Pyrrolidine dithiocarbamate inhibition of luteolin-induced apoptosis through up-regulated phosphorylation of Akt and caspase-9 in human leukemia HL-60 cells.
Previously, we observed that luteolin effectively inhibited cell growth and induced apoptosis in HL-60 cells. In that study, we also explored the modulatory effects and molecular mechanisms of pyrrolidine dithiocarbamate (PDTC) on the cytotoxicity of luteolin to HL-60 cells. In this study, we found that PDTC was able to inhibit luteolin-induced cell apoptosis in a dose-dependent manner. When HL-60 cells were treated with PDTC for 0.5 h before 60 microM luteolin treatment, the DNA ladder disappeared. Moreover, flow cytometry showed that PDTC had dose dependently decreased the percentage of apoptotic HL-60 cells and had not interfered with luteolin's ability to change the mitochondrial membrane potential or its ability to trigger the release of cytochrome c to cytosol. Detection by Western blotting, however, did show that PDTC had interfered with luteolin's ability to cleave poly(ADP-ribose)polymerase and DNA fragmentation of factor-45. Three hours after the PDTC-pretreated HL-60 cells were treated with 60 microM luteolin, the product cleaved from Akt started to appear. Therefore, not only was PDTC able to stop the apoptosis of HL-60 cells treated with luteolin, it was also found to increase phosphorylation of Akt and caspase-9. These results suggest that in the luteolin-induced apoptotic pathway, phosphorylation of procaspase-9 by survival signals might play an important role in the ultimate fate of HL-60 cells.
Cheng
An-Chin
AC
Department of Physical Therapy, Shu-Zen College of Medicine and Management, Kaohsiung County, Taiwan.
Huang
Tzou-Chi
TC
Lai
Ching-Shu
CS
Kuo
Jen-Min
JM
Huang
Ying-Tang
YT
Lo
Chih-Yu
CY
Ho
Chi-Tang
CT
Pan
Min-Hsiung
MH
D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D045304:Cytochromes c / Q000378:metabolism; D053938:DNA Fragmentation; D005434:Flow Cytometry; D018922:HL-60 Cells; D006801:Humans; D047311:Luteolin / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000648:ultrastructure; D010766:Phosphorylation; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D011759:Pyrrolidines / Q000494:pharmacology*; D013859:Thiocarbamates / Q000494:pharmacology*
D000975:Antioxidants; D051017:Apoptosis Regulatory Proteins; D011506:Proteins; D011759:Pyrrolidines; D013859:Thiocarbamates; C109664:caspase-activated DNase inhibitor; C020972:pyrrolidine dithiocarbamic acid; D045304:Cytochromes c; D011065:Poly(ADP-ribose) Polymerases; D051057:Proto-Oncogene Proteins c-akt; C506433:CASP9 protein, human; D053453:Caspase 9; D020169:Caspases; D047311:Luteolin