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

Abstract

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 replicationmediated DNA damage with activation of histone γH2AX. 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 β-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. Cancer Res; 70(11); 4470-80. ©2010 AACR.

Expression of Leukemia-Associated Fusion Proteins Increases Sensitivity to Histone Deacetylase Inhibitor–Induced DNA Damage and Apoptosis

“…However, the later downregulation of BER enzymes is still significant as it likely contributes to the continued or accelerated accumulation of DNA damage. Moreover, while we observed overlap in the DNA repair genes downregulated by LAFPs and vorinostat, the literature suggests that there are possibly other repair genes and pathways uniquely regulated by either as well (12,14,15,28). Indeed, we found that several DSB repair genes were down regulated by HDI, LAFP, or both ( Supplementary Fig.…”

“…by numerous mechanisms (11)(12)(13)(14)(15). In this work, we examined whether expression of LAFPs would improve response to HDI treatment.…”

“…Our laboratory and other groups have shown that one mechanism by which HDIs arrest growth and induce apoptosis in malignant cells is through the accumulation of DNA damage, which can occur through induction of reactive oxygen species (ROS; ref. 11), downregulation of DNA repair proteins (12)(13)(14), replication fork stalling (15), and impairment of DNA repair protein function (12,16). Interestingly, various HDIs have shown promising activity in LAFP-expressing AMLs.…”

Histone deacetylase inhibition redistributes topoisomerase IIb from heterochromatin to euchromatin

“…7A and B). Notably, it has recently been demonstrated that HDAC inhibition slows replication and leads to replication-associated DNA damage and H2AX phosphorylation, 50 and we suspect that this is likely to be the cause of the TSA-induced peri-heterochromatic gH2AX seen here. Thus increased background H2AX phosphorylation and the redistribution of topoisomerase IIβ are likely to be independent effects of the TSA-mediated remodelling of heterochromatin.…”

Sodium Butyrate Inhibits the Self-Renewal Capacity of Endometrial Tumor Side-Population Cells by Inducing a DNA Damage Response

“…In this study, NaB inhibited primary colony-forming potential and regeneration of SP cells, indicating suppression of self-renewal capacity. Most recently, Conti and colleagues showed that SAHA treatment of cancer cells slows down replication forks, activates dormant origins, and induces DNA damage (40). They also found gH2AX could be used as a convenient pharmacodynamic biomarker for HDACi-induced DNA damage (41).…”