Lysine-specific demethylase 1 (LSD1) is upregulated in many cancers, especially neuroblastoma. We set out to explore whether geranylgeranoic acid (GGA) inhibits LSD1 activity by using recombinant human LSD1. GGA inhibited LSD1 activity with IC50 similar to that of the clinically used drug tranylcypromine. In human neuroblastoma SH-SY5Y cells, GGA induced NTRK2 gene expression alongside upregulation of histone H3 with dimethylated lysine-4 in the regulatory regions of the NTRK2 gene. Dihydrogenation of GGA reinforced the LSD1-inhibitory effect in a position- dependent manner. The inhibitory effects of dihydro-derivatives of GGA on recombinant LSD1 strongly correlated with the induction of NTRK2 gene expression in SH-SY5Y cells. These data demonstrate for the first time the efficient LSD1-inhibitor activity of GGA and its derivatives, providing a novel prospect of preventing cancer onset by using GGA to regulate epigenetic modification. (C) 2014 Elsevier Inc. All rights reserved.