The crosstalk between breast cancer cells and tumor associated macrophages (TAMs) greatly contributes to tumor progression and immunosuppression. In this work, cat eye syndrome chromosome region candidate 2 (CECR2) is identified to overexpress in breast cancer patients, which can recognize v-rel avian reticuloendotheliosis viral oncogene homolog A (RelA) and activate nuclear factor κB (NF-κB) to release colony stimulating factor-1 (CSF-1). Pharmacological inhibition of CECR2 by the bromodomain competitor (Bromosporine, Bro) can downregulate CSF-1 to inhibit M2 type TAMs. To amplify the immunotherapeutic effect, a chimeric peptide-based and optical controlled CECR2 competitor (designated as N-PB) is constructed to enhance the nuclear targeted delivery of Bro and initiate an immunogenic cell death (ICD). In vivo results indicate a favorable breast cancer targeting ability and primary tumor suppression effect of N-PB under optical irradiation. Importantly, N-PB downregulates CSF-1 by competitive inhibition of CECR2 and NF-κB(RelA) interactions, thus inhibiting immunosuppressive M2-like TAMs while improving the antitumorigenic M1-like phenotype. Ultimately, the systemic anti-tumor immunity is activated to suppress the metastatic breast cancer in an optical controlled manner. This study provides a promising therapeutic target and reliable strategy for metastatic breast cancer treatment by interrupting immunosuppressive crosstalk between tumor cells and macrophages.
Keywords: Cat eye syndrome chromosome region candidate 2 (CECR2); Colony stimulating factor-1 (CSF-1); Immunotherapy; Macrophage; Nuclear targeted delivery.
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