Phospholipase A2-activating protein (PLAA) enhances cisplatin-induced apoptosis in HeLa cells

Fan Zhang, Giovanni Suarez, Jian Sha, Johanna C. Sierra, Johnny W. Peterson, Ashok K. Chopra

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

Phospholipase A2 (PLA2)-activating protein (PLAA) is a novel signaling molecule that regulates eicosanoid production and participates in inflammatory responses. In our current study, we revealed that PLAA production was induced by the chemotherapeutic drug cisplatin in HeLa cervical carcinoma cells. To determine the potential pro-apoptotic effects of PLAA induction by cisplatin, we utilized HeLa (Tet-off) cells overexpressing the plaa gene (plaa high) and compared them with control (plaa low) cells, which produce endogenous plaa from the chromosome. Cisplatin-stimulated plaa high cells contained significantly higher levels of DNA fragmentation, caspase 3, 8 and 9 activities, PLA2 enzyme activity, and cytochrome c leakage from mitochondria than did the cisplatin-stimulated plaa low cells. Importantly, siRNA against PLAA (siRNA-PLAA) reduced the levels of cisplatin-induced PLAA, DNA fragmentation, and PLA2 activation, while promoting cell viability in both plaa high and plaa low cells. Cisplatin-induced-cytochrome c leakage in plaa high cells was reduced by siRNA-PLAA and restored by the addition of exogenous arachidonic acid (AA), suggesting to us that PLAA induction by cisplatin promoted cytochrome c leakage/mitochondrial damage partially by accumulating AA. In addition, cisplatin-stimulated plaa high cells produced less cytoprotective clusterin than did the cisplatin-stimulated plaa low cells, and siRNA-PLAA promoted clusterin production from both plaa high and plaa low cells. We showed that clusterin reduced DNA fragmentation in cisplatin-stimulated plaa high and plaa low cells, which is consistent with the notion that clusterin promotes cancer chemoresistance. Furthermore, cisplatin-stimulated plaa high cells produced more IL-32 (a pro-apoptotic protein) than did cisplatin-stimulated plaa low cells, and siRNA-PLAA reduced IL-32 production from both plaa high and plaa low cells. Finally, our proteomic analysis revealed that cisplatin-stimulated plaa high cells contained higher levels of phosphorylated JNK/c-Jun and FasL than did plaa low cells treated the same way. In summary, our data indicated that PLAA induction enhanced cisplatin-induced-apoptosis through four pathways, namely by: 1) accumulation of AA and mitochondrial damage, 2) downregulation of the cytoprotective clusterin, 3) upregulation of the pro-apoptotic IL-32, and 4) induction of JNK/c-Jun signaling and FasL expression.

Original languageEnglish (US)
Pages (from-to)1085-1099
Number of pages15
JournalCellular Signalling
Volume21
Issue number7
DOIs
StatePublished - Jul 1 2009

Keywords

  • Apoptosis
  • Cisplatin
  • HeLa cells
  • PLAA
  • Signaling cascade
  • siRNA

ASJC Scopus subject areas

  • Cell Biology

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