GROWTH INHIBITION OF HUMAN PROMONOCYTIC LEUKAEMIC U937 CELLS BY INTERFERON GAMMA IS IRREVERSIBLE AND NOT CELL CYCLE PHASE-SPECIFIC

• Published in: Cytokine (Philadelphia, Pa.) Pa.), 1999-09, Vol.11 (9), p.673-678
• Main Authors: Joshi, Chirag V, Supriya, Patil, Ajitkumar, P
• Format: Article
• Language: English
• Subjects: Bromodeoxyuridine; Cell Cycle - drug effects; Cell Division - drug effects; DNA Replication - drug effects; Epithelial Cells - drug effects; growth inhibition/interferon gamma/U937 cells/cell cycle; Growth Inhibitors - pharmacology; Humans; Interferon-gamma - pharmacology; U937 Cells - cytology; U937 Cells - drug effects
• ISSN: 1043-4666; 1096-0023
• DOI: 10.1006/cyto.1998.0474

Growth of human promonocytic leukaemic U937 cells was found arrested within 24h upon exposure to interferon gamma (IFN-γ). Removal of the interferon did not result in the resumption of growth, as is evident from the absence of doubling of viable cell count and3H-thymidine incorporation. 5-Bromo-2′-deoxyuridine-based flow cytometric analysis of the growth-arrested cells, 24h subsequent to the removal of IFN-γ, showed absence of DNA synthesis, confirming the irreversible nature of the growth inhibition. Propidium iodide-based flow cytometric analysis of the growth-arrested cells showed a distribution which is typical of a growth inhibition without resulting in the accumulation of cells in any specific phase of the cell cycle. These results indicated that IFN-γ arrested growth of U937 cells in an irreversible and cell cycle phase-independent manner. These observations were in contrast to our earlier report on the reversible and cell cycle phase-specific growth inhibition of human amniotic (fetal epithelial) WISH cells by the interferon.