KISS1 and melanoma: The KISS1 gene was discovered in 1996 as a metastasis suppressor gene in malignant melanoma cells [14], and it was later heavily enrolled in the control of reproduction, with functions related to the sexual differentiation of the brain, the release of hypothalamic gonadotropin-releasing hormone (GnRH), puberty onset, and the maintenance of reproduction in adults [15,16,17,18].