CDR1as is overexpressed in laryngeal squamous cell carcinoma to promote the tumour's progression via miR-7 signals.

Objectives: To investigate the roles played by the circular RNA (circRNA) molecule ciRS-7 (CDR1as) and tumour suppressor miRNA-7 (miR-7) in laryngeal squamous cell carcinoma (LSCC).

Methods: Specimens of LSCC tissue (n = 30) and corresponding relative normal tissue (n = 30) were collected to determine their levels and clinical significance of CDR1as/mir-7 expression. The CDR1as and miR-7 were overexpressed in LSCC cells to investigate its function and mechanism in vitro and in vivo.

Results: Patients with high TNM stages, poorly differentiated tumours, lymph node metastases and poor prognosis had high CDR1as levels but low miR-7 levels. CDR1 expression was negatively associated with miR-7 expression in LSCC. Overexpression of CDR1as in vitro enhanced cell vitality, and promoted the proliferation, migration, and invasion of two LSCC cell lines (Hep2 and AMC-HN-8.) However, these effects could be abrogated by knockdown of CDR1as or the forced expression of miR-7. Mechanistically, overexpressed CDR1 molecules functioned as miR-7 sponges and upregulated the key targets of miR-7, CCNE1, and PIK3CD in Hep2 and AMC-HN-8 cells. In vivo studies demonstrated the tumourigenic role of CDR1as. Overexpression of CDR1as alone promoted tumour growth and increased expression of the proliferation indices ki-67, CCNE1, and PIK3CD. Although the tumour suppressor miR-7 effectively inhibited the tumour growth, this effect could be counteracted by co-treatment with CDR1as in vivo.

Conclusion: CDR1as is an oncogene that promotes LSCC progression by regulating miR-7 signals.