Knockdown of NUPR1 Enhances the Sensitivity of Non-small-cell Lung Cancer Cells to Metformin by AKT Inhibition

Abstract

Background/aim: Metformin is a widely used drug for type 2 diabetes mellitus and has recently attracted broad attention for its therapeutic effects on many cancers. This study aimed to investigate the molecular mechanism of metformin's anticancer activity.

Materials and methods: Cell viability was measured by MTT assay. Gene and protein expression levels were determined by reverse transcription-polymerase chain reaction and western blot analyses, respectively.

Results: Metformin and phenformin markedly induced NUPR1 expression in a dose- and time-dependent manner in H1299 non-small-cell lung cancer (NSCLC) cells. The silencing of NUPR1 in H1299 NSCLC cells enhanced cell sensitivity to metformin or ionizing radiation. Our previous report showed that metformin induces AKT serine/threonine kinase (AKT) activation in an activating transcription factor 4 (ATF4)-dependent manner and that the inhibition of AKT promotes cell sensitivity to metformin in H1299 NSCLC cells. Interestingly, ATF4-induced AKT activation in H1299 NSCLC cells treated with metformin was suppressed by the knockdown of NUPR1.

Conclusion: Targeting NUPR1 could enhance the sensitivity of H1299 NSCLC cells to metformin by AKT inhibition.

Keywords: AKT; ATF4; Metformin; NUPR1; non-small-cell lung cancer.