The relative resistance of non-cycling cells in 9L multicellular spheroids to spirohydantoin mustard

Yoshinori Sano, Takao Hoshino*, Rolf Bjerkvig, Dennis F. Deen

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

16 Citations (Scopus)

Abstract

Surviving fractions of 9L spheroid cells treated with 1.5, 3.0 and 6.0 μg/ml of spirohydantoin mustard (SHM) decreased when assayed 6 hr after treatment but increased thereafter. Flow cytometric analysis showed that exponentially growing 9L monolayer cells treated with SHM accumulated at the G2/M border within 24 hr. Cells dissociated from spheroids treated with 3 and 6.0 μg/ml of SHM accumulated at the G2/M border during the first 24 hr after treatment and remained there for the next 12 hr. However, 50% of the cells remained at the 2C DNA peak. Spheroid cells with 2C DNA content 24 hr after treatment were assumed to be non-cycling cells at the time of treatment, and cells that accumulated at the G2/M peak appeared to be cycling cells at the time of treatment; approximately 50% of cells in untreated 9L spheroids are in the noncycling pool. G1 and/or early S phase 9L cells in exponential growth elutriated immediately after treatment with SHM had significantly lower (P > 0.001) plating efficiencies than 9L cells in S and G2/M phases. When spheroids were dissociated, elutriated and plated for colony-forming efficiency 24 hr after treatment with 3 μg/ml of SHM, fractions enriched in 2C DNA content had significantly higher (P > 0.001) plating efficiencies than elutriated cells enriched in 4C DNA. These results indicate that SHM is less effective against non-cycling 9L spheroid cells with 2C DNA content than against cycling 9L spheroids cells.

Original languageEnglish
Pages (from-to)1451-1456
Number of pages6
JournalEuropean Journal of Cancer and Clinical Oncology
Volume19
Issue number10
DOIs
Publication statusPublished - Oct 1983
Externally publishedYes

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