Mechanisms of grape seed procyanidin-induced apoptosis in colorectal carcinoma cells.
BACKGROUND
Grape seed procyanidins (GSP) can inhibit cell proliferation and tumorigenesis, and induce apoptosis in human breast, prostate, skin and colorectal carcinoma cell lines.


METHODS
In order to study the mechanism of apoptosis, four colorectal cell lines, HT-29, SW-480, LoVo and Colo 320DM, were used. GSP-treated cells were assessed for viability by trypan blue exclusion, for loss of mitochondrial membrane potential by rhodamine 123 staining, for increased apoptosis by annexin V labeling, and for changes in the levels of proteins involved in apoptosis by immunoblotting.


RESULTS
GSP had no significant pro-apoptotic effect on the Colo 320DM cell line. In HT-29, SW-480 and LoVo cells, GSP (12.5-50 mg/l) inhibited proliferation in a dose-dependent manner. In these three lines, GSP treatment increased the proportion of rhodamine 123-negative cells and annexin V-positive cells, while immunoblotting revealed increased levels of apoptosis activation protein, caspase-3 and the cleavage fragment of PARP (a caspase-3 substrate), but the level of Bcl-2 did not change.


CONCLUSIONS
GSP inhibited the proliferation of some colorectal carcinoma cell lines and was associated with an apoptotic mechanism involving a loss of mitochondrial membrane potential and caspase-3 activation in these cells.
Hsu
Chih-Ping
CP
Department of Medical Technology, Yuanpei University, Hsinchu, Taiwan.
Lin
Ying-His
YH
Chou
Chih-Chung
CC
Zhou
Shi-Ping
SP
Hsu
Ya-chun
YC
Liu
Chia-Ling
CL
Ku
Fu-Man
FM
Chung
Yuan-Chiang
YC