Regulation by kruppel like factor in the colon

描述(申请人提供)：结直肠癌的发生是一个多步骤的过程 包括癌基因激活和肿瘤丢失的过程 抑制基因。结肠中的大多数肿瘤性病变是通过 从正常到过度增殖的上皮、腺瘤和 癌症，假设细胞过度增殖是由 无论是自发突变还是肠道增殖增加都会导致 克隆性扩张与癌变。尽管多个基因突变 已被描述，调控肠道过度增殖的分子事件是 未知。最近，一种真核锌指蛋白，肠道富集型Kruppel样蛋白 因子(GKLF/KLF4)，已被确定为 控制增长停滞。我们的实验室已经证明GKLF基因表达 在结肠癌组织中减少，而且一种结构性表达 结肠癌细胞系中的反义GKLF DNA导致细胞 过度增殖。这些数据表明，GKLF的下调可能导致 不受抑制的细胞生长。此外，GKLF的mRNA水平随着结肠的增加而增加。 上皮细胞获得更多分化的表型。我们假设 GKLF的上调是结肠上皮细胞形成的关键 而GKLF的下调将使结肠细胞 变得过度增殖，最终变成肿瘤性转化。精准的 GKLF在结肠中的生理功能尚不清楚，其上调和 下游目标目前尚不清楚。目前这项研究的目的是： (1)通过检测GKLF的作用阐明GKLF的生理特性 有义、反义或显性负性突变的结构性过度表达 GKLF DNA对正常结肠上皮细胞生长和分化的影响 (2)研究GKLF在细胞中的作用 通过检测其对细胞周期蛋白、细胞周期蛋白依赖性激酶的影响来实现细胞周期进程 (CDKs)表达，以及对细胞周期蛋白D1基因转录调控的影响； (3)研究GKLF基础转录调控的分子机制 基因和维生素D3或干扰素-伽马可促进GKLF的表达。 总的来说，从这项建议中获得的信息将增加我们的 了解GKLF对增长、差异化和 结肠上皮细胞恶变。最终，如果 GKLF下调过程可以操纵，或许可以使用 用于化学预防癌症形成的这一过程的抑制剂 胃肠道。

DESCRIPTION (provided by applicant): Colorectal carcinogenesis is a multi-step process including both the activation of oncogenes and the loss of tumor suppressor genes. Most of the neoplastic lesions in the colon arise through the progression from normal to hyperproliferative epithelium, adenoma and carcinoma, It is hypothesized that cellular hyperproliferation resulting from either spontaneous mutation or increased in intestinal proliferation leads to clonal expansion and carcinogenesis. Although multiple genetic mutations have been described, the molecular events governing intestinal hyperproliferation is unknown. Recently, an eukaryotic zinc finger protein, gut-enriched Kruppel-like factor (GKLF/KLF4), has been identified to be an important factor in controlling growth arrest. Our laboratory has shown that GKLF gene expression is reduced in colon cancer tissue and that constitutive expression of an antisense GKLF DNA in a colon tumor cell line results in cell hyperproliferation. These data suggest that down-regulation of GKLF may lead to uninhibited cell growth. Furthermore, GKLF mRNA levels increased as colonic epithelium acquired more differentiated phenotype. We hypothesize that up-regulation of GKLF is essential for colonic epithelium to become differentiated and that down-regulation of GKLF will render colonic cells to become hyperproliferated and ultimately neoplastic transformation. The precise physiological function of GKLF in the colon is not clear and its up- and down-stream targets are currently unknown. The aims of the current study are: (1) to elucidate the physiological properties of GKLF by examining the effect of constitutive overexpression of sense, antisense or dominant-negative mutant GKLF DNA on cell growth and differentiation in normal colon epithelial; adenoma; and cancer cell lines; (2) to investigate the role of GKLF in cell cycle progression by examining its effect on cyclins, cyclin-dependent kinases (cdks) expression, and on transcriptional regulation of the cyclin D1 gene; and (3) to examine molecular mechanisms governing basal transcription of the GKLF gene as well as vit D3- or interferon-gama-promoted GKLF expression. Collectively, the information gained from this proposal will add to our understanding the contribution of GKLF to growth, differentiation, and malignant transformation of the colonic epithelial cells. Ultimately, if the GKLF down-regulation process can be manipulated, it may be possible to use inhibitors of this process for chemoprevention of cancer formation in the gastrointestinal tract.