, Volume 44, Issue 2, pp 103–113 | Cite as

The Antiproliferative Effect of EPA in HL60 Cells is Mediated by Alterations in Calcium Homeostasis

  • Jens Erik Slagsvold
  • Caroline Hild Hakvåg Pettersen
  • Turid Follestad
  • Hans Einar Krokan
  • Svanhild Arentz Schønberg
Original Article


Studies show that n-3 polyunsaturated fatty acids (PUFA) inhibit proliferation and induce apoptosis in cancer cells. Recent reports indicate that this effect is due to activation of the unfolded protein response (UPR). However, what causes this activation has been unclear. We examined the effects of eicosapentaenoic acid (EPA) on the human leukemia cell line HL60 and the econazole (Ec) resistant HL60 clone E2R2. Ec depletes Ca2+ from the ER and blocks Ca2+ influx in mammalian cells, leading to activation of the UPR and apoptosis. EPA inhibited growth of HL60 cells strongly, while E2R2 cells were much less affected. Gene expression analysis of HL60 cells revealed extensive changes in transcripts related to the ER homeostasis, Ca2+-homeostasis and cell cycle/apoptosis. Protein levels of phosphorylated eIF2α, a selective translation inhibitor and UPR hallmark, activating transcription factor 4 (ATF4) and sequestosome-1 were moderately increased, whereas the cell cycle/progression protein cyclin D1 was decreased in HL60. In contrast, EPA concentrations that strongly inhibited and caused activation of the UPR in HL60 cells had no effect on the expression level of these UPR markers in E2R2 cells. Given that the only known difference between these cells is Ec-resistance, our results strongly suggest that the inhibitory effect of EPA on HL60 cells is initially meditated through alterations of the Ca2+-homeostasis followed by activation of the UPR.


Cancer E2R2 Econazole-resistant EPA HL60 UPR PUFA 


ATF3, ATF4 and ATF6

Activating transcription factor 3, 4 and 6


Growth arrest- and DNA damage-inducible gene 153/C/EBP-homologous protein (CHOP/Gadd153)




Eicosapentaenoic acid (20:5n-3)


Endoplasmic reticulum


ER-associated degradation


Eukaryote translation initiation factor 2α


eIF2α kinase 3


Heme oxygenase (decycling) 1


Inositol 1,4,5-triphosphate


Polyunsaturated fatty acids




Store-operated Ca2+ channels


Unfolded protein response



We thank Professor Stuart A. Berger, University Health Network, Toronto, Canada, for kindly providing the E2R2 cells. Thanks to Gro Leite Størvold, Hilde Bremseth, Anne Gøril Lundemo for technical assistance and Professor Kristian S. Bjerve for good support. The project was financed by The Faculty of Medicine, NTNU, The Cancer Research Fund, Trondheim University Hospital and The Research Council of Norway through grants from the Functional Genomics Program (FUGE). Microarray experiments were performed at the microarray core facility at the Norwegian Microarray Consortium (NMC), Trondheim, which is supported by FUGE, The Norwegian Research Council. Financial support was also given by the cross-disciplinary project “BIOEMIT-Prediction and modification in functional genomics: combining bioinformatical, bioethical, biomedical and biotechnological research”, NTNU.


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Copyright information

© AOCS 2008

Authors and Affiliations

  • Jens Erik Slagsvold
    • 1
  • Caroline Hild Hakvåg Pettersen
    • 1
  • Turid Follestad
    • 2
  • Hans Einar Krokan
    • 3
  • Svanhild Arentz Schønberg
    • 1
    • 4
  1. 1.Department of Laboratory Medicine, Children’s and Women’s HealthNorwegian University of Science and Technology (NTNU)TrondheimNorway
  2. 2.Department of Mathematical SciencesNorwegian University of Science and Technology (NTNU)TrondheimNorway
  3. 3.Department of Cancer Research and Molecular MedicineNorwegian University of Science and Technology (NTNU)TrondheimNorway
  4. 4.Department of Laboratory Medicine, Children’s and Women’s HealthNorwegian University of Science and Technology, St Olav’s HospitalTrondheimNorway

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