Regulation by kruppel like factor in the colon

描述（由申请人提供）：结直肠癌发生是一个多步骤的过程， 这一过程包括癌基因的激活和肿瘤的消失 抑制基因结肠中的大多数肿瘤性病变是通过 从正常到过度增殖上皮、腺瘤和 据推测，细胞过度增殖导致的癌， 自发突变或肠道增殖增加导致 克隆扩张和致癌作用。虽然多种基因突变 已经描述，控制肠过度增殖的分子事件是 未知最近，一种真核锌指蛋白，肠道富集的Kruppel样 因子（GKLF/KLF 4），已被确定为是一个重要的因素， 控制生长停滞。我们的实验室已经证明GKLF基因表达 在结肠癌组织中减少， 反义GKLF DNA在结肠肿瘤细胞系中导致细胞 过度增殖这些数据表明，下调GKLF可能导致 不受抑制的细胞生长。此外，GKLF mRNA水平随着结肠 上皮细胞获得了更多的分化表型。我们假设 GKLF的上调对于结肠上皮成为 分化和下调GKLF将使结肠细胞， 变得过度增殖并最终发生肿瘤转化。的精确 GKLF在结肠中的生理功能尚不清楚， 下游目标目前未知。本研究的目的是： (1)通过检测GKLF的作用来阐明GKLF的生理特性， 有义、反义或显性失活突变体的组成型过表达 GKLF DNA对正常结肠上皮细胞生长和分化的影响 （2）探讨GKLF在细胞凋亡中的作用， 通过检测其对细胞周期蛋白、细胞周期蛋白依赖性激酶 （cdks）表达，以及对细胞周期蛋白D1基因的转录调控的影响;以及 (3)研究控制GKLF基础转录的分子机制 基因以及维生素D3或γ-干扰素促进的GKLF表达。 总的来说，从这项提案中获得的信息将增加我们的 了解GKLF对生长、分化和 结肠上皮细胞的恶性转化。最终，如果 GKLF的下调过程是可以操纵的， 该过程的抑制剂用于化学预防癌症形成， 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.