Inhibition of lipoxygenase pathway in macrophages co-cultivated with tumor cells

Crotoxin promotes macrophage reprogramming towards an antiangiogenic phenotype

Crotoxin (CTX) is the primary toxin of South American rattlesnake Crotalus durissus terrificus venom. CTX reduces tumour mass, and tumour cell proliferation and these effects seem to involve the formation of new vessels. Angiogenesis has a key role in tumour growth and progression and is regulated by macrophage secretory activity. Herein, the effect of CTX on macrophage secretory activity associated with angiogenesis was investigated in vitro. Thymic endothelial cells (EC) were incubated in the presence of macrophages treated with CTX (12.5 nM) or supernatants of CTX-treated macrophages and endothelial cell proliferation, migration and adhesion activities, and the capillary-like tube formation in the matrigel-3D matrix was measured. Angiogenic mediators (MMP-2, VEGF and TNF-α) were measured in the cell culture medium. Macrophages pre-treated with CTX and supernatant of CTX-treated macrophages inhibited EC proliferation, adhesion to its natural ligands, and migration (as evaluated in a wound-healing model and Time Lapse assay) activities. Decreased capillary-like tube formation and MMP-2, VEGF and TNF-α levels in the supernatant of macrophages treated with CTX was also described. CTX promotes macrophage reprogramming towards an antiangiogenic phenotype.

Lipoxin A4 and its analog suppress hepatocellular carcinoma via remodeling tumor microenvironment

Macrophages play an important role in tumor inflammatory microenvironment, lipoxin (LX), the 'stop signal' for inflammation, has been extensively studied preclinically for its anti-inflammatory or inflammatory pro-resolving effect. Here, we showed that LXA(4) could promote the apoptosis and inhibit the proliferation, migration and angiogenesis of HepG2 hepatocarcinoma cells stimulated by lipopolysaccharide (LPS) or activated macrophage-conditioned media (ACM). Moreover, BML-111, the analog of LXA(4), effectively inhibited the proliferation, invasion and angiogenesis of tumor in H22 hepatocarcinoma cell bearing mice. These results showed that LXA(4) could be a possible candidate for liver cancer therapy, and blocking the activation of macrophages would be an effective drug target.