Photodynamic Therapy-Induced Apoptosis in Lymphoma Cells: Translocation of Cytochrome c Causes Inhibition of Respiration as Well as Caspase Activation

Photodynamic therapy (PDT) is a novel and promising antitumor treatment. Our previous study showed that hydrophilic/lipophilic tetra-α-(4-carboxyphenoxy) phthalocyanine zinc- (TαPcZn-) mediated PDT (TαPcZn-PDT) inhibits the proliferation of human hepatocellular carcinoma Bel-7402 cells by triggering apoptosis and arresting cell cycle. However, mechanisms of TαPcZn-PDT-induced apoptosis of Bel-7402 cells have not been fully clarified. In the present study, therefore, effect of TαPcZn-PDT on apoptosis, P38MAPK, p-P38MAPK, Caspase-8, Caspase-3, Bcl-2, Bid, Cytochrome c, and mitochondria membrane potential in Bel-7402 cells without or with P38MAPK inhibitor SB203580 or Caspase-8 inhibitor Ac-IEFD-CHO was investigated by haematoxylin and eosin (HE) staining assay, flow cytometry analysis of annexin V-FITC/propidium iodide (PI) double staining cells and 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolylcarbocyanine iodide (JC-1), and immunoblot assay. We found that TαPcZn-PDT resulted in apoptosis induction, activation of P38MAPK, Caspase-8, Caspase-3, and Bid, downregulation of Bcl-2, release of Cytochrome c from mitochondria, and disruption of mitochondrial membrane potential in TαPcZn-PDT-treated Bel-7402 cells. In contrast, SB203580 or Ac-IEFD-CHO attenuated induction of apoptosis, activation of P38MAPK, Caspase-8, Caspase-3, and Bid, downregulation of Bcl-2, release of Cytochrome c from mitochondria, and disruption of mitochondrial membrane potential in TαPcZn-PDT-treated Bel-7402 cells. Taken together, we conclude that Caspase-3, Bcl-2, Bid, and mitochondria are involved in autoregulatory feedback of P38MAPK/Caspase-8 during TαPcZn-PDT-induced apoptosis of Bel-7402 cells.

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Antioxidants prevent UV-induced apoptosis by inhibiting mitochondrial cytochrome c release and caspase activation in Spodoptera frugiperda (Sf9) cells

Cell Biology International ◽

10.1016/s1065-6995(03)00071-4 ◽

2003 ◽

Vol 27 (6) ◽

pp. 483-490 ◽

Cited By ~ 29

Author(s):

M Mohan

Keyword(s):

Cytochrome C ◽

Spodoptera Frugiperda ◽

Sf9 Cells ◽

Mitochondrial Cytochrome ◽

Caspase Activation ◽

Cytochrome C Release ◽

Induced Apoptosis ◽

Mitochondrial Cytochrome C

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Resistance of leukemic cells to 2-chlorodeoxyadenosine is due to a lack of calcium-dependent cytochrome c release

Blood ◽

10.1182/blood.v99.2.655 ◽

2002 ◽

Vol 99 (2) ◽

pp. 655-663 ◽

Cited By ~ 45

Author(s):

Joya Chandra ◽

Emma Mansson ◽

Vladimir Gogvadze ◽

Scott H. Kaufmann ◽

Freidoun Albertioni ◽

...

Keyword(s):

Cytochrome C ◽

Dna Fragmentation ◽

Cell Lines ◽

Resistant Cell ◽

Leukemic Cells ◽

Caspase Activation ◽

Cytochrome C Release ◽

Deoxyguanosine Kinase ◽

Induced Apoptosis ◽

Resistant Cells

Abstract The purine nucleoside 2-chlorodeoxyadenosine (CdA) is often used in leukemia therapy. Its efficacy, however, is compromised by the emergence of resistant cells. In the present study, 3 CdA-resistant cell lines were generated and characterized. Their ability to accumulate 2-chloroadenosine triphosphate (CdATP) varied, reflecting differences in activities of deoxycytidine kinase (dCK) and deoxyguanosine kinase (dGK). Nonetheless, the selected lines were uniformly resistant to CdA-induced apoptosis, as assessed by caspase activation and DNA fragmentation. In contrast, cytosols from resistant cells were capable of robust caspase activation when incubated in the presence of cytochrome c and dATP. Moreover, replacement of dATP with CdATP also resulted in caspase activation in the parental and some of the resistant cell lines. Strikingly, CdA-induced decreases in mitochondrial transmembrane potential and release of cytochrome c from mitochondria were observed in the parental cells but not in any resistant lines. The lack of cytochrome c release correlated with an increased ability of mitochondria from resistant cells to sequester free Ca2+. Consistent with this enhanced Ca2+buffering capacity, an early increase in cytosolic Ca2+after CdA treatment of parental cells but not resistant cells was detected. Furthermore, CdA-resistant cells were selectively cross-resistant to thapsigargin but not to staurosporine- or Fas-induced apoptosis. In addition, CdA-induced caspase-3 activation and DNA fragmentation were inhibited by the Ca2+ chelator BAPTA-AM in sensitive cells. Taken together, the data indicate that the mechanism of resistance to CdA may be dictated by changes in Ca2+-sensitive mitochondrial events.

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