[Differential invasion and metastasis capacities of methotrexate enantiomer-resistant A549 cell lines].

Objective: To study the differential in vitro motor and invasion capacities of methotrexate (MTX) enantiomer-resistant tumor cells.

Methods: The incremental concentrations and successive low-dose induction were employed to acquire the cell series resistant to 15 µmol/L MTX enantiomer, namely L-(+)-MTX/A549 and D-(-)-MTX/A549. Their drug-resistant indices were determined by MTT assay and their migration capacities by wound healing assay. Double soft-agar clone formation was used to detect the colony efficiency and size. And Transwell was employed to detect the in vitro movement and invasion capacity of three cell types.

Results: The resistance indices of L-(+)-MTX/A549 and D-(-)-MTX/A549 were (6.1 ± 1.0) and (20.3 ± 1.8) respectively. At 72 hours after wound healing assay, the number of L-(+)-MTX/A549 entering scratch zone was fewer than that of D-(-)-MTX/A549; The numbers of colony formation in D-(-)-MTX/A549, L-(+)-MTX/A549 and parental cells were (50 ± 7), (44 ± 6), (52 ± 7) and the rates of colony formation (1.68% ± 0.23%), (1.49% ± 0.18%), (1.73% ± 0.23%) respectively. And there was no significant significance among three groups (P > 0.05). But the size of D-(-)-MTX/A549 was larger than that of L-(+)-MTX/A549. Transwell detected infiltration and invasion through artificial basement membrane Matrigel. The numbers of D-(-)-MTX/A549, L-(+)-MTX/A549 and parent cells were (267 ± 30), (106 ± 16) and (134 ± 16) respectively. The data were significant between D-(-)-MTX/A549 cells and L-(+)-MTX/A549 or parent cells (P < 0.05) but not significant between L-(+)-MTX/A549 and parent cells (P > 0.05).

Conclusion: The D-(-)-MTX-induced NSCLC A549 cells have greater motor and invasion capacities than those of L-(+)-MTX-induced ones. It suggests that MTX enantiomer has different capacities of tumor invasion and metastasis after acquiring resistance.