Sorafenib perpetuates cellular anticancer effector functions by modulating the crosstalk between macrophages and natural killer cells

Abstract

Alternatively polarized macrophages (MU) shape the microenvironment of hepatocellular carcinoma (HCC) and temper anticancer immune responses. We investigated if sorafenib alters the HCC microenvironment by restoring classical macrophage polarization and triggering tumor-directed natural killer (NK) cell responses. In vivo experiments were conducted with sorafenib (25 mg/kg)-treated C57BL/6 wildtype as well as hepatitis B virus (HBV) and lymphotoxin transgenic mice with and without HCC. Monocyte-derived MU or tumor-associated macrophages (TAM) isolated from HCC tissue were treated with sorafenib (0.07-5.0 lg/mL) and cocultured with autologous NK cells. MU and NK cell activation was analyzed by flow cytometry and killing assays, respectively. Cytokine and growth factor release was measured by enzyme-linked immunosorbent assay. Short-term administration of sorafenib triggered activation of hepatic NK cells in wildtype and tumor-bearing mice. In vitro, sorafenib sensitized MU to lipopolysaccharide, reverted alternative MU polarization and enhanced IL12 secretion (P 5 0.0133). NK cells activated by sorafenib-treated MU showed increased degranulation (15.3 6 0.2% versus 32.0 6 0.9%, P < 0.0001) and interferon-gamma (IFN-c) secretion (2.1 6 0.2% versus 8.0 6 0.2%, P < 0.0001) upon target cell contact. Sorafenib-triggered NK cell activation was verified by coculture experiments using TAM. Sorafenib-treated MU increased cytolytic NK cell function against K562, Raji, and HepG2 target cells in a dose-dependent manner. Neutralization of interleukin (IL)12 or IL18 as well as inhibition of the nuclear factor kappa B (NF-jB) pathway reversed NK cell activation in MU/NK cocultures. Conclusion: Sorafenib triggers proinflammatory activity of TAM and subsequently induces antitumor NK cell responses in a cytokine-and NF-jB-dependent fashion. This observation is relevant for HCC therapy, as sorafenib is a compound in clinical use that reverts alternative polarization of TAM in HCC. (HEPATOLOGY 2013;57:2358-2368 T umor-associated macrophages (TAM) located in the hepatocellular carcinoma (HCC) environment increase HCC recurrence after resection and reduce patient survival. 1,2 TAM thereby fosters tumor cell proliferation and tumor spread. 3 Natural killer (NK) cell numbers and activity, on the other hand, are associated with lower HCC stages and improved patient survival. 4,5 An outstanding feature of Abbreviations: AFP, alpha-fetoprotein; C57BL/6 wt , C57BL/6

Expanded and Activated Natural Killer Cells for Immunotherapy of Hepatocellular Carcinoma

“…In mice, sorafenib reduced the number of NK cells and their activity against tumor cells (40). However, others have noted that short-term administration of sorafenib activates hepatic NK cells through activation of tumor-associated macrophages (41) and that sorafenib inhibits the shedding of major histocompatibility complex class I-related chain A (MICA), an NKG2D ligand (42). We found that expanded NK cells considerably enhanced the antitumor cytotoxicity of sorafenib and that NK-cell cytotoxicity appeared to be unaffected regardless of whether sorafenib was added to the cultures, suggesting that a combination of sorafenib plus expanded NK cells could have additive antitumor effects in HCC.…”

NK cell receptor imbalance and NK cell dysfunction in HBV infection and hepatocellular carcinoma

“…59,113,114 Other suppressive cells that are abundant in tumors including HCC, such as myeloid-derived suppressor cells and M2-polarized tumor-associated macrophages, also suppress the expression of NK cell-activating receptors and impair NK cell function by secreting TGF-b and IL-10 or IDO. 17,48,115 In addition, tumor-associated fibroblasts prevent IL-2-induced upregulation of the activating receptors NKp44, DNAM-1 and NKp30, which depend on cell-to-cell contact and PGE2 release; thus, tumor-associated fibroblasts strongly inhibit NK-cell function. 116 Similar studies have also reported that HCCassociated fibroblasts trigger NK cell dysfunction via PGE2 and IDO.…”

Interplay between cancer cells, macrophages and natural killer cells may actually decide the outcome of therapy with sorafenib

“…We read with great interest the article of Sprinzl et al 1 in HEPATOLOGY. The group highlighted the antitumoral effects of sorafenib in hepatocellular carcinoma (HCC) from an immunological point of view.…”