Abstract
The induction of apoptosis by doxorubicin (DOX) alone or in the presence of efflux blockers, verapamil (VPL) or trifluoperazine (TFP), and of bcl-2 and mdr-1 gene expression was analysed in murine leukaemic P388 and doxorubicin resistant P388/R84 cells. Incubation with DOX (0.1-1 μM) for 24 hours induced apoptosis in sensitive cells but not in the resistant P388/R84 cells. Flow cytometric analysis of apoptosis by terminal dideoxynucleotidyl (TdT) assay showed that 1 μM DOX induced apoptosis in 70% of P388 cells and in less than 5% of P388/R84 cells. When P388/R84 resistant cells were co-incubated with DOX and efflux blockers (10 μM VPL or 15 μM TFP), enhanced cellular DOX accumulation was accompanied by apoptosis. Quantitative analysis of DNA fragmentation by 14C-thymidine incorporation and gel electrophoresis of fragmented DNA confirmed the results from TdT assay and showed enhancement of DOX-induced DNA fragmentation in the presence of efflux blockers (VPL or TFP). DOX + VPL and DOX + TFP combination treatments induced apoptosis in upto 55% and 83% of P388/R84 cells, respectively. mdr-1 mRNA and P-gp expression were not altered during DOX-induced apoptosis. The results suggest that in murine leukemic cells, down-regulation of bcl-2 mRNA expression occurs during DOX-induced apoptosis and it depends on the cellular drug retention determined by mdr-1/P-gp drug efflux.
| Original language | English |
|---|---|
| Pages (from-to) | 3369-3376 |
| Number of pages | 8 |
| Journal | Anticancer Research |
| Volume | 17 |
| Issue number | 5 A |
| State | Published - Sep 1 1997 |
| Externally published | Yes |
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Keywords
- Apoptosis
- bcl-2 and mdr-1
- Doxorubicin
- Drug resistance
ASJC Scopus subject areas
- Cancer Research
- Oncology
Cite this
Bcl-2 and mdr-1 gene expression during doxorubicin-induced apoptosis in murine leukemic P388 and P388/R84 cells. / Ramachandran, Cheppail; You, Wei; Krishan, Awtar.
In: Anticancer Research, Vol. 17, No. 5 A, 01.09.1997, p. 3369-3376.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Bcl-2 and mdr-1 gene expression during doxorubicin-induced apoptosis in murine leukemic P388 and P388/R84 cells
AU - Ramachandran, Cheppail
AU - You, Wei
AU - Krishan, Awtar
PY - 1997/9/1
Y1 - 1997/9/1
N2 - The induction of apoptosis by doxorubicin (DOX) alone or in the presence of efflux blockers, verapamil (VPL) or trifluoperazine (TFP), and of bcl-2 and mdr-1 gene expression was analysed in murine leukaemic P388 and doxorubicin resistant P388/R84 cells. Incubation with DOX (0.1-1 μM) for 24 hours induced apoptosis in sensitive cells but not in the resistant P388/R84 cells. Flow cytometric analysis of apoptosis by terminal dideoxynucleotidyl (TdT) assay showed that 1 μM DOX induced apoptosis in 70% of P388 cells and in less than 5% of P388/R84 cells. When P388/R84 resistant cells were co-incubated with DOX and efflux blockers (10 μM VPL or 15 μM TFP), enhanced cellular DOX accumulation was accompanied by apoptosis. Quantitative analysis of DNA fragmentation by 14C-thymidine incorporation and gel electrophoresis of fragmented DNA confirmed the results from TdT assay and showed enhancement of DOX-induced DNA fragmentation in the presence of efflux blockers (VPL or TFP). DOX + VPL and DOX + TFP combination treatments induced apoptosis in upto 55% and 83% of P388/R84 cells, respectively. mdr-1 mRNA and P-gp expression were not altered during DOX-induced apoptosis. The results suggest that in murine leukemic cells, down-regulation of bcl-2 mRNA expression occurs during DOX-induced apoptosis and it depends on the cellular drug retention determined by mdr-1/P-gp drug efflux.
AB - The induction of apoptosis by doxorubicin (DOX) alone or in the presence of efflux blockers, verapamil (VPL) or trifluoperazine (TFP), and of bcl-2 and mdr-1 gene expression was analysed in murine leukaemic P388 and doxorubicin resistant P388/R84 cells. Incubation with DOX (0.1-1 μM) for 24 hours induced apoptosis in sensitive cells but not in the resistant P388/R84 cells. Flow cytometric analysis of apoptosis by terminal dideoxynucleotidyl (TdT) assay showed that 1 μM DOX induced apoptosis in 70% of P388 cells and in less than 5% of P388/R84 cells. When P388/R84 resistant cells were co-incubated with DOX and efflux blockers (10 μM VPL or 15 μM TFP), enhanced cellular DOX accumulation was accompanied by apoptosis. Quantitative analysis of DNA fragmentation by 14C-thymidine incorporation and gel electrophoresis of fragmented DNA confirmed the results from TdT assay and showed enhancement of DOX-induced DNA fragmentation in the presence of efflux blockers (VPL or TFP). DOX + VPL and DOX + TFP combination treatments induced apoptosis in upto 55% and 83% of P388/R84 cells, respectively. mdr-1 mRNA and P-gp expression were not altered during DOX-induced apoptosis. The results suggest that in murine leukemic cells, down-regulation of bcl-2 mRNA expression occurs during DOX-induced apoptosis and it depends on the cellular drug retention determined by mdr-1/P-gp drug efflux.
KW - Apoptosis
KW - bcl-2 and mdr-1
KW - Doxorubicin
KW - Drug resistance
UR - http://www.scopus.com/inward/record.url?scp=0030775164&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0030775164&partnerID=8YFLogxK
M3 - Article
C2 - 9413174
AN - SCOPUS:0030775164
VL - 17
SP - 3369
EP - 3376
JO - Anticancer Research
JF - Anticancer Research
SN - 0250-7005
IS - 5 A
ER -