Functional role of caspases in sphingosine-induced apoptosis in human hepatoma cells.
We have previously shown that sphingosine increased caspase-3 activity and induced apoptosis in human hepatoma cells. Our data also suggest that other caspases may be involved in sphingosine-triggered apoptosis. In order to clarify this issue, we used different approaches to study the functional role of several initiator or executioner caspases in apoptosis induced by sphingosine. Activation of procaspases-2, -7, and -8, was clearly demonstrated during sphingosine-triggered apoptosis. Pretreatment with chemical inhibitors for caspase-7 and -8, attenuated apoptotic cell death induced by sphingosine. Conversely, pretreatment with specific caspase-2 inhibitor Z-VDVAD-FMK did not show any protective effect. In addition, enforced expression of constitutively activated AKT kinase which is known to inhibit apoptosis induced by sphingosine, potently suppressed activation of procaspases-7 and -8. In summary, these data suggest that in addition to caspases-3, caspase-7 and -8 are involved in the apoptosis induced by sphingosine.
Department of Physiology, Kaohsiung Medical University, Kaohsiung 807, Taiwan, Republic of China. m740127@kmu.edu.tw
Hui-Chiu
HC
Chang
Chin
C
Hsu
Hseng-Kuang
HK
Hsu
Rei-Cheng
RC
Yang
D017209:Apoptosis; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D053143:Caspase 2; D053179:Caspase 7; D053181:Caspase 8; D020169:Caspases / Q000096:biosynthesis / Q000502:physiology*; D002460:Cell Line; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D006801:Humans; D009842:Oligopeptides / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D013110:Sphingosine / Q000378:metabolism*; D013997:Time Factors
D009842:Oligopeptides; D011518:Proto-Oncogene Proteins; C427308:benzoylcarbonyl-valyl-aspartyl-valyl-alanyl-aspartyl-fluoromethyl ketone; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; C505520:CASP7 protein, human; C505530:CASP8 protein, human; D053143:Caspase 2; D053179:Caspase 7; D053181:Caspase 8; D020169:Caspases; D013110:Sphingosine