Research Papers:

cAMP-mediated autophagy inhibits DNA damage-induced death of leukemia cells independent of p53

Seham Skah, Nina Richartz, Eva Duthil, Karin M. Gilljam, Christian Bindesbøll, Elin Hallan Naderi, Agnete B. Eriksen, Ellen Ruud, Marta M. Dirdal, Anne Simonsen and Heidi Kiil Blomhoff _

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Oncotarget. 2018; 9:30434-30449. https://doi.org/10.18632/oncotarget.25758

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Seham Skah1,*, Nina Richartz1,*, Eva Duthil1, Karin M. Gilljam1, Christian Bindesbøll1, Elin Hallan Naderi2, Agnete B. Eriksen1, Ellen Ruud3,4, Marta M. Dirdal3, Anne Simonsen1,5 and Heidi Kiil Blomhoff1

1Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway

2Department of Oncology, Section for Head and Neck Oncology, Oslo University Hospital, Oslo, Norway

3Department of Hematology and Oncology, Division of Pediatric and Adolescent Medicine, Oslo University Hospital, Oslo, Norway

4Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway

5Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway

*These authors have contributed equally to this work

Correspondence to:

Heidi Kiil Blomhoff, email: [email protected]

Keywords: cAMP-signaling; autophagy; DNA damage; p53; apoptosis

Received: March 14, 2018     Accepted: June 23, 2018     Published: July 13, 2018


Autophagy is important in regulating the balance between cell death and survival, with the tumor suppressor p53 as one of the key components in this interplay. We have previously utilized an in vitro model of the most common form of childhood cancer, B cell precursor acute lymphoblastic leukemia (BCP-ALL), to show that activation of the cAMP signaling pathway inhibits p53-mediated apoptosis in response to DNA damage in both cell lines and primary leukemic cells. The present study reveals that cAMP-mediated survival of BCP-ALL cells exposed to DNA damaging agents, involves a critical and p53-independent enhancement of autophagy. Although autophagy generally is regarded as a survival mechanism, DNA damage-induced apoptosis has been linked both to enhanced and reduced levels of autophagy. Here we show that exposure of BCP-ALL cells to irradiation or cytotoxic drugs triggers autophagy and cell death in a p53-dependent manner. Stimulation of the cAMP signaling pathway further augments autophagy and inhibits the DNA damage-induced cell death concomitant with reduced nuclear levels of p53. Knocking-down the levels of p53 reduced the irradiation-induced autophagy and cell death, but had no effect on the cAMP-mediated autophagy. Moreover, prevention of autophagy by bafilomycin A1 or by the ULK-inhibitor MRT68921, diminished the protecting effect of cAMP signaling on DNA damage-induced cell death. Having previously proposed a role of the cAMP signaling pathway in development and treatment of BCP-ALLs, we here suggest that inhibitors of autophagy may improve current DNA damage-based therapy of BCP-ALL - independent of p53.

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