DIFFERENTIAL RESPONSE OF ELUTRIATED 9L-CELLS TO TREATMENT WITH 1,3-BIS(2-CHLOROETHYL)-1-NITROSOUREA

  • 1 January 1981
    • journal article
    • research article
    • Vol. 41  (11) , 4404-4407
Abstract
Earlier cytokinetic studies using 9L monolayer culture [rat brain tumor] cells showed that cells began accumulating in the G2 phase (4C position in the DNA distribution) within 30 h after administration of 1,3-bis(2-chloroethyl)-1-nitrosourea (3 .mu.g/ml). Most of these cells reached the G2 phase at 48 h and remained there for another 24 h. Similar studies using 9L spheroid culture cells show that 9L cells also began to accumulate at the 4C DNA position 30 h after administration of 1,3-bis(2-chloroethyl)-1-nitrosourea (3 .mu.g/ml); however, only 1/2 of the cells accumulated in the 4C peak during the first 48 h after treatment, while the other 1/2 remained at the 2C position. Those that remained at the 2C peak might correspond to the Go cells that exist in 9L spheroids. When 1/2 the cells were in 2C and 1/2 were in 4C, the spheroids were dissociated using an enzyme cocktail and sorted using centrifugal elutriation. Cells from each elutriated fraction were analyzed for DNA content using flow cytometry and for viability using a colony-forming efficiency assay. In spheroids, 1,3-bis(2-chloroethyl)-1-nitrosourea (3 .mu.g/ml) is more effective against noncycling cells. Repopulation is more vigorous in G2-arrested cells, which presumably were cycling at the time of treatment. [The cytotoxic drug BCNU3 has been used extensively in the chemotherapy of human malignant brain tumors.].