Molecular Characterization of the Two CD95 Pathways

描述（由申请人提供）： CD 95（CD 95/Fas）是一种死亡受体，其通过募集凋亡信号分子FADD、半胱天冬酶-8、半胱天冬酶-10和c-FLIP形成死亡诱导信号复合物（DISC）来诱导凋亡。我们以前已经证明，细胞可以通过CD 95以不同的方式死亡，依赖于（II型）或独立于（I型）线粒体，最近发现，只有在I型细胞中，而在II型细胞中，细胞内DISC的形式。最近，我们发现可溶性CD 95配体（sCD 95 L）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种肿瘤细胞系的详细分析显示，II型细胞具有上皮遗传特征，而I型细胞对应于更多的间质肿瘤。因此，在I型和II型肿瘤细胞中观察到的差异可能反映了癌变的不同阶段，这类似于上皮-间质转化（EMT）。此外，我们发现I型和II型细胞对两种主要抗肿瘤药物（分别攻击微丝或微管）的反应存在很大差异，这种差异敏感性需要功能性CD 95途径。我们假设，在EMT样过程中，肿瘤细胞发生遗传变化，以不同的方式对CD 95 L或抗肿瘤药物产生应答，并且可以通过分别在II型或I型细胞中选择性诱导或逆转EMT来操纵肿瘤细胞的差异应答。我们假设肿瘤细胞的这种不同敏感性的原因与I型和II型细胞中CD 95 DISC的特异性有关。为了解决这些假设，我们提出了以下三个具体目标。具体目标#1”确定肿瘤细胞中EMT的诱导或逆转是否导致CD 95途径中的1/11型典型变化。具体目标#2”表征I型和II型细胞中不同的信号起始复合物。具体目标#3：鉴定I型/II型细胞中调节CD 95信号传导差异的分子组分。这项研究的结果不仅可以更好地了解CD 95在肿瘤细胞中的差异信号传导，而且还可以通过改变肿瘤细胞的CD 95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.