The Pharmacology of TUG-891, a Potent and Selective Agonist of the Free Fatty Acid Receptor 4 (FFA4/GPR120), Demonstrates Both Potential Opportunity and Possible Challenges to Therapeutic Agonism

Abstract

-2-yl)methoxy)phenyl)propanoic acid] was recently described as a potent and selective agonist for the long chain free fatty acid (LCFA) receptor 4 (FFA4; previously G protein-coupled receptor 120, or GPR120). Herein, we have used TUG-891 to further define the function of FFA4 and used this compound in proof of principle studies to indicate the therapeutic potential of this receptor. TUG-891 displayed similar signaling properties to the LCFA a-linolenic acid at human FFA4 across various assay end points, including stimulation of Ca 21 mobilization, b-arrestin-1 and b-arrestin-2 recruitment, and extracellular signal-regulated kinase phosphorylation. Activation of human FFA4 by TUG-891 also resulted in rapid phosphorylation and internalization of the receptor. While these latter events were associated with desensitization of the FFA4 signaling response, removal of TUG-891 allowed both rapid recycling of FFA4 back to the cell surface and resensitization of the FFA4 Ca 21 signaling response. TUG-891 was also a potent agonist of mouse FFA4, but it showed only limited selectivity over mouse FFA1, complicating its use in vivo in this species. Pharmacologic dissection of responses to TUG-891 in model murine cell systems indicated that activation of FFA4 was able to mimic many potentially beneficial therapeutic properties previously reported for LCFAs, including stimulating glucagon-like peptide-1 secretion from enteroendocrine cells, enhancing glucose uptake in 3T3-L1 adipocytes, and inhibiting release of proinflammatory mediators from RAW264.7 macrophages, which suggests promise for FFA4 as a therapeutic target for type 2 diabetes and obesity. Together, these results demonstrate both potential but also significant challenges that still need to be overcome to therapeutically target FFA4.

Discovery and Characterization of a Novel Small-Molecule Agonist for Medium-Chain Free Fatty Acid Receptor G Protein-Coupled Receptor 84

“…As demonstrated in Table 1, ZQ-16 did not evoke calcium responses in HEK293 cells expressing other FFARs, including GPR40, GPR41, GPR119, and GPR120, at concentrations up to 100 mM. These receptors were functional, since they could be activated by reported ligands with EC 50 values comparable to published data (Briscoe et al, 2003;Xiong et al, 2004;Overton et al, 2006;Shimpukade et al, 2012;Hudson et al, 2013;Suzuki et al, 2013;Song et al, 2015). These results indicate that ZQ-16 is a selective agonist for GPR84.…”

Omega-3 Fatty Acids and Other FFA4 Agonists Inhibit Growth Factor Signaling in Human Prostate Cancer Cells

“…TUG-891 for effects mediated by human FFA4 (Hudson et al, 2013b). The relative potencies of EPA, DHA, GW9508, and TUG-891 are also consistent with previously published values.…”

“…TUG-891, a pharmacologic agent that is not a lipid, is not incorporated into phospholipid and acts reversibly (Hudson et al, 2013b). In Fig.…”

“…The relative potencies of EPA, DHA, GW9508, and TUG-891 are also consistent with previously published values. TUG-891 was developed as a selective FFAR inhibitor, and has higher potency than the endogenous n-3 FAs (Hudson et al, 2013b). GW9508, the FFA1-selective agonist, inhibited proliferation with an IC 50 of 950 nM.…”

“…Both FFA1 and FFA4 are coupled to G q/11 as well as arrestin-3, but many of their actions appear to be arrestin-mediated (Mancini and Poitout, 2013;Butcher et al, 2014). Selective agonists for FFA1 and FFA4 are rapidly being developed (Sun et al, 2010;Hudson et al, 2013b;Du et al, 2014), making it possible to test whether such agents elicit therapeutic effects of interest.…”