Heterogeneity of a cultured neoplastic glial line. Establishment and characterisation of six clones

Heterogeneity of chemosensitivity in six clonal cell lines derived from a spontaneous murine astrocytoma and its relationship to genotypic and phenotypic characteristics

Heterogeneity in drug sensitivity must, in part, account for the relative lack of success with single agent chemotherapy for glioblastoma multiforme (GBM). In order to develop in vitro model systems to investigate this, clones derived from the VM spontaneous murine astrocytoma have been characterised with regard to drug sensitivity. Six clonal cell lines have been tested for sensitivity to a panel of cytotoxic drugs using an intermediate duration 35S-methionine uptake assay. These lines have previously been extensively characterised with regard to morphological, antigenic, kinetic, tumourigenic potential in syngeneic animals and chromosomal properties and display considerable heterogeneity. The present study indicates that heterogeneity extends to sensitivity to all classes of cytotoxic drugs. The greatest difference in sensitivity between the clones was seen in response to cell cycle-specific drugs like the Vinca alkaloids (14-fold and 20-fold for vincristine (VCR) and vindesine (VIND) respectively), while the nitrosoureas, CCNU and BCNU displayed a smaller fold difference in sensitivity (4.3 and 3.6-fold difference respectively). All the clones were considerably more resistant to the adriamycin (ADM), cis-platinum (C-PLAT) and the Vinca alkaloids than the parental cell line although the difference in sensitivity between the clones and parental cell line were less marked for the nitrosoureas and procarbazine (PCB). It has also been possible to examine the relationship between drug sensitivity and the phenotypic and genotypic properties of these clonal cell lines. There is a relationship between chromosome number and sensitivity of a wide variety of cytotoxic drugs including the nitrosoureas, Vinca alkaloids, PCB, C-PLAT, BLEO but not ADR or 5-FU. Clones with small numbers of chromosomes were more resistant than clones with gross polyploidy. Similarly, sensitivity to Vinca alkaloids and ADM, but not other classes of drugs, was greatest in cells with numerous cytoplasmic processes and which did not express large amounts of cell surface fibronectin. Preliminary experiments have been conducted on reconstituting clonal mixtures of cells with different sensitivity to Vinca alkaloids and results from these studies indicate that the drug resistance phenotype is dominant, with clonal mixtures of sensitive and resistant cell adopting the sensitivity of the more resistant partner. These cell lines should prove to be useful models for examining the cell biological basis of drug resistance in glioma and may lead to the identification and exploitation of novel cellular targets in new therapies for GBM.

A2B5 surface ganglioside binding distinguishes between two GFAP-positive clones from a human glioma-derived cell line

A human glioma-derived cell line which expresses both the astrocytic markers, glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS) and cell surface gangliosides recognised by the A2B5 monoclonal antibody has been cloned. Two clones are described, which are A2B5-positive and A2B5-negative, respectively. These neoplastic clones may provide a suitable in vitro model with which to assess the significance of surface ganglioside expression in relation to function and lineage of mammalian glia.

The chemotherapeutic response of a murine (VM) model of human glioma

Using a cell line derived from the VM spontaneous murine astrocytoma, a reliable in vitro-in vivo model of human malignant glioma has been developed. In this paper we examine the effects of cytotoxic drugs with known activity against other animal brain tumour models and human disease on the in vivo VM model. The drugs BCNU, CCNU and vincristine produced significant volume reduction in tumours growing at a subcutaneous location in syngeneic animals. Procarbazine was ineffective. Similarly, BCNU, CCNU and vincristine produced small but statistically significant increases in survival of VM mice bearing the intracerebral tumour, but procarbazine was again ineffective. The modest, but significant, response of the VM model to the nitrosoureas mimics the human situation more closely than previously described animal models.

The development of an animal model of glioma for use in experimental neuro-oncology

A cell line, 497-P(1), derived from the VM spontaneous murine astrocytoma has been used to develop an in vitro in vivo model of human glioma. This paper describes the growth characteristics of tumours produced after intracerebral or subcutaneous inoculation of 497-P(1) cells into syngeneic VM mice. The results show that cell line 497-P(1) provides the basis for a reproducible animal model of glioma which fulfils many of the criteria required for experimental therapy studies.

Tumorigenicity of six clones of a cultured neoplastic cell line derived from a spontaneous murine astrocytoma: morphology and immunocytochemistry of tumours

Six clones obtained from the neoplastic, astrocytic murine cell line VMDk P497 were injected intracerebrally into syngeneic hosts and the tumorigenicity of each clone was established. Five of the 6 clones produced tumours with incidences ranging from 25% to 100% and mean latencies of 43-100 days, according to the clone injected. Histological, immunocytochemical and electron microscopical examination of the resulting tumours revealed differences in the degree of invasiveness, but otherwise only slight variations in phenotype between the clones. Generally, the tumours were glioblastoma-like, showing a pleomorphic histoarchitectural pattern; the predominant cell types throughout were poorly differentiated, and lacked both antigenic and morphological characteristics, particularly the presence of intermediate filaments, of mature astrocytes. The basal lamina proteins, fibronectin and laminin, were, however, expressed in all tumours examined. This phenotypic change on cloning and syngeneic transplantation may be of considerable significance in future therapeutic studies using this glioma model.

Glial fibrillary acidic protein, vimentin and fibronectin in primary cultures of human glioma and fetal brain

The expression of glial fibrillary acidic protein (GFAP), vimentin and fibronectin (Fn) was studied in cells cultured from human glioma and fetal brain by indirect immunofluorescence (IIF) microscopy and multiple labelling experiments. In the primary cultures a major part (20%-70%) of the cells usually displayed both GFAP and vimentin and the rest of the cells only vimentin. A prominent variation in GFAP and vimentin fluorescence intensity sometimes made interpretation of double IIF stainings difficult. However, occasional GFAP-positive cells appeared vimentin negative in primary glioma cultures, whereas in fetal brain primary cultures cells that were preferentially GFAP positive also showed at least a weak vimentin immunoreactivity. Only a fraction of the cells, roughly corresponding to the GFAP-negative cells, were Fn positive in the primary cultures. As judged by double IIF, the GFAP-positive cells were usually Fn negative, while the Fn-positive cells were vimentin positive. This could also be demonstrated in triple IIF experiments. During serial subcultivation the amount of cells expressing GFAP decreased, while the number of Fn-positive cells increased. By the third to fourth passage GFAP positivity was usually lost, all cells expressed vimentin and most cells also Fn. The results of the present study demonstrate a general coexpression of GFAP and vimentin in cultured astroglial cells, in addition to cells expressing only vimentin. Interestingly, occasional glioma cells seem to contain GFAP as the only intermediate filament protein as detected by immunocytochemistry.(ABSTRACT TRUNCATED AT 250 WORDS)