NUCLEAR RETINOIC ACID RECEPTORS IN HEAD/NECK CARCINOGENESIS & CHEMOPREVENTION

维生素A及其类似物(维甲酸)可预防鳞状细胞癌 正常非角化上皮细胞在体内和体外的分化 体外抑制口腔癌前病变(白斑)的研究 实验动物上呼吸道癌变。 维甲酸发挥这些作用的机制(S)尚不清楚。 核维甲酸受体(RARs)作为配体激活的功能 反式作用转录调控因子及其调节作用 维甲酸对某些基因表达的影响。假说 这个项目的基础是：(A)维甲酸抑制 恶性细胞，以及(B)这些效应是由基因变化引起的 通过核维甲酸受体介导的表达。的目标 这个项目是：确定区域资源受体与调解的相关性 维甲酸对人的生长和分化的影响 头颈部鳞状细胞癌(HNSCC)细胞体外培养。三 13-顺式维甲酸诱导HNSCC细胞株的研究 (13cRA)人口腔粘膜和白斑的体外和活组织检查 在13cRA治疗前和治疗期间从患者身上采集的病变将 用于：(A)确定RAR-α、RAR-β的存在和水平， 在HNSCC细胞的mRNA水平上的RAR-γ和RXR-α(由Northern 印迹)和蛋白质水平(通过免疫印迹和放射性 视黄醇结合)；(B)确定是否有任何 RARs在HNSCC细胞中通过维甲酸处理而调节；(C)确定 维甲酸治疗前后RARs的水平 与HNSCC细胞对HNSCC效应的反应有关 13cRA对鳞状细胞分化标志物转谷氨酰胺酶的影响 总蛋白和K1角蛋白在mRNA和蛋白质水平上的差异； (D)确定是否阻止一个或多个RAR的表达 通过反义寡核苷酸或信使核糖核酸将抑制任何效应 13cRA在HNSCC细胞上的表达；(E)确定 RARs与谷氨酰胺转氨酶、包皮蛋白和K1角蛋白的表达 在“正常”粘膜细胞和口腔白斑病变活检组织中 13cRA体内治疗前后的原位杂交研究 使用针对RARs和分化标记的mRNAs的核苷酸探针，以及 免疫组织化学分析每个受体的抗体和 分化标记。这些研究有望提供重要的 关于区域资源评估机构参与#年行动机制的资料 维甲酸对体外培养的HNSCC及癌前病变口腔上皮细胞的影响 体内的细胞。

Vitamin A and some of its analogs (retinoids) prevent squamous differentiation of normal nonkeratinizing epithelial cells in vivo and in vitro and suppress oral premalignant lesions (leukoplakia) in man and carcinogenesis in the upper aerodigestive tract in experimental animals. The mechanism(s) by which retinoids exert these effects is not known. Nuclear retinoic acid receptors (RARs) function as ligand-activated trans-acting transcription modulating factors and mediate the effects of retinoids on the expression of certain genes. The hypotheses underlying this project are: (A) Retinoids' ability to suppress malignant cells, and (B) These effects result from changes in gene expression mediated via nuclear retinoid receptors. The objectives of this project are: To determine the relevance of the RARs for mediation of the effects of retinoids on the growth and differentiation of human head and neck squamous cell carcinoma (HNSCC) cells in vitro. Three HNSCC cell lines before and during treatment with 13-cis retinoic acid (13cRA) in vitro and biopsies of human oral mucosa and leukoplakia lesions taken from patients before and during treatment with 13cRA will be used to: (a) Determine the presence and level of RAR-alpha, RAR-beta, RAR-gamma, and RXR-alpha in HNSCC cells at the mRNA level (by Northern blotting) and at the protein level (by immunoblotting and radioactive retinoid binding); (b) Determine whether the expression of any of the RARs is modulated in HNSCC cells by retinoid treatment; (c) Determine whether the level of any of the RARs before and after retinoid treatment is related to the responsiveness of the HNSCC cells to the effects of 13cRA on squamous cell differentiation markers transglutaminase, involucrin, and K1 keratin at the mRNA level and at the protein level; (d) Determine whether blocking the expression of one or more of the RARs by antisense oligonucleotides or mRNA will inhibit any of the effects of 13cRA on the HNSCC cells; (e) Determine the presence and level of RARs and the expression of transglutaminase, involucrin, and K1 keratin in "normal" mucosa cells and in biopsies from oral leukoplakia lesions before and after treatment with 13cRA in vivo by in situ hybridization with nucleotide probes for RARs' and differentiation markers' mRNAs, and immunohistochemical analysis with antibodies to each receptor and differentiation marker. These studies are expected to provide important information on the involvement of RARs in the mechanism of action of retinoids on HNSCC in vitro and possibly on premalignant oral epithelial cells in vivo.