Objective: Differentiation-inducing factor-1 (DIF-1) and -3 are novel lead anti-tumor agents that were originally isolated from the cellular slime mold Dictyostelium discoideum. We previously showed that the DIF derivatives Br-DIF-1, DIF-3(+2), and Bu-DIF-3 strongly suppress lysophosphatidic acid (LPA)-induced cell migration in mouse osteosarcoma LM8 cells in vitro. Here, we investigated the effects of these three DIF derivatives on the cell migration (wound healing) of LM8 cells and mouse 3T3-L1 fibroblast cells (a model of non-transformed cells).

Methods: A wound healing assay was performed to estimate the anti-cell migration activities of the compounds; cell growth was assessed by using a cell number indicator.

Results: After monolayers of LM8 cells or 3T3-L1 cells were wounded by scratching and incubated with 10% serum-containing media for 20 h or 8 h, respectively, cell-free areas (wounds) in the monolayer were occupied (healed) by neighboring cells to some extent even in the presence of Ara-C (an inhibitor of cell proliferation). This phenomenon is attributed to the migration of the neighboring cells into the wounds. Wound healing (cell migration) of LM8 cells was strongly suppressed in the presence of 10 μM Br-DIF-1, DIF-3(+2), or Bu-DIF-3. These DIF derivatives more effectively suppressed the cell migration of LM8 cells than of 3T3-L1 cells.

Conclusion: The results support our expectation that these DIF derivatives are promising lead anti-metastatic agents that may not affect normal cell migration.