Table 2.
Kinetic parameters of steroid metabolism by MDA-MB-231 and MCF-7 cells.
| Hormone precursor | Metabolite | MDA-MB-231 |
MCF-7 |
||
|---|---|---|---|---|---|
| Km (nM) | Vmax (fmol/106 cells/h) | Km (nM) | Vmax (fmol/106 cells/h) | ||
| DHEA | DHEA-S | 55.4 ± 20.5 | 0.22 ± 0.04 | 229.2 ± 52.2∗ | 2873.0 ± 327.4∗ |
| AD | 126.1 ± 36.6 | 1994.0 ± 364.5 | 114.6 ± 3.6 | 147.4 ± 8.1∗ | |
| T | 56.3 ± 21.4 | 91.2 ± 15.9 | 107.5 ± 6.3∗ | 9.96 ± 1.42∗ | |
| E1 | E2 | 174.0 ± 94.1 | 703.0 ± 164.5 | 168.6 ± 8.7 | 628.6 ± 62.0 |
| E1-S | 119.5 ± 68.1 | 1.08 ± 0.38 | 101.9 ± 22.9 | 30.4 ± 2.5∗ | |
| E2-S | 38.0 ± 13.6 | 0.16 ± 0.02 | 113.8 ± 35.5∗ | 24.7 ± 4.9∗ | |
| E2-G | 87.9 ± 32.2 | 0.33 ± 0.07 | 123.5 ± 8.4 | 7.29 ± 1.36∗ | |
Kinetic parameters were calculated using GraphPad Prism 6.0 software following the incubation of the cells for 48 h with increasing concentrations of DHEA or E1 (25–100 nM). All data represent the means ± SD of three independent biological replicates. Values in bold and marked with an asterisk (∗) are significantly different compared with MDA-MB-231 cells (P < 0.05).