Targeting the PI3K/Akt Cell Survival Pathway to Induce Cell Death of HIV-1 Infected Macrophages with Alkylphospholipid Compounds Amanda Lucas1., Yuri Kim2., Omayra Rivera-Pabon1, Sunju Chae2, Dong-Hyun Kim2*, Baek Kim1* 1 Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York, United States of America, 2 Department of Pharmacy, College of Pharmacy, Kyung-Hee University, Seoul, South Korea Abstract Background: HIV-1 infected macrophages and microglia are long-lived viral reservoirs persistently producing viral progenies. HIV-1 infection extends the life span of macrophages by promoting the stress-induced activation of the PI3K/Akt cell survival pathway. Importantly, various cancers also display the PI3K/Akt activation for long-term cell survival and outgrowth, and Akt inhibitors have been extensively searched as anti-cancer agents. This led us to investigate whether Akt inhibitors could antagonize long-term survival and cytoprotective phenotype of HIV-1 infected macrophages. Principal Findings: Here, we examined the effect of one such class of drugs, alkylphospholipids (ALPs), on cell death and Akt pathway signals in human macrophages and a human microglial cell line, CHME5, infected with HIV-1 BaL or transduced with HIV-1 vector, respectively. Our findings revealed that the ALPs, perifosine and edelfosine, specifically induced the death of HIV-1 infected primary human macrophages and CHME5 cells. Furthermore, these two compounds reduced phosphorylation of both Akt and GSK3b, a downstream substrate of Akt, in the transduced CHME5 cells. Additionally, we observed that perifosine effectively reduced viral production in HIV-1 infected primary human macrophages. These observations demonstrate that the ALP compounds tested are able to promote cell death in both HIV-1 infected macrophages and HIV-1 expressing CHME5 cells by inhibiting the action of the PI3K/Akt pathway, ultimately restricting viral production from the infected cells. Significance: This study suggests that Akt inhibitors, such as ALP compounds, may serve as potential anti-HIV-1 agents specifically targeting long-living HIV-1 macrophages and microglia reservoirs. Citation: Lucas A, Kim Y, Rivera-Pabon O, Chae S, Kim D-H, et al. (2010) Targeting the PI3K/Akt Cell Survival Pathway to Induce Cell Death of HIV-1 Infected Macrophages with Alkylphospholipid Compounds. PLoS ONE 5(9): e13121. doi:10.1371/journal.pone.0013121 Editor: Paul Digard, University of Cambridge, United Kingdom Received July 16, 2010; Accepted September 5, 2010; Published September 30, 2010 Copyright: 2010 Lucas et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This study was supported by NIH AI077401 (B.K.), TL1 RR024135 from the National Center for Research Resources, NIH (A.L.L.) and National Research Foundation of Korea Grant funded by the Korean Government R33-2008-000-100018 (D.H.K). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: baek_kim@urmc.rochester.edu (BK); dhkim@khu. ac.kr (DHK) . These authors contributed equally to this work Introduction Targeting the actions of Human Immunodeficiency Virus Type 1 (HIV-1) proteins is currently a major anti-viral strategy that has led to effective controls of HIV-1 replication and pathogenesis. Unfortunately, this anti-HIV-1 strategy becomes ineffective due to the robust evolution and escape capacity of HIV-1, in which viral populations resistant to the currently available antiviral agents are selected. New anti-HIV-1 strategies which may avoid this viral escape are being extensively researched, and one promising strategy is to target host factors and cellular mechanisms that HIV- 1 hijacks for its replication and pathogenesis. HIV-1 infected macrophages exhibit extended life spans, allowing these cells to become long-lived HIV-1 reservoirs that persistently produce virus [1]. In addition, HIV-1 infected human microglia, resident macrophages of the central nervous system (CNS), isolated from patients displayed enhanced survival compared to uninfected microglia isolated from the same patients [2]. Importantly, it is known that HIV-1 infected macrophages and microglia secrete nitric oxide and various toxic viral proteins, such as gp120 and Tat, establishing cytotoxic extracellular environments near the infected cells [2]. Numerous studies reported that in the brain, these HIV-1 related toxic molecules induce the death of nearby neurons, ultimately leading to HIV- associated neurodegenerative diseases (HAND) in HIV-1 infected patients [3,4]. However, it is not clearly understood how HIV-1 infected macrophages and microglia are able to live for a long period of time and persistently produce viral progenies while these infected cells are also constantly exposed to the same cytotoxic environments that kill the nearby neurons. To understand the paradox between the long-lived survival phenotype of HIV-1 infected macrophages and the constant exposure of the cells to the toxic extracellular conditions, we hypothesized that HIV-1 may activate cellular pathways related to cell survival in infected macrophages and microglia. Indeed, we recently reported that HIV-1 infection triggers the activation of PLoS ONE | www.plosone.org 1 September 2010 | Volume 5 | Issue 9 | e13121