Inhibition of Class I Histone Deacetylases 1 and 2 Promotes Urothelial Carcinoma Cell Death by Various Mechanism
Authors
Maria Pinkerneil, Michele J. Hoffmann, Rene Deenen, Karl Köhrer, Tanja Arent, Wolfgang A. Schulz, and Günter Niegisch
Institution
Heinrich Heine University
Country
Germany
Year
2016
Journal
Cancer Biology and Signal Transduction
Abstract
Class I histone deacetylases HDAC1 and HDAC2 contribute to
cell proliferation and are commonly upregulated in urothelial
carcinoma. To evaluate whether specific inhibition of these
enzymes might serve as an appropriate therapy for urothelial
carcinoma, siRNA-mediated knockdown and specific pharmacologic
inhibition ofHDAC1andHDAC2were applied in urothelial
carcinoma cell lines (UCC) with distinct HDAC1 and HDAC2
expression profiles. HDACs and response marker proteins were
followed by Western blotting and qRT-PCR. Effects of class I
HDAC suppression on UCCs were analyzed by viability, colony
forming, and caspase-3/7 assays; flow cytometry, senescence and
lactate dehydrogenase cytotoxicity assays; and immunofluorescence
staining. Whereas single knockdowns of HDAC1 or
HDAC2 were impeded by compensatory upregulation of the
other isoenzyme, efficient double knockdown of HDAC1 and
HDAC2 reduced proliferation by up to 80% and induced
apoptosis-like cell death in all UCCs. Clonogenic growth
was cell line– and HDAC-dependently reduced, with double
knockdown of HDAC1 and HDAC2 being usually most efficient.
Class I HDAC-specific inhibitors, especially the more
specific HDAC1/2 inhibitors romidepsin and givinostat, significantly
reduced proliferation of all UCCs (IC50, 3.36 nmol/L–
4.59 mmol/L). Romidepsin and givinostat also significantly
inhibited clonogenic growth of UCCs, with minor effects
on nontumorigenic controls. Intriguingly, these compounds
induced primarily S-phase disturbances and nonapoptotic
cell death in UCCs. Thus, although both ways of inhibiting
HDAC1/2 share mechanisms and efficaciously inhibit cell
proliferation, their modes of action differ substantially. Regardless,
combined inhibition of HDAC1/2 appears to represent
a promising strategy for urothelial carcinoma therapy.