[hsa_circ_0000231 affects the progression of tongue squamous cell carcinoma by activating Wnt/β-catenin signaling pathway]

Abstract

Objective: To explore the action mechanism of hsa_circ_0000231 in the occurrence and development of tongue squamous cell carcinoma (TSCC). Methods: Tissue samples of 60 TSCC patients were examined. The patients, including 32 males and 28 females, aged from 36 to 84 years old, underwent surgery in the Affiliated Hospital of Nantong University and Affiliated Tumor Hospital of Nantong University from December 2014 to December 2017. Saliva samples were obtained from healthy volunteers (5 males and 5 females, aged from 40 to 75 years old) and 10 TSCC patients. The TSCC cell lines (CAL-27, Tca-8113 and HN-4) were used. The expression levels of hsa_circ_0000231 in 60 pairs of freshly matched TSCC and para-carcinoma tissue samples, 10 pairs of saliva samples and 3 TSCC cell lines were detected by quantitative real-time polymerase chain reaction (qRT-PCR). hsa_circ_0000231 gene interference and lentiviral transfection were constructed, hsa_circ_0000231 in TSCC cell lines CAL-27 and Tca-8113 was knocked down, and the expressions of hsa_circ_0000231 in hsa_circ_0000231 interference group (sh-circ) and no-load lentivirus group (negative control) were tested with qRT-PCR. Cells with the highest knock-down efficiency were selected for CCK-8 test, colony formation assay, transwell invasion assay and scratch assay. The expressions of EMT-related proteins including E-cadherin, snail protein, N-cadherin and vimentin and proteins related to Wnt/β-catenin signaling pathway including β-catenin, C-myc, Bcl-2, MMP-9 and Cyclin D1 were measured by western blot. After TSCC cells in the interference group were co-cultured with Wnt/β-catenin pathway activator LiCl, the expressions of above proteins were re-measured by western blot. TSCC cells in interference group and control group were subcutaneously injected into nude mice to compare the effect of hsa_circ_0000231 knockdown on the growths of the tumors grafted subcutaneously in the nude mice. Statistical analysis software 25.0 was used for data analysis, and t-test or chi-square test was used for comparison between groups. Results: hsa_circ_0000231 was highly expressed in the tissue and saliva samples of TSCC patients and cell lines CAL-27, Tca-8113 and HN-4, but lowly expressed in paired para-carcinoma tissues, saliva samples of healthy people and normal human oral keratinocytes (all P<0.05). Log-rank univariate analysis showed that hsa_circ_0000231 expression level, tumor differentiation degree and T stage were related to the survival of TSCC patients (all P<0.05). Multivariate Cox risk regression model analysis suggested that hsa_circ_0000231 expression level (χ²=5.77,P=0.016) and T stage (χ²=5.27,P=0.029) were independent factors for the poor prognosis of TSCC patients. Western blot showed the expressions of snail protein, N-cadherin and vimentin were down-regulated, but E-cadherin was up-regulated in interference group compared with control group. In interference group, the expressions of β-catenin, C-myc, Bcl-2, MMP-9 and CyclinD1 were down-regulated, which were reversed after TSCC cells were co-cultured with LiCl. The knockdown of hsa_circ_0000231 reduced the proliferation, invasion and metastasis abilities of CAL-27 and Tca-8113 cells, which were reversed after TSCC cells were co-cultured with LiCl. The growth rate and volume of the tumors grafted subcutaneously in interference group using LiCl were greater than those in negative control group. Conclusion: hsa_circ_0000231 is an independent prognostic factor of TSCC. Highly expressed hsa_circ_0000231 can promote the proliferation, invasion and metastasis of TSCC cells.