NUCLEAR RETINOIC ACID RECEPTORS IN HEAD/NECK CARCINOGENESIS & CHEMOPREVENTION

维生素A和它的一些类似物（类维生素A）防止鳞状细胞癌 体内正常非角质化上皮细胞的分化， 体外和抑制人口腔癌前病变（白斑病）， 实验动物上呼吸消化道的致癌作用。 类维生素A发挥这些作用的机制尚不清楚。 核视黄酸受体（RAR）作为配体激活的 反式作用转录调节因子和介导的影响 类维生素A对某些基因表达的影响。 的假设 该项目的基础是：（A）类维生素A抑制 （B）这些效应是由基因改变引起的。 通过核类视色素受体介导的表达。 的目标 该项目是：确定风险评估报告对调解的相关性 类维生素A对人生长和分化的影响 头颈部鳞状细胞癌（HNSCC）细胞。 三 用13-顺式维甲酸处理之前和期间的HNSCC细胞系 人口腔粘膜和白斑的体外（13 cRA）和活检 在用13 cRA治疗之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， HNSCC细胞中mRNA水平的RAR-γ和RXR-α（通过北方 印迹法）和蛋白质水平（通过免疫印迹和放射性 类视色素结合）;（B）确定是否存在任何类视色素结合的表达。 通过类视色素处理调节HNSCC细胞中的RAR; 类维生素A治疗前后任何RAR的水平 与HNSCC细胞对以下作用的反应性有关： 13 cRA对鳞状细胞分化标志物转氨酶， 在mRNA水平和蛋白质水平上的外皮蛋白和K1角蛋白; (d)确定是否阻断一个或多个RAR的表达 通过反义寡核苷酸或mRNA将抑制任何作用， （e）测定HNSCC细胞上13 cRA的存在和水平; RAR与转氨酶、外皮蛋白和K1角蛋白的表达 在“正常”粘膜细胞和口腔白斑病病变的活组织检查中 13 cRA治疗前后的原位杂交研究 与RAR和分化标志物mRNA的核苷酸探针，和 用针对每种受体的抗体进行免疫组织化学分析， 分化标记 这些研究将提供重要的 关于RAR参与药物作用机制的信息 类维生素A对体外HNSCC和可能对癌前口腔上皮细胞的作用 体内细胞

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.