Hypoxic tumour cell-derived exosomal miR-340-5p promotes radioresistance of oesophageal squamous cell carcinoma via KLF10

Abstract

Background Radiotherapy resistance is a major obstacle in the treatment of oesophageal squamous cell carcinoma (OSCC). Hypoxia is a critical cause of radioresistance. However, the communication between hypoxic cells and aerobic cells via exosomes during the transfer of radiation resistance remains unclear. Methods Exo-miR-340-5p levels were analysed by RNA-seq and qRT-PCR. We co-cultured OSCC cells with isolated normoxic and hypoxic exosomes to study their impact on radiosensitivity. We used a specific exo-miR-340-5p mimic and knock-down retrovirus to explore the role of this miRNA in the transfer of radioresistance from hypoxic to normoxic cells. Dual-luciferase reporter and RIP assays were used to verify KLF10 as a putative target of miR-340-5p. Several in vitro assays were conducted and xenograft models were established to investigate the effect of exo-miR-340-5p on OSCC radiosensitivity. The plasma exo-miR-340-5p levels in OSCC patients were analysed to study the clinical value of this parameter. Results Hypoxic exosomes alleviated radiation-induced apoptosis and accelerated DNA damage repair. miR-340-5p was highly expressed in hypoxic exosomes and was transferred into normoxic cells, where it induced radioresistance. Overexpression of miR-340-5p in normoxic OSCC cells mimicked the radioresistance of cells co-cultured with hypoxic exosomes. Knockdown of miR-340-5p in hypoxic exosomes reversed the radioresistance effect, indicating that exo-miR-340-5p is critical for hypoxic EV-transferred radioresistance. KLF10 was identified as the direct target of miR-340-5p. Moreover, metformin was found to increase the expression of KLF10 and enhance the radiosensitivity of OSCC. Higher levels of miR-340-5p in the plasma exosomes from OSCC patients are related to a poorer radiotherapy response and prognosis. Conclusions Hypoxic tumour cell-derived exosomal miR-340-5p confers radioresistance in OSCC by targeting KLF10/UVRAG, suggesting that miR-340-5p could be a potential biomarker and therapeutic target for the enhancement of radiosensitivity in OSCC. Metformin can increase KLF10 expression, which ameliorates the radioresistance induced by exo-miR-340-5p transfer. Therefore, metformin could be further investigated as a therapeutic option for the treatment of OSCC.

DCTPP1, an Oncogene Regulated by miR-378a-3p, Promotes Proliferation of Breast Cancer via DNA Repair Signaling Pathway

“…γH2A is an established marker of DNA damage ( 23 ). Relative to mock-silenced cells, DCTPP1-deficient induced BRCA cells had significantly higher γH2A levels ( Figure 5B ).…”

A Radioresponse-Related lncRNA Biomarker Signature for Risk Classification and Prognosis Prediction in Non-Small-Cell Lung Cancer

“…Then, cultured for 2 weeks later, 1% crystal violet was applied in staining clonogenic cells. The clonogenic survival curves were generated according to the following formula model: SF = 1 − (1 − e −kd ) n as previously described [ 17 ].…”

“…The immunofluorescence of γ H2AX was detected by the anti- γ H2AX primary antibody (1 : 500, Abcam, UK) and the detailed process was described in the previous protocol [ 17 ]. Cells were snapped under a confocal fluorescence microscope (Leica).…”

The Significance of Exosomes in Pathogenesis, Diagnosis, and Treatment of Esophageal Cancer

“… 40 Recently, it has been shown that hypoxic tumor cell-derived exosomal miR-340-5p conferred radioresistance in ESCC by targeting kruppel-like factor 10 (KLF10)/UV radiation resistance-associated gene protein (UVRAG). 57 The level of miR-340-5p in the plasma exosomes was closely related to radiotherapy response and prognosis. miR-340-5p might be a therapeutic target for overcoming radioresistance in ESCC.…”

“… 70 In addition, circulatory exosomal miR-340-5p and miR-339-5p might be promising biomarkers for prediction of radiotherapy response and prognosis in patients with ESCC. 57 , 58 Exosomal miRNAs will have great potential application in tumor individualized treatment.…”