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

项目总结/摘要 化疗耐药转移性疾病对癌症患者构成最严重的威胁，尽管化疗耐药转移性疾病的发生率增加。 为临床医生提供了大量有针对性的治疗选择。虽然对晚期癌症的深入研究 研究进展揭示了许多导致化疗耐药的机制，但对这些机制知之甚少。 使细胞对细胞毒性化疗不敏感的细胞内信号机制。为了解决 为了弥补这一知识空白，我们最近进行了一次大规模的RNA干扰（RNAi）筛选， 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 细胞对化疗剂的敏感性。在这个RNAi筛选中，我们鉴定了一种新的磷酸酶MK-STYX， 其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功能。 磷酸化的机器所需的ATP合成，从而服务于一个重要的作用， 诱导化疗诱导的细胞死亡。本项目的目标是确定MK-STYX如何 调节细胞ATP水平，从而调节内源性凋亡。我们提出以下具体目标， 解决这一假设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)确定MK-STYX调节化疗耐药性的机制; (3)确定MK-STYX在结直肠癌进展和化疗耐药性中的作用。 与我们的中心假设一致，我们已经表明，MK-STYX的损失增加ATP的生产。 因此，我们预测，由于MK-STYX的损失导致的细胞ATP的升高足以抑制 溶酶体形成和进入凋亡。我们已经证明，MK-STYX与两个额外的 线粒体蛋白质，我们将机械地确定线粒体功能和分子 这些相互作用的后果。我们还发现MK-STYX表达的缺失与 结直肠癌的进展为了确定MK-STYX的缺失是否介导了化疗耐药性， 在体内，我们将使用细胞系在结肠直肠异种移植模型上测试标准化疗的功效，所述细胞系 证明MK-STYX的可变表达，或已被操作以降低内源性MK-STYX 程度.我们还将确定MK-STYX蛋白水平在一组患者中的预后意义。 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.