[MiR-1-3p inhibits mitophagy in esophageal squamous cell carcinoma by targeting SLC7A11].

Objective

To investigate the effect of miR-1-3p on mitophagy in human esophageal squamous cell carcinoma (ESCC) cells and the related mechanisms.

Methods

The differentially expressed miRNAs in ESCC were screened using the GEO database. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to measure miR-1-3p expression in normal esophageal epithelial cells (HET-1A) and ESCC cell lines (TE1, KYSE30, KYSE150, KYSE410, Eca109). Bioinformatics tools were utilized to predict target genes of miR-1-3p, subcellular localization was confirmed by fluorescence in situ hybridization. The targeting relationship between miR-1-3p and SLC7A11 was validated using dual-luciferase reporter assay. Cell proliferation and apoptosis were detected by CCK8 assay and flow cytometry, respectively. Furthermore, experimental validation demonstrated that overexpression of SLC7A11 rescued the presence of the miR-1-3p/SLC7A11 axis. Confocal microscopy was used to detect changes in mitochondrial autophagic lysosomes, while transmission electron microscopy was employed to observe mitophagy and morphological alterations. Western blot was conducted to evaluate the expression of autophagy-related proteins LC3 and P62. Flow cytometry was used to measure mitochondrial membrane potential and reactive oxygen species (ROS). Immunohistochemistry was applied to assess SLC7A11 expression in 133 ESCC patient tissues and 115 normal esophageal epithelial tissues. The correlation between SLC7A11 expression level and clinicopathological features was analyzed. Survival analysis was performed using the Kaplan-Meier method, and Cox proportional hazard regression models were used for multivariate analysis.

Results

The expression of miR-1-3p in ESCC cells was significantly lower than that in HET-1A cells (P＜0.05). SLC7A11 was a target gene of miR-1-3p. Transfection of miR-1-3p mimic inhibited the proliferation of ESCC cells. CCK-8 assay results showed that the proliferative capacity of KYSE30 and KYSE410 cells in the miR-1-3p mimic group (absorbance values: 2.88±0.24 and 2.88±0.18, respectively) was significantly lower than that in the miRNA mimic negative control (NC) group (3.94±0.27, P＜0.001; 4.20±0.21, P＜0.001). Meanwhile, the proliferative capacity of KYSE30 and KYSE410 cells in the miR-1-3p mimic+SLC7A11-overexpression (OE) group (absorbance values: 3.57±0.15 and 3.60±0.13, respectively) was significantly higher than that in the miR-1-3p mimic +empty vector (EV) group (2.54±0.10, P＜0.001, 2.36±0.16, P＜0.001). Additionally, transfection of miR-1-3p mimic promoted apoptosis. Flow cytometry results demonstrated that the apoptosis rates of KYSE30 and KYSE410 cells in the miR-1-3p mimic group [(9.22±0.05)% and (6.55±0.37)%, respectively] were significantly higher than those in the miRNA mimic NC group [(0.81±0.17)%,P＜0.001); (1.04±0.12)%, P＜0.001]. Conversely, the apoptosis rates of KYSE30 and KYSE410 cells in the miR-1-3p mimic + SLC7A11-OE group [(0.73±0.04)% and (1.19±0.05)%, respectively] were significantly lower than those in the miR-1-3p mimic+EV group [(9.83±0.41)%, P＜0.001); (6.09±0.17)%, P＜0.00)]. MiR-1-3p mimic downregulated SLC7A11 protein expression and the LC3Ⅱ/LC3I ratio (P＜0.05), upregulated P62 protein expression (P＜0.05), this phenomenon can be rescued by overexpressing SLC7A11 (P＜0.05). Additionally, miR-1-3p mimic increased ROS levels and decreased mitochondrial membrane potential (JC-1 aggregate/monomer ratio), this phenomenon can be rescued by overexpressing SLC7A11 (P＜0.05). SLC7A11 expression was higher in ESCC tissues compared to normal esophageal epithelial tissues (P＜0.001), and SLC7A11 serves as an independent prognostic factor in ESCC (HR=2.15, 95% CI: 1.27-3.65, P=0.004).

Conclusion

miR-1-3p inhibits mitophagy in esophageal squamous cell carcinoma by targeting SLC7A11.