Metabolic reprogramming: A new paradigm for targeting cisplatin resistant cells

描述(由申请人提供)： 肺癌是世界上癌症死亡的主要原因之一。早期非小细胞肺癌(NSCLC)的治疗以手术为主，小细胞肺癌(SCLC)以化疗为主。大多数退伍军人表现为局部晚期或转移性疾病，这使得切除是不可能的。对于这些患者，顺铂或其肾毒性较小的类似卡铂是用于非小细胞肺癌和小细胞肺癌的主要化疗药物。大多数肺癌患者最初对顺铂治疗有反应；然而，耐药性的产生是不可避免的，这会导致疾病的进展。因此，开发一种治疗顺铂耐药肺癌的新策略无疑将对这些患者的治疗产生重大影响。虽然在过去的十年里有大量关于顺铂耐药的文献，但到目前为止还没有药物可以逆转顺铂的耐药性或选择性地杀死这些耐药细胞。我们在顺铂耐药细胞中发现了新的生化变化，可以作为选择性消除它们的靶点。首先，我们发现，所有顺铂耐药细胞系，包括患者的原代培养细胞，与正常细胞或其亲本细胞相比，具有更高的ROS水平。因此，增加ROS的药物，如elesclomol，可以将它们推到他们的耐受极限，最终导致细胞死亡。其次，这些顺铂耐药细胞在体外和体内条件下由于分泌增加而降低了细胞内硫氧还蛋白-1(TRX1)的水平，这可能是导致ROS水平升高的主要因素。第三，顺铂耐药细胞不再依赖糖酵解代谢，而是依赖氨基酸和/或脂肪酸(氧化代谢)作为其碳骨架来源。值得注意的是，剥夺谷氨酰胺或抑制脂肪酸合成途径中的关键酶可以选择性地杀死顺铂耐药细胞。综上所述，我们假设细胞内TRX1减少，导致ROS积累增加，可能导致顺铂耐药肿瘤的代谢重新编程。在这一应用中，我们计划通过以下方式进一步证实和利用这些发现：(I)确定作为其能量和生物合成的主要碳源的顺铂耐药肺癌细胞从糖酵解代谢转换到氧化代谢；(Ii)研究TRX1是ROS积累、顺铂敏感性和肿瘤代谢改变的关键因素；(Iii)确定ROS生成剂或代谢抑制物可以选择性地杀死顺铂耐药细胞 体外实验也发生在体内，(Iv)确定ROS、TRX1与肿瘤代谢变化之间的可能关系也在顺铂治疗失败的患者的肿瘤样本中发现。为了进一步评估我们发现的临床相关性，我们将证实一种ROS产生剂或代谢抑制剂对患者新鲜分离的顺铂耐药肺癌细胞也具有高度的细胞毒性。总体而言，这项拟议的工作将被视为一种新的方法，通过利用这些耐药细胞为生存而采用的主要生化差异来克服顺铂耐药。因此，通过针对这些差异，我们可以有选择地消除这些耐药细胞，并将正常组织毒性降至最低。此外，从这一应用中获得的发现也可以作为一个平台来研究选择性地杀死其他肿瘤类型的顺铂耐药细胞的可能方法。

DESCRIPTION (provided by applicant): Lung carcinoma is one of the leading causes of cancer deaths in the world. Treatment for early stage non small cell lung cancer (NSCLC) is surgery while chemotherapy is the mainstay of treatment in small cell lung cancer (SCLC). Most veterans present as locally advanced or metastatic disease which makes resection not possible. For these patients, cisplatin or its less nephrotoxic analog carboplatin is the main chemotherapeutic drug used for both NSCLC and SCLC. The majority of lung cancer patients will respond initially to cisplatin treatment; however, development of drug resistance is inevitable which results in disease progression. Thus, development of a new strategy to treat cisplatin resistant lung cancer will undoubtedly have a major impact for the treatment of these patients. Although there are overwhelming publications in the past decade on cisplatin resistance, but thus far no drugs are available which could reverse cisplatin resistance or selectively kill these resistant cells. We have discovered novel biochemical changes in cisplatin resistant cells which can be utilized as targets to selectively eradicate them. Firstly, we have found that all cisplatin resistant cells lines including primary culture from patients possess higher reactive oxygen species (ROS) levels when compared to normal cells or their parental cell counterparts. Consequently, agents which increase ROS such as elesclomol can push them beyond their tolerance limit which ultimately leads to cell death. Secondly, these cisplatin resistant cells have decreased intracellular thioredoxin-1 (TRX1) levels as a result of increasing secretion under in vitro and in vivo conditions which could be a primary contributory factor to higher ROS levels. Thirdly, cisplatin resistant cells are no longer dependent on glycolysis metabolism, but rely on amino acids and/or fatty acids (oxidative metabolism) as their carbon skeleton source. Significantly, glutamine deprivation or inhibition of key enzyme in fatty acid synthetic pathway can selectively kill cisplatin resistant cells. Taken together, we hypothesize that decreased intracellular TRX1, which results in higher ROS accumulation, could lead to metabolic reprogramming in cisplatin resistant tumors. In this application, we plan to further confirm and exploit these findings by (i) determine that cisplatin resistant lung cancer cells switch from glycolytic metabolism to oxidative metabolism as their main carbon source for energy and biosynthesis, (ii) investigate that TRX1 is a key factor in ROS accumulation, cisplatin sensitivity, and alteration in tumor metabolism, (iii) determine that ROS generation agent or metabolic inhibitor which can selectively kill cisplatin resistant cells in vitro also occurs in vivo, (iv) determine the possible relationships between ROS, TRX1, and changes in tumor metabolism are also found in tumor samples obtained from patients who have failed cisplatin treatment. To further evaluate the clinical relevance of our findings, we will confirm that a ROS producing agent or metabolic inhibitor is also highly cytotoxic to freshly isolated cisplatin resistant lung cancer cells from patients. Overall, this proposed work will sere as a novel approach to overcome cisplatin resistance by exploiting the primary biochemical differences which these resistant cells adopt to survive. Thus, by targeting these differences, we can selectively eradicate these resistant cells with minimal normal tissue toxicity. Furthermore, the findings obtained from this application can also be used as a platform to investigate possible ways to selectively kill cisplatin resistant cells from other tumor types.