The genesp53, mdm2, p21, c-myc,bcr/abl, bcr, bcl2, bax,
and gapdh participate in the regulation of cell
proliferation and differentiation, apoptosis and cell distribution for the cell
cycle ex vivo in the Ph+cells of chronic myeloid
leukemia containing the Ph chromosome andbcr/abloncogene.
Expression of these genes correlates with regulation of cell proliferation and
differentiation by alternating proliferation and maturation stages for three
main Ph+cell types that occur under chronic myeloid leukemia. Thep53,
p21, mdm2, and gapdh genes overexpress in active
proliferating myeloid cells in the cell cycle S+ G2/M phases and when the phases
are coincident with the proliferation stage. Expression of these genes decreases
to a considerable level under alternation of the Ph+cell
proliferation and maturation stages and whenever the expression is greatly
diminished under significant neutrophil accumulation and especially under
repeated alternation of the stages. In the course of neutrophil maturation, gene
expression levels decrease in the range of gapdh > actin > c-myc,
bcr/abl,p21 > p53 > bcl2 > bax.The expression levels of
these genes in neutrophils are lower than those in myelocytes and lower by an
order of magnitude than that in the cells with a prolonged proliferation stage.
TheBcr/ablexpression gene under prolonged maturation and
neutrophil accumulation is inhibited; however it is enhanced by 2–3 times
for the proliferation stage with myelocyte accumulation.
Minimalbcr/ablexpression is observed under overexpression
ofp53, mdm2, p21, c-myc,as well as under cell maximum at
the S and G2/M phases. Bcr/abloverexpression is observed under
low expression of thep53, p21, mdm2genes. In the Ph+
cells with a high P/D efficiency index (5–20), overexpression of the
genes in the range ofbcr> gapdh>bcr/abl, as well as a
decreased expression of thep53, bcl2, mdm2, p21<< gapdh
genes is observed for Ph+cells from the CML blast crisis and
CML acceleration phase. Low control of cell proliferation and cell cycle by
gene-regulators presumably promotesbcr/abloverexpression and
activаtes the production ofbcr/abl+ cells.
Apoptosis in the Ph+ cells is induced by expression of thebax
> bcl2, р53, p21, c-myc andgapdhgenes.
The blocking of Ph+cell apoptosis, neutrophil accumulation, and
decrease in the expression of the p53, mdm2 and p21,
c-myc,bcr/abl genes occur at the maturation
stage.