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Tumor-specific macrophage targeting through recognition of retinoid X receptor beta
- Tang, Tang, Wei, Yushuang, Kang, Jinyoung, She, Zhi-Gang, Kim, Dokyoung, Sailor, Michael J., Ruoslahti, Erkki, Pang, Hong-Bo
- Journal of controlled release 2019 v.301 pp. 42-53
- antibodies, disease course, macrophages, mice, nanocarriers, neoplasms, peptides
- Macrophages play important and diverse roles during cancer progression. However, cancer therapies based on macrophage modulation are lacking in tools that can recognize and deliver therapeutic payloads to macrophages in a tumor-specific manner. As a result, treatments tend to interfere with normal macrophage functions in healthy organs. We previously identified a macrophage-binding peptide, termed CRV. Here, we show that upon systemic administration into tumor-bearing mice, CRV selectively homes to tumors, extravasates, and preferentially binds to macrophages within. CRV exhibits a higher affinity for tumor macrophages than for other cells in tumors or for other macrophage types elsewhere in the body. We further identified and validated retinoid X receptor beta (RXRB) as the CRV receptor. Intriguingly, although it is known as a nuclear receptor, RXRB shows a prominent cell surface localization that is largely restricted to tumor macrophages. Systemic administration of anti-RXRB antibodies also results in tumor-selective binding to macrophages similar to CRV. Lastly, we demonstrate the ability of CRV to improve the delivery of nano-carriers into solid tumors and macrophages within. In summary, we describe here a novel cell surface marker and targeting tools for tumor macrophages that may aid in future development of macrophage-modulatory cancer therapies.