Secreted factors from M1 macrophages drive prostate cancer stem cell plasticity by upregulating NANOG, SOX2 and CD44 through NF?B signaling [LNCaP]
The inflammatory tumor microenvironment (TME) is a key driver of tumor-promoting processes. Tumor-associated macrophages are one of the main immune cell types in the TME and their density increases during cancer progression. Here, we investigated the influence of pro-inflammatory (M1) and immunosuppressive (M2) macrophages on prostate cancer lineage plasticity. Our findings reveal that M1 macrophage secreted factors upregulate genes related to stemness while downregulating genes associated with androgen response in LNCaP prostate cancer cells. Cancer stem cell plasticity markers NANOG, KLF4, SOX2, OCT4 and CD44 were stimulated by the secreted factors from M1 macrophages. Moreover, AR and its target gene KLK3 were observed to be suppressed in LNCaP cells treated exposed to secreted factors from M1 macrophages. Inhibition of NF-?B signaling using the IKK16 inhibitor resulted in downregulation of NANOG, SOX2 and CD44. Our study highlights that the secreted factors from M1 macrophages drive prostate cancer cell plasticity by upregulating the expression of cancer stem cell plasticity markers through NF-?B signaling pathway. Overall design: To investigate the effects of secreted factors from pro-inflammatory (M1) and immunesuppressive (M2) macrophages on LNCaP prostate cells, we treated LNCaP cells with conditioned medium (CM) from M0, M1 or M2 polarized THP-1 macrophages for 48 hours. In addition, we combined M1 CM with DMSO or NF?B inhibitor IKK16 to study the role of NF?B signaling on M1 CM -induced gene expression. We established RNA-seq for control (RPMI medium), M0 CM, M1 CM and  M2 CM as well as M1 CM with DMSO and M1 CM with IKK16 -treated LNCaP cells.