Frequent mutations in NOTCH1 ligand-binding regions in Japanese oral squamous cell carcinoma

•We analyzed the mutation in ligand binding region of NOCTH1 in oral cancer.•Eight of 84 Japanese oral squamous cell carcinomas had mutations.•All mutations were G>A transition and accompanied by amino acid substitutions.•3D simulation of the mutant NOTCH1 structure suggests the conformational change.•Disease free survival was longer for patients with NOTCH1-mutations than without mutations. Recent studies showed that head and neck squamous cell carcinoma (HNSCC) including oral squamous cell carcinoma (OSCC) of Caucasian, Chinese and Indian patients frequently have NOTCH1 mutations. We found eight of 84 OSCC in Japanese patients have point mutations (9.5%) correspond to the ligand binding region of NOTCH1 protein. Two set of them are the same mutations and all mutations are non-synonymous G>A transitions. In addition, median disease-free survival is significantly longer in patients with NOTCH1-mutated tumors as compared to those without the mutation (P