Vitamin K(2) selectively induced apoptosis in ovarian TYK-nu and pancreatic MIA PaCa-2 cells out of eight solid tumor cell lines through a mechanism different from geranylgeraniol.
OBJECTIVE
In this study, we examined the effects of vitamin K(2) (menaquinone 4), which has a geranylgeranyl side chain, on various lines of cells derived from human solid tumors and compared them with the effects of geranylgeraniol (GGO).


METHODS
Cell proliferation was determined with 3'-[1-[(phenylamino)carbonyl]-3,4-tetrazolium- bis (4-methoxy-6-nitro) benzene-sulfonic acid hydrate (XTT), and the induction of apoptosis was analyzed by TUNEL staining and flow cytometry as well as by measurement of DNA fragmentation, released nucleosomes and caspase-3 activity. Levels of Bcl-2, Bax and cytochrome c were determined by immunoblotting.


RESULTS
GGO inhibited the growth of all eight cell lines derived from solid tumors, while vitamin K(2) selectively inhibited the proliferation of ovarian TYK-nu and pancreatic MIA PaCa-2 cancer cells, inducing apoptosis in both cell lines. Far more time was required for the induction of apoptosis in these two cell lines by vitamin K(2) than by GGO. Apoptotic signals induced in TYK-nu cells during the first 2 days that followed the addition of vitamin K(2) to the culture medium were reversible, but these signals became irreversible after 3 days of treatment with vitamin K(2). The induction of apoptosis in TYK-nu cells by vitamin K(2) was inhibited by cycloheximide and also by starvation at a low concentration of serum. Neither cycloheximide nor starvation had any effect on the induction of apoptosis by GGO. Cytochrome c was released simultaneously with the initiation of apoptosis on treatment of TYK-nu cells with vitamin K(2) or GGO. However, GGO induced the release of cytochrome c from isolated mitochondria, while vitamin K(2) did not. The amount of Bcl-2 in TYK-nu cells was reduced by vitamin K(2), but not by GGO.


CONCLUSIONS
In contrast to GGO, vitamin K(2) induced apoptosis selectively in pancreatic MIA-PaCa 2 and ovarian TYK-nu cancer cells. It is suggested that de novo protein synthesis might be necessary for induction of apoptosis by vitamin K(2) but not by GGO, and thus, that vitamin K(2) and GGO might induce apoptosis by different mechanisms.
Shibayama-Imazu
Toshiko
T
Laboratory of Biological Chemistry, School of Pharmaceutical Sciences, Showa University, Hatanodai, Shinagawaku, Tokyo 142-8555, Japan. imazuto@pharm.showa-u.ac.jp
Sakairi
Shizuka
S
Watanabe
Akiko
A
Aiuchi
Toshihiro
T
Nakajo
Shigeo
S
Nakaya
Kazuyasu
K
D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002469:Cell Separation; D003574:Cytochrome c Group / Q000378:metabolism; D053938:DNA Fragmentation; D004224:Diterpenes / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D020287:In Situ Nick-End Labeling; D008297:Male; D008928:Mitochondria / Q000201:enzymology; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D014407:Tumor Cells, Cultured; D014812:Vitamin K / Q000494:pharmacology*; D051028:bcl-2-Associated X Protein
C494826:BAX protein, human; D003574:Cytochrome c Group; D004224:Diterpenes; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D014812:Vitamin K; C017338:geranylgeraniol; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases