The aim of this study was to assess the biological characteristics of four new malignant mesothelioma (MM) cell lines. Since simian virus (SV)40 sequences have been recently detected in MM, SV40 large T antigen (Tag) expression was also analysed.MM cell lines were characterized by morphological, ultrastructural and cytogenetic analysis. Expression of Tag and of relevant MM markers was studied by immunocytochemistry, surface antigens by indirect immunofluorescence and immunomodulating cytokines by enzyme-linked immunosorbent assay (ELISA).The four MM cell lines, established from pleural effusions, showed a slow proliferation rate and pleomorphic changes during culture. Cell lines expressed vimentin, cytokeratins 8 and 18, and the mesothelial antigen recognized by HBME-1 monoclonal antibody, but not carcinoembryonic antigen. Surface human leukocyte antigen (HLA)-class I and intercellular adhesion molecule (ICAM)-1 molecules were present on all the cell lines. While HLA class II and CD86 were constitutively undetectable, HLA-class II was present after interferon (IFN)-c stimulation. All cell lines displayed abnormal karyotypes with chromosome 6 abnormalities. Transforming growth factor (TGF)-b 2 and interleukin (IL)-6 were constitutively secreted, while tumour necrosis factor (TNF)-a was secreted only in response to lipopolysaccharide. Intranuclear Tag was expressed in two cell lines.The persistence of large T antigen with human leukocyte antigen class I and intercellular adhesion molecule-1 positivity may point to large T antigen as a target for cytotoxic T-lymphocyte-based immunotherapy in some malignant mesothelioma patients. Eur Respir J 1999; 13: 527±534. Malignant mesothelioma (MM) is an aggressive cancer of the mesothelium, most often occurring in the pleural cavity and associated with previous exposure to asbestos fibres. Owing to the long latency period after exposure and the widespread use of asbestos fibres for many years, the incidence of MM is expected to rise until 2020 [1]. MM has been demonstrated to be resistant to any conventional therapy regimens including chemotherapy, radiotherapy and surgery, and the prognosis remains poor [2].The discrepancy between the rising incidence of MM and the lack of success of new more effective therapeutic strategies may be related at least in part to inadequate knowledge of the biological properties of this rare tumour. It is hoped that a better understanding of MM biology may provide the rationale for new therapeutic strategies. In particular, improved knowledge of the modalities of MM development and progression, the genetic alterations, the phenotypic and antigenic profile, the identification of growth factors and cytokines secreted by MM and of their auto/paracrine loops, and finally, the sensitivity to antiproliferative drugs seem to be essential steps.As far as tumour development and progression are concerned, recent data pointed to the presence of the oncogenetic simian virus (SV)40 genome and SV40 large T antigen (Tag) in MM specimens and to a pos...

In order to analyze the presence and the function of the "insulin-like growth factor I (IGF-I) system" in human non-small-cell lung cancer (N-SCLC) we tested 5 cell lines of different histological sub-types: A549, Ca-Lu-6, SK-Lu-1 (adenocarcinoma); Ca-Lu-1, SK-Mes-1 (squamous carcinoma) and one normal fibroblast-like fetal lung cell line (IMR-90) for expression of the IGF-I peptide and its RNA transcribed from the IGF-I gene; IGF-binding proteins (IGF-BP); IGF-I receptor (IGF-I-R) and its mRNA. In addition, we examined the capacity of exogenous human recombinant IGF-I to enhance the in vitro cell proliferation. In medium conditioned from cell cultures, we detected immunoreactive IGF-I material by radioimmunoassay. Western ligand blot and affinity labelling demonstrated the presence of several molecular species of IGF-BPs (IGF-BP-4, -1, -2, -3) as well. Northern blot analysis of polyA+ RNA from all cell lines examined revealed the presence of IGF-I and IGF-I-R mRNA. Moreover, binding studies on cultured cell lines showed one class of high-affinity, operative type-I IGF cell-surface binding sites. Finally, by thymidine uptake and colorimetric metabolic MTT assays, we found that most neoplastic cell lines react mitogenically to IGF-I and that its physiological effect is abolished by an anti-IGF-I-receptor antibody. These data indicate the importance of the IGF-I system in N-SCLC growth. Furthermore, they suggest that this mitogenic complex should be appraised as a possible target for anti-neoplastic drugs, antibodies or growth-factor analogues offering potential new approaches to therapy.

1 This study has two specific aims: (a) to compare the antioestrogenic activity of two steroidal analogues of 17,B-oestradiol, the 7a-alkylamide, ICI 164,384 182,780 and ICI 164,384 to reduce, in a timedependent fashion, oestrogen-and/or IGF-I-stimulated growth of ER + cell lines, possibly by negatively interfering with an IGF-I-like material secretion and IGF-I-receptor number. 4 Our data provide the first evidence that, on ER+ human breast carcinoma cell lines, steroidal antioestrogens inhibit cell growth and modulate the IGF-I mitogenic system. The mechanism of this latter effect has yet to be identified.

The pathogenesis and progression of breast cancer involve complex interactions between hormones and polypeptide growth factors such as insulin-like growth factor-I (IGF-I). IGF-I has been found in stromal fibroblasts derived from malignant and benign breast tissue and it is a mitogen for several breast cancer cell lines. It circulates bound to specific high-affinity binding proteins, which could act as either positive or negative modulators of tumorigenesis. This study has been addressed to characterize IGF-I and its binding proteins in the serum of 85 unselected patients with early breast cancer. The IGF-I concentration was assessed by radioimmunoassay of 69 out of 85 samples before and after dissociation of the IGF-I and IGF-binding protein (IGF-BP) complex whereas IGF-BP of all 85 sera were analyzed by Western ligand blotting; estradiol and progesterone were measured by radioimmunoassay in native serum samples. In our study no differences in IGF-I serum levels between pre- and post-menopausal patients were observed. Patients with higher estradiol and progesterone serum levels did not present different IGF-I concentrations compared to patients with lower serum levels. Furthermore, IGF-I median values were not found to depend on estrogen receptor (ER) status. A heterogeneous quali-quantitative molecular pattern of binding proteins was detected: IGF-BP3 and IGF-BP1 were the most and the least expressed respectively. No correlations between ER status, or parameters related to the hormonal status, and IGF-I or binding proteins expression were observed. No significant differences in IGF-I concentration and IGF-BP expression were observed between cancer patients and a control group matched for age and menopausal status. Finally, preliminary collection of 20 sera derived from patients with late breast cancer was analyzed for IGF-I and its binding proteins content.

Summary The potent mitogenic activity of insulin-like growth factor (IGF-I) on breast epithelium is inhibited by retinoic acid in oestrogen receptor-positive (ER+) breast cancer cell lines. We studied and compared the effects of N-(4-hydroxyphenyl)-retinamide (4-HPR) in terms of growth inhibition and modulation of the IGF-I system in ER+ (MCF-7) and oestrogen receptor-negative (ER-)