ACLY and ACC1 Regulate Hypoxia-Induced Apoptosis by Modulating ETV4 via α-ketoglutarate.
ACLY and ACC1 Regulate Hypoxia-Induced Apoptosis by Modulating ETV4 via α-ketoglutarate.
复制标题
DOI：
10.1371/journal.pgen.1005599
复制
发表时间：
2015-10
期刊：
影响因子：
4.5
通讯作者：
Chi JT
中科院分区：
文献类型：
--
作者：
Keenan MM;Liu B;Tang X;Wu J;Cyr D;Stevens RD;Ilkayeva O;Huang Z;Tollini LA;Murphy SK;Lucas J;Muoio DM;Kim SY;Chi JT
为了繁殖实体瘤，癌细胞必须适应各种肿瘤微环境（TME）应激（例如缺氧或乳酸酸中毒）并在其下存活。为了系统地鉴定在应激下调节癌细胞存活的基因，我们在缺氧或乳酸酸中毒下进行了全基因组shRNA筛选。我们发现，乙酰辅酶A羧化酶（ACACA或ACC 1）或ATP柠檬酸裂解酶（ACLY）的基因缺失可保护癌细胞免受缺氧诱导的凋亡。此外，ACLY或ACC 1的缺失降低了致癌转录因子ETV 4的水平和活性。沉默ETV 4也保护细胞免受缺氧诱导的凋亡，并导致与沉默ACLY或ACC 1非常相似的转录反应，包括抗凋亡程序。代谢组学分析发现，虽然对照细胞中α-酮戊二酸水平在缺氧条件下降低，但当ACC 1或ACLY耗尽时，α-酮戊二酸在缺氧条件下反而增加。补充α-酮戊二酸可挽救缺氧诱导的细胞凋亡，并重现ETV 4表达和活性的降低，可能通过表观遗传机制。因此，ACC 1和ACLY通过增加α-酮戊二酸来调节缺氧条件下ETV 4的水平。这些结果表明，ACC 1/ACLY-α-酮戊二酸-ETV 4轴是一种新的手段，代谢状态调节转录输出的生活与缺氧下的死亡决定。由于许多脂肪生成抑制剂作为癌症治疗剂正在研究中，我们的研究结果表明，这些抑制剂的使用需要仔细考虑致癌驱动因素，肿瘤缺氧，进展和休眠。更广泛地说，我们的筛选为将来研究其他肿瘤细胞的应激适应机制提供了一个框架。在大多数实体瘤的发展过程中，肿瘤中存在特征性生理差异，这是由于肿瘤细胞生长超过其局部血液供应。肿瘤中发生的两种生理差异或“应激”是低氧水平（缺氧）和乳酸积累（乳酸酸中毒）。经历缺氧和乳酸酸中毒的癌细胞往往对化疗和放疗更有抵抗力，更容易转移。因此，重要的是要了解肿瘤细胞如何适应和生存这些压力。我们使用了一个大规模的筛选实验，以找到哪些基因和蛋白质参与肿瘤细胞的适应和生存缺氧或乳酸酸中毒。我们发现，抑制参与脂质合成的两个基因中的任何一个都可以使肿瘤细胞在缺氧中存活。这是因为沉默这些基因导致代谢产物α-酮戊二酸的增加，这抑制了缺氧条件下导致细胞死亡的转录因子。这项研究特别推进了我们对肿瘤细胞如何在缺氧和乳酸酸中毒中存活的理解，并更广泛地增强了我们对实体瘤细胞生物学的理解。
In order to propagate a solid tumor, cancer cells must adapt to and survive under various tumor microenvironment (TME) stresses, such as hypoxia or lactic acidosis. To systematically identify genes that modulate cancer cell survival under stresses, we performed genome-wide shRNA screens under hypoxia or lactic acidosis. We discovered that genetic depletion of acetyl-CoA carboxylase (ACACA or ACC1) or ATP citrate lyase (ACLY) protected cancer cells from hypoxia-induced apoptosis. Additionally, the loss of ACLY or ACC1 reduced levels and activities of the oncogenic transcription factor ETV4. Silencing ETV4 also protected cells from hypoxia-induced apoptosis and led to remarkably similar transcriptional responses as with silenced ACLY or ACC1, including an anti-apoptotic program. Metabolomic analysis found that while α-ketoglutarate levels decrease under hypoxia in control cells, α-ketoglutarate is paradoxically increased under hypoxia when ACC1 or ACLY are depleted. Supplementation with α-ketoglutarate rescued the hypoxia-induced apoptosis and recapitulated the decreased expression and activity of ETV4, likely via an epigenetic mechanism. Therefore, ACC1 and ACLY regulate the levels of ETV4 under hypoxia via increased α-ketoglutarate. These results reveal that the ACC1/ACLY-α-ketoglutarate-ETV4 axis is a novel means by which metabolic states regulate transcriptional output for life vs. death decisions under hypoxia. Since many lipogenic inhibitors are under investigation as cancer therapeutics, our findings suggest that the use of these inhibitors will need to be carefully considered with respect to oncogenic drivers, tumor hypoxia, progression and dormancy. More broadly, our screen provides a framework for studying additional tumor cell stress-adaption mechanisms in the future. During the development of most solid tumors, there are characteristic physiological differences in the tumor that result from tumor cells outgrowing their local blood supply. Two of these physiological differences, or “stresses,” that occur in the tumor are low oxygen levels (hypoxia) and an accumulation of lactic acidic (lactic acidosis). Cancer cells experiencing hypoxia and lactic acidosis tend to be more resistant to chemo- and radio-therapy and metastasize more readily. Therefore, it is important to understand how tumor cells adapt to and survive these stresses. We used a large scale screening experiment in order to find which genes and proteins are involved in tumor cell adaptation and survival under hypoxia or lactic acidosis. We found that inhibiting either of two genes involved in lipid synthesis allowed tumor cells to survive hypoxia. This occurred because silencing these genes led to an increase in the metabolite α-ketoglutarate, which repressed a transcription factor that contributed to cell death under hypoxia. This research specifically advances our understanding of how tumor cells survive hypoxia and lactic acidosis and more broadly enhances our understanding of the cellular biology of solid tumors.