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Inhibition of microRNA-21 increases radiosensitivity of esophageal cancer cells through phosphatase and tensin homolog deleted on chromosome 10 activation

Authors

  • S. Huang,

    1. Department of Radiation Oncology, First Affiliated Hospital, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi, China
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  • X-Q. Li,

    1. Department of Radiation Oncology, First Affiliated Hospital, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi, China
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  • Xin Chen,

    1. Department of Radiation Oncology, First Affiliated Hospital, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi, China
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  • S-M. Che,

    1. Department of Radiation Oncology, First Affiliated Hospital, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi, China
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  • W. Chen,

    1. Center for Molecular Medicine, First Affiliated Hospital, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi, China
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  • X-Z. Zhang

    Corresponding author
    1. Department of Radiation Oncology, First Affiliated Hospital, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi, China
    • Professor Xiao-Zhi Zhang, MD, PhD, Department of Radiation Oncology, First Affiliated Hospital, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, China. Email: zhang9149@163.com

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  • Authors' Contributions: Designing the study: Shan Huang, Xiao-Zhi Zhang; Collecting, analyzing, and interpreting the data: Shan Huang, Xiao-Qing Li, Xin Chen, Wei Chen; Writing the report: Shan Huang, Shao-Min Che; Making the decision to submit for publication: Shan Huang, Xiao-Zhi Zhang.

SUMMARY

The radioresistance of esophageal squamous cell carcinoma is a great obstacle to treatment. Although it has been demonstrated that microRNA-21 (miR-21) can act as an ‘oncogene’ in esophageal squamous cell carcinoma, its role in radioresistance remains unexplored. The aims of this study were to investigate the role of miR-21 in esophageal squamous carcinoma cells' radioresistance and to identify the possible mechanism. The relatively radioresistant esophageal squamous cancer TE-1 cells (TE-R60) was established by fractionated irradiation. By lentiviral transduction with miRZip-21, the miR-21 expression in TE-1 cells was stably downregulated, which was renamed as ‘anti-miR-21 TE-1 cells.’ The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) was knocked down in anti-miR-21 TE-1 cells through short interfering RNA. The expression level of miR-21 and PTEN messenger RNA were measured by quantitative real-time reverse transcription polymerase chain reaction or reverse transcription polymerase chain reaction. The expression level of PTEN, phospho-Akt, and Akt protein were detected by Western blot. Clongenic assay was used to analyze the cells' radiosensitivity. miR-21 was overexpressed, and PTEN was suppressed in established radioresistant TE-R60 cells compared with the parent cells (1.3-fold and 70.83%). The inhibition of miR-21 significantly increased the cells' radiosensitivity (P < 0.05) and the PTEN protein expression (2.3-fold) in TE-1 cells. In addition, phospho-Akt protein, downstream target of PTEN, reduced significantly in anti-miR-21 TE-1 cells. Knockdown of PTEN in anti-miR-21 TE-1 cells could abrogate the miR-21 inhibition-induced radiosensitization (P < 0.05). Inhibition of miR-21 increased radiosensitivity of esophageal cancer TE-1 cells, and this effect was possibly through the activation of PTEN. Inhibition of miR-21 may form a novel therapeutic strategy to increase the radiosensitivity of esophageal cancer.

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