Table 2.
MTX resistance-related variables in precursor B and T cell ALL
| Precursor B cell ALL | T cell ALL | ||||
|---|---|---|---|---|---|
| N | Median (range) | N | Median (range) | P value | |
| TSIA cont. | 85 | 0.058 (0.01–0.76) | 30 | 0.062 (0.01–0.22) | 0.595 |
| TSIA short | 87 | 0.37 (0.16–12.97) | 30 | 1.44 (0.16–40.0) | <0.001 |
| MTX-Glu1–6 | 97 | 1210 (120–4838) | 31 | 630 (314–1943) | <0.001 |
| MTX-Glu4–6 | 83 | 856 (80–3190) | 25 | 260 (0–843) | <0.001 |
| DHFR mRNA | 37 | 3.86 (0.27–55.06) | 17 | 12.42 (1.48–34.11) | <0.001 |
| TS mRNA | 37 | 2.64 (0.24–23.04) | 18 | 10.26 (1.64–25.04) | <0.001 |
| FPGS mRNA | 32 | 6.26 (1.12–39.64) | 20 | 2.39 (0.52–17.20) | 0.008 |
| FPGH mRNA | 27 | 2.12 (0.16–18.00) | 16 | 4.83 (0.18–27.65) | 0.196 |
| RFC mRNA | 35 | 0.89 (0.24–6.90) | 20 | 0.79 (0.23–4.79) | 0.668 |
| FPGS activity | 57 | 1.01 (0.03–11.33) | 16 | 0.18 (0.02–1.57) | <0.001 |
P value is determined by the Mann–Whitney U test; TSIA continuous (TSIA cont.) and short-term exposure (TSIA short) are expressed as the concentration of MTX (in μM) necessary to inhibit 50 % of the TS activity (TSI50) compared to the controls incubated without MTX (in triplicate); the concentration of MTX polyglutamates (MTX-Glu1–6 and MTX-Glu4–6) are expressed as pmol MTX-Glun/109 cells; mRNA expression of folate enzymes is expressed as ratio normalized to β-actin; FPGS activity is expressed as pmol MTX-Glu2 formed/h/106 cells