Oxidized low-density lipoprotein retards the growth of proliferating cells by inhibiting nuclear translocation of cell cycle proteins.
OBJECTIVE
Our study tested the hypothesis that the mitogenic effect of oxidized low-density lipoprotein (oxLDL) on vascular cells may be further enhanced by the presence of cytokines and growth factors known to be present in the atherosclerotic environment.


RESULTS
Quiescent fibroblasts and vascular smooth muscle cells were treated with 10 or 50 microg/mL minimally-oxidized LDL in combination with serum for 24 or 48 hours. Surprisingly, these cells showed inhibited release from growth arrest and a significant reduction in the number of cells completing the cell cycle when compared with cells treated with serum alone. This was not due to an induction of apoptosis. The antiproliferative effects were not closely associated with changes in the expression of cell cycle proteins. Instead, oxLDL inhibited the translocation of cell cycle proteins cell division cycle (Cdc) 2, cyclin-dependent kinase (Cdk) 2, Cdk 4, Cyclin A, Cyclin B1, Cyclin D1, and proliferative cell nuclear antigen (PCNA) into the nucleus, as compared with separate treatments with serum alone. Kinase activation associated with specific cell cycle proteins was also inhibited by oxLDL.


CONCLUSIONS
oxLDL, in the presence of serum, has a surprising inhibitory effect on cell proliferation that occurs through an inhibition of import of cell cycle proteins into the cell nucleus.
Zettler
Marjorie E
ME
Cell Biology Laboratory, Division of Stroke and Vascular Disease, St Boniface General Hospital Research Centre, Winnipeg, Manitoba, Canada.
Prociuk
Michele A
MA
Austria
J Alejandro
JA
Zhong
Guangming
G
Pierce
Grant N
GN
D021581:Active Transport, Cell Nucleus / Q000187:drug effects*; D000818:Animals; D017209:Apoptosis; D001161:Arteriosclerosis / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D006133:Growth Substances / Q000494:pharmacology; D006801:Humans; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000378:metabolism; D011817:Rabbits
D018797:Cell Cycle Proteins; D016895:Culture Media, Serum-Free; D006133:Growth Substances; D008077:Lipoproteins, LDL; C099252:oxidized low density lipoprotein