Effects of dexamethasone and betamethasone on in vitro cultures from human astrocytoma

Abstract

Summary.-Cultures of human astrocytoma have been derived by collagenase digestion and are presumed, from their aneuploid karyotypes, to be predominantly neoplastic. Early passage cultures in proliferative phase have been cloned in the presence of dexamethasone and betamethasone, both commonly used in management of patients with brain tumours. These steroids raise both the cloning efficiency and the proliferative capacity of cells within each clone. Inhibition was detected only in very high steroid concentrations (25-50 ,ug/ml). Since these concentrations are unlikely to be attained in vivo it is concluded that anticipated physiological levels of these steroids enhance cell survival at low densities in culture. The significance of this in vivo is discussed.

Control of cell proliferation in human glioma by glucocorticoids

“…Cell cultures were derived from biopsy samples of human anaplastic astrocytoma by disaggregation in collagenase, and maintained as monolayers on plastic (Corning or Falcon) in a modification of Hams F12 medium (Guner et al, 1977) (, 2 Ci/mmol) washed and fixed in methanol. Unincorporated precursor was removed in 3 washes of ice-cold 10% trichloroacetic acid.…”

“…Although cytotoxicity has been demonstrated in other systems (Wellington & Moon, 1961;Mealey et al, 1971) concentrations of steroid (> 10-5M) which exceed the anticipated pharmacological level have been used. Where physiological (10-10-10-8M) or pharmacological (10-6-1 0-5M) concentrations have been used with human tumour cultures, both stimulation of cell proliferation (Mealey et al, 1971;Guner et al, 1977) and inhibition (Jones et al, 1978;Braunschweiger et al, 1978) Wilson et al (1972) suggested that the same may be true for cultured glioma.…”

“…The action of such steroids on the tumour cells is not entirely clear, and a previous report (Guner et al, 1977) showed that glucocorticoids could greatly enhance both the survival and proliferation of astrocytoma cultures in a colony-forming assay.…”

Assay of anticancer drugs in tissue culture: Cell cultures of biopsies from human astrocytoma

“…Primary cultures of cells with long thin processes tended to form a network in subconfluent cultures, but gave way to polygonal or spindle-shaped cells after serial passage. Although karyotypes were not performed on all the lines used, examination of some, and of many similar lines derived in the same manner, showed considerable aneuploidy with modal chromosome numbers ranging from 40-46 chromosomes (Guner et al, 1977, Freshney, 1980. Recent evidence has shown that these cell cultures are capable of growth on confluent monolayers of normal contact-inhibited cells, while cells cultured from normal brain are not and that they have a higher labelling index with [3H] TdR at terminal cell density than cultures derived from normal brain .…”

“…The selection of a microtitration plate assay for this series of measurements was influenced by difficulties in obtaining reasonable plating efficiencies for a clonogenic assay. However, the selection of the appropriate CO2 tension (2%), use of glucocorticoids in the medium (Guner et al, 1977) and cloning on homologous feeder layers With the microtitration assay, cultures are usually available for testing_ within 3 weeks of surgery and with an assay taking 10-14 days to perform, a result is available within 4-5 weeks of operation. Currently patients who are to receive chemotherapy for cerebral glioma at the National Hospital do so after completion of radiotherapyusually a minimum of 7-10 weeks after operation.…”