THE CONTRIBUTION OF SMC TO THE PATHOLOGY OF GASTROINTESTINAL STROMAL TUMORS

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目及 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 该项目是基于Notch信号是平滑肌细胞（SMC）分化和细胞周期进程的重要调节因子，以及胃肠道间质瘤（GIST）与SMC共享分子标志物的观察。人GIST细胞表达Notch受体，并且它们的生长被阻断内源性Notch信号传导的γ分泌酶抑制剂抑制。与GIST焦点相关的挑战是：用于信号传导研究的有限的病毒转导效率，并且直到最近，只有一种分离的GIST细胞可用。因此，在上一个资助期，我们主要关注人原发性SMC，以解决Notch信号调节SMC分化表型的基本分子机制。我们在正常细胞中的发现将被应用于与GIST相关的细胞分化疗法可能是阻止GIST病理异常生长和进展的一种机制的想法。人SMC中Notch信号传导的激活通过Notch受体的组成型活性细胞内结构域形式的腺病毒转导来完成。其次，Notch靶基因HRT 1和HRT 2的表达被用于了解这些bHLH因子在Notch介导的SMC调节中的功能。SMC分化标志物表达、转录、周转和稳定性的分析确定Notch为SMC分化表型提供强信号。然而，令人惊讶的是，HRT活性拮抗Notch信号传导，并抑制SMC分化表型。这些发现提供了一个新的Notch负反馈机制，可能有助于调节血管重塑所需的成熟表型和过渡表型之间的平衡的框架。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This project is based on the observations that Notch signaling is an important regulator of smooth muscle cell (SMC) differentiation and cell cycle progression, and that gastrointestinal stromal tumors (GIST) share molecular markers with SMC. Human GIST cells express Notch receptors, and their growth is inhibited by gamma secretase inhibitors that block endogenous Notch signaling. Challenges associated with the GIST focus are: limited viral transduction efficiency for signaling studies, and until recently, the availability of only one isolate of GIST cells. Therefore, in the last funding period we focused mainly on human primary SMC to address basic molecular mechanisms by which Notch signaling regulates SMC differentiation phenotypes. Our findings in normal cells will be applied to the idea that cell differentiation therapies related to GIST may be one mechanism to stop abnormal growth and progression of GIST pathologies. Activation of Notch signaling in human SMC was accomplished with adenoviral transduction of constitutively active intracellular domain forms of the Notch receptors. Secondly, expression of the Notch target genes, HRT1 and HRT2, was used to understand the functions of these bHLH factors in Notch-mediated SMC regulation. Analysis of SMC differentiation marker expression, transcription, turnover, and stability determined that Notch provides a strong signal for the SMC differentiated phenotype. Surprisingly, however, HRT activity antagonizes Notch signaling, and suppresses the SMC differentiated phenotype. These findings provide the framework for a novel Notch negative feedback mechanism that may serve to regulate the balance between the mature phenotype and the transitional phenotype necessary for vascular remodeling.