Emerging roles for the relaxin/RXFP1 system in cancer therapy.

A role for the hormone relaxin in cancer was described well before the receptor was identified. Relaxin predominantly increases the growth and invasive potential in cancers of different origins. However, relaxin was also shown to promote cell differentiation and to act in a dose-and time-dependent manner in different cancer cell models used. Following the discovery of the relaxin like family peptide receptor 1 (RXFP1) as the cellular receptor for RLN1 and RLN2, research has focussed on the ligand interaction with the large extracellular domain of RXFP1 and resulting molecular signaling mechanisms. RXFP1 activation mediates anti-apoptotic functions, angiogenesis and chemoresistance in cancer cells. This minireview summarizes the known biological functions of RXFP1 activation in different cancer entities in-vitro and in-vivo and outlines possible mechanisms to therapeutically address the relaxin-RXFP1 system in cancer cells.