Tumorigenic cell culture lines from a spontaneous VM/Dk murine astrocytoma (SMA)

One of the few spontaneous gliomas in inbred animals, the VM/Dk spontaneous murine astrocytoma (SMA), has seen limited use. Previously restricted to an in vivo system, the SMA was only transplantable intracerebrally (IC) using nonquantifiable suspensions of normal brain and tumor tissue. Prior attempts at establishing permanent tumorigenic SMA cell lines have not succeeded; tumorigenicity was lost during serial in vitro passage. We have established three different cell culture lines from a serially IC-transplanted SMA and two from tumors that arose from intraperitoneal (IP) injection of the IC-transplanted SMA. In contrast to previous cell cultures and transplantable lines of SMA, all five cell lines are not only tumorigenic IC but subcutaneously (SC) as well. Astrocytic feature are present in three of five lines to varying degrees, evidenced by in vitro and in vivo morphology, response to dibutyryl cyclic AMP (db-cAMP), and the presence of neuroglial fibers: None of the lines express CNPase, S-100, or GFA proteins in significant amounts. P560, highly tumorigenic and possessing the most astrocytic features of the five lines, extends the use of the spontaneous astrocytoma system of the inbred VM/Dk mouse strain by allowing quantitative in vivo and in vitro experiments.

Synergism between BCNU and irradiation in the treatment of anaplastic gliomas. An in vivo study using the avian sarcoma virus-induced glioma model

The therapeutic effects of irradiation, BCNU, or combined irradiation and BCNU were studied in the avian sarrcoma virus (ASV)-induced glioma model in rats. Whole-head orthovoltage radiation therapy was given in six equal fractions over 2 weeks, and BCNU was administered intraperitoneally as a single dose of 10 mg/kg. Two series of experiments were performed in order to duplicate the results. In Series I, the median survival times of the experimental groups, in days after randomization were as follows: control group (no treatment), 69; group receiving 200 rads, 84 (p less than 0.05); group receiving BCNU, 80.5 (p less than 0.1); and group receiving 2000 rads + BCNU, 112 (p less than 0.001). In Series 2, the median survival times were: control group, 73.5; group receiving 2300 rads, 85 (p less than 0.01); group receiving BCNU, 92.5 (p less than 0.025); and group receiving 2300 rads + BCNU, 123.5 (p less than 0.001). In both series, combined therapy was significantly better than either radiation or BCNU alone. This is the first time that a synergistic effect of BCNU and irradiation has been reported in an in vivo brain-tumor model and supports the clinical use of this combination in the treatment of malignant gliomas.

Cytopathologic characteristics of permanent cell lines derived from anaplastic human gliomas

Five permanent cell lines derived from human gliomas were examined at 24-hour intervals to determine optimal phases of their population growth curves for comparative morphologic studies. In early exponential growth phase, individual cytologic criteria were well displayed, while the increased cellular density of late exponential and plateau phase growth was advantageous for evaluating growth pattern, bizarre multinucleate giant cells and abnormal mitoses. These morphologic characteristics of permanent cell lines derived from human gliomas are potentially useful for correlation with their biologic, immunologic, biochemical and cell biologic parameters.

Heterotransplantation of human craniopharyngiomas in athymic "nude" mice

Surgical biopsies from 2 human craniopharyngiomas were transplanted subcutaneously into 6 athymic "nude" mice. Morphologically characteristic craniopharyngiomas grew in 5 of these animals. In 4 animals growth was sufficient to allow transplantation into a second generation of animals. In all, 11 craniopharyngiomas were present at autopsy in the 14 animals into which the tumors had been transplanted. The tumors that grew in the animals had the same adamantinomatous architecture, epithelial nests, and keratinized nodules that were present in the original surgical sample and that are characteristic of human craniopharyngiomas. It may be possible to study growth characteristics and therapeutic sensitivities of human craniopharygniomas growing in "nude" mice.

Dihydrofolate reductase in primary brain tumors, cell cultures of central nervous system origin, and normal brain during fetal and neonatal growth

Dihydrofolate reductase (DHFR) was measured during the development in rats of brain tumors induced following inoculation with avian sarcoma virus. Increasing activity of this enzyme in brain was correlated with the course of primary brain tumor growth. The specific activities of DHFR in primary human brain tumor tissues were comparable to those found in avian sarcoma virus-induced brain tumors in rats. Specific activities of DHFR in cell cultures derived from human and rat primary intracranial gliomas and sarcomas were up to 6 times those found in adult rat liver. The presence of DHFR in neoplasms of central nervous system origin is relevant to the development of folate antagonists which, unlike methotrexate, can readily cross the blood-brain barrier. In normal developing rat brain, DHFR specific activity was high in embryos at 19 days of gestation and declined thereafter, until at 20 days after birth the activity was very low. The methotrexate titration assay was used to measure enzyme levels in the brains of fetal and newborn rats, and good correlation with the spectrophotometric assay was observed. The pattern was different in liver, showing maximum activity 11 days after birth and retaining high activity in adult liver. Both the cofactor requirement and the sensitivity to methotrexate indicate that the enzyme in the brain is DHFR.

