Non-apoptotic cell death pathways in response to metabolic stress and chemotherap

描述（由申请人提供）：在医学肿瘤学中长期存在的矛盾是，尽管大多数人类癌症已经获得了细胞凋亡的缺陷，但是某些化疗剂如DNA烷化剂仍然是通过诱导癌细胞死亡来治疗癌症患者的最有效手段。这表明可能涉及替代细胞死亡途径。这些可能包括坏死和自噬性细胞死亡。癌症细胞和正常细胞之间的一个根本区别是它们的生化代谢。肿瘤细胞表现出异常的生长和增殖倾向，因此需要能量来源来进行生物合成。这可能使癌细胞更容易受到细胞代谢紊乱的影响。几种癌蛋白，如c-myc、Akt和Ras，已显示通过调节细胞代谢促进细胞生长，并因此可引发细胞由生物能量衰竭诱导的细胞死亡。我们建议探索这样一种假设，即靶向细胞代谢可以是杀死癌细胞的一种策略，这些癌细胞通常已经削弱了凋亡机制。我们还将研究某些癌蛋白，如c-myc，Akt和Ras是否以及如何差异化地影响细胞代谢，使细胞对细胞代谢的扰动敏感，并研究肿瘤细胞如何通过诱导自噬来应对代谢应激。我们将：1）研究细胞死亡可以通过由DNA烷基化损伤引起的代谢扰动在细胞凋亡缺陷细胞中诱导的假设。我们的初步数据表明，坏死可以诱导DNA烷基化损伤作为糖酵解抑制的结果，这是由NAD耗尽导致的核酶PARP的激活。我们将在体外和体内进一步研究这一理论，并将研究由这种非凋亡性细胞死亡引发的促炎反应。2）。研究自噬在化疗药物治疗的癌细胞中的作用。自噬作为细胞对营养饥饿和应激的一种重要反应，对细胞存活和细胞死亡具有相反的作用。自噬的这些相反作用一方面可能导致癌细胞死亡，另一方面可能导致癌细胞对治疗的抗性。我们将研究DNA烷基化损伤是否以及如何诱导自噬，以及自噬如何与其他形式的细胞死亡相互作用。3）。研究癌蛋白如c-myc、Ras和Akt可以影响细胞代谢并使癌细胞因生物能量衰竭而死亡的假设。c-myc、Ras和Akt癌蛋白参与细胞生长、增殖和死亡。这些蛋白质已被证明可以调节细胞代谢，从而促进癌细胞的合成代谢过程，但可能通过不同的机制。我们计划在遗传上确定的鼠细胞以及人类癌细胞中表达特定的癌基因，以研究它们如何差异地影响细胞代谢，关于它们引发癌细胞死于代谢紊乱的能力。 公共卫生相关性：治疗癌症的主要策略是选择性诱导癌细胞死亡。大多数人类癌症是由于细胞凋亡导致死亡的能力丧失而进化的，并且获得了对细胞代谢的特定需求。该项目的总体目标是研究化疗如何诱导非凋亡细胞死亡，并通过抑制细胞代谢，从而靶向细胞代谢可以通过诱导癌细胞特异性死亡来治疗癌症患者。

DESCRIPTION (provided by applicant): A paradox in medical oncology has long existed that although the majority of human cancers have acquired a deficiency in apoptosis, certain chemotherapeutic agents such as DNA alkylating agents remain the most effective means of treating cancer patients by inducing cancer cell death. This suggests that alternative cell death pathways may be involved. These may include necrosis and autophagic cell death. One fundamental difference between cancer and normal cells is their biochemical metabolism. Tumor cells display an abnormal propensity for growth and proliferation, thus are in net need of energy source for biosynthesis. This may render cancer cells more susceptible to the perturbation of cell metabolism. Several oncoproteins, such as c- myc, Akt, and Ras, have been shown to promote cell growth by regulating cell metabolism, and thus may prime cells to cell death induced by bioenergetic failure. We propose to explore the hypothesis that targeting cellular metabolism can be a strategy to kill cancer cells that often have crippled apoptosis machinery. We will also study whether and how certain oncoproteins such as c-myc, Akt, and Ras may differentially affect cell metabolism and render cells susceptible to the perturbation of cell metabolism, and study how tumor cells may respond to metabolic stress by inducing autophagy. We will: 1) Study the hypothesis that cell death can be induced in apoptosis-deficient cells by metabolic perturbation resulting from DNA alkylating damage. Our preliminary data indicates that necrosis can be induced by DNA alkylating damage as a result of the inhibition of glycolysis, which is caused by the NAD depletion resulting from the activation of a nuclear enzyme PARP. We will further examine this theory in vitro and in vivo, and will study the pro-inflammatory response triggered by this non-apoptotic cell death. 2). Study the role of autophagy in cancer cells treated with chemotherapeutic agents. As an important cellular response to nutrient starvation and stress, autophagy has been shown to have opposite effects on cell survival and cell death. These opposing effects of autophagy may on one hand contribute to cancer cell death, on the other hand, to cancer cell resistance to therapy. We will study in this Aim whether and how DNA alkylating damage can induce autophagy, and how autophagy interplays with other forms of cell death. 3). Study the hypothesis that oncoproteins such as c-myc, Ras, and Akt can affect cell metabolism and prime cancer cells to die from bioenergetic failure. c-myc, Ras, and Akt oncoproteins are involved in cell growth, proliferation, and death. These proteins have been shown to regulate cell metabolism thus promoting cancer cell anabolic processes, however maybe through different mechanisms. We plan to express specific oncogenes in genetically defined murine cells as well as human cancer cells to study how they may differentially affect cellular metabolism, with respect to their ability to prime cancer cells to die of metabolic perturbation. PUBLIC HEALTH RELEVANCE: A major strategy for treating cancer is to selectively induce cancer cell death. Most human cancers evolved as a result of the loss of ability to die by apoptosis, and have acquired specific needs for cell metabolism. The overall goal of this project is to study how non-apoptotic cell death can be induced by chemotherapy, and by the inhibition of cell metabolism, thus targeting cell metabolism can be harnessed to treat cancer patients by inducing cancer cell specific death.