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Increased stringency of the 1,25‐dihydroxyvitamin D 3 ‐induced G1 to S phase block in polyploid HL60 cells
Author(s) -
Zhang Fan,
Rathod Bina,
Jones Jennifer B.,
Wang Qing Mei,
Bernhard Eric,
Godyn Janusz J.,
Studzinski George P.
Publication year - 1996
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/(sici)1097-4652(199607)168:1<18::aid-jcp3>3.0.co;2-b
Subject(s) - polyploid , phase (matter) , block (permutation group theory) , biology , chemistry , microbiology and biotechnology , genetics , combinatorics , mathematics , ploidy , gene , organic chemistry
Treatment of mammalian cells with 1,25‐dihydroxyvitamin D 3 (1,25D 3 ) produces a G1 to S (G1/S) phase cell cycle block. In addition, it has been noted that a smaller proportion of cells accumulates in the G2/M compartment in 1,25D 3 ‐treated cultures. Since cyclins have a major influence on the regulation of cell cycle progression, we determined the expression of cyclins A and B as markers of the G2 phase and of cyclin E as the marker of G1/S transition. No increase in the steady‐state levels of cyclin A or cyclin B mRNA was detected in the total cell population or in the cyclin B1 protein in the G2/M cell cycle compartment. In contrast, immunodetectable cyclin E protein was increased in cell cultures as a whole and specifically in the G2/M compartment cells. Determination of BrdU incorporation into DNA by flow cytometry showed marked inhibition of DNA replication in cells with DNA content higher than 4C, and autoradiography of 3 H‐TdR‐pulsed cells showed that polynucleated cells did not replicate DNA after 96 h of treatment with 1,25D 3 or analogs. Taken together, these experiments show that at least a portion of the G2/M compartment in 1,25D 3 ‐arrested cultures of HL60 cells represents G1 cells at a higher ploidy level, which are blocked from entering the high ploidy S phase. © 1996 Wiley‐Liss, Inc.