Evidence for APOBEC3B mRNA and protein expression in oral squamous cell carcinomas

• Published in: Experimental and molecular pathology 2016-12, Vol.101 (3), p.314-319
• Main Authors: Fanourakis, Galinos, Tosios, Konstantinos, Papanikolaou, Nikolaos, Chatzistamou, Ioulia, Xydous, Marios, Tseleni-Balafouta, Sofia, Sklavounou, Alexandra, Voutsinas, Gerassimos E, Vastardis, Heleni
• Format: Article
• Language: English
• Subjects: Active Transport, Cell Nucleus; Adult; Aged; APOBEC3B; Carcinoma, Squamous Cell - genetics; Carcinoma, Squamous Cell - metabolism; Carcinoma, Squamous Cell - pathology; Cell Nucleus - metabolism; Cytidine Deaminase - genetics; Cytidine Deaminase - metabolism; Female; Gene Frequency; Genomics; Head and neck squamous cell carcinoma; Humans; Immunohistochemistry; Male; Middle Aged; Minor Histocompatibility Antigens - genetics; Minor Histocompatibility Antigens - metabolism; Mouth Neoplasms - genetics; Mouth Neoplasms - metabolism; Mouth Neoplasms - pathology; Mutation; Oral squamous cell carcinoma; RNA, Messenger - genetics; RNA, Messenger - metabolism
• ISSN: 0014-4800; 1096-0945
• DOI: 10.1016/j.yexmp.2016.11.001

It has been demonstrated that APOBEC3B possesses cytidine deaminase activity, which is likely to result in C-to-T signature mutations. Increased expression of the APOBEC3B gene has been shown to correlate with higher incidence of such mutations in various cancer types, such as breast, bladder, lung, and head and neck carcinomas. In the current study, we used in silico methods, immunohistochemistry and qRT-PCR to detect the presence of APOBEC3B signature mutations and examine the levels and patterns of APOBEC3B expression in oral squamous cell carcinomas (OSCCs). Using the Cancer Genome Atlas (TCGA) database, we have found a high incidence of C-to-T transitions in head and neck squamous cell carcinomas (HNSCCs), of which OSCCs constitute the largest subgroup. Additionally, we compared APOBEC3B expression, at both mRNA and protein level, between OSCCs and non-cancerous samples. APOBEC3B was detected in both groups, but nuclear localization was consistent only in normal oral cells. APOBEC3B mRNA levels were clearly higher in OSCCs than in controls. These results suggest that while in normal oral cells APOBEC3B has an important nuclear function to fulfill, this activity may be hindered in a subgroup of tumor cells, due to the more prominent localization of the enzyme in the cytoplasm. •APOBEC3B mRNA expression was higher in OSCCs than in controls.•APOBEC3B protein expression was high in both OSCCs and normal samples.•Nuclear localization of APOBEC3B protein was consistent only in normal oral cells and not in OSCCs.