ABSTRACT

Cancer cell plasticity generates heterogeneous oncogenic subpopulations in tumors. How macroautophagy/autophagy, a catabolic system required for sustaining cell homeostasis, affects cancer cell plasticity, remains elusive. In this study, we report that MAP1LC3A/LC3A (microtubule associated protein 1 light chain 3 alpha), a key molecule in autophagy, is negatively associated with histological grade and distant metastasis of lung cancer. This is achieved in part, if not all, by maintaining the mitochondria and energy homeostasis to meet the proliferation demand of lung cancer cells driven by SOX2 (SRY-box transcription factor 2) signaling. Basal autophagy is preferentially active in SOX2-positive lung cancer cells with high-proliferative and low-invasive properties. The high-proliferative cancer cells exhibit higher oxygen consumption rate (OCR), elevated reactive oxygen species (ROS), and profound fragmented mitochondrial patterns compared to their high-invasive counterparts. SOX2 expression promotes LC3A expression and enhances proliferation but attenuates invasion in lung cancer cells. LC3A silencing enriches cells harboring low-proliferative and high-invasive features, concomitant with decreased OCR and ROS levels and reduced expression of SOX2. Our findings provide novel insights into how basal autophagy cross talks with SOX2 proliferation signaling to regulate mitochondrial metabolism and determines cancer cell plasticity with an impact on lung tumor progression.

Abbreviations

ATG14: autophagy related 14; CDH2: cadherin 2; ChIP-qPCR: chromatin immunoprecipitation quantitative polymerase chain reaction; CQ: chloroquine; ECAR: extracellular acidification rate; EMT: epithelial-mesenchymal transition; EPCAM: epithelial cell adhesion molecule; MAP1LC3A/LC3A: microtubule associated protein 1 light chain 3 alpha; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MAP1LC3C/LC3C: microtubule associated protein 1 light chain 3 gamma; NDUFV2: NADH:ubiquinone oxidoreductase core subunit V2; OCR: oxygen consumption rate; ROS: reactive oxygen species; RT-qPCR: reverse-transcriptase quantitative polymerase chain reaction; SC: scrambled control; shRNA: short hairpin RNA; SNAI2: snail family transcriptional repressor 2; SOX2: SRY-box transcription factor 2; SQSTM1/p62: sequestosome 1; TGFB/TGF-β: transforming growth factor beta; TOMM20: translocase of outer mitochondrial membrane 20; ZEB1: zinc finger E-box binding homeobox 1

中文翻译：

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LC3A介导的自噬调节肺癌细胞可塑性

摘要

癌细胞可塑性在肿瘤中产生异质的致癌亚群。巨自噬/自噬（维持细胞稳态所需的分解代谢系统）如何影响癌细胞的可塑性仍然难以捉摸。在这项研究中，我们报道了自噬中的关键分子 MAP1LC3A/LC3A（微管相关蛋白 1 轻链 3 α）与肺癌的组织学分级和远处转移呈负相关。这部分（如果不是全部的话）是通过维持线粒体和能量稳态来满足由 SOX2（SRY-box 转录因子 2）信号驱动的肺癌细胞的增殖需求来实现的。基础自噬在具有高增殖和低侵袭特性的 SOX2 阳性肺癌细胞中优先活跃。高增殖癌细胞表现出更高的耗氧率（OCR），与高侵入性对应物相比，活性氧（ROS）升高，线粒体模式严重碎片化。SOX2 表达促进LC3A表达并增强增殖但减弱肺癌细胞的侵袭。LC3A沉默丰富了具有低增殖和高侵袭性特征的细胞，伴随着 OCR 和 ROS 水平降低以及SOX2表达降低。我们的研究结果为基础自噬如何与 SOX2 增殖信号交互作用以调节线粒体代谢并确定癌细胞可塑性对肺肿瘤进展的影响提供了新的见解。

缩写

ATG14：自噬相关14；CDH2：钙粘蛋白 2；ChIP-qPCR：染色质免疫沉淀定量聚合酶链反应；CQ：氯喹；ECAR：细胞外酸化率；EMT：上皮间质转化；EPCAM：上皮细胞粘附分子；MAP1LC3A/LC3A：微管相关蛋白 1 轻链 3 α；MAP1LC3B/LC3B：微管相关蛋白1轻链3β；MAP1LC3C/LC3C：微管相关蛋白 1 轻链 3 γ；NDUFV2：NADH：泛醌氧化还原酶核心亚基 V2；OCR：耗氧率；ROS：活性氧；RT-qPCR：逆转录酶定量聚合酶链反应；SC：加扰控制；sh RNA：短发夹RNA；SNAI2：蜗牛家族转录抑制因子 2；SOX2：SRY-box 转录因子 2；SQSTM1/p62：隔离体 1；TGFB/TGF-β：转化生长因子β；TOMM20：线粒体外膜转位酶 20；ZEB1：锌指电子盒装订同源盒1