Inhibiting miR-33b-5p Enhances Chemoresistance in Lung Adenocarcinoma by Targeting YWHAH to Regulate Epithelial-mesenchymal Transition

Background/Aim: Lung adenocarcinoma (LUAD) is the most malignant type of lung cancer, whose clinical treatment is seriously hindered by chemoresistance. Numerous reports have demonstrated that miR-33b-5p plays an essential role in alleviating the chemoresistance of multiple cancers, but there are currently no reports about the effects of miR-33b-5p on the chemoresistance in LUAD. Our study aimed to investigate the impacts of miR-33b-5p on the chemoresistance in LUAD and the underlying mechanism. Materials and Methods: Bioinformatics analyses were employed to investigate the relation between miR-33b-5p and YWHAH. The MTT assay and flow cytometry were respectively adopted to determine cell viability and apoptosis. A transwell assay was employed to evaluate cellular invasion and migration. qRT-PCR and western blotting were respectively employed to detect the gene expression of miR-33b-5p and the protein expression of YWHAH, MMP2, Snail, and Zeb1. Results: Three bioinformatics analysis approaches predicted that YWHAH was the underlying targeted gene of miR-33b-5p and revealed the associated mechanisms. The concentration of paclitaxel (TAX) and cisplatin (DDP) needed to induce chemoresistance of LUAD cells was determined as 100 μM. Migration and invasion, as well as protein expression of YWHAH, MMP2, MMP8, Snail and Zeb1 were increased, but the apoptosis and levels of miR-33b-5p were reduced in A549 cells with chemoresistance. Knockdown of miR-33b-5p exerted the same effects produced by chemoresistance, but additional knockdown of YWHAH reversed the effects generated by inhibiting miR-33b-5p. Conclusion: Our study confirmed that knockdown of miR-33b-5p aggravated chemoresistance in LUAD via targeting YWHAH to regulate EMT.