PO.ET06.04 · 实验与分子治疗
靶向p53缺陷型头颈癌中的胆固醇通路
Targeting cholesterol pathways in p53 deficient head and neck cancers
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
p53功能丧失是HNSCC不良预后的主要驱动因素，超过70%的肿瘤携带失活性TP53突变。尽管历经数十年努力，突变型p53仍然"无法成药"。胆固醇对于膜完整性和致癌信号传导至关重要，胆固醇水平升高与多种癌症的侵袭性相关。在HNSCC中，肿瘤高表达胆固醇上调基因的患者死亡风险高出50%，突显该通路作为临床相关治疗靶点的价值。我们此前已证明，HPV阳性HNSCC细胞保留了野生型（WT）p53活性，且p53在转录水平调控多条代谢通路，包括胆固醇调控基因。这些观察结果促使我们研究p53丧失如何重塑胆固醇代谢，以及这种代谢转变是否在p53缺陷型HNSCC中造就可靶向的脆弱性。在HPV阳性HNSCC细胞中沉默WT p53（siRNA或CRISPRi）增加了细胞内胆固醇和增殖——这一效应可通过胆固醇剥夺逆转。这种p53缺陷还提高了SREBP1/2（胆固醇代谢的主转录调控因子）的表达和成熟，以及多个下游SREBP靶标。在HPV阴性p53突变型HNSCC细胞系中同样观察到胆固醇升高和SREBP1/2激活，表明p53依赖性胆固醇代谢是一种更广泛的功能，独立于HPV状态。在HNSCC患者来源异种移植（PDX）中，与p53-WT肿瘤相比，p53突变型肿瘤表现出更高的SREBP1表达和优先的核定位，证实了体内胆固醇通路的重编程。为检验通路依赖性，我们检查了SREBP1基因消融（通过siRNA或在CRISPR敲除数据集中）在HNSCC和其他鳞状癌细胞系中的效应。与WT对应细胞相比，SREBP1丧失选择性地降低了p53缺陷型细胞的活力。用小分子fatostatin对SREBP1/2进行药理学抑制，在p53缺陷型相比p53充足型HNSCC细胞系中也产生了平均2.7倍更强的细胞毒性反应。在同基因细胞系来源异种移植（CDX）模型中，fatostatin治疗（32天内315 mg/kg）显著抑制了p53缺陷型肿瘤的生长。一项涵盖>900个细胞系的泛癌药物基因组学筛选进一步确定p53缺陷是fatostatin敏感性的决定因素。总之，这些发现表明p53丧失赋予了对SREBP驱动的胆固醇代谢的依赖性，并支持在基因组学定义的HNSCC亚群中对该通路进行治疗性靶向。
查看英文原文 English abstract
Loss of p53 function is a major driver of poor outcomes in HNSCC, with over 70% of tumors harboring deactivating TP53 mutations. Despite decades of effort, mutant p53 remains “undruggable”. Cholesterol is essential for membrane integrity and oncogenic signaling, and elevated cholesterol levels correlate with aggressiveness across many cancers. In HNSCC, patients whose tumors express high levels of cholesterol-upregulating genes have a 50% higher risk of death, highlighting this pathway as a clinically relevant therapeutic target. We previously showed that HPV+ HNSCC cells retain wild-type (WT) p53 activity and that p53 transcriptionally regulates multiple metabolic pathways, including cholesterol-regulating genes. These observations led us to investigate how p53 loss rewires cholesterol metabolism and whether this metabolic shift creates a targetable vulnerability in p53-deficient HNSCC. Silencing WT p53 in HPV+ HNSCC cells (siRNA or CRISPRi) increased intracellular cholesterol and proliferation - an effect reversed by cholesterol deprivation. This p53 deficiency also elevated expression and maturation of SREBP1/2, master transcriptional regulators of cholesterol metabolism, along with multiple downstream SREBP targets. Elevated cholesterol and activated SREBP1/2 were similarly observed in HPV-negative p53-mutant HNSCC lines, indicating that p53-dependent cholesterol metabolism is a broader function independent of HPV status. In HNSCC patient-derived xenografts (PDXs), p53-mutant tumors exhibited higher expression and preferential nuclear localization of SREBP1 compared to p53-WT tumors, confirming cholesterol pathway reprogramming in vivo . To test pathway dependency, we examined the effects of SREBP1 genetic ablation (via siRNA or in CRISPR knock-out datasets) in HNSCC and other squamous carcinoma lines. SREBP1 loss selectively reduced viability in p53-deficient cells compared with WT counterparts. Pharmacologic inhibition of SREBP1/2 with the small molecule fatostatin also produced an average 2.7-fold greater cytotoxic response in p53-deficient versus p53-proficient HNSCC lines. In isogenic cell line-derived xenograft (CDX) models, fatostatin treatment (315 mg/kg over 32 days) significantly suppressed growth of p53-deficient tumors. A pan-cancer pharmacogenomic screen of >900 cell lines further identified p53 deficiency as a determinant of fatostatin sensitivity. Together, these findings demonstrate that p53 loss confers dependency on SREBP-driven cholesterol metabolism and support therapeutic targeting of this pathway in a genomically defined subset of HNSCC.
利益披露 Disclosure
J. Gencel-Augusto, None..
N. Tian, None..
A. Goldberg, None.