Flowcytometric and cytogenetic analysis of human cultured cell lines derived from high- and low-grade astrocytomas

Five human cell lines cultured from high- and low-grade astrocytomas in cerebral hemisphere have been analyzed for DNA and protein distribution by flowcytometric (FCM) and correlated with cytogenetic profiles. Simultaneous calibration with chicken erythrocytes as a co-running standard provided an estimate of chromosomal number of predominate stem cells of each cell line by the ratio of the DNA content of the major peak (G1) to that of chicken erythrocyte (T/E ratio) of FCM. Various lines had different distributions of chromosomal number, ranging from near diploid to tetraploid. Each line had a stem-cell population and chromosomal markers indicative of clonal selection, but no common marker specific to astrocytomas. The histogram of DNA distribution obtained by FCM correlated well with the chromosomal distribution by cytogenetic analysis. In addition, simultaneous measurement of protein and DNA content in multidimensional FCM demonstrated a sigmoid configuration of the profiles, which indicated a gradual increase of protein content associated with an increase of chromosomal number or with progression of cell cycle. To avoid confusion of a bimodal chromosomal distribution with the G2/M phase of the cell cycle, and to determine chromosomal numbers associated with a DNA histogram, simultaneous cytogenetic and FCM study are required. More rapid than cytogenetic analysis, the T/E ratio allows estimation of chromosomal number of the stem-cell population associated with DNA histograms of cultured glioma-derived cell lines.