(1) Background: Triple-negative breast cancer (TNBC) is a distinct subgroup of breast cancer presenting a high level of recurrence, and neo-adjuvant chemotherapy is beneficial in its therapy management. Anti-PD-L1 immunotherapy improves the effect of neo-adjuvant therapy in TNBC. (2) Methods: Immune-modulation and ferroptosis-related R-packages were developed for integrative omics analyses under ferroptosis-inducer treatments: TNBC cells stimulated with ferroptosis inducers (GSE173905, GSE154425), single cell data (GSE191246) and mass spectrometry on breast cancer stem cells. Clinical association analyses were carried out with breast tumors (TCGA and METABRIC cohorts). Protein-level validation was investigated through protein atlas proteome experiments. (3) Results: Erastin/RSL3 ferroptosis inducers upregulate CD274 in TNBC cells (MDA-MB-231 and HCC38). In breast cancer, CD274 expression is associated with overall survival. Breast tumors presenting high expression of CD274 upregulated some ferroptosis drivers associated with prognosis: IDO1, IFNG and TNFAIP3. At the protein level, the induction of Cd274 and Tnfaip3 was confirmed in breast cancer stem cells under salinomycin treatment. In a 4T1 tumor treated with cyclophosphamide, the single cell expression of Cd274 was found to increase both in myeloid- and lymphoid-infiltrated cells, independently of its receptor Pdcd1. The CD274 ferroptosis-driver score computed on a breast tumor transcriptome stratified patients on their prognosis: low score was observed in the basal subgroup, with a higher level of recurrent risk scores (oncotypeDx, ggi and gene70 scores). In the METABRIC cohort, CD274, IDO1, IFNG and TNFAIP3 were found to be overexpressed in the TNBC subgroup. The CD274 ferroptosis-driver score was found to be associated with overall survival, independently of TNM classification and age diagnosis. The tumor expression of CD274, TNFAIP3, IFNG and IDO1, in a biopsy of breast ductal carcinoma, was confirmed at the protein level (4) Conclusions: Ferroptosis inducers upregulate PD-L1 in TNBC cells, known to be an effective target of immunotherapy in high-risk early TNBC patients who received neo-adjuvant therapy. Basal and TNBC tumors highly expressed CD274 and ferroptosis drivers: IFNG, TNFAIP3 and IDO1. The CD274 ferroptosis-driver score is associated with prognosis and to the risk of recurrence in breast cancer. A potential synergy of ferroptosis inducers with anti-PD-L1 immunotherapy is suggested for recurrent TNBC.
（1）背景：三阴性乳腺癌（TNBC）是乳腺癌的一个独特亚型，具有高复发率特征，新辅助化疗在其治疗管理中具有积极作用。抗PD-L1免疫疗法可增强TNBC新辅助治疗效果。（2）方法：开发铁死亡相关R语言分析工具包，对铁死亡诱导剂处理下的多组学数据进行整合分析：包括铁死亡诱导剂刺激的TNBC细胞数据集（GSE173905、GSE154425）、单细胞测序数据（GSE191246）及乳腺癌干细胞质谱数据。采用TCGA和METABRIC队列的乳腺肿瘤数据进行临床关联分析，并通过蛋白质图谱实验进行蛋白水平验证。（3）结果：Erastin/RSL3铁死亡诱导剂可上调TNBC细胞系（MDA-MB-231和HCC38）中CD274表达。在乳腺癌中，CD274表达与总生存期相关。高表达CD274的乳腺肿瘤上调了多个与预后相关的铁死亡驱动因子：IDO1、IFNG和TNFAIP3。蛋白水平验证证实，盐霉素处理的乳腺癌干细胞中Cd274和Tnfaip3表达被诱导上调。在环磷酰胺处理的4T1肿瘤模型中，单细胞测序显示髓系和淋巴系浸润细胞中Cd274表达均升高，且不依赖于其受体Pdcd1。基于乳腺肿瘤转录组计算的CD274铁死亡驱动评分可对患者预后进行分层：基底样亚组评分较低，但复发风险评分（oncotypeDx、ggi及gene70评分）较高。METABRIC队列数据显示，TNBC亚组中CD274、IDO1、IFNG和TNFAIP3均过表达。CD274铁死亡驱动评分与总生存期相关，且独立于TNM分期和诊断年龄。乳腺导管癌活检组织的蛋白水平检测证实了CD274、TNFAIP3、IFNG和IDO1的肿瘤表达。（4）结论：铁死亡诱导剂可上调TNBC细胞PD-L1表达，而PD-L1是接受新辅助治疗的高危早期TNBC患者免疫治疗的有效靶点。基底样和TNBC肿瘤高表达CD274及铁死亡驱动因子IFNG、TNFAIP3和IDO1。CD274铁死亡驱动评分与乳腺癌预后及复发风险相关，提示铁死亡诱导剂与抗PD-L1免疫疗法可能存在协同作用，为复发性TNBC治疗提供新策略。
Ferroptosis Inducers Upregulate PD-L1 in Recurrent Triple-Negative Breast Cancer
肿瘤(癌症)患者之家