LncRNA PVT1 Confers Cisplatin Resistance of Esophageal Cancer Cells through Modulating the miR-181a-5p-Glutaminase (GLS) Axis

Esophageal carcinoma (ESCA) is one of the prevalent malignancies worldwide. Cisplatin (CDDP) is a conventional chemotherapy drug. However, the acquired cisplatin resistance limits its extensively clinical applications. In this study, the roles and underlying mechanisms of lncRNA PVT1 in cisplatin-resistant ESCA are investigated. PVT1 was significantly upregulated in ESCA patient specimens and cell lines. Higher PVT1 level was associated with a poor survival rate of ESCA patients. Silencing PVT1 effectively increased cisplatin sensitivity of ESCA cells. We established cisplatin-resistant ESCA cell line (EC109 CDDP Res) and detected that PVT1 and glutamine metabolism were remarkedly elevated in CDDP-resistant esophageal cancer cells. Bioinformatical analysis and luciferase assay illustrated that PVT1 sponged miR-181a-5p to form a ceRNA network, resulting in the downregulation of miR-181a-5p expression in ESCA cells. Glutaminase (GLS), which is a key enzyme in the glutamine metabolism, was identified and validated as a direct target of miR-181-5p in ESCA cells. Inhibiting glutamine metabolism effectively re-sensitized CDDP-resistant cells. Rescue experiments demonstrated that restoration of miR-181a-5p in PVT1-overexpressing CDDP-resistant ESCA cells successfully overcame the PVT1-promoted cisplatin resistance through targeting GLS. Summarily, our study revealed molecular mechanisms of the lncRNA PVT1-promoted cisplatin resistance in ESCA by modulating the miR-181a-5p-GLS axis.