Chemoprevention of upper aerodigestive tract cancer by dietary zinc

描述（由申请人提供）：尽管自20世纪80年代中期以来，世界范围内的癌症死亡率有所下降，但包括食管鳞状细胞癌（ESCC，食管癌的主要亚型）和舌鳞状细胞癌（口腔癌的主要部位）在内的上气消化（UADT）癌症仍然致命。因此，迫切需要澄清发病机制和新的预防策略。全球膳食锌缺乏症（ZD）估计影响30%的人口（各次区域为4-73%），其中发展中国家的缺乏率更高。重要的是，ZD增加了UADT癌症的风险。在过去的六年里，我们在了解锌在UADT癌症发展和预防中的分子作用方面取得了重大进展。利用无偏全基因组表达谱、生物信息学、分子病理学和我们的动物模型，我们发现：(1)大鼠短期饮食ZD诱导促炎介质S100a8和S100a9的过度表达，与食管增生有关。锌调节S100A8-RAGE相互作用与下游NF-kB/COX-2信号传导之间的联系，证明锌调节早期食管癌发生的炎症途径；（ii）长期ZD诱导癌症相关的炎症基因信号，促进ESCC，而口服锌补充可逆转这一信号并预防ESCC。（iii）补充锌可以通过抑制炎症来抑制足锌饮食的大鼠和肿瘤抑制因子缺乏小鼠的UADT肿瘤发展，这表明锌即使在足锌受试者中也具有化学预防作用；（iv）利用nanoStringTM技术，我们发现膳食ZD以组织特异性的方式改变microRNA的表达。炎性ZD食管具有明显的microRNA基因特征，其致癌miR-31和miR-21过表达，类似于人类ESCC/舌SCC。ZD大鼠食管miR-31和miR-21水平与ESCC的出现直接相关。miR-31和miR-21在大鼠/人舌鳞状细胞癌中的原位杂交研究表明，它们的上调是细胞类型特异性的，并且对锌治疗有反应。在Aim 1中，我们验证了膳食ZD绕过Rage-/-信号通路维持炎症的要求，并通过激活替代炎症途径促进Rage-/-小鼠的前胃癌发生的假设。在第二项研究中，我们分析了膳食锌对致癌物治疗大鼠舌癌发展和消退过程中基因表达（microRNA, mRNA）的调节作用。在Aim 3中，我们验证了一种假设，即由基质中膳食ZD诱导的ZD大鼠体内miR-21的抑制可能抵消ZD的促炎作用并抑制ESCC。在Aim 4中，我们通过研究膳食ZD与大鼠食管炎症相关mRNA和microRNA表达变化之间的剂量反应关系，确定了锌在预防UADT癌中的需求量。这些研究的数据将促进我们对锌在UADT癌的发展和预防中如何影响与炎症相关的基因（mRNA和microrna）的认识。

DESCRIPTION (provided by applicant): Though cancer mortality rates have declined worldwide since the mid 1980s, upper aerodigestive (UADT) cancer, including esophageal squamous cell cancer (ESCC, predominant subtype of esophageal cancer) and tongue SCC (major site of oral cancer), remains deadly. Thus, clarification of pathogenetic mechanisms and new prevention strategies are urgently needed. Global dietary zinc (Zn) deficiency (ZD) is estimated to affect 30% of the population (4-73% across subregions), with higher rates in developing countries. Importantly, ZD increases the risk of UADT cancer. In the past six years we have made significant progress toward understanding the molecular role of Zn in UADT cancer development and prevention. Using unbiased whole genome expression profiling, bioinformatics, molecular pathology, and our well-characterized animal models, we have found that: (i) short-term dietary ZD in rats induces overexpression of proinflammation mediators, S100a8 and S100a9, associated with esophageal hyperplasia. Zn modulates the link between S100A8-RAGE interaction and downstream NF-kB/COX-2 signaling, evidence that Zn regulates an inflammatory pathway in early esophageal carcinogenesis; (ii) prolonged ZD induces a cancer-associated inflammatory gene signature that fuels ESCC and oral Zn replenishment reverses this signature and prevents ESCC. (iii) Zn- supplementation suppresses UADT tumor development in rats and tumor suppressor-deficient mouse strains on a Zn-sufficient diet through attenuation of inflammation, evidence that Zn has chemopreventive effects even in Zn-sufficient subjects; (iv) Using the nanoStringTM technology, we discovered that dietary ZD alters microRNA expression in a tissue-specific manner. The inflammatory ZD esophagus has a distinct microRNA gene signature with overexpression of oncogenic miR-31 and miR-21, resembling that in human ESCC/tongue SCC. In ZD rats esophageal miR-31 and miR-21 levels are directly associated with the appearance of ESCC. In situ hybridization study of miR-31 and miR-21 expression in rat/human tongue SCC reveals that their upregulation is cell type-specific and is Zn-therapy responsive. In Aim 1, we test the hypothesis that dietary ZD bypasses the requirement for RAGE-signaling in sustaining inflammation and promotes forestomach carcinogenesis in Rage-/- mice by activating alternative inflammatory pathway(s). In Aim 2, we dissect dietary Zn modulation of gene expression (microRNA, mRNA) in tongue cancer development and regression in carcinogen-treated rats. In Aim 3, we test the hypothesis that in vivo inhibition of miR-21 in ZD rats that is induced by dietary ZD in stroma might offset the inflammation-promoting effect of ZD and inhibit ESCC. In Aim 4, we determine the requirement for Zn in the prevention of UADT cancer by investigating the dose response relationship between dietary ZD and alterations of inflammation-related mRNA and microRNA expression in the rat esophagus. The data from the proposed studies should advance our knowledge of how Zn affects genes (mRNA and microRNAs) related to inflammation in the development and prevention of UADT cancer.