TY - JOUR
T1 - Liposomal temocene (m-THPPo) photodynamic treatment induces cell death by mitochondria-independent apoptosis
AU - Soriano, Jorge
AU - Garcia-Diaz, Maria
AU - Mora, Margarita
AU - Sagristá, Maria Lluïsa
AU - Nonell, Santi
AU - Villanueva, Angeles
AU - Stockert, Juan Carlos
AU - Cañete, Magdalena
N1 - Copyright © 2013 Elsevier B.V. All rights reserved.
PY - 2013/5/28
Y1 - 2013/5/28
N2 - BACKGROUND: The cell death pathway activated after photodynamic therapy (PDT) is controlled by a variety of parameters including the chemical structure of the photosensitizer, its subcellular localization, and the photodynamic damage induced. The present study aims to characterize a suitable m-THPPo liposomal formulation, to determine its subcellular localization in HeLa cells and to establish the cell death mechanisms that are activated after photodynamic treatments. METHODS: Liposomes containing m-THPPo were prepared from a mixture of DPPC and DMPG at a 9:1 molar ratio. In order to procure the best encapsulation efficiency, the m-THPPo/lipid molar ratio was considered. HeLa cells were incubated with liposomal m-THPPo and the subcellular localization of m-THPPo was studied. Several assays such as TUNEL, annexin V/propidium iodide and Hoechst-33258 staining were performed after photodynamic treatments. The apoptotic initiation was assessed by cytochrome c and caspase-2 immunofluorescence. RESULTS: m-THPPo encapsulated in liposomes showed a decrease of the fluorescence and singlet oxygen quantum yields, compared to those of m-THPPo dissolved in tetrahydrofuran. Liposomal m-THPPo showed colocalization with LysoTracker® and it induced photoinactivation of HeLa cells by an apoptotic mechanism. In apoptotic cells no relocalization of cytochrome c could be detected, but caspase-2 was positive immediately after photosensitizing treatments. CONCLUSIONS: Photodynamic treatment with liposomal m-THPPo leads to a significant percentage of apoptotic morphology of HeLa cells. The activation of caspase-2, without the relocalization of cytochrome c, indicates a mitochondrial-independent apoptotic mechanism. GENERAL SIGNIFICANCE: These results provide a better understanding of the cell death mechanism induced after liposomal m-THPPo photodynamic treatment.
AB - BACKGROUND: The cell death pathway activated after photodynamic therapy (PDT) is controlled by a variety of parameters including the chemical structure of the photosensitizer, its subcellular localization, and the photodynamic damage induced. The present study aims to characterize a suitable m-THPPo liposomal formulation, to determine its subcellular localization in HeLa cells and to establish the cell death mechanisms that are activated after photodynamic treatments. METHODS: Liposomes containing m-THPPo were prepared from a mixture of DPPC and DMPG at a 9:1 molar ratio. In order to procure the best encapsulation efficiency, the m-THPPo/lipid molar ratio was considered. HeLa cells were incubated with liposomal m-THPPo and the subcellular localization of m-THPPo was studied. Several assays such as TUNEL, annexin V/propidium iodide and Hoechst-33258 staining were performed after photodynamic treatments. The apoptotic initiation was assessed by cytochrome c and caspase-2 immunofluorescence. RESULTS: m-THPPo encapsulated in liposomes showed a decrease of the fluorescence and singlet oxygen quantum yields, compared to those of m-THPPo dissolved in tetrahydrofuran. Liposomal m-THPPo showed colocalization with LysoTracker® and it induced photoinactivation of HeLa cells by an apoptotic mechanism. In apoptotic cells no relocalization of cytochrome c could be detected, but caspase-2 was positive immediately after photosensitizing treatments. CONCLUSIONS: Photodynamic treatment with liposomal m-THPPo leads to a significant percentage of apoptotic morphology of HeLa cells. The activation of caspase-2, without the relocalization of cytochrome c, indicates a mitochondrial-independent apoptotic mechanism. GENERAL SIGNIFICANCE: These results provide a better understanding of the cell death mechanism induced after liposomal m-THPPo photodynamic treatment.
KW - Former Faculty of Pharmaceutical Sciences
KW - apoptosis
KW - liposome
KW - photosensitizer
KW - temocene
U2 - 10.1016/j.bbagen.2013.05.021
DO - 10.1016/j.bbagen.2013.05.021
M3 - Journal article
C2 - 23721802
VL - 1830
SP - 4611
EP - 4620
JO - B B A - General Subjects
JF - B B A - General Subjects
SN - 0304-4165
IS - 10
ER -