Abstract 4841: Suppression of metastasis by KP54 and non-KP54 kisspeptins

KISS1 is a secreted neuropeptide which can act as a metastasis suppressor protein. Expression of KISS1 inhibits metastatic colonization at secondary sites, rendering disseminated cells dormant. In order for KISS1 to suppress metastasis, it must be secreted outside of the cell, where furin cleaves KISS1 into kisspeptins. This cleavage liberates an internal kisspeptin, Kisspeptin-54 (KP54, K67 to F121), which is amidated and has the ability to bind a Gq/11-coupled protein receptor KISS1R. The mechanism of action for KISS1 metastasis suppression has long been assumed to be KP54 interacting with KISS1R. However, expression of KISS1R is not necessary for KISS1 metastasis suppression, and the extracellular processing of KISS1 hints at an alternative hypothesis: a different kisspeptin may be responsible for suppressing metastasis. To test this hypothesis, all possible kisspeptins were generated based on known dibasic cleavage sites (M1-Q145; M1-R56; M1-R67; M1-R124; R56-R66; R67-F121; R56-F121; R56-Q145; R67-Q145; R124-Q145) and were cloned to include the same secretion sequence as nascent KISS1. These kisspeptins (KISS1 Manufactured Peptides, or KMP) were independently expressed in B16-F10 murine melanoma cells. To test for experimental metastasis, B16-F10 cells expressing KMP were injected intravenously into the lateral tail vein of syngeneic mice and the lungs were examined for metastatic load. While KP54 suppressed metastasis, additional KMP lacking the KISS1R binding site (LRF-NH2) were able to completely suppress metastasis (p