Preservation of brain tumor specimens for drug sensitivity testing

Assessment of brain tumor cell motility in vivo and in vitro

Brain tumor dispersal far from bulk tumor contributes to and, in some instances, dominates disease progression. Three methods were used to characterize brain tumor cell motility in vivo and in vitro: 1) 2 weeks after implantation in rat cerebral cortex, single C6 cells labeled with a fluorescent tag had migrated to brain sites greater than 16 mm distant from bulk tumor; 2) time-lapse videomicroscopy of human brain tumor cells revealed motility of 12.5 microns/hr. Ruffling leading edges and pseudopod formation were most elaborate in more malignant cells; 3) an in vitro assay was devised to quantitatively evaluate motility from a region of high cell density to one of lower cell density. Human brain tumor cells were plated in the center of a petri dish, washed, and refed, establishing a 2-cm circular zone of cells in the dish center. Motility was determined by counting cells daily at predetermined distances from the central zone perimeter. Cells were found 1 cm from the perimeter by 24 hours and 3 cm from the perimeter by 4 days. Increasing serum concentration increased motility; however, neither fibronectin nor arrest of cells in the G0 phase by hydroxyurea altered motility. The addition of cytochalasin B to block cytoskeletal assembly prevented cell motility. Motility increased with increased malignancy. Subpopulations of cells were created by clonal amplification of cells that had migrated most rapidly to the dish periphery. Although morphologically indistinguishable when compared to the original cell line from which they were derived, these subpopulations demonstrated significantly increased motility.

Radiosensitizing effect of estramustine in malignant glioma in vitro and in vivo

Estramustine-phosphate (EMP), a combination of nornitrogen mustard and 17 beta-estradiol, has been demonstrated to exert specific antiproliferative effects on human glioma cells in vitro. The cytotoxic effect is, at least partially, mediated by inhibiting microtubule function. In this study the combined effect of EMP and radiation was evaluated in the human glioma cell-lines, 251-MG and 105-MG, in vitro, and in the rat glioma BT4C in vitro and in vivo. In all cell-lines an additive effect of EMP and radiation was obtained in vitro. Assuming equal effect of EMP is obtained in subsequent radiation fractions, the cell kill will be increased from 2-3 to 5-10 logs if delivering 30 fractions of 2 Gy combined with EMP. In the BT4C rat model the combined effect was found to be synergistic. Flow cytometry demonstrated an arrest in G2/M phase in all cell-lines after EMP treatment. This block in G2/M phase in addition to the previously demonstrated induction of free oxygen radicals, and the increase of blood flow with an assumed subsequent increase of oxygenation, might provide an explanation for the observed radiosensitizing effect of estramustine.