AZ-3451

Oral cancer is notoriously painful. Activation of protease-activated receptor 2 (PAR₂, encoded by F2RL1) by proteases in the cancer microenvironment is implicated in oral cancer pain. PAR₂ is a G protein-coupled receptor (GPCR) expressed on neurons and cells in the cancer microenvironment. Sustained signaling of PAR₂ from endosomes of neurons mediates sensitization and nociception. We focused on the differential contribution of PAR₂ on oral cancer cells and neurons to oral cancer pain and whether encapsulation of a PAR₂ inhibitor, AZ3451 in nanoparticles (NP) more effectively reverses PAR₂ activation. We report that F2RL1 was overexpressed in human oral cancers and cancer cell lines. Deletion of F2RL1 on cancer cells reduced cancer-associated mechanical allodynia. A third-generation polyamidoamine dendrimer, functionalized with cholesterol was self-assembled into NPs encapsulating AZ3451. NP encapsulated AZ3451 (PAMAM-Chol-AZ NPs) more effectively reversed activation of PAR₂ at the plasma membrane and early endosomes than free drug. The PAMAM-Chol-AZ NPs showed greater efficacy in reversing nociception than free drug, with respect to both level and duration, in three preclinical mouse models of oral cancer pain. The antinociceptive efficacy was confirmed with an operant orofacial assay. Genetic deletion of F2RL1 on cancer cells or F2rl1 on neurons each partially reversed mechanical cancer allodynia. The remaining nociception could be effectively reversed by PAMAM-Chol-AZ NPs. These findings suggest that PAR₂ on oral cancer cells and neurons contribute to oral cancer nociception and NPs loaded with a PAR₂ antagonist provide increased antinociception and improved oral function compared to free drug.

Type 2 inflammation in asthma develops with exposure to stimuli to include inhaled allergens from house dust mites (HDM). Features include mucus hypersecretion and the formation of pro-secretory ion transport characterised by elevated basal Cl^- current. Studies using human sinonasal epithelial cells treated with HDM extract report a higher protease activated receptor-2 (PAR-2) agonist-induced calcium mobilisation that may be related to airway sensitisation by allergen-associated proteases. Herein, this study aimed to investigate the effect of HDM on Ca²⁺ signalling and inflammatory responses in asthmatic airway epithelial cells. Primary bronchial epithelial cells (hPBECs) from asthma donors cultured at air-liquid interface were used to assess electrophysiological, Ca²⁺ signalling and inflammatory responses. Differences were observed regarding Ca²⁺ signalling in response to PAR-2 agonist 2-Furoyl-LIGRLO-amide (2-FLI), and equivalent short-circuit current (I_eq) in response to trypsin and 2-FLI, in ALI-asthma and healthy hPBECs. HDM treatment led to increased levels of intracellular cations (Ca²⁺, Na⁺) and significantly reduced the 2-FLI-induced change of I_eq in asthma cells. Apical HDM-induced Ca²⁺ mobilisation was found to mainly involve the activation of PAR-2 and PAR-4-associated store-operated Ca²⁺ influx and TRPV1. In contrast, PAR-2, PAR-4 antagonists and TRPV1 antagonist only showed slight impact on basolateral HDM-induced Ca²⁺ mobilisation. HDM trypsin-like serine proteases were the main components leading to non-amiloride sensitive I_eq and also increased interleukin-33 (IL-33) and thymic stromal lymphopoietin (TSLP) from asthma hPBECs. These studies add further insight into the complex mechanisms associated with HDM-induced alterations in cell signalling and their relevance to pathological changes within asthma.