Tumor-promoting macrophages induce the expression of the macrophage-specific receptor CD163 in malignant cells

Tumor‐associated macrophages (TAMs) represent a distinct malignancy‐promoting phenotype suggested to play a key role in tumor formation and metastasis. We aimed to investigate the expression of the monocyte/macrophage‐restricted receptor CD163 in bladder tumor biopsies and assess the potential mechanism inducing the CD163 expression in tumor cells. A high CD163 mRNA expression (n = 87) was significantly associated with a poor 13‐year overall survival (log‐rank test, χ2 = 8.931; p = 0.0028). Moreover, CD163 mRNA expression was significantly increased in muscle invasive (T2–T4), p = 0.017, and aggressive (grade III/IV) cancers (p = 0.015). The expression strongly correlated with local expression of IL‐6 (r = 0.72; p