Molecular Characterization of the Two CD95 Pathways

描述（申请人提供）：CD95 （CD95/Fas）是一种死亡受体，通过募集凋亡信号分子FADD、caspase-8、caspase-10和c-FLIP形成死亡诱导信号复合体（DISC）来诱导细胞凋亡。我们之前已经证明细胞可以通过CD95以不同的方式死亡，要么依赖于（II型），要么独立于（I型）线粒体，最近发现只有在I型细胞中，而在II型细胞中形成细胞内DISC。最近，我们证明可溶性CD95配体（sCD95L）仅对II型细胞具有细胞毒性，而在I型细胞中，它激活其他非凋亡途径。对NCI药物筛选小组的60个肿瘤细胞系的详细分析显示，II型细胞具有上皮遗传谱，而I型细胞对应更多的间充质肿瘤。因此，I型和II型肿瘤细胞的差异可能反映了癌变的不同阶段，类似于上皮-间质转化（EMT）。此外，我们发现I型和II型细胞对两类主要抗肿瘤药物（分别攻击微丝或微管）的反应存在很大差异，这种差异的敏感性需要功能性CD95途径。我们假设，在EMT样过程中，肿瘤细胞的基因改变以不同的方式对CD95L或抗肿瘤药物产生反应，并且肿瘤细胞的差异反应可以通过选择性地诱导或恢复II型或I型细胞中的EMT来控制。此外，我们假设肿瘤细胞的这种差异敏感性的原因与I型和II型细胞中的CD95 DISC的特定特性有关。为了解决这些假设，我们提出以下三个具体目标。确定肿瘤细胞中EMT的诱导或逆转是否会导致CD95通路中的1/11型典型变化。描述I型和II型细胞中不同的信号起始复合物。特异性目标#3：确定I型/ II型细胞中调节CD95信号传导差异的分子成分。这项研究的结果不仅可以更好地理解肿瘤细胞中CD95的差异信号传导，还可以通过改变肿瘤细胞的CD95细胞类型来设计新的肿瘤治疗策略。

DESCRIPTION (provided by applicant): CD95 (CD95/Fas) is a death receptor that induces apoptosis through recruitment of the apoptosis signaling molecules FADD, caspase-8, caspase-10 and c-FLIP forming the death inducing signaling complex (DISC). We have previously demonstrated that cells can die in different ways through CD95, either dependent on (Type II) or independent of (Type I) mitochondria and recently found that only in Type I cells whereas in Type II cells an intracellular DISC forms. Recently, we demonstrated that soluble CD95 ligand (sCD95L) is only cytotoxic to Type II cells whereas in Type I cells it activates other nonapoptotic pathways. A detailed analysis of the 60 tumor cell lines of the drug screening panel of the NCI revealed that Type II cells have an epithelial genetic profile whereas Type I cells correspond to more mesenchymal tumors. The differences seen in Type I and Type II tumor cells may therefore reflect different stages of carcinogenesis, which resembles the epithelial-mesenchymal transition (EMT). Furthermore, we found that Type I and Type II cells greatly differ in their responses to two major classes of antitumor drugs (that attack microfilaments or microtubules, respectively) and that this differential sensitivity requires a functional CD95 pathway. We hypothesize that during EMT-like processes tumor cells genetically change to respond to CD95L or antitumor drugs in different ways and that the differential responses of tumor cells can be manipulated by selectively inducing or reverting EMT in Type II or Type I cells, respectively, Furthermore, we hypothesize that the reason for this differential sensitivity of tumor cells is linked to specific properties of the CD95 DISC in Type I and Type II cells. To address these hypotheses we propose the following three Specific Aims. Specific Aim #1" Determine whether induction or reversion of EMT in tumor cells causes the Type 1/11 typical changes in the CD95 pathway. Specific Aim #2" Characterize the different signal initiation complexes in Type I and Type II cells. Specific Aim #3: Identify the molecular components in Type I/Type II cells that regulate the difference in CD95 signaling. The results of this study will not only provide a better understanding of the differential signaling of CD95 in tumor cells but may also allow to design new strategies for tumor therapy by changing the CD95 cell type of tumor cells.