Modulating tumor-associated macrophage polarization by anti-maRCO mAb exerts anti-osteosarcoma effects through regulating osteosarcoma cell proliferation, migration and apoptosis.

PURPOSE

Osteosarcoma is a primary bone tumor lacking optimal clinical treatment options. Tumor-associated macrophages in the tumor microenvironment are closely associated with tumor development and metastasis. Studies have identified the macrophage receptor with collagenous structure (MARCO) as a specific receptor expressed in macrophages. This study aimed to investigate whether anti-MARCO mAb treatment can induce macrophage polarization in the tumor microenvironment and elicit anti-tumor effects.

METHODS

THP-1 cells were treated with 20 ng/mL phorbol 12-myristate 13-acetate and 80 ng/mL interleukin-4 for 48 h to induce macrophage polarization to alternatively activated macrophages (M2). Enzyme-linked immunosorbent assay, real-time quantitative polymerase chain reaction, flow cytometry, and bioinformatic analyses were performed to evaluate macrophage polarization. The co-culture groups included a blank group, an M2 macrophage and U2OS co-culture group, and an anti-MARCO mAb-treated M2 macrophage group. Cell viability assays, cell scratch tests, apoptosis, and cell cycle analyses were performed to determine the effects of anti-MARCO mAb-treated macrophages on osteosarcoma cells.

RESULTS

It was demonstrated that anti-MARCO mAb can drive macrophages toward classically activated macrophage (M1) polarization. Anti-MARCO mAb promoted the secretion of pro-inflammatory factors by macrophages, including tumor necrosis factor-alpha (TNF-α), interleukin-1beta, interleukin-6 and interleukin-23. Studies on in vitro co-culture models have revealed that macrophages treated with anti-MARCO mAb can suppress the growth and migration of osteosarcoma cells, induce cell apoptosis, and inhibit cell cycle progression of osteosarcoma cells through M1 polarization of macrophages in vitro.

CONCLUSION

Anti-MARCO mAb treatment exerts anti-osteosarcoma effects by affecting macrophage polarization toward M1 macrophages, offering a potential new therapeutic approach for treating osteosarcoma.