Downregulation of SOX21-AS1 Alleviated Cisplatin Resistance in Cervical Cancer Through Epithelial-Mesenchymal Transition Inhibition.

Cisplatin is widely used in chemotherapies in cervical cancer (CC). Nevertheless, drug resistance in cancer patients poses a major threat to efficacy of treatment. To explore the underlying modulatory mechanism of SOX21-AS1 in cisplatin resistance in CC cell and mice models, Gepia database was referred for SOX21-AS1 expression in cancer tissues and normal ones. Reverse transcription quantitative real-time polymerase chain reaction was used to measure the differential expression of SOX21-AS1 in parental Siha cells and cisplatin-resistant Siha/DDP cells. Luciferase reporter gene assays were conducted to verify putative bindings between SOX21-AS1 and miR-9-3p. Western blot method was employed to evaluate the changes in cleaved-caspase 7 protein expression. Cisplatin resistance was evaluated in each transfected group using cell counting kit 8 method after cells were exposed to cisplatin (0, 7.5, 15, 30, 60, 120, and 240 μg/mL) for 24 hours. Flow cytometry method was used to measure the apoptosis rates. Cell migration and invasion were measured using Transwell assays. Immunofluorescence method was applied to observe epithelial to mesenchymal transition (EMT) markers, including E-cadherin, Snail, matrix metalloproteinase (MMP)3, and MMP9. Siha/DDP cell groups stably transfected with sh-NC and sh-SOX21-AS1 were injected through tail vein of Balb/C mice. Lung tissue sections were used for hematoxylin and eosin staining and immunohistochemistry analysis. SOX1-AS1 expression was higher in cancer tissues than normal ones and was also higher in Siha/DDP rather than Siha cells. SOX21-AS1 was targeted by miR-9-3p in CC cells. Downregulation of SOX21-AS1 or overexpression of miR-9-3p inhibited cisplatin resistance in Siha/DDP cells and reduced cell invasion and migration and attenuated EMT progression. In vivo, the SOX21-AS1 knockdown led to less severe lung metastasis. Downregulation of SOX21-AS1 alleviated cisplatin resistance in CC through EMT inhibition.