Prostate cancer is one of the most prevalent
malignancies and is the second leading cause of
cancer-related deaths in men. Fruit and vegetable consumption is a novel, non-toxic therapeutic approach that can be used to prevent and treat
prostate cancer. Citrus peels and their extracts have been reported to have potent pharmacological activities and health benefits due to the abundance of
flavonoids in citrus fruits, particularly in the peels. Our previous studies demonstrated that
oral administration of
Gold Lotion (GL), an extract of multiple varieties of citrus peels containing abundant
flavonoids, including a large percentage of polymethoxyflavones (PMFs), effectively suppressed
azoxymethane (AOM)-induced colonic
tumorigenesis. However, the efficacy of GL against
prostate cancer has not yet been investigated. Here, we explored the anti-
tumor effects of GL using a human prostate
tumor xenograft mouse model. Our data demonstrated that treatment with GL by both intraperitoneal (i.p.) injection and
oral administration dramatically reduced both the weights (57%-100% inhibition) and volumes (78%-94% inhibition) of the
tumors without any observed toxicity. These inhibitory effects were accompanied by mechanistic down-regulation of the
protein levels of inflammatory
enzymes (
inducible nitric oxide synthase, iNOS and
cyclooxygenase-2, COX-2),
metastasis (matrix
metallopeptidase-2,
MMP-2 and
MMP-9), angiogenesis (
vascular endothelial growth factor,
VEGF), and proliferative molecules, as well as by the induction of apoptosis in prostate
tumors. Our findings suggest that GL is an effective anti-
cancer agent that may potentially serve as a novel therapeutic option for
prostate cancer treatment.