XIAP antagonist embelin inhibited proliferation of cholangiocarcinoma cells

Cody J. Wehrkamp, Ashley R. Gutwein, Sathish K Natarajan, Mary Anne Phillippi, Justin L Mott

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Cholangiocarcinoma cells are dependent on antiapoptotic signaling for survival and resistance to death stimuli. Recent mechanistic studies have revealed that increased cellular expression of the E3 ubiquitin-protein ligase X-linked inhibitor of apoptosis (XIAP) impairs TRAIL- and chemotherapy-induced cytotoxicity, promoting survival of cholangiocarcinoma cells. This study was undertaken to determine if pharmacologic antagonism of XIAP protein was sufficient to sensitize cholangiocarcinoma cells to cell death. We employed malignant cholangiocarcinoma cell lines and used embelin to antagonize XIAP protein. Embelin treatment resulted in decreased XIAP protein levels by 8 hours of treatment with maximal effect at 16 hours in KMCH and Mz-ChA-1 cells. Assessment of nuclear morphology demonstrated a concentrationdependent increase in nuclear staining. Interestingly, embelin induced nuclear morphology changes as a single agent, independent of the addition of TNF-related apoptosis inducing ligand (TRAIL). However, caspase activity assays revealed that increasing embelin concentrations resulted in slight inhibition of caspase activity, not activation. In addition, the use of a pan-caspase inhibitor did not prevent nuclear morphology changes. Finally, embelin treatment of cholangiocarcinoma cells did not induce DNA fragmentation or PARP cleavage. Apoptosis does not appear to contribute to the effects of embelin on cholangiocarcinoma cells. Instead, embelin caused inhibition of cell proliferation and cell cycle analysis indicated that embelin increased the number of cells in S and G2/M phase. Our results demonstrate that embelin decreased proliferation in cholangiocarcinoma cell lines. Embelin treatment resulted in decreased XIAP protein expression, but did not induce or enhance apoptosis. Thus, in cholangiocarcinoma cells the mechanism of action of embelin may not be dependent on apoptosis.

Original languageEnglish (US)
Article numbere90238
JournalPloS one
Volume9
Issue number3
DOIs
StatePublished - Mar 6 2014

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Cholangiocarcinoma
antagonists
cell proliferation
apoptosis
Cell Proliferation
Apoptosis
X-Linked Inhibitor of Apoptosis Protein
caspases
TNF-Related Apoptosis-Inducing Ligand
cells
Cells
Caspases
cell lines
embelin
ubiquitin-protein ligase
Cell Line
proteins
DNA fragmentation
Caspase Inhibitors
Ubiquitin-Protein Ligases

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

Cite this

XIAP antagonist embelin inhibited proliferation of cholangiocarcinoma cells. / Wehrkamp, Cody J.; Gutwein, Ashley R.; Natarajan, Sathish K; Phillippi, Mary Anne; Mott, Justin L.

In: PloS one, Vol. 9, No. 3, e90238, 06.03.2014.

Research output: Contribution to journalArticle

Wehrkamp, Cody J. ; Gutwein, Ashley R. ; Natarajan, Sathish K ; Phillippi, Mary Anne ; Mott, Justin L. / XIAP antagonist embelin inhibited proliferation of cholangiocarcinoma cells. In: PloS one. 2014 ; Vol. 9, No. 3.
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