A-967079

Prenatal exposure to valproic acid (pre-VPA) in rodents is a well-established model of autism spectrum disorder associated with altered sensory processing. We examined the contribution of peripheral ion channels to pre-VPA-induced mechanical and cold allodynia. Pregnant C57BL (WT) and Cav3.2-/- mice were exposed to VPA or saline, and offspring were assessed at 4 and 8 weeks. Sensory behavior was evaluated with von Frey (mechanical allodynia), Hargreaves (thermal hyperalgesia), and acetone (cold allodynia) tests. The effect of systemic delivery of inhibitors of various ion channels expressed in the afferent pain pathway (T-type calcium channels, TRPM3, TRPM8, TRPA1, TRPV1, high voltage activated calcium channels and sodium channels) was tested in male mice. This was complemented by current-clamp recordings in dorsal root ganglion (DRG) neurons. WT and Cav3.2-/- pre-VPA males developed mechanical allodynia at 4 and 8 weeks, while only Cav3.2-/- pre-VPA females showed this phenotype. Thermal sensitivity was unaltered. Cold allodynia occurred at 4 weeks in WT and Cav3.2-/- males and WT females. A967079, ononetin, AMTB, gabapentin, and VPA reduced mechanical allodynia in 8-week-old pre-VPA males, while Z944 and II-2 were ineffective. In the acetone assay at 4 weeks, A967079, ononetin, and AMTB were effective, whereas gabapentin, VPA, and II-2 showed no effect. Electrophysiology revealed normal rheobase but reduced firing frequency in DRG neurons from pre-VPA WT males, suggesting the possibility of central sensitization rather than peripheral hyperactivity. Our findings demonstrate that prenatal VPA induces mechanical and cold allodynia that is overcome by TRPA1, TRPM3, and TRPM8 blockers.

Neuroblastoma (NB) is a childhood cancer with a high relapse rate despite intensive treatment. TRPA1 is a pain‐sensing ion channel with downstream impacts on proliferative and pro‐apoptotic pathways. Here, we evaluated TRPA1 expression in NB and performed pharmacological inhibition in preclinical models to assess its potential as a therapeutic target in NB.

TRPA1 protein levels were assessed in NB patient tumors on tissue microarrays. Bulk and single‐cell gene expression data were retrieved from publicly available databases. The effects of three TRPA1 inhibitors (AP‐18, A967079, and Bay 390) on NB cell viability and cell death were evaluated using NB patient‐derived xenograft (PDX)‐derived organoids. In vivo testing was performed in a MYCN‐amplified NB PDX model. Drug combination testing was performed using combination or sequential treatments and evaluated using drug synergy scores.

TRPA1 is widely expressed in NB patient tumors and preclinical patient‐derived NB models. Pharmacological TRPA1 inhibition decreased NB cell viability and increased cell death. In vivo TRPA1 inhibition alone did not significantly affect NB tumor growth. Pretreatment with TRPA1 inhibition prior to chemotherapy resulted in synergistic effects in vitro.

TRPA1 is expressed in NB tumors, and pharmacological TRPA1 inhibition can be effective in vitro and synergistic when used as pretreatment to chemotherapy. However, the tested inhibitors did not show in vivo efficacy, at least as monotherapy.