Novel extranuclear-targeted anthracyclines override the antiapoptotic functions of Bcl-2 and target protein kinase C pathways to induce apoptosis

Christina M. Barrett, Felicia L. Lewis, J. Brent Roaten, Trevor W. Sweatman, Mervyn Israel, John L. Cleveland, Leonard Lothstein

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Bcl-2 inhibits apoptosis induced by numerous antitumor drugs, including doxorubicin and daunorubicin and is, thus, a major impediment to successful cancer chemotherapy. Here, we report the ability of a novel family of nonnuclear targeted anthracyclines to induce rapid apoptosis in cells despite Bcl-2 or Bcl-XL expression. Typified by N-benzyladriamycin-14-valerate (AD 198) and N-benzyladriamycin-14-pivalate (AD 445), this family of compounds binds to the C1 regulatory domain of protein kinase C (PKC), competitively inhibits phorbol ester binding in cell-free studies, and induces PKC translocation in intact cells. PKC-δ has an established role as a pro-apoptotic protein through the association of the holoenzyme or catalytic fragment with mitochondria. In proliferating 32D.3 myeloid cells, or in 32D.3 cells engineered to overexpress Bcl-2, substantial levels of PKC-δ are associated with mitochondria. However, after a 1-h exposure to 5 μM AD 198, cytochrome c release, caspase-3 activation, poly(ADP-ribose) polymerase (PARP) cleavage, PKC-δ cleavage, and DNA fragmentation are observed. Pretreatment of 32D.3 cells with the selective PKC-δ inhibitor, rottlerin, but not the general PKC inhibitor, GF 109203X, or PKC-α and -β inhibitor, Gö 6976, delayed the 50% cell kill to >24 h for control and Bcl-2 overexpressing 32D.3 cells treated with 5 μM AD 198. Rottlerin delayed PKC-δ and PARP cleavage to >20 h post-drug exposure and also delayed mitochondrial membrane depolarization. In contrast, the pan-caspase inhibitor Z-Val-Ala-Asp-CH 2F blocked PKC-δ and PARP cleavage, but not mitochondrial membrane depolarization. These results suggest that AD 198 induces mitochondrial-dependent apoptosis in 32D.3 cells by activating PKC-δ holoenzyme on mitochondria, which, in turn, overrides the antiapoptotic effects of Bcl-2.

Original languageEnglish (US)
Pages (from-to)469-481
Number of pages13
JournalMolecular Cancer Therapeutics
Volume1
Issue number7
StatePublished - May 1 2002

Fingerprint

Anthracyclines
Protein Kinase C
Apoptosis
Poly(ADP-ribose) Polymerases
Protein C Inhibitor
Protein Kinase Inhibitors
Mitochondria
Holoenzymes
Mitochondrial Membranes
Apoptosis Regulatory Proteins
Daunorubicin
Caspase Inhibitors
Phorbol Esters
DNA Fragmentation
Myeloid Cells
Cytochromes c
Caspase 3
Antineoplastic Agents
Doxorubicin
N-benzyladriamycin-14-valerate

All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research

Cite this

Novel extranuclear-targeted anthracyclines override the antiapoptotic functions of Bcl-2 and target protein kinase C pathways to induce apoptosis. / Barrett, Christina M.; Lewis, Felicia L.; Roaten, J. Brent; Sweatman, Trevor W.; Israel, Mervyn; Cleveland, John L.; Lothstein, Leonard.

In: Molecular Cancer Therapeutics, Vol. 1, No. 7, 01.05.2002, p. 469-481.

Research output: Contribution to journalArticle

Barrett, Christina M. ; Lewis, Felicia L. ; Roaten, J. Brent ; Sweatman, Trevor W. ; Israel, Mervyn ; Cleveland, John L. ; Lothstein, Leonard. / Novel extranuclear-targeted anthracyclines override the antiapoptotic functions of Bcl-2 and target protein kinase C pathways to induce apoptosis. In: Molecular Cancer Therapeutics. 2002 ; Vol. 1, No. 7. pp. 469-481.
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