Studies have shown that tumor-associated macrophages (TAMs) are crucial for the establishment and maintenance in immunosuppressive tumor immune microenvironment (TIME), which can help tumor cells to achieve immune escape and attenuate antitumor therapy. Siglecs, the receptors of sialic acid (SA), widely exist in TAMs, which could be targeted to disrupt TIME and inhibit tumor growth at the root. Therefore, a SA-modified VCR liposome was reported (VCR-SSAL). Cellular and pharmacodynamic experiments showed that VCR-SSAL exhibited strong TAMs targeting and tumor-killing ability. Interestingly, VCR-SSAL treatment induced a phenomenon in which the cancerous tissues were "fell off" from the growth site, after which the wound gradually healed. Three months after the wound healed, the mice whose tumors fell off were re-inoculated, and the tumor fell off again without treatment, with an exfoliation rate of 100%. We speculated that this special efficacy might be due to that VCR loaded in VCR-SSAL could activate adaptive immunity by inducing DNA damage, promoting cytotoxic T lymphocytes (CTLs) infiltration into tumor sites, and enhancing the antitumor immune response. Thus, this study might provide new insights into the application of traditional chemotherapeutic drugs.
Keywords: Sialic acid; Sucrose octasulfate triethylamine gradient method; Tumor exfoliation; Tumor-associated macrophage; Vincristine sulfate liposome.
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