GLO1 activity, drug resistance and P-glycoprotein expression in U937, K562 and their resistant cell lines
| Cell Lines . | GLO1 Activity (μmol/min/mg protein)* . | Degree of Resistance (fold)‡ . | P-Glycoprotein Expression1-153 . | |
|---|---|---|---|---|
| VP-16 . | ADM . | |||
| U937 | 8.79 ± 0.16 | 1.0 | 1.0 | − |
| UK711 | 13.63 ± 0.14† | 5.1 | 3.3 | − |
| UK110 | 18.65 ± 0.56† | 4.6 | 3.5 | − |
| K562 | 1.85 ± 0.20 | 1.0 | 1.0 | − |
| K562/ADM | 3.58 ± 0.27† | 9.4 | 27.3 | ++ |
| Cell Lines . | GLO1 Activity (μmol/min/mg protein)* . | Degree of Resistance (fold)‡ . | P-Glycoprotein Expression1-153 . | |
|---|---|---|---|---|
| VP-16 . | ADM . | |||
| U937 | 8.79 ± 0.16 | 1.0 | 1.0 | − |
| UK711 | 13.63 ± 0.14† | 5.1 | 3.3 | − |
| UK110 | 18.65 ± 0.56† | 4.6 | 3.5 | − |
| K562 | 1.85 ± 0.20 | 1.0 | 1.0 | − |
| K562/ADM | 3.58 ± 0.27† | 9.4 | 27.3 | ++ |
Cytosolic fractions were isolated, and enzyme assays were performed as described in “Materials and methods.” Values are means ± SD determined in triplicate.
P < 0.01 versus wild type (U937 or K562) cells, evaluated by an unpaired Student t test.
Cells were treated with VP-16 or ADM for 24 h. The number of viable cells was estimated by MTS tetrazolium method. Degree of resistance; IC50 resistant/IC50 parental cell line.
The expression of P-glycoprotein detected by Western blot analysis. The level of P-glycoprotein was then classified as follows: −, not observed; ++, overexpression.