Multifactorial anticancer effects of digalloyl-resveratrol encompass apoptosis, cell-cycle arrest, and inhibition of lymphendothelial gap formation in vitro.
BACKGROUND
Digalloyl-resveratrol (di-GA) is a synthetic compound aimed to combine the biological effects of the plant polyhydroxy phenols gallic acid and resveratrol, which are both radical scavengers and cyclooxygenase inhibitors exhibiting anticancer activity. Their broad spectrum of activities may probably be due to adjacent free hydroxyl groups.


METHODS
Protein activation and expression were analysed by western blotting, deoxyribonucleoside triphosphate levels by HPLC, ribonucleotide reductase activity by (14)C-cytidine incorporation into nascent DNA and cell-cycle distribution by FACS. Apoptosis was measured by Hoechst 33258/propidium iodide double staining of nuclear chromatin and the formation of gaps into the lymphendothelial barrier in a three-dimensional co-culture model consisting of MCF-7 tumour cell spheroids and human lymphendothelial monolayers.


RESULTS
In HL-60 leukaemia cells, di-GA activated caspase 3 and dose-dependently induced apoptosis. It further inhibited cell-cycle progression in the G1 phase by four different mechanisms: rapid downregulation of cyclin D1, induction of Chk2 with simultaneous downregulation of Cdc25A, induction of the Cdk-inhibitor p21(Cip/Waf) and inhibition of ribonucleotide reductase activity resulting in reduced dCTP and dTTP levels. Furthermore, di-GA inhibited the generation of lymphendothelial gaps by cancer cell spheroid-secreted lipoxygenase metabolites. Lymphendothelial gaps, adjacent to tumour bulks, can be considered as gates facilitating metastatic spread.


CONCLUSIONS
These data show that di-GA exhibits three distinct anticancer activities: induction of apoptosis, cell-cycle arrest and disruption of cancer cell-induced lymphendothelial disintegration.
Madlener
S
S
Institute of Clinical Pathology, Medical University of Vienna, Vienna, Austria.
Saiko
P
P
Vonach
C
C
Viola
K
K
Huttary
N
N
Stark
N
N
Popescu
R
R
Gridling
M
M
Vo
N T-P
NT
Herbacek
I
I
Davidovits
A
A
Giessrigl
B
B
Venkateswarlu
S
S
Geleff
S
S
Jäger
W
W
Grusch
M
M
Kerjaschki
D
D
Mikulits
W
W
Golakoti
T
T
Fritzer-Szekeres
M
M
Szekeres
T
T
Krupitza
G
G
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D004396:Coloring Agents; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D005434:Flow Cytometry; D005707:Gallic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D017629:Gap Junctions / Q000187:drug effects / Q000502:physiology; D018922:HL-60 Cells / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D008168:Lung / Q000166:cytology / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D013267:Stilbenes / Q000494:pharmacology*
D000970:Antineoplastic Agents; D004396:Coloring Agents; D013267:Stilbenes; C534866:digalloylresveratrol; D005707:Gallic Acid