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

描述(申请人提供)：医学肿瘤学长期以来一直存在一个悖论，即尽管大多数人类癌症获得了细胞凋亡缺陷，但某些化疗药物，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。这表明可能涉及其他细胞死亡途径。这些可能包括坏死和自噬细胞死亡。癌症细胞和正常细胞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，因此需要净能量进行生物合成。这可能会使癌细胞更容易受到细胞新陈代谢的干扰。一些癌蛋白，如c-myc、Akt和RAS，已被证明通过调节细胞代谢来促进细胞生长，从而可能启动细胞导致生物能量衰竭而导致的细胞死亡。我们建议探索这样一种假设，即以细胞代谢为靶点可以作为一种策略来杀死通常具有瘫痪的凋亡机制的癌细胞。我们还将研究某些癌蛋白，如c-myc、Akt和RAS是否以及如何差异地影响细胞代谢，使细胞容易受到细胞代谢的干扰，并研究肿瘤细胞如何通过诱导自噬来响应代谢应激。我们将：1)研究一种假说，即DNA烷化损伤引起的新陈代谢紊乱可导致凋亡缺陷细胞死亡。我们的初步数据表明，由于糖酵解的抑制而导致的DNA烷化损伤可以导致坏死，而糖酵解的抑制是由于核酶PARP的激活导致NAD耗尽而引起的。我们将在体外和体内进一步检验这一理论，并将研究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物质饥饿和应激的一种重要反应，已被证明对细胞的存活和死亡具有相反的影响。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产生抵抗力。在这个目标中，我们将研究DNA烷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c-myc、ras和Akt等癌蛋白可以影响细胞新陈代谢并促使癌细胞死于生物能量衰竭的假说。C-myc、RAS和Akt癌蛋白参与细胞的生长、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，但可能是通过不同的机制。我们计划在基因定义的小鼠细胞和人类癌细胞中表达特定的癌基因，以研究它们如何在不同的方面影响细胞代谢，就它们启动癌细胞死于代谢扰动的能力而言。 公共卫生相关性：治疗癌症的一个主要策略是选择性地诱导癌细胞死亡。大多数人类癌症的进化是由于丧失了通过细胞凋亡而死亡的能力，并获得了对细胞新陈代谢的特殊需求。该项目的总体目标是研究化疗如何通过抑制细胞代谢来诱导非凋亡性细胞死亡，从而通过诱导癌细胞特异性死亡来靶向细胞代谢来治疗癌症患者。

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.