Previously discovered bacterial depsipeptides (FR900359 and YM-254890) bind directly to Gαq and stabilize its inactive complex with GDP, but suffer from limitations of distribution and bioavailability...The thiazolidinedione analogs, rosiglitazone and pioglitazone, had no effect...SIGNIFICANCE STATEMENT: Troglitazone, unlike other thiazolidinediones, directly binds and inhibits activity of heterotrimeric G protein Gq, with a weaker effect on Gi. Troglitazone may find usage as a repurposed drug scaffold to build novel small-molecule Gαq inhibitors with better bioavailability than depsipeptide Gαq inhibitors.

These results indicate that the inhibition of LPA receptor signaling by metformin, especially the consequent suppression of LPAR3-mediated cell migration, may contribute to the antitumor effects of metformin.

We and others reported that Gαq/11 inhibitor FR900359 (FR) can inhibit both Gαq- and, surprisingly, Giβγ-mediated intracellular Ca2+ mobilization...However, in T24 bladder cancer cells, Gi inhibitor PTX, but not Gαq/11 inhibitors, FR, YM254890 (YM) or Gq/11 siRNA, inhibited Ca2+ increase triggered by native A2BAR activation...Thus, Gαq/11 is vital for Ca2+ increase in some cell types, but Giβγ-mediated Ca2+ signaling can be Gαq/11-dependent or independent based on cell type and receptor activated. Besides G proteins, PKC also modulates cytosolic Ca2+ increase depending on cell type and receptor.

However, in T24 bladder cancer cells, G i inhibitor PTX, but not G αq/11 inhibitors, FR, YM254890 (YM) or G q/11 siRNA, inhibited Ca 2+ increase triggered by native A 2B AR activation...Thus, G αq/11 is vital for Ca 2+ increase in some cell types, but G iβγ -mediated Ca 2+ signaling can be Gα q/11 -dependent or independent based on cell type and receptor activated. Besides G proteins, PKC also modulates cytosolic Ca 2+ increase depending on cell type and receptor.

Compound F33 emerged as the most favorable candidate, and displayed moderate inhibitory activity against Gαq/11 proteins (IC = 9.4 μM) and two UM cell lines MP41 (IC = 6.7 μM) and 92.1 (IC = 3.7 μM). Being a small molecule inhibitor of Gαq/11 proteins, F33 could effectively suppress the activation of downstream signaling pathways in a dose-dependent manner, and significantly inhibits UM in vitro.F33 represents a promising lead compound for developing therapeutics for UM by targeting Gαq/11 proteins.

We used the highly specific Gq/11 inhibitor FR900359 (FR) to elucidate signaling networks that drive proliferation, metabolic reprogramming, and dedifferentiation of UM cells...ssGSEA, unsupervised analysis, and functional studies indicated that mTORC1 and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 2 (PFKFB2) drive metabolic reprogramming in UM cells. Together, these results identified protein kinase signaling networks driven by oncogenic Gq/11 that regulate critical aspects of UM cell biology and provide targets for therapeutic investigation.

In this study, we treated GNAQ-mutant uveal melanoma cell lines with a Gαq/11 inhibitor, YM-254890, and conducted a kinase signaling proteomic screen using multiplexed-kinase inhibitors followed by mass spectrometry...Analysis of RNA-sequencing and proteomic data showed that Gαq signaling regulates STK10 expression and MARK3 activity. Our findings suggest an involvement of STK10 and MARK3 in the Gαq/11 oncogenic pathway and prompt further investigation into the specific roles and targeting potential of these kinases in uveal melanoma.

Synergistic effects on calcium flux and cell migration are inhibited by the Gα inhibitor pertussis toxin and the Gα inhibitor YM254890, suggesting that the Gα and Gα pathways are involved in the synergy. Enhanced calcium signaling and cell migration are also observed in NCI-H23 and HeLa cells, which coexpress CXCR4 and HRH1. Taken together, our findings demonstrate an interplay between CXCR4 and HRH1, and suggest the possibility of the CXCR4-HRH1 heteromer as a potential therapeutic target for anticancer therapy.

We further demonstrate that a 2-week combination treatment of 0.3-0.4 mg/kg of YM-254890 administered by intraperitoneal injection and 25-40 mg/kg linsitinib administered by oral gavage effectively inhibits the growth of metastatic UM tumors in immunodeficient NOD scid gamma (NSG) mice and identify the IGF1 pathway as a potential resistance mechanism in response to Galphaq/11 inhibition in UM. These data suggest that the combination of Galphaq/11 and IGF1R inhibition provides a promising therapeutic strategy to treating metastatic UM.

GPCR-dependent signaling by PM-restricted wild type αq is strongly inhibited by YM, demonstrating that resistance to YM inhibition by membrane-binding mutants is specific to constitutively active αqQ209L. Together, these results indicate that changes in membrane binding impact the ability of YM to inhibit αqQ209L and suggest that YM contributes to inhibition of αqQ209L by promoting its relocalization.

Lidocaine (10 mM; a concentration within the clinically used range) activates T2R calcium responses that are inhibited by pertussis toxin, an inhibitor of G - coupled GPCRs, and by suramin, an inhibitor of G . This was distinct from the structurally-related T2R agonist denatonium, which activates calcium responses inhibited by G inhibitor YM-254890 but not pertussis toxin...Lidocaine or other T2R agonists may aid in eradication of residual cancer cells and extend time between initial surgery and reoccurrence/metastasis as an alternative or complementary therapy. With their promising effects on oral and oropharyngeal SCC cells and accessibility of the oral cavity to topically applied lidocaine gels, further work is warranted to understand the effects of bitter local anesthetics and T2R signaling in HNSCC and normal surrounding epithelia.