LncRNA PART1 Exerts Tumor-Suppressive Functions in Tongue Squamous Cell Carcinoma via miR-503-5p

Xiqun Zhao1 ,* Yanqing Hong2 ,* Qingyuan Cheng,3 Lixin Guo4 1Department of Pediatric Dentistry, Jinan Stomatological Hospital, Jinan, Shandong 250001, People’s Republic of China; 2Prosthodontic Lab, Jinan Stomatological Hospital, Jinan, Shandong 250001, People’s Republic of China; 3Department of Stomatology, Jinan LiCheng District Hospital of Traditional Chinese Medicine, Jinan, Shandong 250001, People’s Republic of China; 4Department of Scientific Education, Jinan Stomatological Hospital, Jinan, Shandong 250001, People’s Republic of China*These authors contributed equally to this workCorrespondence: Lixin GuoDepartment of Scientific Education, Jinan Stomatological Hospital, No. 101, Jing Liu Road, Shizhong District, Jinan, Shandong 250001, People’s Republic of ChinaTel +86-15589970752Email caomang1993h@163.comBackground: Tongue squamous cell carcinoma (TSCC) accounts for one-third of oral cancers. Previous studies had reported that lncRNA/miRNA regulated the biological behaviors of different cancer cells. However, the mechanisms of PART1 in regulating tumorigenesis and TSCC development via targeting miR-503-5p had not been studied.Methods: The expressions of PART1 and miR-503-5p in tissues and cultured cell lines were detected by qRT-PCR. StarBase 3.0 was used to predict the binding sites of PART1, then dual-luciferase assay and RNA pull-down assay were executed to confirm whether miR-503-5p was a target of PART1. TSCC cells were co-transfected with PART1-overexpressed plasmid or miR-503-5p mimics in vitro, and the transfection efficiency was evaluated through qRT-PCR. Western blot was performed to assess the expressions of EMT-related proteins. CCK-8 and clone formation assays were conducted to detect cell proliferation, TUNEL assay was used to detect apoptosis, and transwell assay was executed to test migration and invasion.Results: The low PART1 expression and high miR-503-5p expression were found in TSCC tissues and cell lines (CAL-27 and SCC9). PART1 expression was positively correlated with patients’ prognosis. The targeting and binding relationship between PART1 and miR-503-5p was confirmed, and overexpressed PART1 diminished the expression of miR-503-5p as well. Moreover, PART1 facilitated apoptosis, inhibited proliferation, invasion and migration of TSCC cells, and these influences were impeded by miR-503-5p overexpression.Conclusion: LncRNA PART1 played a cancer-suppressing role in TSCC by targeting miR-503-5p, which provided a potential target for TSCC treatment.Keywords: tongue squamous cell carcinoma, LncRNA PART1, miR-503-5p, proliferation, invasion, migration