Drug-resistant breast carcinoma (MCF-7) cells are paradoxically sensitive to apoptosis.
The purpose of this study was to determine whether expression of tissue transglutaminase (TG2) and caspase-3 proteins in drug-resistant breast carcinoma MCF-7/DOX cells would render these cells selectively susceptible to apoptotic stimuli. Despite high resistance to multidrug resistance (MDR)-related drug, doxorubicin (> or =150-fold), the MCF-7/DOX cells were extremely sensitive to apoptotic stimuli. Thus, calcium ionophore, A23187 (A23187) and the protein kinase C inhibitor staurosporine (STS) each induced rapid and time-dependent apoptosis in MCF-7/DOX cells. The apoptosis induced by either agent was accompanied by caspase-3 activation and other downstream changes that are typical of cells undergoing apoptosis. The alterations upstream of caspase-3 activation, however, such as loss in mitochondrial membrane potential (DeltaPsi), release of cytochrome c, and activation of caspase-8, and caspase-9, were detected only in STS-treated cells. The A12387 failed to induce any of the caspase-3 upstream changes, implying that A23187-induced apoptosis may utilize one or more novel upstream pathways leading to the activation of caspase 3. In summary, these data demonstrate that MCF-7/DOX cells are much more sensitive to apoptotic stimuli than previously thought and that A23187-induced apoptosis may involve some novel, yet unidentified, upstream pathway that leads to the activation of caspase-3 and other downstream events.
Chen
Jack S K
JS
Department of Bioimmunotherapy, The University of Texas, M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
Konopleva
Marina
M
Andreeff
Michael
M
Multani
Asha S
AS
Pathak
Sen
S
Mehta
Kapil
K
D000903:Antibiotics, Antineoplastic / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology*; D000001:Calcimycin / Q000494:pharmacology; D002277:Carcinoma / Q000473:pathology*; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D045304:Cytochromes c / Q000378:metabolism; D004317:Doxorubicin / Q000627:therapeutic use; D019008:Drug Resistance, Neoplasm; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D007476:Ionophores / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D019311:Staurosporine / Q000494:pharmacology
D000903:Antibiotics, Antineoplastic; D004791:Enzyme Inhibitors; D007476:Ionophores; D000001:Calcimycin; D004317:Doxorubicin; D045304:Cytochromes c; C505407:CASP3 protein, human; C505530:CASP8 protein, human; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases; D019311:Staurosporine