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Restoration of wild-type p53 activity in p53-null HL-60 cells confers multidrug sensitivity
HL-60 cells that stably express transfected wild-type (wt) p53 were used to determine whether restoration of wt p53 increased the chemosensitivity of cells that normally lack p53 activity. The wt p53 HL-60 transfectants (SN3 cells) were more sensitive than the parental (S) cells to a number of commo...
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Published in: | Clinical cancer research 1998-05, Vol.4 (5), p.1315-1322 |
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Main Authors: | , , , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Online Access: | Get full text |
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Summary: | HL-60 cells that stably express transfected wild-type (wt) p53 were used to determine whether restoration of wt p53 increased
the chemosensitivity of cells that normally lack p53 activity. The wt p53 HL-60 transfectants (SN3 cells) were more sensitive
than the parental (S) cells to a number of common anticancer drugs representing various mechanisms of action, whereas HL-60
cells transfected with p53 genes mutated at codons 248 and 143 were not sensitized. The sensitization ratio due to the transfected
wt p53 varied from about 2-fold for cisplatin to over 50-fold for thymidine. Cells treated with the thymidylate synthase inhibitor
5-fluoro-2'-deoxyuridine (FdUrd) were used to study changes in various p53-associated gene expressions. A higher percentage
of apoptotic cells among the SN3 cells was observed than among the S cells at each concentration of FdUrd. The S cells had
undetectable levels of bax and high levels of bcl-2, whereas the SN3 cells had undetectable levels of bcl-2 levels and appreciable
basal levels of bax. After FdUrd treatment of SN3 cells, both p53 and bax levels increased, but the induction of bax was faster
than that of p53 and paralleled the appearance of apoptotic DNA laddering. FdUrd treatment induced p21 expression and increased
the G1 fraction of the SN3 cells but did not induce p21 or change the phase distribution in the S cells. FdUrd treatment also
induced the expression and phosphorylation of cyclin D1 in the SN3 cells but not in the S cells. These results show that transfected
wt p53 confers multidrug sensitivity to HL-60 cells by re-adjustment of the expressions of apoptosis genes and displays other
properties characteristic of endogenously originated wt p53. |
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ISSN: | 1078-0432 1557-3265 |