Triapine and a more potent dimethyl derivative induce endoplasmic reticulum stress in cancer cells

Robert Trondl, Lea S. Flocke, Christian R. Kowol, Petra Heffeter, Ute Jungwirth, Georg E. Mair, Ralf Steinborn, E. Enyedy, Michael A. Jakupec, Walter Berger, Bernhard K. Keppler

Research output: Contribution to journalArticle

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Abstract

Triapine (3-AP; 3-aminopyridine-2-carboxaldehyde thiosemicarbazone), a ribonucleotide reductase inhibitor, has been extensively evaluated in clinical trials in the last decade. This study addresses the role of endoplasmic reticulum (ER) stress in the anticancer activity of 3-AP and the derivative N4,N4-dimethyltriapine (3-AP-Me), differing from 3-AP only by dimethylation of the terminal nitrogen. Treatment of colon cancer cells with 3-AP or 3-AP-Me activated all three ER stress pathways (PERK, IRE1a, ATF6) by phosphorylation of eIF2a and upregulation of gene expression of activating transcription factors ATF4 and ATF6. In particular, 3-AP-Me led to an upregulation of the alternatively spliced mRNA variant XBP1 (16-fold). Moreover, 3-AP and 3-AP-Me activated the cellular stress kinases c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinases, and inhibition of JNK activity antagonized the cytotoxic effect of both compounds. Subsequent to induction of the unfolded protein response, a significant upregulation of proapoptotic proteins was detected, including the transcription factor CHOP and Bim, an essential factor for ER stress-related apoptosis. In correlation with the higher degree of ER stress after 3-AP-Me treatment, also a more potent depolarization of mitochondrial membranes was found. These data suggest that 3-AP and 3-AP-Me induce apoptosis via ER stress. This was further corroborated by showing that inhibition of protein biosynthesis with cycloheximide prior to 3-AP and 3-AP-Me treatment leads to a significant reduction of the antiproliferative properties of both compounds. Taken together, this study demonstrates that induction of ER stress contributes to the mode of action of 3-AP and that terminal dimethylation leads to an even more pronounced manifestation of this effect.

Original languageEnglish
Pages (from-to)451-459
Number of pages9
JournalMolecular Pharmacology
Volume85
Issue number3
DOIs
Publication statusPublished - Mar 2014

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Endoplasmic Reticulum Stress
Neoplasms
Up-Regulation
Phosphotransferases
Transcription Factor CHOP
Activating Transcription Factors
Apoptosis
Ribonucleotide Reductases
Unfolded Protein Response
JNK Mitogen-Activated Protein Kinases
Mitochondrial Membranes
Protein Biosynthesis
p38 Mitogen-Activated Protein Kinases
Cycloheximide
Colonic Neoplasms
3-aminopyridine-2-carboxaldehyde thiosemicarbazone
Nitrogen
Phosphorylation
Clinical Trials
Gene Expression

ASJC Scopus subject areas

  • Pharmacology
  • Molecular Medicine

Cite this

Trondl, R., Flocke, L. S., Kowol, C. R., Heffeter, P., Jungwirth, U., Mair, G. E., ... Keppler, B. K. (2014). Triapine and a more potent dimethyl derivative induce endoplasmic reticulum stress in cancer cells. Molecular Pharmacology, 85(3), 451-459. https://doi.org/10.1124/mol.113.090605

Triapine and a more potent dimethyl derivative induce endoplasmic reticulum stress in cancer cells. / Trondl, Robert; Flocke, Lea S.; Kowol, Christian R.; Heffeter, Petra; Jungwirth, Ute; Mair, Georg E.; Steinborn, Ralf; Enyedy, E.; Jakupec, Michael A.; Berger, Walter; Keppler, Bernhard K.

In: Molecular Pharmacology, Vol. 85, No. 3, 03.2014, p. 451-459.

Research output: Contribution to journalArticle

Trondl, R, Flocke, LS, Kowol, CR, Heffeter, P, Jungwirth, U, Mair, GE, Steinborn, R, Enyedy, E, Jakupec, MA, Berger, W & Keppler, BK 2014, 'Triapine and a more potent dimethyl derivative induce endoplasmic reticulum stress in cancer cells', Molecular Pharmacology, vol. 85, no. 3, pp. 451-459. https://doi.org/10.1124/mol.113.090605
Trondl, Robert ; Flocke, Lea S. ; Kowol, Christian R. ; Heffeter, Petra ; Jungwirth, Ute ; Mair, Georg E. ; Steinborn, Ralf ; Enyedy, E. ; Jakupec, Michael A. ; Berger, Walter ; Keppler, Bernhard K. / Triapine and a more potent dimethyl derivative induce endoplasmic reticulum stress in cancer cells. In: Molecular Pharmacology. 2014 ; Vol. 85, No. 3. pp. 451-459.
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