Prostate cancer associated natural killer cells show a pro-angiogenic and pro-inflammatory phenotype.

Abstract

e17544 Background: Prostate cancer (PCa) represents the second most common cancer worldwide in men. Angiogenesis has been shown to play a crucial role in PCa progression in several preclinical models. Production of pro-angiogenic factors can correlate with metastasis, Gleason score and prognosis in PCa and plasma levels of VEGF were shown to be higher in patients with metastatic PCa than those with localized disease. Natural killer (NK) cells, effector lymphocytes of the innate immunity, have been found to be immunosuppressed in solid cancers, including PCa. Methods: Here, we phenotypically and functionally characterize circulating NK cells from PCa patients and their interaction with endothelial cells and macrophages. NK cell subset distribution has been investigated by multicolor flow cytometry (FACS) for surface antigens on peripheral blood samples PCa patients (TANKs). Conditioned media (CM) from FACS-sorted TANKs were used for functional studies of angiogenesis, on human umbilical-vein endothelial cells (HUVEC), studies for macrophage recruitment (migration assay on Boyden chambers) and polarization. Molecular studies were performed by real time PCR (qPCR) on HUCECs and macrophages exposed to CM of TANKs. Protein arrays were performed to characterize the secretome on FACS-sorted TANKs. Results: We found that TANKs acquire a pro-angiogenic/ dNK-like CD56brightCD9+CD49a+CXCR4+ phenotype. The same phenotype was observed on cytolytic NK cells, from healthy donors, exposed to CMs of three different PCa cell lines (PC-3, DU-145, LNCaP), together with increased production of CXCL8, Angiogenin, Angiopoietin1 and reduced production of TNFa, IFNg and GranzymeA. CMs from TANKs support the formation on capillary-like structures on HUVEC, together with increased expression of VEGF, VEGR-2, CXCL8, ICAM-1 and VCAM-1. Secretome analysis revealed the ability of TANKs release pro-angiogenic pro-invasive factors (CLXL8, MMP-1, MMP-9; uPAR) and cytokines/chemokines involved in macrophage recruitment (CCL1, CCL2, CCL5, CCL7, CCL13, CXCL1, CXCL11) and M2-like polarization (IL-10). Finally, CMs from TANKs can recruit THP-1 monocyte and polarize THP-1 macrophage towards CD206, Arginase1, CXCL8-expressing M2-like/TAM phenotype. Conclusions: Our results place PCa TANKs as effector cells able in supporting angiogenesis in PCa by directly interaction with endothelial cells and via macrophage polarization.