Carcinogenesis.
2011 Dec;32(12):1872-80. doi: 10.1093/carcin/bgr215. Epub 2011 Sep 26.
Polyphenol-rich sweet potato greens extract inhibits proliferation and induces apoptosis in prostate cancer cells in vitro and in vivo.
Author information
Abstract
Sweet potato
(Ipomoea batatas) leaves or greens, extensively consumed as a vegetable in
Africa and Asia, are an excellent source of dietary polyphenols such as
anthocyanins and phenolic acids. Here, we show that sweet potato greens extract
(SPGE) has the maximum polyphenol content compared with several commercial
vegetables including spinach. The polyphenol-rich SPGE exerts significant
antiproliferative activity in a panel of prostate cancer cell lines while
sparing normal prostate epithelial cells. Mechanistically, SPGE perturbed cell
cycle progression, reduced clonogenic survival, modulated cell cycle and
apoptosis regulatory molecules and induced apoptosis in human prostate cancer
PC-3 cells both in vitro and in vivo. SPGE-induced apoptosis has a
mitochondrially mediated component, which was attenuated by pretreatment with
cyclosporin A. We also observed alterations of apoptosis regulatory molecules
such as inactivation of Bcl2, upregulation of BAX, cytochrome c release and
activation of downstream apoptotic signaling. SPGE caused DNA degradation as
evident by terminal deoxynucleotidyl transferase-mediated dUTP-nick-end
labeling (TUNEL) staining of increased concentration of 3'-DNA ends.
Furthermore, apoptotic induction was caspase dependent as shown by cleavage of
caspase substrate, poly (adenosine diphosphate-ribose) polymerase. Oral
administration of 400 mg/kg SPGE remarkably inhibited growth and progression of
prostate tumor xenografts by ∼69% in nude mice, as shown by tumor volume
measurements and non-invasive real-time bioluminescent imaging. Most
importantly, SPGE did not cause any detectable toxicity to rapidly dividing
normal tissues such as gut and bone marrow. This is the first report to
demonstrate the in vitro and in vivo anticancer activity of sweet potato greens
in prostate cancer.
PMID:
21948980
PMCID:
DOI:
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