C18-Ceramide in Head & Neck Cancer Growth and Therapy

描述(由申请人提供)：这项建议的长期目标是开发基于机制的治疗策略，用于治疗人头颈部鳞状细胞癌(HNSCC)。鞘磷脂神经酰胺是一种被认为是一种肿瘤抑制脂类，在包括HNSCC在内的人类癌症中，它介导了化疗药物的抗增殖作用。这里的数据显示，在HNSCC患者的肿瘤组织中，仅有一种神经酰胺C18-神经酰胺的水平显著低于其邻近正常组织。长寿保证基因1(LAG1)被认为是寿命的第一调节基因，它特异性地参与C18-神经酰胺的合成，通过诱导凋亡抑制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的生长调节和化疗反应中起关键作用的总体假设。提出了两个特定的目的：1)通过LAG1活性确定C18-神经酰胺在HNSCC生长调节中的作用。这一特定的目的将集中在评估LAG1通过调节端粒酶和诱导凋亡来调节HNSCC细胞生长的新假说：a)确定HNSCC患者肿瘤中C18-神经酰胺下调的机制；b)确定C18神经酰胺的增加在通过调节端粒酶和/或诱导HNSCC细胞凋亡来抑制生长中的作用；以及c)确定LAG1通过C18-神经酰胺抑制端粒酶活性的机制；以及ii)诱导这些细胞凋亡的机制。具体目的2)确定LAG1通过C18神经酰胺在HNSCC中抗癌药物生长抑制作用中的作用。这一特定的目的将检验这样一种假设，即在特定化疗药物的反应下，LAG1的激活导致C18-神经酰胺的产生增加，从而通过调节端粒酶和诱导凋亡来抑制HNSCC细胞的生长：a)确定诱导LAG1和C18-神经酰胺产生的化疗药物的亚群；b)确定LAG1/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；以及c)测试C18-神经酰胺通过葡萄糖神经酰胺合成酶和/或神经酰胺酶的过度表达而减弱的推论--这增加了神经酰胺的清除，导致对化疗诱导的细胞死亡的抵抗力的发展。这些实验将有助于确定通过C18-神经酰胺特异性LAG1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.