MK-STYX: A Requisite Gatekeeper to Mitochondrial Function and Death

项目摘要/摘要 化疗耐药的转移性疾病是对癌症患者最严重的威胁，尽管 阿森纳为临床医生提供有针对性的治疗选择。在对晚期癌症进行密集研究的同时 进展揭示了许多导致化疗耐药的机制，但人们对此知之甚少 使细胞对细胞毒性化疗不敏感的细胞内信号机制。为了努力解决 针对这一知识鸿沟，我们最近进行了大规模RNA干扰(RNAi)筛查 全面鉴定人类基因组中改变或修饰肿瘤的关键激酶和磷酸酶 细胞对化疗药物的敏感性。在这个RNAi筛选中，我们发现了一种新的磷酸酶MK-Styx， 它能有效地抑制肿瘤细胞对多种化疗药物的反应。 我们的中心假设是MK-Styx通过调节线粒体功能来特异性地控制线粒体的功能 三磷酸腺苷合成所需的机械的磷酸化，从而在 诱导化疗诱导的细胞死亡。该项目的目标是确定MK-Styx如何 调节细胞内的三磷酸腺苷水平，从而调节内在的细胞凋亡。我们提出以下具体目标： 阐述这一假说，并了解其在转移性结直肠癌中的意义： (1)确定MK-Styx在线粒体中的催化机制； (2)明确MK-Styx调控化疗耐药的机制； (3)明确MK-Styx在结直肠癌进展和化疗耐药中的作用。 与我们的中心假设一致，我们已经表明MK-Styx的丢失增加了ATP的产生。 因此，我们预测，由于MK-Styx的缺失而导致的细胞内ATP的升高足以抑制 凋亡体的形成和进入细胞凋亡。我们已经证明了MK-Styx与另外两个 线粒体蛋白质，我们将从机械上确定线粒体的功能和分子 这些互动中的每一个都会产生后果。我们还表明，MK-Styx表达的丧失与 伴随着结直肠癌的进展。确定MK-Styx的缺失是否介导了细胞的化疗耐药 体内，我们将在结直肠癌异种移植模型上测试标准化疗的有效性，使用的细胞系 证明MK-Styx的可变表达，或已被操纵以减少内源性MK-Styx 级别。我们还将确定MK-Styx蛋白水平在一组患者中的预后意义。 患有结直肠癌。

PROJECT SUMMARY/ABSTRACT Chemoresistant metastatic disease presents the most serious threat to cancer patients despite the increased arsenal of targeted therapeutic options available to clinicians. While intense study into late-stage cancer progression has revealed a number of mechanisms that contribute to chemoresistance, little is known about the intracellular signaling mechanisms that desensitize cells to cytotoxic chemotherapy. In an effort to address this knowledge gap, we recently performed a large-scale RNA-interference (RNAi) screen intended to comprehensively identify critical kinases and phosphatases in the human genome that alter or modify tumor cell sensitivity to chemotherapeutic agents. In this RNAi screen, we identified a novel phosphatase, MK-STYX, which potently suppressed the response of tumor cells to a wide variety of chemotherapeutic drugs. Our central hypothesis is that MK-STYX specifically controls mitochondrial function by regulating phosphorylation of the machinery required for ATP synthesis, and thereby serves an essential role in the induction of chemotherapeutic-induced cell death. The objective of this project is to determine how MK-STYX regulates cellular ATP levels, and thus modulates intrinsic apoptosis. We propose the following specific aims to address this hypothesis and to understand its significance in the context of metastatic colorectal carcinoma: (1) Identify the catalytic mechanism of MK-STYX in the mitochondria; (2) Identify the mechanism whereby MK-STYX regulates chemoresistance; (3) Establish the role of MK-STYX in colorectal cancer progression and chemoresistance. Consistent with our central hypothesis, we have shown that loss of MK-STYX increases ATP production. Therefore, we predict that the elevation in cellular ATP due to loss of MK-STYX is sufficient to inhibit apoptosome formation and entry into apoptosis. We have shown that MK-STYX interacts with two additional mitochondrial proteins and we will mechanistically determine the mitochondrial function and the molecular consequences of each of these interactions. We have also shown that loss of MK-STYX expression correlates with colorectal cancer progression. To determine whether loss of MK-STYX mediates chemoresistance in vivo, we will test the efficacy of standard chemotherapies on a colorectal xenograft model using cell lines that demonstrate variable expression of MK-STYX, or have been manipulated to decrease endogenous MK-STYX levels. We will also determine the prognostic significance of MK-STYX protein levels in a cohort of patients with colorectal cancer.