The gas-phase metallicity of a galaxy is a sensitive parameter to search for the imprints of the cluster environment, as it traces the star-formation history, and the gas enrichment or depletion. In this talk I will present my recent work, where I have examined the gas metallicity of star-forming galaxies in a sample of local Universe clusters, as a function of mass, luminosity, environment, HI content, stellar metallicity, and stellar age. Well defined sequences of luminosity-metallicity and stellar mass-metallicity have been found. A flattening of the slope of the mass-metallicity relation has been observed for galaxies located in the core of the two more massive clusters of the sample, suggesting that the effect of the cluster environment depends both on the galaxy mass and the host cluster mass. Based on these results I explore cluster-specific effects (e.g. ram-pressure stripping, pressure confinement etc), predicted by hydrodynamic models, capable of yielding the observed mass-dependent enhancement of the metallicity.