The Effect of PSC 833 on the Inhibition of Induction of Pgp Expression
| Initial Pgp3-150 Levels . | PSC 8333-151 . | % Induction3-152 . | ||||
|---|---|---|---|---|---|---|
| IDA . | MX2 . | EPI . | DAU . | AraC . | ||
| Pgp-negative | − | 80% (4/5) | 100% (5/5) | 100% (5/5) | 100% (3/3) | 100% (3/3) |
| + | 20% (1/5) | 0% (0/5) | 0% (0/5) | 0% (0/3) | 0% (0/3) | |
| Pgp-positive | − | 50% (1/2) | 100% (3/3) | 50% (2/4) | 100% (2/2) | 66% (2/3) |
| + | 0% (0/2) | 33.3% (1/3) | 25% (1/4) | 0% (0/2) | 0% (0/3) | |
| Initial Pgp3-150 Levels . | PSC 8333-151 . | % Induction3-152 . | ||||
|---|---|---|---|---|---|---|
| IDA . | MX2 . | EPI . | DAU . | AraC . | ||
| Pgp-negative | − | 80% (4/5) | 100% (5/5) | 100% (5/5) | 100% (3/3) | 100% (3/3) |
| + | 20% (1/5) | 0% (0/5) | 0% (0/5) | 0% (0/3) | 0% (0/3) | |
| Pgp-positive | − | 50% (1/2) | 100% (3/3) | 50% (2/4) | 100% (2/2) | 66% (2/3) |
| + | 0% (0/2) | 33.3% (1/3) | 25% (1/4) | 0% (0/2) | 0% (0/3) | |
Pgp status was expressed as the ratio of the arithmetic mean of fluorescence (MCF) of MRK 16 versus the IgG2a control as described in Materials and Methods.
Blasts were treated with 20 ng/mL IDA, 50 ng/mL MX2, 100 ng/mL EPI, 80 μg/mL DAU, or 10 ng/mL AraC for 16 hours in the presence or absence of 1 μmol/L PSC 833 before being subjected to Pgp analysis as described in Materials and Methods.
Pgp induction (upregulation) was defined as a change in Pgp expression of treated compared with untreated blasts of ≥10% as described in Materials and Methods.