Mechanism Of TRIM22 Regulating Radiotherapy Sensitivity For Head And Neck Squamous Cell Carcinoma

Objective: Studies have shown that Tripartite Motif Protein 22(TRIM22)is a positive cofactor for NF-κB-mediated transcription,which plays an important role in various tumors.However,its role in head and neck squamous cell carcinoma(HNSCC)has not been reported.Previous studies from our group have shown that TRIM22 is involved in the regulation of p53 pathway and is associated with radiosensitivity.In this study,clone formation,cell cycle and apoptosis assays were used to determine the regulation of Trim22 on radiosensitivity of head and neck squamous cell carcinoma and its underlying mechanism.Methods: Differential expression of TRIM22 in paraneoplastic and carcinoma tissues in HNSCC was analyzed by TCGA database and verified by Western Blot and qRT-PCR on head and neck squamous carcinoma and paraneoplastic tissues.A head and neck squamous carcinoma Fadu cell line was constructed as a radioresistant line and TRIM22 protein expression was detected by Western Blot assay.TRIM22 expression was inhibited by silencing of small interfering RNA in head and neck squamous carcinoma cell lines,and the transfection efficiency was verified by qRT-PCR assay;different doses(0,2,4,6 and 8Gy)of 6MV-X ray were taken to irradiate head and neck squamous carcinoma Fadu cell lines and the silenced cells,and the effect on the sensitivity to radiotherapy was investigated by plate cloning assay;flow cytometry was applied to cell cycle and apoptosis;and the expression of autophagy-related proteins was detected by immunoblotting assay.Results: The results of differential gene analysis in TCGA database and gene and protein expression assays in clinical histological samples showed that TRIM22 was highly expressed in HNSCC cancer tissues.The results of Western Blot and qRT-PCR showed that TRIM22 protein and mRNA levels were significantly higher in radioresistant cells than in parental cells.Clonogenic assays showed that silencing TRIM22 increased the radiosensitivity of HNSCC and was more pronounced in the resistant cell line FaduR.Western Blot showed that both TRIM22 silencing and radiotherapy activated autophagy-related proteins,and an increase in the LC3Ⅱ/LC3 Ⅰ protein ratio was observed,suggesting that TRIM22 silencing and radiotherapy synergistically induced autophagy in HNSCC.Conclusions: Silencing of TRIM22 increases the sensitivity of HNSCC to radiotherapy and its mechanism of action is associated with induction of cell cycle arrest,increased apoptosis and activation of cellular autophagy.TRIM22 has potential value as a therapeutic target to increase the sensitivity of HNSCC patients to radiotherapy and improve the efficacy of radiotherapy.