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Liposomal temocene (m-THPPo) photodynamic treatment induces cell death by mitochondria-independent apoptosis

Jorge Soriano1, María García-Díaz, Margarita Mora

  • 1Departamento de Biología, Universidad Autónoma de Madrid, Madrid, Spain.

Biochimica Et Biophysica Acta
|June 1, 2013
PubMed
Abstract

Insights

Photodynamic therapy using liposomal m-THPPo induces apoptosis in HeLa cells. This cell death pathway is mitochondrial-independent, activated by caspase-2 without cytochrome c release.

Area of Science:

  • Cell Biology
  • Photochemistry
  • Biochemistry

Background:

  • Photodynamic therapy (PDT) efficacy depends on photosensitizer properties and cellular response.
  • Understanding PDT-induced cell death mechanisms is crucial for optimizing treatment.

Purpose of the Study:

  • Characterize liposomal m-THPPo for PDT applications.
  • Determine m-THPPo's subcellular localization in HeLa cells.
  • Elucidate the cell death pathways activated by liposomal m-THPPo.

Main Methods:

  • Liposomes encapsulating m-THPPo were prepared and characterized.
  • Subcellular localization was assessed using LysoTracker®.
  • Cell death was evaluated via TUNEL, annexin V/propidium iodide, and Hoechst-33258 staining.
  • Apoptosis initiation was monitored by cytochrome c and caspase-2 immunofluorescence.

Main Results:

  • Liposomal m-THPPo exhibited reduced fluorescence and singlet oxygen quantum yields compared to free m-THPPo.
  • Liposomal m-THPPo localized to lysosomes and induced apoptosis in HeLa cells.
  • Caspase-2 activation was observed, but cytochrome c relocalization was absent.

Conclusions:

  • Liposomal m-THPPo effectively induces apoptotic cell death in HeLa cells.
  • The observed apoptosis is mediated by a mitochondrial-independent pathway involving caspase-2.
  • This study enhances understanding of liposomal m-THPPo-induced cell death mechanisms in PDT.
Keywords:
ApoptosisDMPGDMSODPPCH-33258Hoechst-33258LiposomeMLVsPBSPCSPDTPIPSPhotosensitizerROSTBTHFTemocenedimethylsulfoxidedimyristoylphosphatidylglyceroldipalmitoylphosphatidylcholinem-THPPom-tetra (hydroxyphenyl) porphycene (temocene)multilamellar vesiclesphosphate buffered salinephotodynamic therapyphoton correlation spectroscopyphotosensitizerpropidium iodidereactive oxygen speciestetrahydrofurantoluidine blue

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