C18-Ceramide in Head & Neck Cancer Growth and Therapy

描述（由申请人提供）：本提案的长期目标是开发基于机制的治疗人类头颈部鳞状细胞癌（HNSCC）的治疗策略。鞘脂神经酰胺，一种被提出的肿瘤抑制脂质，在包括HNSCC在内的人类癌症的化疗药物反应中介导抗增殖。这里的数据表明，只有一种神经酰胺，即c18 -神经酰胺，在大约80%的HNSCC患者的肿瘤组织中，与邻近的正常组织相比，其水平显著降低。诱导长寿保证基因1 (LAG1)，该基因被认为是寿命的第一个调节因子，具体参与c18 -神经酰胺的合成，通过凋亡抑制HNSCC细胞的生长，并调节端粒酶活性。这些数据提示了C18:0神经酰胺在HNSCC的生长调节和化疗反应中起关键作用的总体假设。本文提出了两个具体目标：1)通过LAG1活性确定c18 -神经酰胺在HNSCC生长调控中的作用。这一特定的目的将集中在评估LAG1通过c18 -神经酰胺通过调节端粒酶和诱导凋亡来调节HNSCC细胞生长的新假设；a)确定HNSCC患者肿瘤中c18 -神经酰胺下调的机制；b)确定通过调节端粒酶和/或诱导细胞凋亡，增加C18神经酰胺的生成在HNSCC细胞系中抑制生长的作用；c)确定LAG1通过C18-神经酰胺抑制端粒酶活性的机制；ii)诱导这些细胞凋亡。2)通过C18神经酰胺确定LAG1在HNSCC中抗癌药物生长抑制功能中的作用。这一特定的目的将验证一种假设，即在特定化疗药物的作用下，LAG 1的激活导致c18 -神经酰胺的生成增加，从而通过调节端粒酶和诱导细胞凋亡来抑制HNSCC细胞的生长；a)定义诱导LAG1和c18 -神经酰胺生成的化疗药物（单独或联合）的亚群；b)确定LAGl/ c18 -神经酰胺途径对于化疗诱导的细胞生长抑制是否充分和/或必要；c)通过糖基神经酰胺合成酶和/或神经酰胺酶的过度表达来验证c18 -神经酰胺的衰减，从而增加神经酰胺的清除，从而导致对化疗诱导的细胞死亡产生耐药性。这些实验将有助于确定LAG1通过c18 -神经酰胺在化疗诱导的HNSCC抑制生长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.