Study of Ras-Mediated Apoptosis

描述(申请人提供)：抗癌疗法的一个长期信条是，这种疗法选择性地针对快速分裂的细胞。然而，这一理论基础并不令人满意，因为一些可治愈的癌症生长相对缓慢，许多快速分裂的癌细胞对抗肿瘤治疗具有抵抗力。近年来，对细胞凋亡调控的分子机制进行了研究，有证据表明，由于肿瘤的发展，调控细胞凋亡的信号转导通路的扰动，调节了肿瘤细胞对促凋亡治疗的敏感性。因此，定义和操纵肿瘤细胞的凋亡阈值将进一步加深我们对人类癌症病因和发病机制的理解，从而允许开发更有效的治疗方法。 我们已经证明，RAS作为一种信号转导分子，调节着两个截然相反的生物学过程：细胞增殖和细胞凋亡。在正常生长条件下，RAS传递有丝分裂信号，促进细胞分化/增殖。在内源性PKC被抑制的情况下，相同的RAS被重定向到参与细胞凋亡的过程。我们还证明了RAS从不同的凋亡途径招募信号。BCL-2保护细胞免受RAS介导的细胞死亡。 在这个方案中，我们设计了一些关键的实验来研究RAS介导的细胞凋亡的机制。例如，利用反义寡核苷酸技术或siRNA系统，我们将确定哪些PKC亚型参与了这一过程。利用优先激活其中一个RAS途径的ras突变体，我们能够剖析RAS信号并识别下游的凋亡效应因子。此外，利用不同的bcl2突变体，我们能够确定bcl2如何干扰RAS介导的细胞凋亡。 我们的研究将利用分子和细胞技术，针对三个特定的目标：(1)确定调控RAS介导的细胞凋亡的信号；(2)确定介导细胞凋亡过程的RAS下游效应分子；(3)确定Bcl2在RAS启动的细胞凋亡中的抗凋亡作用。总体而言，这些实验将有助于我们进一步了解RAS介导的细胞凋亡是如何调控的。这样的理解旨在转化为针对含有致癌ras的肿瘤的癌症治疗的新策略。

DESCRIPTION (provided by applicant): One long-standing dogma of anticancer therapies has been that such treatments selectively target rapidly-dividing cells. However, this rationale is not satisfactory, as some curable cancers may grow relatively slowly and many rapidly dividing cancer cells are resistant to antineoplastic therapies. In recent years, the molecular mechanisms regulating apoptosis have been investigated, and evidence has emerged indicating that perturbation of the signaling cascades regulating apoptosis, as a result of tumor development, regulates the sensitivity of cancer cells to pro-apoptotic treatments. Therefore, defining and manipulating the apoptotic thresholds of neoplastic cells will further our understanding of the etiology and pathogenesis of human cancer and accordingly permit the development of more efficient treatments. We have demonstrated that Ras, as a signal transducer, regulates two distinct and opposite biological processes: cell proliferation and apoptosis. Under normal growth conditions, Ras transmits mitogenic signals to promote cell differentiation/proliferation. Under the conditions in which endogenous PKC is suppressed, the same Ras is re-directed to participate in the apoptotic process. We also demonstrated that Ras recruits signals from various apoptotic pathways. Bcl-2 protects cells against Ras-mediated cell death. In this proposal, we design a number of critical experiments to study the mechanisms of Ras- mediated apoptosis. For example, using antisense oligo technique or siRNA system, we will determine which PKC isoforms are involved in this process. Employing ras mutants that preferentially activate one of Ras pathways, we are able to dissect Ras signaling and identify the downstream apoptotic effectors. Also, using various bcl-2 mutants, we are able to determine how Bcl-2 interferes with Ras-mediated apoptosis. Our studies, using molecular and cellular techniques, will be directed at three specific aims: (1) to determine the signals in the regulation of Ras-mediated apoptosis; (2) to define the downstream effectors of Ras which mediate the apoptotic process; and (3) to determine the anti-apoptotic function of Bcl-2 in Ras-initiated apoptosis. Overall, the experiments will help us to further understand how Ras-mediated apoptosis is regulated. Such understanding is aimed to translate into new strategy for cancer therapy targeting tumors containing oncogenic ras.