Kisspeptins (Kp),
peptide products of the
Kisspeptin-1 (KISS1) gene are endogenous
ligands for a
G protein-coupled receptor 54 (GPR54). Previous findings have shown that KISS1 acts as a
metastasis suppressor in numerous
cancers in humans. However, recent studies have demonstrated that an increase in KISS1 and GPR54 expression in human
breast tumors correlates with higher
tumor grade and metastatic potential. At present, whether or not Kp signaling promotes
breast cancer cell invasiveness, required for
metastasis and the underlying mechanisms, is unknown. We have found that
kisspeptin-10 (Kp-10), the most potent Kp, stimulates the invasion of human
breast cancer MDA-MB-231 and Hs578T cells using
Matrigel-coated Transwell chamber assays and induces the formation of invasive stellate structures in three-dimensional invasion assays. Furthermore, Kp-10 stimulated an increase in matrix
metalloprotease (MMP)-9 activity. We also found that Kp-10 induced the transactivation of
epidermal growth factor receptor (EGFR). Knockdown of the GPCR scaffolding
protein, β-
arrestin 2, inhibited Kp-10-induced EGFR transactivation as well as Kp-10 induced invasion of
breast cancer cells via modulation of MMP-9 secretion and activity. Finally, we found that the two receptors associate with each other under basal conditions, and FRET analysis revealed that GPR54 interacts directly with EGFR. The stability of the receptor complex formation was increased upon treatment of cells by Kp-10. Taken together, our findings suggest a novel mechanism by which Kp signaling via GPR54 stimulates
breast cancer cell invasiveness.