Berberine is clinically important natural
isoquinoline alkaloid that affects various
biological functions, such as cell proliferation, migration and survival. The activation of
AMP-activated protein kinase (AMPK) regulates
tumor cell migration. However, the specific role of AMPK on the metastatic potential of
cancer cells remains largely unknown. The present study investigated whether
berberine induces AMPK activation and whether this induction directly affects mouse
melanoma cell migration, adhesion and invasion.
Berberine strongly increased AMPK phosphorylation via
reactive oxygen species (ROS) production. 5-Aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (
AICAR), a well-known AMPK activator, also inhibited
tumor cell adhesion and invasion and reduced the expression of epithelial to mesenchymal transition (EMT)-related genes. Knockdown of AMPKα subunits using siRNAs significantly abated the
berberine-induced inhibition of
tumor cell invasion. Furthermore,
berberine inhibited the metastatic potential of
melanoma cells through a decrease in ERK activity and
protein levels of
cyclooxygenase-2 (COX-2) by a
berberine-induced AMPK activation. These data were confirmed using specific
MEK inhibitor,
PD98059, and a
COX-2 inhibitor,
celecoxib.
Berberine- and
AICAR-treated groups demonstrated significantly decreased lung
metastases in the pulmonary
metastasis model in vivo. Treatment with
berberine also decreased the metastatic potential of A375 human
melanoma cells. Collectively, our results suggest that
berberine-induced AMPK activation inhibits the metastatic potential of
tumor cells through a reduction in the activity of the ERK signaling pathway and COX-2
protein levels.