MiR-34c downregulation leads to SOX4 overexpression and cisplatin resistance in nasopharyngeal carcinoma

BMC Cancer. 2020 Jun 26;20(1):597. doi: 10.1186/s12885-020-07081-z.


Background: A major cause of disease-related death in nasopharyngeal carcinoma (NPC) is the development of distant metastasis (DM) despite combination chemoradiotherapy treatment. We previously identified and validated a four microRNA (miRNA) signature that is prognostic for DM. In this study, characterization of a key component of this signature, miR-34c, revealed its role in chemotherapy resistance.

Methods: Two hundred forty-six NPC patient biopsy samples were subject to comprehensive miRNA profiling and immunohistochemistry (IHC). Two human normal nasopharyngeal cell lines (immortalized; NP69 and NP460), as well as the NPC cell line C666-1, were used for miR-34c gain-of-function and loss-of-function experiments. Signaling pathways were assessed using quantitative real-time PCR (qRT-PCR) and Western blot. Cell viability was measured using the ATPlite assay.

Results: MiR-34c was downregulated in NPC patient samples, and confirmed in vitro to directly target SOX4, a master regulator of epithelial-to-mesenchymal transition (EMT). MiR-34c downregulation triggered EMT-representative changes in NP69 and NP460 whereby Snail, ZEB1, CDH2, and SOX2 were upregulated, while Claudin-1 and CDH1 were downregulated. Phenotypically, inhibition of miR-34c led to cisplatin resistance, whereas miR-34c over-expression sensitized NPC cells to cisplatin. TGFβ1 decreased miR-34c and increased SOX4 expression in vitro. The TGFβ receptor 1 inhibitor SB431542 reduced SOX4 expression and increased cisplatin sensitivity. Finally, IHC revealed that lower SOX4 expression was associated with improved overall survival in chemotherapy-treated NPC patients.

Conclusion: miR-34c is downregulated in NPC. Repression of miR-34c was shown to increase SOX4 expression, which leads to cisplatin resistance, while TGFβ1 was found to repress miR-34c expression. Taken together, our study demonstrates that inhibition of the TGFβ1 pathway could be a strategy to restore cisplatin sensitivity in NPC.

Keywords: Cisplatin; EMT; Nasopharyngeal cancer; SOX4; TGFβ1; miR-34c.

MeSH terms

  • Benzamides / pharmacology
  • Biopsy
  • Cell Line, Tumor
  • Cisplatin / pharmacology*
  • Cisplatin / therapeutic use
  • Dioxoles / pharmacology
  • Down-Regulation
  • Drug Resistance, Neoplasm / drug effects
  • Drug Resistance, Neoplasm / genetics*
  • Epithelial-Mesenchymal Transition / genetics
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Nasopharyngeal Carcinoma / drug therapy*
  • Nasopharyngeal Carcinoma / genetics
  • Nasopharyngeal Carcinoma / mortality
  • Nasopharyngeal Carcinoma / pathology
  • Nasopharyngeal Neoplasms / drug therapy*
  • Nasopharyngeal Neoplasms / genetics
  • Nasopharyngeal Neoplasms / mortality
  • Nasopharyngeal Neoplasms / pathology
  • Nasopharynx / pathology
  • RNA-Seq
  • SOXC Transcription Factors / genetics*
  • Transforming Growth Factor beta1 / antagonists & inhibitors
  • Transforming Growth Factor beta1 / metabolism*


  • 4-(5-benzo(1,3)dioxol-5-yl-4-pyridin-2-yl-1H-imidazol-2-yl)benzamide
  • Benzamides
  • Dioxoles
  • MIRN34 microRNA, human
  • MicroRNAs
  • SOX4 protein, human
  • SOXC Transcription Factors
  • TGFB1 protein, human
  • Transforming Growth Factor beta1
  • Cisplatin