Role of GLI in Tumor progression

描述（由申请人提供）：发育期间和正常成体组织中的音刺猬（SHH）信号传导是增殖和形态发生的重要调节机制。SHH结合并拮抗肿瘤抑制因子PTCH的活性，PTCH是皮肤基底细胞癌（BCC）、髓母细胞瘤和横纹肌肉瘤中重要的守门分子。功能丧失和功能获得研究支持锌指转录因子GLI家族在刺猬信号传递中的作用。在BCC（最常见的癌症形式）中，由于PTCH或途径中的其它分子的突变，GLI表达被一致地诱导。GLI或GL 12在小鼠皮肤中的表达足以诱导BCC。 为了更好地理解GLI在肿瘤进展中的作用，我们广泛表征了表达GLI的RK 3E上皮细胞以鉴定推定的靶基因。结合抑制性消减杂交和基因芯片技术鉴定GLI诱导的转录本。所鉴定的转录物没有与其他几种癌基因（包括RAS、c-MYC或GKLF/KLF 4）的转化相关的改变。与对照细胞相比，小鼠胚胎细胞窝藏有缺陷的等位基因的PTCH表现出增加的几个这些成绩单的表达，这表明内源性GLI的表达是足够的一些观察到的转录效应。 mRNA原位杂交结果显示，与GLI阴性毛囊相比，GLI阳性毛囊和人BCC中GLI诱导的转录物表达增加。与转化RK 3E的其他癌基因不同，GLI特异性诱导已知在发育中诱导上皮-间质转化（EMT）的分子或癌基因的表达。先前在人BCC中观察到的基因表达的多种改变同样在体外由GLI诱导。 我们建议确定转录对应于直接转录靶基因，以确定特定的GLI诱导的转录物在BCC小鼠模型中的作用，并将特定的GLI诱导的转录物表征为体外和体内转化的潜在效应物。

DESCRIPTION (provided by applicant): Signaling by sonic hedgehog (SHH) during development and in normal adult tissues is an important regulatory mechanism for proliferation and morphogenesis. SHH binds to and antagonizes the activity of the tumor suppressor PTCH, a gatekeeper molecule important in basal cell carcinoma of the skin (BCC), medulloblastoma, and rhabdomyosarcoma. Loss-of-function and gain-of-function studies support a role for the GLI family of zinc finger transcription factors in transmission of the hedgehog signal. In BCC, a most common form of carcinoma, GLI expression is consistently induced as a result of mutation of PTCH or of other molecules in the pathway. Expression of GLI or GL12 in mouse skin is sufficient to induce BCC. To better understand the role of GLI in tumor progression, we extensively characterized GLI-expressing RK3E epithelial cells to identify putative target genes. The techniques of suppression subtractive hybridization and microarray analysis were used in combination to identify GLI-induced transcripts. The identified transcripts were not altered in association with transformation by several other oncogenes, including RAS, c-MYC, or GKLF/KLF4. Compared with control cells, mouse embryo cells harboring defective alleles of PTCH exhibited increased expression of several of these transcripts, suggesting that expression of endogenous GLI is sufficient for some of the observed transcriptional effects. mRNA in situ hybridization revealed increased expression of GLI-induced transcripts in GLI-positive hair follicles and in human BCC, compared with GLI-negative hair follicles. Unlike other oncogenes that transform RK3E, GLI specifically induced expression of molecules or oncogenes known to induce epithelial-mesenchymal transition (EMT) in development. Multiple alterations in gene expression previously observed in human BCC were likewise induced by GLI in vitro. We propose to identify transcripts that correspond to direct transcriptional target genes, to determine a role for specific GLI-induced transcripts in a mouse model of BCC, and to characterize specific GLI-induced transcripts as potential effectors of transformation in vitro and in vivo.