Histone Deacetylase Inhibitor Suberoylanilide Hydroxamic Acid Suppresses Human Adenovirus Gene Expression and Replication

Abstract

Human adenovirus (HAdV) causes minor illnesses in most patients but can lead to severe disease and death in pediatric, geriatric, and immunocompromised individuals. No approved antiviral therapy currently exists for the treatment of these severe HAdV-induced diseases. In this study, we show that the pan-histone deacetylase (HDAC) inhibitor SAHA reduces HAdV-5 gene expression and DNA replication in tissue culture, ultimately decreasing virus yield from infected cells. Importantly, SAHA also reduced gene expression from more virulent and clinically relevant serotypes, including HAdV-4 and HAdV-7. In addition to SAHA, several other HDAC inhibitors (e.g., trichostatin A, apicidin, and panobinostat) also affected HAdV gene expression. We determined that loss of class I HDAC activity, mainly HDAC2, impairs efficient expression of viral genes, and that E1A physically interacts with HDAC2. Our results suggest that HDAC activity is necessary for HAdV replication, which may represent a novel pharmacological target in HAdV-induced disease. IMPORTANCE Although human adenovirus (HAdV) can cause severe diseases that can be fatal in some populations, there are no effective treatments to combat HAdV infection. In this study, we determined that the pan-histone deacetylase (HDAC) inhibitor SAHA has inhibitory activity against several clinically relevant serotypes of HAdV. This U.S. Food and Drug Administration-approved compound affects various stages of the virus lifecycle and reduces virus yield even at low concentrations. We further report that class I HDAC activity, particularly HDAC2, is required for efficient expression of viral genes during lytic infection. Investigation of the mechanism underlying SAHA-mediated suppression of HAdV gene expression and replication will enhance current knowledge of virus-cell interaction and may aid in the development of more effective antivirals with lower toxicity for the treatment of HAdV infections.

Antiviral Effects of Curcumin on Adenovirus Replication

“…Ineffective expression of early viral proteins caused by curcumin may prevent HAdV from shutting down this anti-viral pathway. Second, as previously reported by our research group, HDAC activity is required for HAdV replication [ 19 ], and curcumin has been reported to lower HDAC activity [ 46 ]. Finally, curcumin can inhibit the activity of p300/CREB-binding protein (p300/CBP) [ 47 ], a key cellular protein that interact with E1A and mediates global changes in gene expression within the cell to modify the microenvironment for optimal viral replication [ 48 ].…”

“…If the efficacy of curcumin is solely due to inhibition of E1A protein expression, forced expression of E1A should rescue the ability of HAdV to replicate in curcumin-treated cells. We previously described an HAdV vector in which high-level E1A expression is driven by the human cytomegalovirus (HCMV) immediate early enhancer/promoter [ 19 ], and attempted to circumvent the curcumin-induced block in HAdV replication. Treatment with curcumin dramatically lowered the levels of E1A produced from this virus and, as a result, HAdV replication was not rescued.…”

“…Our research group developed an HTS protocol to identify compounds that inhibit HAdV replication [ 16 ]. We utilized a HAdV type 5-based construct that expressed red fluorescent protein (RFP) as part of the late transcription unit, such that RFP is only expressed at appreciable levels following viral DNA replication [ 19 ]. As such, the degree to which a test compound affects viral gene expression and replication inversely correlates with quantity of RFP present in the treated cells [ 16 ].…”

“…We also screened the Cayman Epigenetic Screening library, containing 150 small molecules that modulate the activity of epigenetic regulatory proteins, including methyltransferases, demethylases, histone acetyltransferases and deacetylases, and acetylated lysine readers, and identified 19 compounds exhibiting anti-HAdV activity [ 17 ]. Finally, we showed that suberoylanilide hydroxamic acid (SAHA), a histone deacetylase (HDAC) inhibitor, effectively inhibits HAdV replication at several stages in the HAdV lifecycle, including gene expression and DNA replication [ 19 ]. The effect of SAHA was attributed to inhibition of Class I HDAC, primarily HDAC2, showing that HDAC activity is required for normal HAdV replication.…”

Identification of human adenovirus replication inhibitors from a library of small molecules targeting cellular epigenetic regulators

“…Several research groups have performed small molecule screens to identify novel anti-HAdV compounds ( Duffy et al, 2013 ; Grosso et al, 2017 ; Hartline et al, 2018 ; Marrugal-Lorenzo et al, 2018 ; Sanchez-Cespedes et al, 2016 ; Wang et al, 2018 ). To facilitate and simplify high-throughput screening for anti-HAdV compounds, we recently developed a wildtype-like HAdV-5 reporter construct that contained the red fluorescent protein (RFP) gene under regulation of the HAdV major late promoter (MLP), such that the level of RFP expression correlated with viral late gene expression and DNA replication ( Saha and Parks, 2019 ). Thus, quantification of fluorescence intensity in cells infected with this virus could be used to easily identify compounds that affect virus infection, gene expression and/or replication.…”