PKB/Akt Activation and Cell Survival with HIV-1 Tat

HIV-1 Tat 的 PKB/Akt 激活和细胞存活

• 批准号: 6947584
• 负责人: FELIPE SAMANIEGO
• 金额: $ 12.9万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-04-12 至 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6947584
• 关键词: AIDS related neoplasm /cancer; Kaposi' s sarcoma; SDS polyacrylamide gel electrophoresis; apoptosis; athymic mouse; biological signal transduction; cell line; clinical research; genetically modified animals; growth factor receptors; human immunodeficiency virus 1; immunoprecipitation; integrins; laboratory mouse; neoplastic growth; phosphorylation; protein kinase; terminal nick end labeling; transcription factor; transfection; vascular endothelial growth factors; virus protein

DESCRIPTION (provided by applicant): No convincing explanation exists for the aggressive growth of Kaposi's sarcoma (KS) in the estimated 8 million people worldwide afflicted with both this disease and human immunodeficiency virus type 1 (HIV-1). Human herpesvirus 8 (HHV-8) is required for the development of KS but is insufficient to cause it unless a second factor, such as HIV-1, is present. The HIV-1 transactivator of transcription (Tat) protein is implicated in KS because it stimulates the invasive and proliferative properties of KS cells and endothelial cells (ECs) in cultures and in tat transgenic mice. In preliminary studies, we found that Tat activates phosphatidylinositol 3'-kinase (PI3K) and Akt, the latter is a key regulator in tumorigenesis and cell survival. We found that immobilized Tat and physiologic levels of Tat in solution promoted the survival of KS SLK cells. It is not known how Tat promotes cell survival or to what extent this effect promotes growth of KS. We hypothesize that HIV-1 Tat activates Akt and promotes cell survival. Our preliminary studies with Tat and our exclusive faf transgenic mice lines will enable us to evaluate Tat's role in PI3K-Akt activation and cell survival. Specific Aim 1. Determine to what extent Tat activates Akt In vitro, and identify the signaling pathway Tat uses to promote cell survival. We will characterize Tat-related Akt phosphorylation and Akt kirtase activity in HHV-8 infected dermal microvasculature endothelial (HHV8-OMVE) cells. We will map the active moiety in Tat by using peptides, truncated Tat mutants, and antibodies. We will target the PI3K-Akt pathway with drugs (LY294002 and Perifosine) and PI3K-AM dominant-negative mutants to determine the role of this pathway in Tat-related cell survival. Specific Aim 2. Determine to what extent Tat activates Akt In vivo and promotes tumor growth by analyzing Tatexpressing cells In nude mice and tat transgenic mice. Tat of different sizes will be expressed and mapped on Tat domains critical to Akt phosphorylation. We will also test designed PISK-Akt inhibitors (LY294002 and Perifosine) and candidate anticancer agents for their role in blocking this pathway and reversing tumor growth. Successful completion of these studies will help identify a novel property of Tat that stimulates a survival mechanism anticipated to play a major role in KS and HHV8-DMVE cells. This research plan will establish the potential of drugs designed to interrupt this pathway implicated in KS and perhaps in other cancers associated with HIV-1 infection.

描述（由申请人提供）： 对于卡波西肉瘤（KS）在全世界估计800万患有这种疾病和人类免疫缺陷病毒1型（HIV-1）的人中的侵袭性生长，没有令人信服的解释。人类疱疹病毒8（HHV-8）是KS发展所必需的，但不足以引起它，除非存在第二个因素，如HIV-1。HIV-1转录反式激活因子（达特）蛋白与KS有关，因为它刺激培养物和塔特转基因小鼠中KS细胞和内皮细胞（EC）的侵袭和增殖特性。在前期研究中，我们发现达特激活磷脂酰肌醇3 '-激酶（PI 3 K）和Akt，后者是肿瘤发生和细胞存活的关键调节因子。我们发现，固定化达特和生理水平的达特在溶液中促进KS SLK细胞的存活。尚不清楚达特如何促进细胞存活或这种作用在多大程度上促进KS生长。我们假设HIV-1达特激活Akt并促进细胞存活。我们对达特和我们独有的faf转基因小鼠系的初步研究将使我们能够评估达特在PI 3 K-Akt活化和细胞存活中的作用。 具体目标1.确定达特在体外激活Akt的程度，并鉴定达特用于促进细胞存活的信号通路。我们将表征HHV-8感染的真皮微血管内皮（HHV 8-OMVE）细胞中Tat相关的Akt磷酸化和Akt kirtase活性。我们将通过使用肽、截短的达特突变体和抗体来绘制达特中的活性部分。我们将用药物（LY 294002和Perifosine）和PI 3 K-AM显性阴性突变体靶向PI 3 K-Akt途径，以确定该途径在Tat相关细胞存活中的作用。 具体目标2。通过分析裸鼠和tat转基因小鼠中表达Tat的细胞，确定达特在体内激活Akt和促进肿瘤生长的程度。不同大小的达特将被表达并定位在Akt磷酸化关键的达特结构域上。我们还将测试设计的PISK-Akt抑制剂（LY 294002和Perifosine）和候选抗癌药物在阻断该途径和逆转肿瘤生长中的作用。 这些研究的成功完成将有助于鉴定达特的一种新性质，该性质刺激预期在KS和HHV 8-DMVE细胞中发挥主要作用的存活机制。这项研究计划将建立旨在中断KS和可能与HIV-1感染相关的其他癌症中的这一途径的药物的潜力。