Effect of chimeric antigen receptor T cells against protease-activated receptor 1 for treating pancreatic cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a devastating malignancy with a 5-year survival rate of 6% following a diagnosis, and novel therapeutic modalities are needed. Protease-activated receptor 1 (PAR1) is abundantly overexpressed by both tumor cells and multiple stroma cell subsets in the tumor microenvironment (TME), thereby offering a suitable immunotherapy target.

METHODS

A chimeric antigen receptor (CAR) strategy was applied to target PAR1 using a human anti-PAR1 scFv antibody fused to the transmembrane region with two co-stimulatory intracellular signaling domains of cluster of differentiation 28 (CD28) and CD137 (4-1BB), added to CD3ζ in tandem.

RESULTS

The engineered PAR1CAR-T cells eliminated PAR1 overexpression and transforming growth factor (TGF)-β-mediated PAR1-upregulated cancer cells by approximately 80% in vitro. The adoptive transfer of PAR1CAR-T cells was persistently enhanced and induced the specific regression of established MIA PaCa-2 cancer cells by > 80% in xenograft models. Accordingly, proinflammatory cytokines/chemokines increased in CAR-T-cell-treated mouse sera, whereas Ki67 expression in tumors decreased. Furthermore, the targeted elimination of PAR1-expressing tumors reduced matrix metalloproteinase 1 (MMP1) levels, suggesting that the blocking of the PAR1/MMP1 pathway constitutes a new therapeutic option for PDAC treatment.

CONCLUSIONS

Third-generation PAR1CAR-T cells have antitumor activity in the TME, providing innovative CAR-T-cell immunotherapy against PDAC.

Protease-activated receptor 1 (PAR1) inhibits synaptic NMDARs in mouse nigral dopaminergic neurons

Protease-activated receptor 1 (PAR1) is a G protein-coupled receptor (GPCR), whose activation requires a proteolytic cleavage in the extracellular domain exposing a tethered ligand, which binds to the same receptor thus stimulating Gα_q/11-, Gα_i/o- and Gα_12-13 proteins. PAR1, activated by serine proteases and matrix metalloproteases, plays multifaceted roles in neuroinflammation and neurodegeneration, in stroke, brain trauma, Alzheimer's diseases, and Parkinson's disease (PD). Substantia nigra pars compacta (SNpc) is among areas with highest PAR1 expression, but current evidence on its roles herein is restricted to mechanisms controlling dopaminergic (DAergic) neurons survival, with controversial data showing PAR1 either fostering or counteracting degeneration in PD models. Since PAR1 functions on SNpc DAergic neurons activity are unknown, we investigated if PAR1 affects glutamatergic transmission in this neuronal population. We analyzed PAR1's effects on NMDARs and AMPARs by patch-clamp recordings from DAergic neurons from mouse midbrain slices. Then, we explored subunit composition of PAR1-sensitive NMDARs, with selective antagonists, and mechanisms underlying PAR1-induced NMDARs modulation, by quantifying NMDARs surface expression. PAR1 activation inhibits synaptic NMDARs in SNpc DAergic neurons, without affecting AMPARs. PAR1-sensitive NMDARs contain GluN2B/GluN2D subunits. Moreover, PAR1-mediated NMDARs hypofunction is reliant on NMDARs internalization, as PAR1 stimulation increases NMDARs intracellular levels and pharmacological limitation of NMDARs endocytosis prevents PAR1-induced NMDARs inhibition. We reveal that PAR1 regulates glutamatergic transmission in midbrain DAergic cells. This might have implications in brain's DA-dependent functions and in neurological/psychiatric diseases linked to DAergic dysfunctions.

pHLIP(Var7)-P1AP suppresses tumor cell proliferation in MDA-MB-231 triple-negative breast cancer by targeting protease activated receptor 1

PURPOSE

Protease-activated receptor 1 (PAR1) is a signaling protein ubiquitously present on the surface of tumor cells, and its homologous protein fragment, PAR1-activating peptide (P1AP), can inhibit protein signal transduction of PAR1/G in tumor cells. pH (Low) insertion peptide (pHLIP) can target the acidic tumor microenvironment (TME) and can be used as an excellent carrier to deliver P1AP to tumor cells for therapeutic purposes.

METHODS

PAR1 expression on the surface of MDA-MB-231 cells and human MCF10A mammary epithelial cells was observed. The binding between fluorescent-labeled pHLIP(Var7)-P1AP and MDA-MB-231 cells under different pH values was analyzed. The effect of pHLIP(Var7)-P1AP on the proliferation of MDA-MB-231 cells was analyzed under the conditions of pH 7.4 and 6.0.

RESULTS

PAR1 was highly expressed on the surface of MDA-MB-231 cells. In an acidic environment (pH 6.0 and 5.0), fluorescent-labeled pHLIP(Var7)-P1AP and MDA-MB-231 cells had a high binding ability, and the binding ability increased with the decrease in pH. In an acidic environment (pH 6.0), pHLIP(Var7)-P1AP significantly inhibited MDA-MB-231 cell proliferation. With 0.5 μg, 1 μg, 2 μg, 4 μg, and 8 μg of pHLIP(Var7)-P1AP, the cell proliferation inhibition rates were 3.39%, 5.27%, 14.29%, 22.14%, and 35.69%, respectively.

CONCLUSION

PAR1 was highly expressed on the surface of MDA-MB-231 cells. pHLIP(Var7)-P1AP can effectively target MDA-MB-231 cells in an acidic environment and inhibit the growth of MDA-MB-231 cells by inhibiting the signal transduction of PAR1/G protein.

TR47, a PAR1-based peptide, inhibits melanoma cell migration in vitro and metastasis in vivo

Activated Protein C (APC) is a serine-protease that displays antithrombotic and anti-inflammatory properties. In addition, cleavage of protease-activated receptor 1 (PAR1) by APC exerts endothelial cytoprotective actions. The effects of APC on endothelial cells may be reproduced by TR47, a PAR1-based peptide that mimics the novel N-terminus of PAR1 generated upon cleavage at Arg-46 by APC. In this study we demonstrate that wild-type APC and its signaling-proficient mutant, APC-2Cys (which has dramatically reduced anticoagulant activity), display similar inhibitory effects towards the transendothelial migration of A375 human melanoma cells. Consistent with this observation, APC and APC-2Cys significantly reduced the in vivo metastatic potential of the B16F10 murine melanoma cells. TR47 recapitulated the in vitro and in vivo protective profiles of APC and APC-2Cys. Treatment of EA.hy926 endothelial cells with TR47 (20 μM) significantly decreased the A375 cell migration. In addition, treatment of C57/BL6 mice with a single TR47 dose (125 μg/animal) strongly reduced the metastatic burden of B16F10 cells. Together, our results suggest that protection of the endothelial barrier by APC/TR47-mediated signaling pathways might be a valuable therapeutic approach to prevent metastasis.