Relationship between Tumor Diameters and Antoni Classification for Schwannoma of the Lower Lip.

Schwannoma is an uncommon benign tumor in the oral and maxillofacial region, and development of schwannoma in the lower lip is rare. Herein, we present the case of a 68-year-old woman who visited Nihon University Itabashi Hospital complaining of a painless mass in the lower lip. The lesion was surgically resected under local anesthesia. On histopathological examination, the resected specimen was a mixture of Antoni types A and B schwannoma. No recurrence has been seen over a postoperative follow-up period of 58 months. In the schwannoma of the lower lip, the mean tumor volume was compared for type A and the mixed type, which tended to be larger in the mixed type. No previous reports have described the relationship between the size of schwannoma in the lower lip and Antoni classification. Therefore, this report discusses the possibility of a relationship between tumor size and Antoni classification for schwannomas in the lower lip.

The dystonia gene THAP1 controls DNA double-strand break repair choice.

The Shieldin complex shields double-strand DNA breaks (DSBs) from nucleolytic resection. Curiously, the penultimate Shieldin component, SHLD1, is one of the least abundant mammalian proteins. Here, we report that the transcription factors THAP1, YY1, and HCF1 bind directly to the SHLD1 promoter, where they cooperatively maintain the low basal expression of SHLD1, thereby ensuring a proper balance between end protection and resection during DSB repair. The loss of THAP1-dependent SHLD1 expression confers cross-resistance to poly (ADP-ribose) polymerase (PARP) inhibitor and cisplatin in BRCA1-deficient cells and shorter progression-free survival in ovarian cancer patients. Moreover, the embryonic lethality and PARPi sensitivity of BRCA1-deficient mice is rescued by ablation of SHLD1. Our study uncovers a transcriptional network that directly controls DSB repair choice and suggests a potential link between DNA damage and pathogenic THAP1 mutations, found in patients with the neurodevelopmental movement disorder adult-onset torsion dystonia type 6.