Cyclin-dependent kinase 4 (CDK4) is a member of cyclin-dependent kinase family which regulates G1 to S cell cycle transition. CDK4 activity is increased in many tumor types. Here, we report a negative automodulatory feedback loop between CDK4 and miR-16 that regulates cell cycle progression in nasopharyngeal carcinoma (NPC). By miRNA array and real-time PCR, we identified upregulation of tumor suppressor miR-16a, which inhibited cell cycle progression and sensitized NPC cells to chemotherapy. CDK4 knockdown reduced the expression of c-Myc, the latter of which directly suppresses the miR-16 expression by directly binding to the miR-16 promoter. Moreover, we found that miR-16 upregulation could reduce CDK4 expression by repressing CCND1 and thus forms a feedback loop via the CDK4/c-Myc/miR-16/CCND1 pathway. Finally, miR-16 was negatively correlated with CDK4 expression in NPC biopsies. In summary, our results define a double-negative feedback loop involving CDK4 and miR-16 mediated by c-Myc that modulates NPC cell growth and chemotherapy sensitivity.
CITATION STYLE
Jiang, Q., Zhang, Y., Zhao, M., Li, Q., Chen, R., Long, X., … Liu, Z. (2016). miR-16 induction after CDK4 knockdown is mediated by c-Myc suppression and inhibits cell growth as well as sensitizes nasopharyngeal carcinoma cells to chemotherapy. Tumor Biology, 37(2), 2425–2433. https://doi.org/10.1007/s13277-015-3966-1
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