Tetraploidy in mammalian cells
ZBIGNIEW DARZYNKIEWICZ (darzynk@nymc.edu)
Thu, 15 May 1997 09:09:58 -0500
Dr. Telford raises the question as to whether it is possible to
discriminate tetraploid G1 from diploid G2 cells. Cyclins E and B1
are specific markers of G1 and G2 cells, respectively and therefore
bivariate analysis of DNA content vs cyclin E or cyclin B1 expression
can be used to distinguish these populations, as reviewed in
Cytometry, 25: 1-13, 1996. This works, however, only when expression
of these cyclins is scheduled as it is in the case on normal cells or
some tumor lines during their unperturbed exponential growth. Several
tumor lines, on the other hand, are characterized by unscheduled
expression of cyclins (i.e. G1 cyclins are expressed in G2 and vice
versa). Perturbation of cell cycle progression, e.g. as induced by
some synchronication techniques, also result in unscheduled
expression of cyclins. In these situations, of course, bivariate
analysis of cyclins E or B1 vs cellular DNA content cannot
distinguish G1 tetraploid from G2 diploid cells.
Zbigniew Darzynkiewicz
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