FOXM1 plays a role in autophagy by transcriptionally regulating Beclin-1 and LC3 genes in human triple-negative breast cancer cells
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Triple-negative breast cancer (TNBC) is associated with poor prognosis owing to its aggressive and heterogeneous nature, and the lack of therapeutic targets. Although Forkhead Box M1 (FOXM1) is one of the most important oncogenes contributing to tumorigenesis, progression, and drug resistance in TNBC, the underlying molecular mechanisms are not well understood. Emerging evidence indicates that autophagy plays a critical role in cell survival and protective mechanism in TNBC. However, signaling pathways that are involved in the regulation of autophagy remain to be elucidated. In the present study, we examined the role of FOXM1 in regulating autophagy in TNBC cells and found that FOXM1 is upregulated during induction of autophagy. We found that inhibition of FOXM1 suppressed starvation and rapamycin-induced autophagy and expression of the major autophagy regulators, LC3 and Beclin-1. Further studies demonstrated that FOXM1 directly binds to the promotors of LC3 and Beclin-1 genes and transcriptionally regulates their expression by chromatin immunoprecipitation (ChIP) and luciferase gene reporter assays. In conclusion, our study provides the first evidence about the role of FOXM1 in regulating expression of LC3 and Beclin-1 and autophagy in TNBC cells. Our findings provide novel insight into the role of FOXM1 regulation of the autophagic survival pathway and potential molecular target for treating TNBC.
• FOXM1 promotes tumorigenesis and progression of TNBC. However, the underlying molecular mechanism by which FOXM1 promotes TNBC tumorigenesis is unclear. The goal of our study was to determine the role of FOXM1 in the regulation of autophagy that plays a role in TNBC progression. Our findings show that FOXM1 binds to promoters of the genes encoding the major autophagy proteins, Beclin and LC3, and provide new insights into the regulation of autophagy, which is being targeted in many clinical trials.
KeywordsAutophagy Beclin-1 FOXM1 LC3 Triple-negative breast cancer
Triple-negative breast cancer
Forkhead Box M1
Microtubule-associated light chain 3
Human epidermal growth factor receptor 2
Eukaryotic elongation factor 2 kinase
Reverse transcriptase and polymerase chain reaction
Acidic vesicular organelles
Small interfering RNAs
Tris-buffered saline–Tween 20
This study was funded by The Scientific and Technological Research Council –TÜBİTAK- research grant (grant number 214S204) and Research Fund of the Erciyes University (Project number: TDA-2016-6415).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflicts of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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