Development of Substrate-Derived Sirtuin Inhibitors with Potential Anticancer Activity

RhoGDI is a key regulator of Rho proteins, coordinating their GTP/GDP and membrane/cytosol cycle. Recently, it was demonstrated by quantitative mass spectrometry that RhoGDI is heavily targeted by post-translational lysine acetylation. For one site in its N-terminal domain, namely K52, we reported earlier that acetylation completely switches off RhoGDI function. Herein we show that K52-acetylated RhoGDI is specifically deacetylated by the sirtuin deacetylase Sirt2. We show that acetylation at K52 decelerates cervical cancer cell proliferation, suggesting RhoGDI acetylation to be a promising therapeutic target. We demonstrate that treatment of cervical cancer cells with a RhoGDI-derived K52-trifluoroacetylated, substrate-derived peptidic sirtuin inhibitor severely impairs cell proliferation. Finally, we conclude that the potency of substrate-derived sirtuin inhibitors depends on structural features, the substrate-derived amino acid sequence as a determinant for selectivity, as well as the presence of an acetyl-lysine analogue to increase its potency. These data reveal a prospective therapeutic potential for novel substrate-derived sirtuin inhibitors.