Detection of Endogenous DNA Double-strand Breaks in Oral Squamous Epithelial Lesions by P53-binding Protein 1

Abstract

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, HDDRand 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.Oral squamous cell carcinoma (OSCC) incidence is estimated to be more than 500,000 annually (1). It is commonly preceded by oral epithelial dysplasia (OED), and its 5-year survival rate can be improved by early-stage diagnosis (2). The 4 th edition of the WHO Classification of Head and Neck Tumours (2017) defines OED as 'a spectrum of architectural and cytological epithelial changes caused by accumulation of genetic changes associated with an increased risk of progression to squamous cell carcinoma (SCC) (3). However, dysplasia grading is poorly reproducible between pathologists. Although OED is traditionally divided into three severity grades, a binary system is also advocated to improve reproducibility. Consensus grading after reviewing by multiple pathologists may enhance diagnostic reliability. The Japanese Society of Oral Oncology recommends a binary system, such as lowgrade and high-grade dysplasia (LGD and HGD), to diagnose OED based on clinical management (4). HGD may include carcinoma in situ, and commonly develop into SCC, hence HGD lesions are usually recommended for active surgical intervention (5). Most LGDs never progress to carcinoma, so a 'wait and see' policy may be adopted for these lesions. Thus, the clinical management of OED is dependent on the histopathological diagnosis by biopsy.Histological findings of architectural and cytological disturbances in biopsy specimens are critical for OED diagnosis. However, there is lack of consistent evidence to indicate translation of individual features into a dysplasia grade. Thus, the issue of poor consensus is based on the current diagnostic criteria underlying the low reproducibility of OED differential diagnosis and necessitates establishment of an ancillary technique to diagnose OED. P53-binding protein 1 (53BP1) is a DNA damage response (DDR) molecule with a BRCA1 C-terminal domain (6). 53BP1 4771 This a...

Potential Immunohistochemical Biomarkers for Grading Oral Dysplasia: A Literature Review

“…In the study by Sawada et al [ 55 ], the higher the grade of dysplasia, the more frequently a TP53 mutation was observed. Imaizumi et al [ 56 ] assessed p53 expression by immunofluorescence as a biomarker to differentiate between oral squamous epithelial lesions. The study consisted of 129 archival oral biopsy samples, including 18 benign squamous lesions, 37 low-grade dysplasias, 22 high-grade dysplasias, and 52 OSCCs.…”

“…Cell division and proliferation p53 [53][54][55]75,76,117], Ki-67 [56,[68][69][70][71][72][73][74][75][76], CD105 [73,74], p63 [39,42,117], CD31 [39], CD34 [43], cycD1 [42], VEGF [43], YAP, Np63 [59], stathmin [80], CDKN1A [53] Epithelial-mesenchymal transition CK5\6 [96], CK19 [98], β-catenin [103,104], N-cadherin [109], E-cadherin [104][105][106][107], TWIST [111], VIM [107,108], PDPN [115,117], MMP-9 [108] Cell death regulation Bcl-2 [123,124], PDCD4 [128], HSP27 [131], cornulin [134] Cellular metabolism HIF-1a [136], iNOS...…”

Molecular Pathological Characteristics of Thyroid Follicular-Patterned Tumors Showing Nodule-in-Nodule Appearance with Poorly Differentiated Component

“…Our previous experiments based on IF analysis of FFPE tissues showed that the presence of 53BP1 NF was increased in irradiated rat thyroid glands in a dose-dependent manner and that the presence of 53BP1 and γH2AX nuclear foci was frequently co-localized in human TFTs as well as irradiated rat thyroid glands, suggesting endogenous activation of the DDR pathways in tumor cells as a hallmark of genomic instability [ 12 ]. So far, we have found that abnormal type 53BP1 expression is closely associated with carcinogenesis in several organs [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]; for instance, both large nuclear foci and diffuse patterns are significantly associated with high-grade urothelial carcinoma with chromosomal instability and poor prognosis in bladder cancers [ 15 ]. In addition, abnormal types of 53BP1 expression are associated with chromosomal instability, a parameter of prognosis in gastric MALT lymphoma [ 19 ].…”

“…TP53 binding protein-1 (53BP1) is a nuclear protein that rapidly localizes at the sites of DNA DSBs to activate the downstream repair process [ 7 , 8 , 9 , 10 , 11 ]. We previously used immunofluorescence (IF) to show that the profile of 53BP1 expression, including the number of nuclear foci which reflects endogenously occurring DDR, is altered during diverse tumorigenesis [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ].…”