Galectin-1 and galectin-3 are beta-galactoside-binding proteins thought to be important for cellular interactions, growth regulation and differentiation. Alterations in cellular content of galectins have been associated with differentiation, transformation and malignant progression. We examined the modulation of galectin-1 and galectin-3 expression in head and neck squamous cell carcinoma (HNSCC) cell lines by treatment with sodium butyrate, a known differentiation-modulating agent, and identified potential mechanisms of butyrate regulation of galectin-1 levels in one of the cell lines. Sodium butyrate effected an increase in galectin-1 protein concentration in 5 of 8 cell lines. One cell line, MDA-886LN, showed a marked time- and dose-dependent increase from barely detectable amounts with butyrate treatment. Concurrently with increased galectin-1 expression, butyrate treatment promoted morphologic changes, induced growth inhibition and inhibited soft agar colony formation in MDA-886LN cells. Butyrate-treated MDA-886LN cells demonstrated increased galectin-1 mRNA content, suggesting a role for butyrate in transcriptional regulation of galectin-1 expression. Treatment with other inhibitors of histone deacetylase also induced an increase in galectin-1 expression. Together, our results indicate that butyrate treatment can modulate galectin-1 content in MDA-886LN HNSCC cells as well as induce morphologic changes and growth inhibition. This action may involve a combination of transcriptional regulation and inhibition of histone deacetylation.