Inhibition of Histone Deacetylase in Cancer Cells Slows Down Replication Forks, Activates Dormant Origins, and Induces DNA Damage

• Published in: Cancer research (Chicago, Ill.) Ill.), 2010-06, Vol.70 (11), p.4470-4480
• Main Authors: CONTI, Chiara, LEO, Elisabetta, EICHLER, Gabriel S, SORDET, Olivier, MARTIN, Melvenia M, FAN, Angela, ALADJEM, Mirit I, POMMIER, Yves
• Format: Article
• Language: English
• Subjects: Antineoplastic agents; Biological and medical sciences; Breast Neoplasms - drug therapy; Breast Neoplasms - enzymology; Breast Neoplasms - genetics; Cell Line, Tumor; Colonic Neoplasms - drug therapy; Colonic Neoplasms - enzymology; Colonic Neoplasms - genetics; DNA Damage; DNA Replication - drug effects; DNA, Neoplasm - biosynthesis; DNA, Neoplasm - genetics; Down-Regulation; HCT116 Cells; Histone Deacetylase Inhibitors - pharmacology; Histone Deacetylases - deficiency; Histone Deacetylases - genetics; Histone Deacetylases - metabolism; Histones - biosynthesis; Humans; Hydroxamic Acids - pharmacology; Medical sciences; Pharmacology. Drug treatments; Tumors; Vorinostat
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/0008-5472.can-09-3028

Protein acetylation is a reversible process regulated by histone deacetylases (HDAC) that is often altered in human cancers. Suberoylanilide hydroxamic acid (SAHA) is the first HDAC inhibitor to be approved for clinical use as an anticancer agent. Given that histone acetylation is a key determinant of chromatin structure, we investigated how SAHA may affect DNA replication and integrity to gain deeper insights into the basis for its anticancer activity. Nuclear replication factories were visualized with confocal immunofluorescence microscopy and single-replicon analyses were conducted by genome-wide molecular combing after pulse labeling with two thymidine analogues. We found that pharmacologic concentrations of SAHA induce replication-mediated DNA damage with activation of histone gammaH2AX. Single DNA molecule analyses indicated slowdown in replication speed along with activation of dormant replication origins in response to SAHA. Similar results were obtained using siRNA-mediated depletion of HDAC3 expression, implicating this HDAC member as a likely target in the SAHA response. Activation of dormant origins was confirmed by molecular analyses of the beta-globin locus control region. Our findings demonstrate that SAHA produces profound alterations in DNA replication that cause DNA damage, establishing a critical link between robust chromatin acetylation and DNA replication in human cancer cells.