miR‐195‐5p inhibits cisplatin resistance in lung adenocarcinoma by regulating DNA damage via targeting E2F7

Lung adenocarcinoma (LUAD) emerges as one of the most lethal malignant tumors worldwide. Platinum-based combination chemotherapy remains one of the main methods for patients with advanced LUAD. Due to the resistance, the effect of this chemotherapy was not satisfactory. Therefore, studying the mechanism of cisplatin (DDP) resistance is essential for promoting the effect of this therapeutic strategy. Therefore, this work sought to probe the impact of E2F Transcription Factor 7 (E2F7) on LUAD resistance and the molecular regulatory mechanism. The mRNA expression level of the target gene E2F7 in LUAD was predicted by bioinformatics analysis, and regulatory miRNA upstream of the target gene was identified. The mRNA and protein expression of E2F7 in LUAD cells was detected through quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and Western blot, respectively. The expression of miR-195-5p in LUAD cells was measured via qRT-PCR. E2F7 high and low expression groups underwent enrichment analysis by utilizing Gene Set Enrichment Analysis software. The targeting relationship of miR-195-5p and E2F7 was validated by conducting a dual-luciferase reporter assay. The cell viability was tested through cell counting kit-8. The cell cycle was examined by flow cytometry. DNA damage level was determined via Comet assay and Western blot assay. The findings indicated that the mRNA and protein levels of E2F7 were high in LUAD. MiR-195-5p was the regulatory miRNA upstream of E2F7, and lowly expressed in LUAD. The cell experiments suggested that E2F7 advanced the DDP resistance of LUAD cells by repressing DNA damage. Finally, the rescue assay manifested that miR-195-5p overexpression could abate inhibition of E2F7 overexpression on the DNA damage and the DDP sensitivity of LUAD cells. MiR-195-5p raised the DDP sensitivity of LUAD cells by advancing the DNA damage in LUAD cells via inhibition of E2F7.