Metastin (45-54) amide, human

Tyr-Asn-Trp-Asn-Ser-Phe-Gly-Leu-Arg-Phe-NH2

Metastin is also known as kisspeptin 1 (KISS1). It is encoded by KISS1 gene, that is mapped to human chromosome 1q32. Metastin is a tumor suppressor protein, made up of 145 amino acids. The protein fragments contain RFamide motif at the C- terminal end. The encoded protein is expressed in the human hypothalamus, gonads, placenta, liver and pancreas. This novel peptide is mainly isolated from the human placenta.

Metastin (45-54) amide has been used in progesterone release experiments from MA-10 cells. It has also been used to induce gonadal differentiation in clownfish.

Metastin functions as a tumor suppressor via inhibiting secondary tumor growth. Activation of KISS1R (KISS1 receptor), upon binding KISS1, enhances intracellular calcium and activates MAPKs, which restricts cell motility and proliferation. Metastin acts as a potential therapeutic target for various cancers including melanoma, thyroid cancer and bladder cancer, squamous cell carcinoma of the esophagus gastric cancer, hepatocellular carcinoma and breast cancer. Metastin has a crucial role in reproduction. It regulates hypothalamic-pituitary-gonadal axis role via controlling gonadotropin-releasing hormone (GnRH) secretion and determines the onset of puberty. Mutation of the gene leads to central precocious puberty (CPP) in male and dysfunction of metastin signaling causes isolated hypogonadotropic hypogonadism (IHH) in humans and mice. Metastin has the ability to enhance the plasma levels of gonadotropins (follicle-stimulating hormone and luteinizing hormone) and stimulate ovulation in prepubertal female rats.

Metastin is an endogenous ligand to G-protein-coupled orphan receptors such as OT7T175 (also known as AXOR12) and GPR54. Novel placenta-derived hormone. The amide form of metastin is found to be 3-10 times more active than the free acid form of metastin.