C18-Ceramide in Head & Neck Cancer Growth and Therapy

描述（由申请方提供）：本提案的长期目标是开发用于治疗人头颈部鳞状细胞癌（HNSCC）的基于机制的治疗策略。鞘脂神经酰胺是一种建议的肿瘤抑制脂质，在人类癌症（包括HNSCC）中介导对化疗药物的抗增殖反应。这里的数据表明，与其邻近的正常组织相比，在患有HNSCC的患者的约80%的肿瘤组织中，仅一种神经酰胺（C18-神经酰胺）的水平显著较低。长寿保证基因1（longevity assurance gene 1，LAG 1）是人类寿命的第一个调节因子，它特异性地参与C18-神经酰胺的合成，通过细胞凋亡抑制HNSCC细胞的生长，并调节端粒酶活性。这些数据表明，C18：0神经酰胺在HNSCC的生长调节和对化疗的反应中起关键作用。提出了两个具体目标：具体目标1）通过LAG 1活性确定C18-神经酰胺在HNSCC生长调节中的作用。该特定目的将集中于评估LAG 1通过C18-神经酰胺经由端粒酶的调节和细胞凋亡的诱导来调节HNSCC细胞的生长的新假设; a）确定C18-神经酰胺在从HNSCC患者获得的肿瘤中下调的机制; B）确定C18神经酰胺生成增加在通过调节端粒酶抑制生长中的作用，和/或或在HNSCC细胞系中诱导凋亡;和c）确定LAG 1通过C18-神经酰胺i）抑制端粒酶活性;和ii）在这些细胞中诱导凋亡的机制。具体目的2）确定LAG 1通过C18神经酰胺在HNSCC中抗癌剂的生长抑制功能中的作用。该特定目的将检验如下假设：响应于特定化疗剂，导致C18-神经酰胺产生增加的LAG 1的活化通过端粒酶的调节和细胞凋亡的诱导导致HNSCC细胞的生长抑制; B）确定LAG 1/C18-神经酰胺途径对于化疗诱导的细胞生长抑制是否足够和/或必需;和c）测试通过葡糖神经酰胺合酶和/或神经酰胺酶的过表达减弱C18-神经酰胺导致对化疗诱导的细胞死亡产生抗性的推论，所述葡糖神经酰胺合酶和/或神经酰胺酶增加神经酰胺的清除。这些实验将有助于确定LAG 1通过C18-神经酰胺在化疗诱导的HNSCC生长抑制中的作用和下游靶点。

DESCRIPTION (provided by applicant): The long-term objective of this proposal is to develop mechanism-based therapeutic strategies for the treatment of human head and neck squamous cell carcinoma (HNSCC). The sphingolipid ceramide, a proposed tumor suppressor lipid, mediates anti-proliferation in response to chemotherapeutic agents in human cancers, including HNSCC. Data here demonstrate that the levels of only one ceramide, C18-ceramide, were significantly lower in about 80% of the tumor tissues of the patients with HNSCC as compared to their adjacent normal tissues. Induction of longevity assurance gene 1 (LAG1), identified as the first regulator of life-span, which is involved specifically in the synthesis of C18-ceramide, suppressed growth of HNSCC cells via apoptosis, and the modulation of telomerase activity. These data suggested the overall HYPOTHESIS that C18:0 ceramide plays a key role in the regulation of growth, and response to chemotherapy in HNSCC. Two specific aims are proposed: Specific Aim 1) Determine the role of C18-ceramide by LAG1 activity in the regulation of growth in HNSCC. This specific aim will concentrate on evaluating the novel hypothesis that LAG1 via C18-ceramide regulates growth of HNSCC cells via modulation of telomerase and induction of apoptosis; a) determine the mechanisms of down-regulation of C18-ceramide in tumors obtained from patients with HNSCC; b) determine the role of increased generation of C18 ceramide in the inhibition of growth by modulation of telomerase and/or induction of apoptosis in HNSCC cell lines; and c) determine the mechanisms by which LAG1 via C18- ceramide i) inhibits telomerase activity; and ii) induces apoptosis in these cells. Specific Aim 2) Establish the role of LAG1 via C18 ceramide in the growth suppression functions of anti-cancer agents in HNSCC. This specific aim will test the hypothesis that activation of LAG 1, resulting in increased generation of C18-ceramide, in response to specific chemotherapeutic agents leads to growth suppression of HNSCC cells via modulation of telomerase and induction of apoptosis; a) define the subset of chemotherapeutic agents (alone or in combination) which induce LAG1, and generation of C18-ceramide; b) determine whether LAGl/C18-ceramide pathway is sufficient and/or necessary for chemotherapy-induced suppression of cell growth; and c) test the corollary that attenuation of C18-ceramide via over expression of glucosylceramide synthase and/or ceramidase - which increase the clearance of ceramide, result in the development of resistance to chemotherapy-induced cell death. These experiments will help identify roles and downstream targets of specifically LAG1 via C18-ceramide in chemotherapy-induced suppression growth of HNSCC.