Chemoproteomic Identification of AKT2 as a Paclitaxel‐Binding Protein via C─C Bond‐Linked Probe PTX‐4 in Paclitaxel‐Resistant Breast Cancer

ABSTRACT Breast cancer remains one of the most prevalent malignancies among women, and taxane‐based chemotherapies such as paclitaxel and docetaxel are central to standard treatment regimens. However, drug resistance in breast cancer limits therapeutic efficacy and contributes to recurrence and metastasis. Identifying resistance‐associated molecular targets is therefore critical for advancing treatment strategies. To investigate paclitaxel resistance, we designed and synthesized four paclitaxel‐derived probes. Among these, PTX‐4, constructed via a stable C─C bond linkage, exhibited superior efficiency. Using a chemoproteomic approach, we systematically profiled paclitaxel‐binding proteins in parental and resistant breast cancer cells. This strategy successfully identified AKT2, an unrecognized paclitaxel‐interacting protein in paclitaxel‐resistant breast cancer. Functional validation demonstrated that AKT2 is a direct target of paclitaxel in paclitaxel‐resistant cells. Knockdown and pharmacological inhibition of AKT2 restored the sensitivity of paclitaxel‐resistant cells to paclitaxel. These findings establish AKT2 as a key mediator of paclitaxel resistance in breast cancer. Targeting AKT2 may offer a promising therapeutic strategy to overcome resistance and improve the clinical efficacy of taxane‐based chemotherapy. This study highlights the advantage of C─C bond‐linked, pharmacologically active probes for chemoproteomic profiling of drug targets.