Pharmacological interference with vacuolar-type H(+)-ATPase (V-ATPase), a proton-translocating enzyme involved in protein transport and pH regulation of cell organelles, is considered a potential strategy for cancer therapy. Macrophages are critically involved in tumor progression and may occur as pro-tumoral M2 phenotype, whereas classically-activated M1 can inhibit tumor development for example by releasing tumor-suppressing molecules, including tumor necrosis factor (TNF)alpha. Here, we show that targeting V-ATPase by selective inhibitors such as archazolid upregulates the expression and secretion of TNFalpha in lipopolysaccharide (LPS)- or LPS/interferon (INF)gamma-activated M1-like macrophages derived from human blood monocytes. In contrast, archazolid failed to elevate TNFalpha production from uncommitted (M0) or interleukin (IL)-4-treated M2-like macrophages. Secretion of other relevant cytokines (i.e., IL-1beta, IL-6, IL-10) or chemokines (i.e. IL-8 and monocyte chemotactic protein-1) from M1 was not affected by archazolid. Though V-ATPase inhibitors elevated the lysosomal pH in M1 comparable to chloroquine or ammonium chloride, the latter agents suppressed TNFalpha secretion. Archazolid selectively increased TNFalpha mRNA levels, which was abolished by dexamethasone. Interestingly, archazolid enhanced the phosphorylation and nuclear translocation of the p65 subunit of NFkappaB and stimulated phosphorylation of SAPK/JNK. In a microfluidically-supported human tumor biochip model, archazolid-treated M1 significantly reduced tumor cell viability. Together, our data show that V-ATPase inhibition selectively upregulates TNFalpha production in classically-activated macrophages along with NFkappaB and SAPK/JNK activation. Such increased TNFalpha release caused by V-ATPase inhibitors may contribute to tumor suppression in addition to direct targeting cancer cells.
PubMed ID: 28189727
Publication type: Not specified
Journal: Biochem Pharmacol
Citation: Biochem Pharmacol. 2017 Apr 15;130:71-82. doi: 10.1016/j.bcp.2017.02.004. Epub 2017 Feb 9.
Date Published: 13th Feb 2017
Registered Mode: Not specified
Created: 13th Oct 2017 at 10:03