DIFFERENTIATION MODULATES COLON CANCER INHIBITING ENZYME

分化调节结肠癌抑制酶

• 批准号: 2517712
• 负责人: MARY J DELONG
• 金额: $ 3.86万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-09-01 至 1998-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2517712
• 关键词: 1,25 dihydroxycholecalciferol; NAD(P)H dehydrogenase; alkaline phosphatase; apoptosis; butyrates; cell differentiation; colon neoplasms; enzyme activity; enzyme induction /repression; gel mobility shift assay; glutathione transferase; northern blottings; nucleic acid sequence; nutrition related tag; oligonucleotides; sodium; tissue /cell culture; transcription factor

DESCRIPTION: (Applicant's Description) The overall goal of this proposal is to investigate the enhancement of two mechanisms preventing colon carcinogenesis modulated by dietary differentiating agents: the elevation of detoxification enzyme levels and an increased rate of colonic cell apoptosis subsequent to cellular differentiation. The two dietary differentiating agents to be studied are sodium butyrate produced by microflora from fiber intake and the vitamin D active metabolite, 1,25-dihydroxyvitamin D3. Differentiation and apoptosis protect colon cells against carcinogenesis by regulating against hyperproliferative growth and elimination of damaged colonocytes. The biochemical detoxification provided in the colon by the enzymes glutathione S-transferase (GST) and NAD(P)H:quinone reductase (QR) eliminates electrophilic carcinogens and their reactive redox-cycling species constantly found in the lumen. A normal diet containing fruits and cruciferous vegetables also contains may inducers of detoxification enzymes such as isothiocyantes, fumarates, coumarins, and allyl sulfides. The coordinate induction of QR and GST is through increased DNA binding of c-Jun and c-Fos at the common AP-1 site in their promoter regions. Using the human colon cell model, HT-29 cells, we have demonstrated a 2- to 3-fold basal level elevation of QR and GST by differentiation with NaB and a synergistic elevation of both enzyme levels and apoptosis by the combination of NaB with QR and GST inducers. Whether similar elevation of the basal level of these enzymes can be achieved with other dietary colonic differentiating agents such as Vitamin D is not known. The mechanism of elevation of these enzymes by differentiating agents is also not known. We propose a study of the influence of Vitamin D-related cellular differentiation of the rate of elevation of both detoxification enzymes and rate of apoptosis. We will investigate using the human colon cell, HT-29, as a model: 1) whether differentiation by 1,25-dihydroxyvitamin D3 enhances increases of basal and induced levels of QR and GST enzymatically and transcriptionally; 2) the importance of c-jun and c-fos activation and their binding at the AP-1 sites in expression of elevated levels of QR and GST during differentiation; and 3) if increase by other differentiating agents such as 1,25-dihydroxyvitamin D3 reflects the increase in apoptotic rate by NaB differentiation or can further enhance its effects.

描述：（申请人的描述）本提案的总体目标是 研究两种机制的增强， 饮食分化剂调节的致癌作用： 解毒酶水平和结肠细胞增殖率的增加 细胞分化后的凋亡。 两种饮食 待研究的分化剂是丁酸钠， 纤维摄入和维生素D活性代谢产物的微生物群落， 1，25-二羟维生素D3。 分化和凋亡保护结肠细胞 通过调节防止过度增殖性生长来防止致癌作用， 清除受损的结肠细胞。 生化解毒提供了 谷胱甘肽S-转移酶（GST）和 NAD（P）H：醌还原酶（QR）消除亲电子致癌物， 它们的反应性氧化还原循环物种不断发现的内腔。 一 含有水果和十字花科蔬菜的正常饮食也含有可能 解毒酶的诱导剂如异硫氰酸酯，异硫氰酸酯， 香豆素和烯丙基硫化物。 QR和GST的坐标归纳为： 通过增加c-Jun和c-Fos在共同AP-1位点的DNA结合， 它们的启动子区域。 使用人结肠细胞模型HT-29细胞，我们 已经证明QR和GST的基础水平升高了2- 3倍， 分化与NaB和两种酶水平的协同升高 NaB与QR和GST诱导剂联合诱导细胞凋亡。 是否 这些酶的基础水平的类似升高可以用 其它饮食结肠分化剂如维生素D是未知的。 分化剂升高这些酶的机制是 也不知道。 我们建议研究维生素D相关的 细胞分化率的升高既解毒 酶和凋亡率。 我们将使用人类结肠进行研究 细胞，HT-29，作为模型：1）是否分化， 1，25-二羟维生素D3增强基础和诱导水平的增加， QR和GST的酶促和转录; 2）c-jun的重要性 和c-fos激活及其在AP-1位点的结合， 在分化过程中QR和GST水平升高;以及3）如果增加 其它分化剂如1，25-二羟维生素D3反映了 通过NaB分化增加凋亡率或可以进一步增强其 方面的影响.