Cancer metastasis, involving multiple processes and various cytophysiological changes,
is a primary cause of cancer death and may complicate the clinical management, even lead to
death. Silibinin is a flavonoid antioxidant and wildly used for its antihepatotoxic properties
and recent studies have revealed pleiotropic anticancer and antiproliferative capabilities of
silibinin. In this study, we first observed that silibinin exerted a dose-dependent inhibitory
effect on the invasion and motility of 786-O renal cell carcinoma cells in the absence of
cytotoxicity. To look at the precise involvement of silibinin in cancer metastasis, 786-O cells
were treated with silibinin at various concentrations, up to 50 μM, for a defined period and
then subjected to gelatin zymography, casein zymography and western blot to investigate the
impacts of silibinin on metalloproteinase-2, -9, urokinase plasminogen activator (u-PA), and
MAPK pathway signaling protein, respectively. The results showed that silibinin treatment
decreased the expressions of MMP-2 and u-PA in a concentration-dependent manner and
decrease the expression of p-p38 and p-Erk1/2. Thus, silibinin may possess an anti-metastatic
activity in 786-O renal cell carcinoma cells. To further evaluate the anti-tumor effect of
silibinin, an in vivo anti-tumor study using nude mice xenograft model by a subcutaneous
inoculation of RCC 786-O cells was performed. Small solid tumors was observed on 8 days
following cell inoculation and a 70.1% reduction of tumor volume by silibinin feeding was
seen on day 44, compared to control animals.
