P-glycoprotein expression does not change the apoptotic pathway induced by curcumin in HL-60 cells

• Published in: Cancer chemotherapy and pharmacology 2004-02, Vol.53 (2), p.179-185
• Main Authors: BIELAK-ZMIJEWSKA, Anna, PIWOCKA, Katarzyna, MAGALSKA, Adriana, SIKORA, Ewa
• Format: Article
• Language: English
• Subjects: Antineoplastic agents; Antineoplastic Agents - pharmacology; Apoptosis - drug effects; Apoptosis - physiology; ATP-Binding Cassette, Sub-Family B, Member 1 - biosynthesis; Biological and medical sciences; Blotting, Western; Caspase 3; Caspase 8; Caspases - biosynthesis; Curcumin - pharmacology; Cytochromes c - biosynthesis; Cytochromes c - genetics; Enzyme Activation - drug effects; Enzyme Activation - radiation effects; Flow Cytometry; Gene Expression - drug effects; General aspects; Genes, MDR - genetics; HL-60 Cells; Humans; Medical sciences; Pharmacology. Drug treatments; Protein Biosynthesis; Proteins - genetics; RNA, Messenger - biosynthesis; Signal Transduction - drug effects; Signal Transduction - physiology; Ultraviolet Rays
• ISSN: 0344-5704; 1432-0843
• DOI: 10.1007/s00280-003-0705-x

One of the mechanisms responsible for the multidrug resistance (MDR) phenotype of cancer cells is overexpression of so-called ATP-dependent drug efflux proteins: the 170-kDa P-glycoprotein (P-gp) encoded by the MDR1 gene and the 190-kDa multidrug resistance-associated protein 1 encoded by the MRP1 gene. The purpose of the present study was to verify the hypothesis postulating that P-gp expression, apart from enabling drug efflux, confers on the cells resistance to apoptosis by inhibiting caspase-8 and caspase-3. Human HL-60 cells, either drug-sensitive or with the MDR phenotype caused by overexpression of P-gp (HL-60/Vinc) or MRP1 (HL-60/Adr), were treated with the natural dye curcumin at 50 micro M or with UVC to induce apoptosis. Symptoms of cell death were assessed by morphological observation after Hoechst staining, DNA fragmentation was measured by flow cytometry and the TUNEL method, and caspase-8 and caspase-3 activation and cytochrome c release from mitochondria were measured by Western blotting. Curcumin induced cell death in HL-60 cells, both sensitive and with the MDR phenotype, which could be classified as caspase-3-dependent apoptosis, together with cytochrome c release, activation of caspase-3 and oligonucleosomal DNA fragmentation. No active caspase-8 was detected. Also UVC caused caspase-3 activation in both the sensitive and the MDR HL-60 cells. Our findings show that there was no correlation between P-gp expression and resistance to caspase-3-dependent apoptosis induced by curcumin and UVC, at least in HL-60 cells. However, we cannot exclude the possibility of parallel P-gp expression and caspase-3 inhibition in some other cell lines, as cancer cells can acquire many different apoptosis-resistance mechanisms.