Long non-coding RNA TP73-AS1 facilitates progression and radioresistance in lung cancer cells by the miR-216a-5p/CUL4B axis with exosome involvement

Lung Cancer

Thorac Cancer. 2020 Aug 25. doi: 10.1111/1759-7714.13602. Online ahead of print.


BACKGROUND: Exosomes have significant implications in cancer progression via transferring various modulatory molecules. Long non-coding RNAs (lncRNAs) play essential biological roles in lung cancer. In this report, we unlock the functional mechanism of tumor protein P73 antisense RNA 1 (TP73-AS1) in lung cancer.

METHODS: The expression analyses of TP73-AS1, microRNA-216a-5p (miR-216a-5p) and Cullin 4B (CUL4B) were performed by quantitative real-time polymerase chain reaction (qRT-PCR). Cell migration and invasion were assessed using wound healing and transwell assays. Flow cytometry was applied to determine cell apoptosis. Colony formation assay was performed for cell survival to evaluate the effect on radiosensitivity. The intergenic interaction was analyzed by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Western blot was used for associated protein determination. An in vivo experiment was conducted by establishing xenograft models in mice.

RESULTS: TP73-AS1 was conspicuously overexpressed in lung cancer tissues and cells. Silencing TP73-AS1 restrained cell migration and invasion while it enhanced apoptosis and radiosensitivity of lung cancer. TP73-AS1 could bind to miR-216a-5p as well as miR-216a-5p and CUL4B. The function of TP73-AS1 downregulation in lung cancer was achieved by miR-216a-5p/CUL4B axis. Inhibition of TP73-AS1 also exerted an inhibitory effect on tumor growth and radioresistance in vivo potentially via regulating miR-216a-5p/CUL4B axis. Moreover, exosomes from lung cancer cells downregulated TP73-AS1 could repress tumor evolution and radioresistance.

CONCLUSIONS: Collectively, TP73-AS1 acted as a sponge of miR-216a-5p to regulate CUL4B in order to promote tumor progression and radioresistance in lung cancer cells with the implication of exosomes, which presents a novel mechanism of tumor action and radioresistance in lung cancer.

KEY POINTS: SIGNIFICANT FINDINGS OF THE STUDY: TP73-AS1 silence inhibits migration and invasion while elevates apoptosis and radiosensitivity in lung cancer cells TP73-AS1 targets miR-216a-5p and miR-216a-5p targets CUL4B WHAT THIS STUDY ADDS: Downregulation of TP73-AS1 reduces tumor growth and radioresistance in vivo via the miR-216a-5p/CUL4B axis Exosomes from si-TP73-AS1-transfected cells inhibits lung cancer progression and radioresistance.