Glial-mesenchymal tropism of in vivo avian sarcoma virus neuro-oncogenesis in rats

Intracerebral inoculation of avian sarcoma virus (ASV) in postnatal animals induces gliomas and sarcomas but no neuronal tumors. High titer Bratislava-77 strain ASV was inoculated intracerebrally in fetal F-344 rats between 17 and 20 days of gestation: a time of active neuronal proliferation. Following birth inoculated rats developed gliomas and sarcomas but no neuronal tumors. The results are evidence that the glial-mesenchymal tropism of in vivo ASV neuro-oncogenesis is independent of stage of neurocytodifferentiation at inoculation.

General immunocompetence of rats bearing avian sarcoma virus-induced intracranial tumors

The mitogenic responsiveness of spleen cells obtained from avian sarcoma virus-inoculated Fischer 344 rats was studied. Sixty % of the rats had astrocytomas, 13% had sarcomas, 7% had mixed gliosarcomas, and 20% had no evidence of tumors. Only spleen cells from rats bearing astrocytomas had significantly diminished responses to phytohemagglutinin and concanavalin A (Con A) when compared to control responses. The decreased responsiveness observed with phytohemagglutinin was limited to the optimal concentration range (10 and 20 microgram) while a broader concentration of Con A (0.01 to 50 microgram) induced significant suppression. Moreover, a more profound immunosuppression was observed with Con A. The results also demonstrated that spleen cells from rats with the largest astrocytomas exhibited the greatest suppression. From the results of this study, it appears the avian sarcoma virus-induced astrocytoma in rats is an immunological parallel of the human disease based on the loss of general immunological competence as assessed by responsiveness of lymphocytes to phytohemagglutinin and Con A.

Workshop on cancer of the brain

✓ The authors provide a summary of a workshop on “Cancer of the Brain.” This conference reviewed the current knowledge about the etiology and pathogenesis of human brain tumors and the experimental induction of comparable animal brain tumors, and considered new lines of research.

Surface antigenic characteristics of human glial brain tumor cells

The surface antigenic characteristics of human glial brain tumor (HGBT) cells were studied by complement-dependent cytotoxic antibody assays and indirect membrane immunofluorescence. Eight permanent, well-characterized cell lines derived from human gliomas were used for analysis with antisera raised by hyperimmunization of nonhuman primates (Macaca fascicularis) with glioblastoma multiforme tissue or established HGBT cells lines. Exhaustive absorption of these antisera to remove predominantly antispecies activity rendered HLA nonreactive "preabsorbed" antisera, which reacted with a large panel of gliomatous and nongliomatous human tumor cells; 1 carcinoma, 2 sarcomas, 2 melanomas, 1 neuroblastoma, and 8 HGBT cell lines. Four lymphoblastoid lines and 2 carcinomas were unreactive. After further absorption with a human osteogenic sarcoma cell line, the antisera demonstrated significant levels of reactivity for 8 tested HGBT cell lines and no longer reacted with the nongliomatous cultured tumor cells lines. Therefore, extensive absorption of nonhuman primate anti-human glioma sera removed all activity for the nongliomatous cell lines tested, but it left significant reactivity against a glial tumor cell line-associated antigen(s) present on all 8 human glioma cell lines tested.

The role of the subependymal plate in glial tumorigenesis

We have studied the sequential morphological events of glial tumorigenesis in neonatal dogs, using high titer subgroup C Bratislava-77 Avian Sarcoma Virus, given as 0.01 ml by intraventricular inoculation. The cells of the subependymal plate are those which seem to form the gliomas; cytoplasmic alterations are evident within 24 h after inoculation and microfoci of gliomas, contiguous with the subependymal plate of the lateral ventricles, are visible within 7 days. Independent tumors are present by the 10th post-inoculation day. These studies support the hypothesis of Globus and Kuhlenbeck, which implicates the cells of the subependymal palte in glial tumorigenesis.

Immunobiology of primary intracranial tumors

The avian sarcoma virus-induced glioma model in rats was used to study the effectiveness of immunotherapy, namely, Bacillus Calmette-Guérin (BCG) with or without sarcoma cells and/or chemotherapy with 1,3-bis (2-chloroethyl)-1-nitrosourea (BCNU), upon survival times. The most consistent prolongation of survival time was produced by triple therapy: BCG + intraperitoneally administered sarcoma cells + intravenously administered BCNU.

