Inhibition of DNA primase by sphingosine and its analogues parallels with their growth suppression of cultured human leukemic cells.
Sphingosine is a potent inhibitor of a mammalian DNA primase in vitro (Simbulan et al., Biochemistry 33, 9007-9012, 1994). Here we measured the inhibition of DNA primase in vitro by 9 sphingosine-analogues with respect to RNA primer synthesis and DNA primase-dependent DNA synthesis, and their potencies of inhibition in vitro were compared with their in vivo effects on human leukemic cells. Sphingosine, phytosphingosine and N, N-dimethylsphingosine strongly inhibited the activity of purified calf thymus DNA primase, and also inhibited the growth of human leukemic cell line HL-60, exerting strong cytotoxicity. Dihydrosphingosine and cis-sphingosine, which showed more subtle inhibition of DNA primase in vitro, moderately inhibited the cell growth in vivo and caused cell death. In contrast, N-acyl-, N-octyl-, and N-acetylsphingosine (ceramides) showing little inhibition of DNA primase suppressed cell growth only slightly. HL 60 cell was arrested at Go/G1 phase by exogenously added sphingosine. From these results, it is suggested that DNA primase is one of targets of sphingosine, an effector molecule in apoptosis.
Tamiya-Koizumi
K
K
Laboratory of Cancer Cell Biology, Nagoya University School of Medicine, Japan.
Murate
T
T
Suzuki
M
M
Simbulan
C M
CM
Nakagawa
M
M
Takemura
M
M
Furuta
K
K
Izuta
S
S
Yoshida
S
S
D000970:Antineoplastic Agents / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects / Q000235:genetics; D019915:DNA Primase; D004261:DNA Replication / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006131:Growth Inhibitors / Q000494:pharmacology*; D018922:HL-60 Cells / Q000187:drug effects / Q000473:pathology; D006801:Humans; D012316:RNA Nucleotidyltransferases / Q000037:antagonists & inhibitors* / Q000187:drug effects* / Q000235:genetics; D013110:Sphingosine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology*
D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D006131:Growth Inhibitors; D019915:DNA Primase; D012316:RNA Nucleotidyltransferases; D013110:Sphingosine