CircTPST2 inhibits cisplatin sensitivity in head and neck squamous cell carcinoma by sponging miR-770-5p and interacting with Nucleolin

Abstract

Abstract Background: Head and neck squamous cell cancer (HNSCC) is the most prevalent head and neck malignancy. Chemoresistance is a major challenge in the treatment of advanced HNSCC. Circular RNAs (circRNAs) are essential for the development of cancer and chemoresistance. The role and mechanism of circRNAs in the regulation of HNSCC chemoresistance are much less explored. Methods: CircRNA microarray analysis was used to detect differentially expressed circRNAs in HNSCC. The expression of circTPST2 and miRNAs in HNSCC cells was assessed by qPCR, and the ring structure of circTPST2 was examined using Sanger sequencing, RNase R, and actinomycin D assays. MiR-770-5p and Nucleolin were found to be downstream target molecules of circTPST2 by Western blotting, biotin-labeled RNA pulldown, RNA immunoprecipitation, mass spectrometry, and rescue experiments. Then, the chemoresistance ability of circTPST2, miR-770-5p and Nucleolin was examined through functional tests such as CCK8 assays and flow cytometry assays. FISH assays were performed to determine the location of circTPST2, miR-770-5p, and Nucleolin. IHC staining assays were applied to detect the expression of circTPST2 and Nucleolin in HNSCC patients. Results: The expression level of circTPST2 was negatively related to the cisplatin sensitivity of HNSCC cell lines. Notably, the expression of circTPST2 was negatively correlated with the overall survival rate of chemotherapeutic patients with HNSCC. Mechanistically, circTPST2 could reduce the cisplatin sensitivity of HNSCC cells through sponge-like adsorption of miR-770-5p, and it could also interact with and upregulate the downstream protein Nucleolin to regulate cisplatin sensitivity in HNSCC cells. Finally, according to the analysis of the TCGA database, the prognosis of patients with high miR-770-5p expression is better after chemotherapy. In contrast, according to the analysis of our HNSCC cohorts, the prognosis of patients with low Nucleolin protein expression is better after chemotherapy. Conclusion: Our results identified the chemotherapy resistance-related circRNA circTPST2, indicating that circTPST2 may serve as a promising chemotherapy regimen selection marker in HNSCC.