Surface morphology of normal and neoplastic rat cells

Nontumorigenic rat cells and their tumorigenic counterparts were studied with scanning electron microscopy under controlled conditions in vitro and with transmission electron microscopy after replantation in vivo to discern if external morphology reflected the cell's neoplastic state or the etiology of transformation. Interphase cells in six of seven nontumorigenic lines were flat and monolayered under confluent conditions and exhibited smooth, nonactive cell surfaces. A nontumorigenic cell line morphologically transformed with human adenovirus-2 consisted of spherical cells with blebbed surfaces. Cells from six tumorigenic lines transformed with avian sarcoma virus had highly active surfaces with many surface projections. Cells from two chemical carcinogen-transformed rat embryo lines were flat with no surface projections in subconfluent culture and rounded with only a few microvilli at high densities, but cells from a sarcoma chemically induced in an adult rat were villous. When villous cells were syngeneically replanted in vivo, they lost most microvilli. The external morphology of cells was influenced by a number of factors simultaneously, with no universal pattern associated with tumorigenic capacity or transforming agent.

Influence of age at inoculation on avian oncornavirus-induced brain tumor incidence, tumor morphology, and postinoculation survival in F344 rats

Intracranial neoplasms were induced by intracerebral inoculation of a standardized, cell-free inoculum of the Bratislava-77 strain of avian sarcoma virus in F344 rats at 1, 9,97 to 99, and 528 days of age. Deaths from diseases that occur spontaneously in aged F344 rats complicated assessment of tumor incidence in rats inoculated at 528 days; 20 of 30 rats inoculated at this age developed brain tumors. All rats inoculated at age 1 day (47 rats), at age 9 days (37 rats), and at 97 to 99 days of age (41 rats) developed brain tumors. The incidence of animals developing tumors was 100% in these three groups, but the incidence of multiple tumors declined with increasing age at inoculation. The mean and variance of postinoculation survival increased from 83.8 +/- 21.5 days for rats inoculated at 1 day of age to 284.6 +/- 151.5 days for rats inoculated at 97 to 99 days of age. Poorly differentiated astrocytomas and astrocytomas of mixed morphology were common among rats inoculated as neonates. Solitary, pilocytic astrocytomas were the most common tumors among rats inoculated as adults.

The role of the subependymal plate in avian sarcoma virus brain tumor induction: comparison of incipient tumors in neonatal and adult rats

F-344 rats were inoculated intracerebrally at 1 and at 133 days of age with the Bratislava-77 strain of avian sarcoma virus. Groups of rats were sequentially sacrificed following inoculation so that early stages of microtumor formation could be evaluated. In neonatally inoculated rats incipient tumors developed in the subependymal region of the lateral ventricles in close juxtaposition to clusters of poorly differentiated germinal cells. Among these animals microtumors were detected as soon as 2 weeks after inoculation; by 4 weeks post-inoculation all rats inoculated at 1 day of age had tumors. In contrast among rats inoculated as adults incipient tumors developed in the cerebral cortex away from the subependymal region but adjacent to the locus of inoculation. Incipient tumors were uncommon in rats inoculated as adults during the first 2 months after inoculation.

Immunobiology of primary intracranial tumors. Part 1: studies of the cellular and humoral general immune competence of brain-tumor patients

Cellular and humoral immune parameters were evaluated in a series of brain-tumor patients, 42 with glioblastoma multiforme, 17 with other anaplastic gliomas, and 17 with meningiomas. A degree of anergy was found, which seems in the group as a whole to be proportional to the degree of anaplasia. In addition, serial bimonthyl testing in individual cases revealed further reduction in certain immune responses coincident with clinical decline.

Immunofluorescent analysis of expression of the RNA tumor virus major glycoprotein, gp71, on the surfaces of normal murine cells

The expression of the major glycoprotein, gp71, of murine leukemia virus was studied on the surfaces of a variety of normal murine cell lines with a monospecific rabbit antiserum raised against purified Friend murine leukemia virus gp71. Using viable cell membrane immunofluorescence, most established and early passage normal murine cell lines were significantly reactive with the antiserum, irrespective of neoplastic transformation, strain genotype, or whether they were of embryonic or adult tissue origin. The only murine cells tested not detectably expressing gp71 determinants were BALB/3T3 lines. Although some Friend gp71 interspecies reactivity was discernible on normal murine cells, the principal reactivity was shown to be group specific. Fresh thymocytes from BALB/cJ (GIX-), C57BL/6J (GIX-), and 129/J (GIX+) mouse strains were also reactive with Friend gp71 antiserum, and this activity, as well as that of an antiserum prepared against purified AKR gp71, were also group specific. An activity discriminating GIX+ from GIX- thymocytes was not observed with either Friend or AKR gp71 antisera.

