miR-34b inhibits nasopharyngeal carcinoma cell proliferation by targeting ubiquitin-specific peptidase 22.

Objectives: This study aimed to investigate the precise role of miR-34b in nasopharyngeal carcinoma (NPC).
Materials and Methods: The expression of miR-34b and transcription of ubiquitin-specific peptidase 22 (USP22) were examined using quantitative reverse transcription-polymerase chain reaction. Western blot analysis was used to measure the protein expression of USP22. A dualluciferase assay was used to investigate the interaction between miR-34b and USP22. Cell viability was determined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. The cell cycle was analyzed by propidium iodide staining followed by flow cytometry analysis.
Results: miR-34b was significantly downregulated in NPC tissues and NPC cell lines. Overexpression of miR-34b in NPC SUNE-6-10B cells inhibited cell viability and proliferation. USP22 was highly expressed in NPC cells and promoted cell viability and proliferation. Restoration of USP22 expression could reverse the effect of miR-34b on NPC cell viability and proliferation.
Conclusion: miR-34b acts as a tumor suppressor in NPC, which is mediated via repression of the oncogene USP22.