Neuroepithelial reprogramming and ERBB vulnerability in canine acanthomatous ameloblastoma.

Canine acanthomatous ameloblastoma (CAA) is a locally invasive benign oral neoplasm that is difficult to distinguish from canine oral squamous cell carcinoma (COSCC) due to overlapping features. Previous studies using bulk RNA sequencing (RNA-seq) have demonstrated pronounced differences in programs related to hypoxia and cell proliferation. However, these studies lacked the resolution to elucidate the cellular heterogeneity of CAA relative to COSCC. We performed single-nucleus RNA-seq to define the cellular gene expression landscape of CAA, COSCC, and healthy gingiva. Across ∼205,000 nuclei, we identified two epithelial states uniquely enriched in CAA. The CAA-specific keratinocytes exhibited a neuronal-like expression program defined by synaptic regulators, KRAS-associated signaling pathways, and markedly elevated expression of PEG3 and ERBB4. These findings were validated by immunohistochemistry, which showed strong nuclear localization of PEG3 exclusively in CAA epithelium. A kinase inhibitor screen independently identified ERBB4 as a candidate therapeutic vulnerability, and pharmacologic inhibition with neratinib was effective. Together, these findings reveal a previously unrecognized neuroepithelial cell state that defines CAA, distinguishes it from COSCC, and reveals unique diagnostic and therapeutic signaling dependencies. Given the molecular/histopathologic parallels between CAA and human ameloblastoma, these data further position CAA as a naturally occurring comparative model for studying ameloblastoma therapeutic vulnerabilities.