Effects of galectin-1 inhibitor OTX008 on oral squamous cell carcinoma cells in vitro and the role of AP-1 and the MAPK/ERK pathway

Objective: To investigate the in vitro effects of inhibiting galectin-1 using the small-molecule inhibitor OTX008 on oral squamous cell carcinoma (OSCC) cell lines and the role of the MAPK pathway. Methods: One normal oral keratinocyte (NOK) and three OSCC cell lines were cultured in vitro and the expression of galectin-1 protein by each quantified using ELISA. Cell lines were treated with galectin-1 (50, 100 and 150 ng/mL) or OTX008 (12.5, 25, 50 and 100 mu g/mL) and cell viability assayed (n = 3). OSCC cell lines with and without 25 mu g/mL OTX008 (n = 3) treatment for 48 h, were analysed using qRT(2)-PCR with a custom array, to assess relative gene expression. Results: All cell lines were found to express galectin-1 protein. Exogenous galectin-1 significantly reduced cell viability in one OSCC cell line over time while the others were only minimally affected. OTX008 treatment reduced cell viability in a dose and time-dependent manner in all cell lines and this was associated with significant regulation of FOS gene expression in the OSCC cell lines. Conclusion: OTX008 decreased the viability of OSCC and NOK cells in a dose-dependent manner. The significant regulation of FOS suggests OTX008 causes early induction of the MAPK pathway via the immediate response gene FOS as a subunit of the AP-1 complex.