IL6 and cancer: PCa cells have upregulated expression of both IL-6 and its receptor IL-6R [158], as well as elevated circulating levels of IL-6 in patients with metastatic PCa and CRPCa [159–161], correlating IL-6 production to cancer morbidity [162–164] and differential autocrine and paracrine modulation of PCa cell lines [141, 164–166].