RT Journal Article SR Electronic T1 Detection of Endogenous DNA Double-strand Breaks in Oral Squamous Epithelial Lesions by P53-binding Protein 1 JF Anticancer Research JO Anticancer Res FD International Institute of Anticancer Research SP 4771 OP 4779 DO 10.21873/anticanres.15292 VO 41 IS 10 A1 TOSHINOBU IMAIZUMI A1 KATSUYA MATSUDA A1 KEI TANAKA A1 HISAYOSHI KONDO A1 NOZOMI UEKI A1 HIROKAZU KUROHAMA A1 CHIEKO OTSUBO A1 YUKI MATSUOKA A1 YUKO AKAZAWA A1 SHIRO MIURA A1 MASAHIRO NAKASHIMA YR 2021 UL http://ar.iiarjournals.org/content/41/10/4771.abstract AB Background/Aim: P53-binding protein 1 (53BP1) is one of the DNA damage response (DDR) molecules. This study aimed to assess 53BP1 expression by immunofluorescence (IF) as a biomarker to differentiate between oral squamous epithelial lesions (OSELs). Materials and Methods: We analyzed 129 archival oral biopsy samples, including 18 benign squamous lesions (BSLs), 37 low-grade dysplasias (LGDs), 22 high-grade dysplasias (HGDs), and 52 oral squamous cell carcinomas (OSCCs). 53BP1 and Ki-67 expressions were examined by double IF to assess the type of 53BP1 expression. Results: We found that OSCC exhibited several 53BP1 nuclear foci, particularly high-DNA damage response (HDDR) and large focus (LF)-type, suggesting the presence of endogenous DNA double-strand breaks in the cancer genome, which could disrupt DDR and induce genomic injury. We also found a difference in 53BP1 expression between LGD and HGD, but not between BSL and LGD. Among the Ki-67-positive cells, HDDR- and LF-type expressions were higher in OSELs of higher grades. Conclusion: 53BP1 expression can be a valuable biomarker for OSELs to help estimate the grade of oral epithelial dysplasia.