Elucidate the mechanism of autophagy in supporting Lkb1-deficient lung tumorigenesis and metastasis

摘要肺癌是癌症死亡的主要原因，与非小细胞肺癌(NSCLC)并列。 占这些案件的85%以上。KRAS是NSCLC中最常见的致癌驱动因素，它赋予了一个 预后差，治疗选择有限。LKB1是非小细胞肺癌中突变频率第三高的基因。这个 KRAS和LKB1的突变约占非小细胞肺癌的30%，随着侵袭性的增加， 转移的频率和对治疗药物的耐药性。自噬能降解蛋白质和细胞器 回收它们以提供代谢底物，这一功能在细胞外营养有限的情况下至关重要。 虽然自噬在癌症中的作用已经被深入研究，但自噬在癌症中的确切作用， 尤其是在体内，仍然难以捉摸，也存在争议。此外，靶向自噬一般用于治疗癌症 并未对临床试验的推进做出重大贡献。因此，识别遗传脆弱性 这使得对自噬抑制的强烈敏感性是迫切需要的，以改善有针对性的自噬- 治疗。LKB1通过激活AMP激活的蛋白激酶(AMPK)来调节能量动态平衡，AMPK 抑制分解代谢过程，上调合成代谢过程，以应对能源危机。基于之前的数据 研究表明，我们开始检验LKB1缺失促进癌细胞增殖但也抑制癌细胞增殖的假设 适应新陈代谢压力，这一特性可能会因自噬的丧失而进一步受损。vbl.使用 在非小细胞肺癌基因工程小鼠模型(GEMM)中，我们发现自噬抑制是合成的 KrasG12D/+中的致死性；Lkb1-/-(KL)介导的肿瘤发生；与自噬完整的KL肺癌相比，丢失 一种重要的自噬基因ATG7的缺失显著地削弱了肿瘤的启动和肿瘤的生长。这是在 与野生型LKB1(KrasG12D/+；P53-/-)肿瘤形成鲜明对比，后者对必要的自噬不太敏感 基因消融。我们的体外研究进一步表明，自噬调节KL所必需的脂类代谢 让癌细胞在营养匮乏中存活。这些观察表明，LKB1突变易导致KRAS- 导致NSCLC自噬抑制，LKB1突变可被探索为预测 肺癌的精准治疗。基于我们最近的发现，我们形成了我们的中心假设：自噬 通过维持Lkb1缺陷的Kras驱动的肺癌的代谢来补偿LKB1的丢失 促进它们的转移。我们将通过以下具体目标来测试这一点：目标1.通过以下方式阐明其机制 自噬调节体内的脂质代谢和KL肿瘤的发生。目标2.确定自噬如何 促进KL肿瘤转移。目标3.找出可能导致抵抗的代谢旁路 KL非小细胞肺癌自噬抑制。成功完成这项提议将：(1)对角色产生新的见解 自噬在调节细胞代谢支持KL肺癌发生和转移中的作用；(2)验证 自噬抑制是针对原发和非原发肿瘤的一种选择性和有效的治疗策略。 转移性KL NSCLC；以及(3)显示代谢旁路是治疗耐药的潜在机制。

Abstract Lung cancer is the leading cause of cancer mortality, with non-small cell lung cancer (NSCLC) accounting for more than 85% of these cases. KRAS, the most common oncogenic driver in NSCLC, confers a poor prognosis with limited treatment options. LKB1 is the third most frequently mutated gene in NSCLC. The mutations in both KRAS and LKB1 account for about 30% of NSCLC, with increased aggressiveness, a high frequency of metastases and resistance to therapeutics. Autophagy degrades proteins and organelles and recycles them to provide metabolic substrates, a function that is critical when extracellular nutrients are limited. Although the role of autophagy in cancer has been intensively studied, the precise role of autophagy in cancer, especially in vivo, remains elusive and controversial. Moreover, targeting autophagy to treat cancer generally has not contributed significantly to the advancement of clinical trials. Therefore, identifying genetic vulnerability that renders strong sensitivity to autophagy inhibition is urgently needed to improve autophagy targeted- therapies. LKB1 regulates energy homeostasis by activating AMP-activated protein kinase (AMPK), which inhibits catabolic processes and upregulates anabolic processes, in response to energy crisis. Based on earlier studies, we began to test the hypothesis that loss of LKB1 promotes cancer cell proliferation but also restricts adaptation to metabolic stress, a property that may be further compromised by loss of autophagy. Using genetically engineered mouse models (GEMMs) of NSCLC, we found that autophagy inhibition was synthetically lethal in KrasG12D/+;Lkb1-/- (KL) mediated tumorigenesis; in contrast to KL lung tumors with intact autophagy, loss of an essential autophagy gene, Atg7, dramatically impaired both tumor initiation and tumor growth. This is in sharp contrast to wild-type LKB1 (KrasG12D/+;p53-/-) tumors that are much less sensitive to essential autophagy gene ablation. Our in vitro study further revealed that autophagy modulates lipid metabolism essential for KL cancer cells to survive nutrient starvation. These observations indicate that LKB1 mutations predispose KRAS- driven NSCLC to autophagy inhibition and that LKB1 mutations could be explored as a predictive biomarker for precision lung cancer therapy. Based on our recent findings, we form our central hypothesis: autophagy compensates for LKB1 loss by maintaining the metabolism of Lkb1-deficient Kras-driven lung tumors and promoting their metastasis. We will test this with following specific aims: Aim 1. Elucidate the mechanism by which autophagy regulates lipid metabolism and KL tumorigenesis in vivo. Aim 2. Determine how autophagy promotes KL tumor metastasis. Aim 3. Identify metabolic bypasses that potentially create resistance to autophagy inhibition in KL NSCLC. Successful completion of this proposal will: (1) yield new insights into the role of autophagy in modulating cellular metabolism in support of KL lung tumorigenesis and metastasis; (2) validate the novel concept that autophagy inhibition is a selective and powerful therapeutic strategy against primary and metastatic KL NSCLC; and (3) reveal metabolic bypass as a potential mechanism of therapy resistance.