(294) Macitentan produces antinociception in a mouse model of head and neck squamous cell carcinoma pain

Abstract

Head and neck squamous cell carcinoma (HNSCC) patients suffer more pain than other cancer patients. We have determined that HNSCC cells produce high levels of endothelin-1 (ET-1), and that ET-1 activation of one of its receptor ETAR produces pain in an HNSCC mouse model. In this study we hypothesized that macitentan, an insurmountable ETAR antagonist, is antinociceptive in a mouse HNSCC model, through its inhibitory effects on neuronal ETAR. Daily macitentan administration produced significant thermal and mechanical antinociception in our HNSCC mouse model for the treatment period (up to 25 days post-cancer inoculation); 45mg/kg macitentan produced the most profound antinociceptive effect. We determined that the maximal antinociceptive effect was at 1 hour post-administration, and disappeared by 3 hours, consistent with the 2 hour half-life of macitentan. We used dissociated mouse trigeminal ganglion cultures to establish a possible mechanism of macitentan-mediated antinociception. Using ratiometric calcium imaging we determined that 100nM ET-1 increased calcium conductance, indicative of neuronal activation, in 26% of neurons. This proportion of activated neurons by calcium imaging correlated with immunofluorescent staining of ETAR in 30% of dissociated neurons. Pre-treatment of the neurons with 20μM macitentan significantly inhibited activation, such that only 4% of neurons showed increased calcium conductance in response to ET-1. Our results suggest a role for macitentan in the treatment of HNSCC-induced pain and other cancers that secrete ET-1. Head and neck squamous cell carcinoma (HNSCC) patients suffer more pain than other cancer patients. We have determined that HNSCC cells produce high levels of endothelin-1 (ET-1), and that ET-1 activation of one of its receptor ETAR produces pain in an HNSCC mouse model. In this study we hypothesized that macitentan, an insurmountable ETAR antagonist, is antinociceptive in a mouse HNSCC model, through its inhibitory effects on neuronal ETAR. Daily macitentan administration produced significant thermal and mechanical antinociception in our HNSCC mouse model for the treatment period (up to 25 days post-cancer inoculation); 45mg/kg macitentan produced the most profound antinociceptive effect. We determined that the maximal antinociceptive effect was at 1 hour post-administration, and disappeared by 3 hours, consistent with the 2 hour half-life of macitentan. We used dissociated mouse trigeminal ganglion cultures to establish a possible mechanism of macitentan-mediated antinociception. Using ratiometric calcium imaging we determined that 100nM ET-1 increased calcium conductance, indicative of neuronal activation, in 26% of neurons. This proportion of activated neurons by calcium imaging correlated with immunofluorescent staining of ETAR in 30% of dissociated neurons. Pre-treatment of the neurons with 20μM macitentan significantly inhibited activation, such that only 4% of neurons showed increased calcium conductance in response to ET-1. Our results suggest a role for macitentan in the treatment of HNSCC-induced pain and other cancers that secrete ET-1.