Immunofluorescent analysis of expression of the RNA tumor virus major glycoprotein, gp71, on surfaces of virus-producing murine and other mammalian species cell lines

The specificity of a single rabbit antiserum pool raised against the purified major glycoprotein, gp71, of Friend murine leukemia virus was determined for a variety of virus-producing mouse, feline, and gibbon ape cell lines by viable cell membrane immunofluorescence absorption. Among murine cells examined, Friend gp71 type specificity was shared only with Rauscher virus-producing cells, and a group specificity was present for all the murine leukemia virus-producing cells tested. Friend and Rauscher murine leukemia virus-infected cells shared interspecies cross-reactivity with feline leukemia and gibbon ape lymphoma virus-producing cells. However, Moloney, Gross, and other virus-producing murine cells shared some, but not all, of these gp71 interspecies determinants with the feline and primate cells. Immunoferritin electron microscopy localized these gp71 antigenic determinants on both virus and cell membranes.

Contained indirect viable-cell membrane immunofluorescence microassay for surface antigen analysis of cells infected with hazardous viruses

A microtechnique for an indirect viable-cell membrane immunofluorescence titration assay was developed using Friend murine leukemia virus (F-MuLV)-producing cells and monospecific rabbit antisera to F-MuLV structural antigens. The assay was sensitive and displayed little variation within or between assays. Since moderate-risk tumor viruses, such as recently discovered primate oncornaviruses or feline leukemia virus (FeLV), may be hazardous to laboratory personnel, the assay was adapted for containment of cells infected with such viruses. Cells producing gibbon ape lymphoma virus or FeLV were grown in class III containment cabinets and transferred in sealed flasks to a class II laminar-flow cabinet, where the assay was performed. This micromethod not only conserved reagents but also minimized the numbers of moderate-risk tumor virus-infected cells handled at one time. Centrifugation was contained using custom-made devices shown to form a gas-tight seal over microtiter plates. Interspecies reactivity of monospecific rabbit antisera against F-MuLV structural antigen gp71, but not against p12, was demonstrated for surface antigens on FeLV-producing cells.

Sequential adsorption analysis of antibodies to neuroectodermal cells by an indirect quantitative method

An indirect radioimmunoassay was developed for the sequential adsorption analysis of rabbit antibodies raised against rat neuroectodermal cells. The quantitativee relationship between primary adsorbed rabbit antitumor antibodies and secondary adsorbed goat antibodies to rabbit IgG was explored by paired radioiodine analysis. In the final indirect method, the amount of unlabeled rabbit antibody removed by cultured monolayers of cells at each step in a sequence of cells could be determined from an equation relating the unlabeled amount to values of bound 125I-labeled goat antirabbit IgG. To obtain the total quantity of rabbit antibody in a particular antiserum reagent, a sequential adsorption analysis was done with successive steps of homologous cells. To obtain the amount of antibody that was cross-reactive for other cell lines, we included those lines in the first several steps of the sequence. The sequential adsorption profile was considered as a more important indicator of the quality of a particular antiserum reagent than was the total amount of antibody contained in it. Neuroectodermal cell lines used as illustrative examples included subclones of the C6 astrocytoma and of the RN-2 schwannoma.

Cellular immunity in rats with primary brain tumors: inhibition of macrophage migration by soluble extracts of avian sarcoma virus-induced tumors

Rats bearing primary tumors of the brain induced by avian sarcoma virus (ASV) were studied with the migration-inhibition factor (MIF) assay for the presence of cell-mediated immunity to tumor-associated antigens. Astrocytomas and sarcomas of the brain were induced in 34 neonatal F344 rats by the intracerebral inoculation of Bratislava-77 ASV. At weekly intervals from 4 to 9 weeks after the inoculation with virus, peritoneal exudate cells (PEC) from rats bearing brain tumors were tested an an MIF assay against soluble and KCl-treated extracts of a syngeneic, ASV-induced sarcoma. Incubation of the PEC with a soluble extract of syngeneic liver or with a KCl extract of a syngeneic, chemically induced tumor served as controls. Of 14 rats tested against the soluble tumor extract, 6 (43%) had statistically significant inhibition of migration (P less than or equal to 0.05). Of 23 animals tested against the KCl extract, 16 (70%) had significant inhibition. Immunity to the KCl extract was significant in most rats at each period. Ten rats were tested against a KCl extract of a hamster ASV-induced tumor; 7 gad significant inhibition of migration. None of 3 tested against a soluble extract of a syngeneic, chemically induced tumor had significant inhibition. Rats bearing ASV-induced brain tumors displayed cell-mediated immunity to tumor-associated antigen or antigens of ASV-induced tumors, which could be solubilized.