

Chromosomal abnormalities and their correlations with asbestos exposure and survival in patients with mesothelioma

Cytogenetic findings of our 30 previously reported and eight new patients with malignant pleural mesothelioma were summarised and correlated with asbestos fibre burden in lung tissue and survival. Successful cytogenetic analyses were performed on cells obtained from the tumours and/or pleural effusions of 34 of the 38 patients. Clonal chromosomal abnormalities were detected in 25 patients, 19 of them studied before treatment. Nine patients, seven of them studied before treatment, had normal karyotypes and/or non-clonal chromosomal abnormalities. Most of the karyotypic findings in the patients with clonal abnormalities were complex and heterogeneous, and no chromosome aberration specific to mesothelioma could be demonstrated. The following numerical abnormalities in decreasing order of frequency were preferentially present in karyotypic changes: -22, +7, -1, -3, -9, +11 and -14 (-/+ denoting partial or total loss or gain). Translocations and deletions involving a breakpoint at 1p11-p22 were the most frequent structural aberrations. Statistically significant correlations were found between high content of asbestos fibres in lung tissue and partial or total losses of chromosomes 1 and 4, and a breakpoint at 1p11-p22 (P = 0.0001, P = 0.003, P = 0.009, respectively). The number of copies of chromosome 7 short arms was inversely correlated with survival (P = 0.02). In this study no diagnostic cytogenetic markers of mesothelioma were found, instead the copy number of chromosome 7 short arms turned out to be a possible prognostic factor in malignant mesothelioma.

Flow cytometric analysis of malignant pleural mesotheliomas

Forty-six cases of malignant pleural mesothelioma were analyzed for histologic subtype, DNA content, and cell cycle characteristics. Sixty-five percent of cases were diploid in DNA content, with intermediate to low proliferative rates. Thirty-one nonmesothelial malignant neoplasms of the lung, of histologic types most easily confused with malignant mesothelioma, were also examined. In contrast to the mesotheliomas, 85% of these nonmesothelial malignant neoplasms of the lung were aneuploid; the aneuploid neoplasms exhibited higher mean proliferative rates (S = 10.6%) than diploid nonmesothelial neoplasms of the lung (S less than 6%). Unlike most malignant neoplasms, mesotheliomas most often display diploid DNA contents and low proliferative rates despite their clinically aggressive behavior.

Specificity of asbestos-induced chromosomal aberrations in short-term cultured human mesothelial cells

Short-term cultured normal human mesothelial cells were exposed for 48 hours to three different asbestos compounds, crocidiolite, chrysotile, and amosite. In the concentration used (0.01 mg/ml) all three asbestiform minerals caused, within a few days, a significant increase of cells showing numerical and/or structural abnormalities. The abnormalities were analyzed in detail using banding techniques. The results were compared with the cytogenetic observations in 52 published cases of mesotheliomas. This comparison revealed only a few similarities as regards numerical deviations. The structural rearrangements in asbestos-exposed cultures, however, in many instances involved chromosome types and chromosome regions preferentially affected in mesotheliomas.