Triple negative breast cancer (TNBC) is defined as lacking the expressions of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). TNBC patients exhibit relatively poor clinical outcomes due to lack of molecular markers for targeted therapies. As such chemotherapy often remains the only systemic treatment option for these patients. While chemotherapy can initially help shrink TNBC tumor size, patients eventually develop resistance to drug, leading to tumor recurrence. We report a combined in vitro/in vivo genome-wide CRISPR synthetic lethality screening approach in a relevant TNBC cell line model to identify several targets responsible for the chemotherapy drug, paclitaxel resistance. Computational analysis integrating in vitro and in vivo data identified a set of genes, for which specific loss-of-function deletion enhanced paclitaxel resistance in TNBC. We found that several of these genes (ATP8B3, FOXR2, FRG2, HIST1H4A) act as cancer stemness negative regulators. Finally, using in vivo orthotopic transplantation TNBC models we showed that FRG2 gene deletion reduced paclitaxel efficacy and promoted tumor metastasis, while increasing FRG2 expression by means of CRISPR activation efficiently sensitized TNBC tumors to paclitaxel treatment and inhibited their metastatic abilities. In summary, the combined in vitro/in vivo genome-wide CRISPR screening approach proved effective as a tool to identify novel regulators of paclitaxel resistance/sensitivity and highlight the FRG2 gene as a potential therapeutical target overcoming paclitaxel resistance in TNBC.

三阴性乳腺癌（TNBC）被定义为缺乏雌激素受体（ER）、孕激素受体（PR）和人表皮生长因子受体2（HER2）的表达。由于缺乏靶向治疗的分子标志物，TNBC 患者的临床结果相对较差。因此，化疗通常仍然是这些患者唯一的全身治疗选择。虽然化疗最初可以帮助缩小 TNBC 肿瘤的大小，但患者最终会对药物产生耐药性，导致肿瘤复发。我们报告了在相关 TNBC 细胞系模型中结合的体外/体内全基因组 CRISPR 合成致死率筛选方法，以确定导致化疗药物紫杉醇耐药的几个靶点。整合体外和体内数据的计算分析确定了一组基因，其中特定的功能缺失缺失增强了 TNBC 中的紫杉醇耐药性。我们发现其中几个基因（ATP8B3、FOXR2、FRG2、HIST1H4A）充当癌症干性负调节因子。最后，利用体内原位移植TNBC模型，我们发现FRG2基因缺失会降低紫杉醇疗效并促进肿瘤转移，而通过CRISPR激活增加FRG2表达可有效使TNBC肿瘤对紫杉醇治疗敏感并抑制其转移能力。总之，体外/体内全基因组 CRISPR 联合筛选方法被证明是有效的工具，可用于识别紫杉醇耐药性/敏感性的新型调节因子，并强调 FRG2 基因作为克服 TNBC 紫杉醇耐药性的潜在治疗靶点。