Methylselenol has been hypothesized to be a critical
selenium (Se) metabolite for anticancer activity in vivo, and our previous study demonstrated that submicromolar
methylselenol generated by incubating methionase with seleno-
l-methionine inhibits the migration and invasive potential of HT1080
tumor cells. However, little is known about the association between
cancer signal pathways and
methylselenol's inhibition of
tumor cell invasion. In this study, we demonstrated that
methylselenol exposure inhibited cell growth and we used a
cancer signal pathway-specific array containing 15 different signal transduction pathways involved in
oncogenesis to study the effect of
methylselenol on cellular signaling. Using real-time RT-PCR, we confirmed that cellular
mRNA levels of
cyclin-dependent kinase inhibitor 1C (CDKN1C),
heme oxygenase 1, platelet/endothelial cell adhesion molecule, and
PPARgamma genes were upregulated to 2.8- to 5.7-fold of the control.
BCL2-related protein A1, hedgehog interacting
protein, and p53 target zinc finger
protein genes were downregulated to 26-52% of the control, because of
methylselenol exposure. These genes are directly related to the regulation of cell cycle and apoptosis.
Methylselenol increased apoptotic cells up to 3.4-fold of the control and inhibited the extracellular-regulated
kinase 1/2 (ERK1/2) signaling and cellular myelocytomatosis oncogene (c-Myc) expression. Taken together, our studies identify 7 novel
methylselenol responsive genes and demonstrate that
methylselenol inhibits ERK1/2 pathway activation and c-Myc expression. The regulation of these genes is likely to play a key role in G1 cell cycle arrest and apoptosis, which may contribute to the inhibition of
tumor cell invasion.