Abstract:
Objective To investigate the expression of long non-coding RNA HOXA transcript at the distal tip (HOTTIP) in oral squamous cell carcinoma (OSCC) and examine its effect on the biological function of OSCC cells.
Methods A total of 52 patients with OSCC who received surgical treatment in The First Affiliated Hospital of Zhengzhou University from January 2020 to June 2021 were collected. The expression levels of HOTTIP in OSCC and adjacent tissues, human OSCC cell lines HSC-4, SCC-9 and CAL-27, and human normal oral keratinocyte line HOK were detected by quantitative real-time polymerase chain reaction (RT-qPCR), and its correlation with clinicopathological data and overall survival (OS) of OSCC patients was analyzed. The effects of down-regulating HOTTIP or co-down-regulating HOTTIP and miR-637 on the proliferation, apoptosis, migration, invasion, and epithelial-mesenchymal transition (EMT) of CAL-27 cells were analyzed using Cell Counting Kit-8 (CCK-8), flow cytometry, Transwell assays, and Western blot. The targeting relationship between HOTTIP and miR-637 was analyzed by dual luciferase reporter gene assays.
Results The expression level of HOTTIP in OSCC tissues was significantly increased compared with adjacent tissues (P<0.05) and was correlated with tumor size, TNM stage, degree of differentiation, lymph node metastasis, and OS (P<0.05). The expression of HOTTIP in HSC-4, SCC-9, and CAL-27 cells significantly increased compared with normal HOK cells (P<0.05). After down-regulation of HOTTIP expression, the proliferation, migration, invasion, and EMT abilities of CAL-27 cells were significantly weakened, whereas the apoptosis rate significantly increased (P<0.05). HOTTIP had a targeting relationship with miR-637; after down-regulating HOTTIP, the expression of miR-637 in CAL-27 cells significantly decreased (P<0.05). After the simultaneous downregulation of HOTTIP and miR-637, the proliferation, migration, invasion, and EMT abilities of CAL-27 cells were significantly enhanced, whereas the apoptosis rate significantly decreased (P<0.05).
Conclusions HOTTIP is highly expressed in OSCC tissues and cells and can target miR-637 to regulate the proliferation, apoptosis, migration, invasion, and EMT of OSCC cells.