Wang Siyu, Zhang Xingda, Chen Quanrun, Wu Hao, Cao Shihan, Zhao Shilu, Li Guozheng, Wang Jianyu, Gong Yajie, Wang Xinheng, Pang Da, Gao Song
Department of Breast Surgery, Harbin Medical University Cancer Hospital, Harbin 150040, China; Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin 150081, China.
Key Laboratory of Tumor Biotherapy of Heilongjiang Province, Harbin Medical University Cancer Hospital, Harbin 150040, China.
J Adv Res. 2024 Dec 17. doi: 10.1016/j.jare.2024.12.026.
Altered epigenetic reprogramming enables breast cancer cells to adapt to hypoxic stress. Hypoxic microenvironment can alter immune cell infiltration and function, limiting the effectiveness of immunotherapy.
The study aimed to identify how fat mass and obesity-associated protein (FTO) helps breast cancer cells cope with the hypoxic microenvironment and the mechanisms behind breast cancer cell resistance to tumor immunity.
Clinical samples were utilized to analyze the impact of FTO on breast cancer progression and the effect of programmed cell death protein 1/ programmed cell death 1 ligand 1(PD-1/PD-L1) immune checkpoint inhibitor treatment. Utilized MeRIP-seq and mRNA-seq to analyze the downstream genes regulated by FTO under hypoxia. Methylation modification regulation of PDK1 by FTO was clarified using RIP. Then mouse models were utilized to analyze the efficacy of inhibiting FTO and 3-Phosphoinositide-dependent protein kinase 1(PDK1) in combination with PD-1/PD-L1 immune checkpoint inhibitor treatment.
N6-Methyladenosine(mA) demethylase FTO was transcriptionally activated by hypoxia inducible factor 1α(HIF-1α). PDK1 was identified as a potential target of FTO under hypoxic conditions through high-throughput sequencing. Mechanistically, overexpression of FTO decreases mA modification sites on PDK1 mRNA, preventing YTH domain family 3(YTHDF3) from recognizing and binding to these sites, thereby inhibiting the degradation of PDK1 mRNA. Overexpression of PDK1 activates the AKT/STAT3 pathway, leading to enhanced PD-L1 expression. Targeting the FTO and PDK1-AKT pathways with FB23 and BX-912 inhibit breast cancer growth, enhance cytotoxic T lymphocyte (CTL) activity, and enhance the effectiveness of the PD-1/PD-L1 checkpoint inhibitor Atezolizumab.
This study reveals that HIF-1α promotes FTO transcription under hypoxic conditions, thereby increasing PD-L1 expression through the PDK1/AKT/STAT3 axis. Inhibition of FTO and PDK1 under hypoxic conditions could serve as a promising immunotherapeutic strategy for breast cancer.
表观遗传重编程改变使乳腺癌细胞能够适应低氧应激。低氧微环境可改变免疫细胞浸润和功能，限制免疫治疗的有效性。
本研究旨在确定脂肪量和肥胖相关蛋白（FTO）如何帮助乳腺癌细胞应对低氧微环境以及乳腺癌细胞对肿瘤免疫产生抗性的背后机制。
利用临床样本分析FTO对乳腺癌进展的影响以及程序性细胞死亡蛋白1/程序性细胞死亡蛋白1配体1（PD-1/PD-L1）免疫检查点抑制剂治疗的效果。利用MeRIP-seq和mRNA-seq分析低氧条件下FTO调控的下游基因。使用RIP阐明FTO对PDK1的甲基化修饰调控。然后利用小鼠模型分析联合抑制FTO和3-磷酸肌醇依赖性蛋白激酶1（PDK1）与PD-1/PD-L1免疫检查点抑制剂治疗的疗效。
N6-甲基腺苷（mA）去甲基化酶FTO被低氧诱导因子1α（HIF-1α）转录激活。通过高通量测序确定PDK1是低氧条件下FTO的潜在靶点。机制上，FTO的过表达减少了PDK1 mRNA上的mA修饰位点，阻止YTH结构域家族3（YTHDF3）识别并结合这些位点，从而抑制PDK1 mRNA的降解。PDK1的过表达激活AKT/STAT3通路，导致PD-L1表达增强。用FB23和BX-912靶向FTO和PDK1-AKT通路可抑制乳腺癌生长，增强细胞毒性T淋巴细胞（CTL）活性，并增强PD-1/PD-L1检查点抑制剂阿替利珠单抗的疗效。
本研究揭示HIF-1α在低氧条件下促进FTO转录，从而通过PDK1/AKT/STAT3轴增加PD-L1表达。在低氧条件下抑制FTO和PDK1可能是一种有前景的乳腺癌免疫治疗策略。
