LINC01783 accelerated tongue squamous cell carcinoma progression via inhibiting miR‐199b‐5p

Abstract Growing studies illustrated that lncRNAs exert critical roles in development and occurrence of tumours including TSCC. In this research, we indicated that LINC01783 was up‐regulated in TSCC cells (SCC1, Cal27, UM1 and SCC4) when compared to NHOK cell. RT‐qPCR analysis indicated that LINC01783 was overexpressed in 22 TSCC cases (73.3%, 22/30) compared with no‐tumour specimens. LINC01783 level was up‐regulated in TSCC specimens when compared to no‐tumour specimens. Ectopic expression of LINC01783 promoted TSCC cell cycle and growth and EMT progression in both TSCC cell SCC1 and Cal27. Overexpression of LINC01783 sponged miR‐199b‐5p in TSCC cell and elevated expression of LINC01783 inhibited miR‐199b‐5p expression. Moreover, we illustrated that miR‐199b‐5p was down‐regulated in TSCC cells and specimen and LINC01783 level was up‐regulated in TSCC specimens when compared to no‐tumour specimens. Elevated expression of LINC01783 promoted TSCC cell growth, cycle and EMT progression by sponging miR‐199b‐5p. These data suggested that LINC01783 functioned as one oncogene and might be one treatment target for TSCC.

cell migration, invasion and growth and inhibited cell apoptosis. 29 Increasing studies demonstrated that lncRNAs played important roles in TSCC development. The cell functions and underlying mechanisms of LINC01783 in TSCC are still unclear.
Our data illustrated that LINC01783 was up-regulated in TSCC cells and specimen and ectopic expression of LINC01783 promoted TSCC cell cycle and growth and EMT progression.

| RT-qPCR
RNA of cell or specimen was isolated using TRIzol reagent. RNA quantity was assessed with spectrophotometer. RT-qPCR assay was utilized to assess miR-199b-5p and LINC01783 level with SYBR Green PCR Mix on the Bio-Rad CFX PCR System. U6 or GAPDH was utilized as reference control for miRNA and LINC01783, respectively.

| Cell proliferation and cycle assay
Cells were cultured in the 96-well dishes at about density of 5000 cells/well and were detected at the 0, 1, 2 and 3 days. Each well was added with 10 μL CCK-8 solution and incubated for 3 hours. The OD (optical density) was measured on spectrophotometer at 450 nm wavelength. Flow cytometry assay was utilized to study cell cycle.
Cell was harvested and then washed in cold PBS and fixed by cold 70% ethanol overnight. Cell was incubated with PI (propidium iodide) solution on the ice for one half hour. Cell cycle was determined with flow cytometry (FACSC, BD).

| Statistical analysis
Results were evaluated by SPSS 19.0 software and shown as mean ± SD. Spearman's correlation assay was utilized to assess the correlation between LINC01783 and miR-199b-5p. t Test was constructed to determine significant difference between two groups. P < 0.05 was supposed to be statistically significant.

| LINC01783 level in TSCC specimen
Then, we studied the LINC01783 level in TSCC specimen. RT-qPCR analysis indicated that LINC01783 was overexpressed in 22 TSCC cases (73.3%, 22/30) compared with no-tumour specimens ( Figure 2A). As Figure 2B indicated, LINC01783 level was up-regulated in TSCC specimens when compared to no-tumour specimens. F I G U R E 5 LINC01783 sponged miR-199b-5p in TSCC cell. (A) To learn mechanism by how LINC01783 modulated TSCC cell function, we predicted potential target miRNAs of LINC01783 using StarBase tool. (B) The expression of miR-199b-5p was determined by RT-qPCR assay. (C) The expression of miR-199b-5p was determined using RT-qPCR assay. (D) Luciferase reporter assay data illustrated that luciferase activity in SCC1 cell treated with LINC01783-WT was decreased with treatment by miR-199b-5p mimic, whereas miR-199b-5p mimic had no effect on the luciferase activity in cell treated with LINC01783-MUT. (E) The luciferase reporter assay data in Cal27 cell was shown. (F) Ectopic expression of LINC01783 inhibited miR-199b-5p expression in SCC1 cell. (G) The expression of miR-199b-5p was measured by RT-qPCR assay. **P < 0.01 and ***P < 0.001 [Colour figure can be viewed at wileyonlinelibrary.com]

| LINC01783 promoted TSCC cell growth and cycle by sponging miR-199b-5p
To study whether LINC01783 promoted TSCC cell growth and cycle through sponging miR-199b-5p, we treated SCC1 cell with pcDNA-LINC01783 and then transfected with miR-199b-5p mimic or scramble. Figure 7A and Figure 7B

| D ISCUSS I ON
Growing studies have illustrated that lncRNAs exert critical roles in development and occurrence of tumours including TSCC. 28,[30][31][32][33] Our results suggested that LINC01783 was up-regulated in TSCC cells and specimen and ectopic expression of LINC01783 promoted TSCC cell cycle and growth and EMT progression in both TSCC cell SCC1 and Cal27. Overexpression of LINC01783 sponged miR-199b-5p in TSCC cell and elevated expression of LINC01783 inhibited miR-199b-5p expression. Moreover, we illustrated that miR-199b-5p was down-regulated in TSCC cells and specimen and LINC01783 level was up-regulated in TSCC specimens when compared to no-tumour specimens. Elevated expression of LINC01783 promoted TSCC cell growth, cycle and EMT progression by sponging miR-199b-5p. These data noted that LINC01783 functioned as one oncogene and might be one treatment target for TSCC.
Previous reference showed that CASC9 induced TSCC cell growth, invasion and migration via modulating miR-423-5p/ SOX12. 34 PART1 inhibited TSCC cell growth, migration and invasion through regulating miR-503-5p. 35 Another study indicated that ln-cRNA ELDR increased cell growth through inducing cyclin E1-ILF3 signalling in oral tumour. 36 Xiong et al 37  ing miR-199b-5p. 29 To learn mechanism by how LINC01783 modulated TSCC cell function, we predicted potential target miRNAs of LINC01783 using StarBase 3.0. We found that LINC01783 may sponge miR-199b-5p and luciferase reporter assay data illustrated that luciferase activity in TSCC cell treated with LINC01783-WT was decreased with treatment by miR-199b-5p mimic, whereas miR-199b-5p mimic had no effect on the luciferase activity in cell treated with LINC01783-MUT. Elevated expression of LINC01783 inhibited miR-199b-5p expression. In addition, we illustrated that miR-199b-5p was down-regulated in TSCC cells and specimen and LINC01783 level was up-regulated in TSCC specimens when compared to no-tumour specimens. Elevated expression of LINC01783 promoted TSCC cell growth, cycle and EMT progression by sponging miR-199b-5p.
Taken together, we illustrated that LINC01783 was up-regulated in TSCC cells and specimen and ectopic expression of LINC01783induced TSCC cell cycle and growth and EMT progression via sponging miR-199b-5p.

CO N FLI C T O F I NTE R E S T
There is no conflict of Interest.

DATA AVA I L A B I L I T Y S TAT E M E N T
Research data are not shared.