TY - JOUR
T1 - Paclitaxel restores radiation-induced apoptosis in a bcl-2-expressing, radiation-resistant lymphoma cell line
AU - Nguyen, L. N.
AU - Munshi, A.
AU - Hobbs, M. L.
AU - Story, M. D.
AU - Meyn R.D., Jr
N1 - Funding Information:
This work was supported in part by Grants RO1CA69003, PO1CA06294, and P3OCA16672 awarded by the National Cancer Institute, U.S. Department of Health and Human Services.
PY - 2001/3/15
Y1 - 2001/3/15
N2 - Purpose: To restore radiation-induced apoptosis in a bcl-2-expressing, radiation-resistant murine lymphoma cell line (LY-ar) by pretreatment with paclitaxel (Taxol). Because this cell line also has high intracellular levels of glutathione (GSH), reportedly due to the bcl-2 expression and involved in the cell's antioxidant functions, paclitaxel treatment was correlated with GSH levels. Methods and Materials: LY-ar cells were pretreated with paclitaxel and then irradiated with 5 Gy. Apoptosis was measured by DNA fragmentation 6 h later. Dose response and time course experiments were performed. Intracellular GSH levels were measured after treatment. Cell survival analysis was performed for various paclitaxel concentrations ± 5 Gy. Results: LY-ar cells pretreated with 0 nM, 10 nM, 25 nM, and 50 nM paclitaxel for 20 h underwent apoptosis at 2%, 15%, 25%, and 22%, respectively. With the addition of 5-Gy irradiation, LY-ar cell apoptosis increased to 4%, 30%, 49%, and 57%. Maximal apoptosis was detected with a paclitaxel pretreatment time of 20 h. Intracellular GSH levels were reduced by nearly 50% with paclitaxel pretreatment. Surviving fractions (SFs) with 0 nM, 10 nM, 25 nM, and 50 nM paclitaxel and 0 Gy were 1.0, 0.50, 0.08, and 0.05, respectively. SFs with 0 nM, 10 nM, 25 nM, and 50 nM paclitaxel and 5 Gy were 0.009, 0.003, 3 × 10-5, and 1 × 10-5, respectively. Conclusion: Radiation-induced apoptosis in LY-ar cells was restored by pretreatment with paclitaxel. This correlated with lowered levels of intracellular GSH. Cell survival analysis indicated that the combination of Taxol and radiation on cell killing was greater than additive.
AB - Purpose: To restore radiation-induced apoptosis in a bcl-2-expressing, radiation-resistant murine lymphoma cell line (LY-ar) by pretreatment with paclitaxel (Taxol). Because this cell line also has high intracellular levels of glutathione (GSH), reportedly due to the bcl-2 expression and involved in the cell's antioxidant functions, paclitaxel treatment was correlated with GSH levels. Methods and Materials: LY-ar cells were pretreated with paclitaxel and then irradiated with 5 Gy. Apoptosis was measured by DNA fragmentation 6 h later. Dose response and time course experiments were performed. Intracellular GSH levels were measured after treatment. Cell survival analysis was performed for various paclitaxel concentrations ± 5 Gy. Results: LY-ar cells pretreated with 0 nM, 10 nM, 25 nM, and 50 nM paclitaxel for 20 h underwent apoptosis at 2%, 15%, 25%, and 22%, respectively. With the addition of 5-Gy irradiation, LY-ar cell apoptosis increased to 4%, 30%, 49%, and 57%. Maximal apoptosis was detected with a paclitaxel pretreatment time of 20 h. Intracellular GSH levels were reduced by nearly 50% with paclitaxel pretreatment. Surviving fractions (SFs) with 0 nM, 10 nM, 25 nM, and 50 nM paclitaxel and 0 Gy were 1.0, 0.50, 0.08, and 0.05, respectively. SFs with 0 nM, 10 nM, 25 nM, and 50 nM paclitaxel and 5 Gy were 0.009, 0.003, 3 × 10-5, and 1 × 10-5, respectively. Conclusion: Radiation-induced apoptosis in LY-ar cells was restored by pretreatment with paclitaxel. This correlated with lowered levels of intracellular GSH. Cell survival analysis indicated that the combination of Taxol and radiation on cell killing was greater than additive.
KW - Apoptosis
KW - Glutathione
KW - Lymphoma
KW - Paclitaxel
KW - Radiation
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U2 - 10.1016/S0360-3016(00)01435-8
DO - 10.1016/S0360-3016(00)01435-8
M3 - Article
C2 - 11240255
AN - SCOPUS:0035869717
SN - 0360-3016
VL - 49
SP - 1127
EP - 1132
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 4
ER -