A Novel Agent with Dual Functions to Treat Head and Neck Cancer

描述（由申请人提供）：口腔黏膜炎（OM）是放疗和化疗抗肿瘤方案常见的破坏性并发症，特别是头颈癌患者，目前尚无有效的治疗方法。我们从一种新的18-kD的胃窦粘膜蛋白（AMP-18）中鉴定出一种21个氨基酸的肽，在两种动物模型中促进损伤口腔粘膜组织的愈合，并提高顺铂和放射治疗的疗效。皮下注射AMP肽可保护小鼠舌表面上皮免受急性辐射损伤。在单独暴露于辐射或顺铂的仓鼠中，用肽治疗也能延缓溃疡的出现并减少口腔粘膜溃疡形成的程度。AMP-18在培养细胞和体内具有多效性，具有抗凋亡、促运动和有丝分裂作用，并通过靶向紧密连接蛋白保护上皮屏障功能和结构。为了确定AMP-18及其肽发挥作用的机制，我们最近确定了胆囊收缩素- b /胃泌素受体（CCKBR）作为AMP-18的受体，并通过免疫组织化学验证了其在正常人口腔粘膜组织中的表达。AMP-18结合CCKBR可激活MAPKs、Rho、Akt和PKC？通路。AMP肽表现出与全长蛋白相同的生物学功能。为了研究用AMP肽治疗OM是否能阻断辐射的溶瘤作用，我们在接受或不接受AMP肽辐射的裸鼠身上建立了人类癌细胞的异种移植模型。AMP肽出乎意料地增强了辐射诱导的生长抑制，而对动物没有任何不良影响。胃癌组织中AMP-18表达下调或缺失，胃癌细胞系中转染和过表达AMP-18可诱导细胞凋亡或衰老，支持了这种抑瘤功能。为了开发AMP肽作为一种治疗剂，我们研究了顺铂存在下AMP肽对头颈癌细胞SCC61生长的影响。用AMP肽或重组人（rh） AMP-18与顺铂一起治疗，可减少细胞生长。因此，AMP肽/rhAMP-18在体外和体内具有双重作用：保护和促进口腔粘膜损伤组织的愈合，增强抗肿瘤策略的疗效。具体目标1是在口腔舌鳞状细胞癌的原位小鼠模型中证明，AMP肽与辐射一起在同一动物中发挥其放射保护和肿瘤抑制特性。目的2是确定AMP肽愈合口腔黏膜组织损伤的机制，但也可以抑制暴露于辐射和/或顺铂后头颈部癌细胞的生长。AMP肽发挥其多效性作用的分子机制的鉴定可能加速其作为头颈癌患者OM的新型治疗药物的发展。

DESCRIPTION (provided by applicant): Oral mucositis (OM) is a common, devastating complication of radiation and chemotherapeutic antineoplastic regimens, particularly in patients with head and neck cancers, for which no effective therapy is currently available. We have identified a 21 amino acid peptide derived from a novel 18-kD Antrum Mucosal Protein (AMP-18) that facilitates healing of injured oral mucosal tissue in two animal models, and increases the efficacy of cisplatin and radiation treatment. Subcutaneous administration of the AMP peptide protected the surface epithelium of mouse tongue against acute radiation injury. Treatment with the peptide also delayed the appearance and reduced the extent of ulcer formation in the buccal mucosa of hamsters exposed to radiation alone, or with cisplatin. AMP-18 functions as a pleiotropic agent in cultured cells and in vivo, exhibits anti- apoptotic, motogenic and mitogenic effects, and protects epithelial barrier function and structure by targeting tight junction proteins. To determine the mechanisms by which AMP-18 and the peptide exerts their effects, we recently identified the cholecystokinin-B/gastrin receptor (CCKBR) as a receptor for AMP-18, and verified its expression in normal human oral mucosal tissue by immunohistochemistry. Binding of AMP-18 to CCKBR activates MAPKs, Rho, Akt and PKC? pathways. The AMP peptide exhibits the same biological functions as does the full-length protein. To find out if treatment of OM with AMP peptide could block the tumorolytic effect of radiation, we created a xenograft model of human cancer cells in nude rats that received radiation with or without AMP peptide. Administration of AMP peptide unexpectedly enhanced radiation-induced growth inhibition without causing any adverse effects in the animals. This tumor suppressor function is supported by observations showing that expression of AMP-18 is downregulated or absent in gastric cancer tissue, and that transfection and overexpression of AMP-18 in gastric cancer cell lines can induce apoptosis or senescence. To develop AMP peptide as a therapeutic agent, we investigated the effects of the peptide on growth of a head and neck cancer cell line, SCC61, in the presence of cisplatin. Treatment with AMP peptide or recombinant human (rh) AMP-18, together with cisplatin, additively reduced cell growth. Thus AMP peptide/rhAMP-18 has dual effects in vitro and in vivo: it protects and facilitates healing of injured oral mucosal tissue, and enhances efficacy of antineoplastic strategies. Specific Aim #1 is to demonstrate in an orthotopic mouse model of squamous cell cancer of the oral tongue, that AMP peptide administered together with radiation exerts both its radioprotective and tumor-suppressing properties in the same animal. Aim #2 is to identify mechanisms by which AMP peptide heals injured oral mucosal tissue, but can also inhibit growth of head and neck cancer cells following exposure to radiation and/or cisplatin. Identification of molecular mechanisms by which AMP peptide exerts its pleiotropic effects could speed its development as a novel therapeutic for OM in patients with head and neck cancers.