"Shock and kill" effects of class I-selective histone deacetylase inhibitors in combination with the glutathione synthesis inhibitor buthionine sulfoximine in cell line models for HIV-1 quiescence.
Latently infected, resting memory CD4+ T cells and macrophages represent a major obstacle to the eradication of HIV-1. For this purpose, "shock and kill" strategies have been proposed (activation of HIV-1 followed by stimuli leading to cell death). Histone deacetylase inhibitors (HDACIs) induce HIV-1 activation from quiescence, yet class/isoform-selective HDACIs are needed to specifically target HIV-1 latency. We tested 32 small molecule HDACIs for their ability to induce HIV-1 activation in the ACH-2 and U1 cell line models. In general, potent activators of HIV-1 replication were found among non-class selective and class I-selective HDACIs. However, class I selectivity did not reduce the toxicity of most of the molecules for uninfected cells, which is a major concern for possible HDACI-based therapies. To overcome this problem, complementary strategies using lower HDACI concentrations have been explored. We added to class I HDACIs the glutathione-synthesis inhibitor buthionine sulfoximine (BSO), in an attempt to create an intracellular environment that would facilitate HIV-1 activation. The basis for this strategy was that HIV-1 replication decreases the intracellular levels of reduced glutathione, creating a pro-oxidant environment which in turn stimulates HIV-1 transcription. We found that BSO increased the ability of class I HDACIs to activate HIV-1. This interaction allowed the use of both types of drugs at concentrations that were non-toxic for uninfected cells, whereas the infected cell cultures succumbed more readily to the drug combination. These effects were associated with BSO-induced recruitment of HDACI-insensitive cells into the responding cell population, as shown in Jurkat cell models for HIV-1 quiescence. The results of the present study may contribute to the future design of class I HDACIs for treating HIV-1. Moreover, the combined effects of class I-selective HDACIs and the glutathione synthesis inhibitor BSO suggest the existence of an Achilles' heel that could be manipulated in order to facilitate the "kill" phase of experimental HIV-1 eradication strategies.
Savarino
Andrea
A
Dept of Infectious, Parasitic and Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161, Rome, Italy. andrea.savarino@iss.it
Mai
Antonello
A
Norelli
Sandro
S
El Daker
Sary
S
Valente
Sergio
S
Rotili
Dante
D
Altucci
Lucia
L
Palamara
Anna Teresa
AT
Garaci
Enrico
E
D019328:Buthionine Sulfoximine / Q000494:pharmacology* / Q000633:toxicity; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology* / Q000633:toxicity; D005978:Glutathione / Q000037:antagonists & inhibitors*; D015497:HIV-1 / Q000187:drug effects*; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D014775:Virus Activation / Q000187:drug effects; D017735:Virus Latency / Q000187:drug effects*
D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D019328:Buthionine Sulfoximine; D005978:Glutathione