Induction of mitochondrial permeability transition and cytochrome C release in the absence of caspase activation is insufficient for effective apoptosis in human leukemia cells

Jayshree L. Hirpara, Mohamed A. Seyed, Kok W. Loh, Hui Dong, R. Manjunatha Kini, Shazib Pervaiz

Research output: Contribution to journalArticle

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Abstract

Induction of mitochondrial permeability transition (MPT) and cytosolic translocation of cytochrome C are considered essential components of the apoptotic pathway. Hence, there is the realization that mitochondrial- specific drugs could have potential for use as chemotherapeutic agents to trigger apoptosis In tumor cells. Recently, we showed that photoproducts of merocyanine 540 (pMC540) induced tumor cell apoptosis. In this study, we focused on identifying mitochondrial-specific compounds from pMC540 and studied their apoptotic potential. One purified fraction, C5, induced a drop In mitochondrial transmembrane potential and cytosolic translocation of cytochrome C in HL60 human leukemia cells. Moreover, the addition of C5 to purified rat liver mitochondria induced MPT as indicated by mitochondrial matrix swelling, which was completely inhibited by cyclosporin A, an inhibitor of the inner-membrane pore. Supernatant of C5-treated mitochondria showed a dose-dependent increase in cytochrome C, which was also inhibited in the presence of cyclosporin A, strongly indicating a direct effect on the inner-membrane pore. Despite the strong mitochondrial reactivity, C5 elicited minimal cytotoxicity (less than 25%) against HL60 leukemia and M14 melanoma cells because of inefficient caspase activation. However, prior exposure to C5 significantly enhanced the apoptotic response to etoposide or the CD95 receptor. Thus, we demonstrate that MPT induction and cytochrome C release by the novel compound C5, in the absence of effective caspase activation, is insufficient for triggering efficient apoptosis in tumor cells. However, when used in combination with known apoptosis inducers, such compounds could enhance the sensitivity of tumor cells to apoptosis. (C) 2000 by The American Society of Hematology.

Original languageEnglish
Pages (from-to)1773-1780
Number of pages8
JournalBlood
Volume95
Issue number5
Publication statusPublished - 1 Mar 2000
Externally publishedYes

Fingerprint

Cytochromes
Caspases
Permeability
Leukemia
Chemical activation
Apoptosis
Tumors
Cells
Mitochondria
Cyclosporine
Neoplasms
Membranes
Mitochondrial Swelling
Etoposide
Cytotoxicity
Liver Mitochondrion
Liver
Swelling
Rats
Membrane Potentials

ASJC Scopus subject areas

  • Hematology

Cite this

Induction of mitochondrial permeability transition and cytochrome C release in the absence of caspase activation is insufficient for effective apoptosis in human leukemia cells. / Hirpara, Jayshree L.; Seyed, Mohamed A.; Loh, Kok W.; Dong, Hui; Kini, R. Manjunatha; Pervaiz, Shazib.

In: Blood, Vol. 95, No. 5, 01.03.2000, p. 1773-1780.

Research output: Contribution to journalArticle

Hirpara, Jayshree L. ; Seyed, Mohamed A. ; Loh, Kok W. ; Dong, Hui ; Kini, R. Manjunatha ; Pervaiz, Shazib. / Induction of mitochondrial permeability transition and cytochrome C release in the absence of caspase activation is insufficient for effective apoptosis in human leukemia cells. In: Blood. 2000 ; Vol. 95, No. 5. pp. 1773-1780.
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