N,N-Dimethyl phytosphingosine sensitizes HL-60/MX2, a multidrug-resistant variant of HL-60 cells, to doxorubicin-induced cytotoxicity through ROS-mediated release of cytochrome c and AIF.
Doxorubicin (Dox) is widely used to treat a variety of tumors. However, resistance to this drug is common, making successful treatment more difficult. Previously, we introduced a novel phytosphingosine derivative, N,N-dimethyl phytosphingosine (DMPS), as a potent anticancer therapeutic agent in human leukemia cells. This study was performed to investigate whether DMPS can sensitize HL-60/MX2, a multidrug-resistant variant of HL-60, to Dox-induced apoptosis. Low concentrations of DMPS sensitized HL-60/MX2 cells to Dox-induced apoptosis. Combined Dox + DMPS treatment-induced apoptosis was accompanied by the activation of caspase-8 and caspase-3 as well as PARP cleavage. Cytochrome c and AIF release were also observed in Dox + DMPS-treated HL60/MX2 cells. Pretreatment with z-VAD-fmk markedly prevented caspase-3 activation and moderately suppressed apoptosis, suggesting that Dox + DMPS-induced apoptosis is somewhat (not completely) dependent on caspase. Cytochrome c and AIF release were not affected by pretreatment with z-VAD-fmk. The ROS scavenger NAC efficiently suppressed not only ROS generation, but also caspase-3-mediated PARP cleavage, apoptosis, and release of cytochrome c and AIF, indicating a role of ROS in combined Dox + DMPS treatment-induced apoptotic death signaling. Taken together, these observations suggest that DMPS may be used as a therapeutic agent for overcoming drug-resistance in cancer cells by enhancing drug-induced apoptosis.
Korea Institute of Radiological and Medical Sciences, Nowon-Gu, Seoul, Republic of Korea.
Byeong Mo
BM
Kim
Yun Jung
YJ
Choi
Yong Heon
YH
Lee
Young Ae
YA
Joe
Sung Hee
SH
Hong
D000111:Acetylcysteine / Q000494:pharmacology; D000590:Amino Acid Chloromethyl Ketones / Q000378:metabolism; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D051033:Apoptosis Inducing Factor / Q000378:metabolism*; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival; D015853:Cysteine Proteinase Inhibitors / Q000378:metabolism; D045304:Cytochromes c / Q000378:metabolism*; D004317:Doxorubicin / Q000494:pharmacology*; D018432:Drug Resistance, Multiple / Q000187:drug effects*; D004789:Enzyme Activation; D016166:Free Radical Scavengers / Q000494:pharmacology; D018922:HL-60 Cells / Q000187:drug effects*; D006801:Humans; D008928:Mitochondria / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology
D000590:Amino Acid Chloromethyl Ketones; D000903:Antibiotics, Antineoplastic; D000975:Antioxidants; D051033:Apoptosis Inducing Factor; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D016166:Free Radical Scavengers; D017382:Reactive Oxygen Species; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D004317:Doxorubicin; D045304:Cytochromes c; D020169:Caspases; C012491:phytosphingosine; D013110:Sphingosine; D000111:Acetylcysteine