The Translationally controlled tumor protein (TCTP) is a multifunctional Ca2+ binding and tubulin-binding protein conserved between plants and metazoans, which in mammals positively regulates cell proliferation, prevents Ca2+-dependent cell death and promotes cell plasticity. In Hydra two TCTP genes have been identified, hyTCTP1 expressed at high levels in all stem cell populations, hyTCTP2 specifically expressed in the interstitial cell lineage. HyTCTP1 and hyTCTP2 both encode the domains previously associated with TCTP functions in mammals, Drosophila and plants. Interestingly, hyTCTP2 but not hyTCTP1 is up-regulated in epithelial cells of animals that lose their interstitial cycling cells, suggesting a possible role in the adaptive response developed by the epithelial lineages to promote animal survival. In this study, we investigated the roles of hyTCTP1 and hyTCTP2 in the protection against heat-shock and in epithelial proliferation in vitro and in vivo. Neither hyTCTP1 nor hyTCTP2 seem to regulate the heat stress response in vitro. In addition, in human cells, the cell viability was not improved after heat stress when hyTCTP1 and hyTCTP2 were overexpressed in the absence of the endogenous human TCTP. These experiments did not clarify whether Hydra proteins promote cell survival after exposure to stress stimuli like heat. The potential role of hyTCTP1 and hyTCTP2 in epithelial proliferation was assessed in Hydra surviving hydroxyurea (HU) treatement. We electroporated specific silencing RNAs (siRNAs) and monitored cell proliferation over eight days. siRNA treatment efficiently down-regulated hyTCTP1 and hyTCTP2 in HU-treated animals. Moreover animals knocked-down for hyTCTP1 or hyTCTP2 showed significant changes in epithelial proliferation. In addition to the fact that we established conditions for an efficient siRNA approach to silence gene expression in HU-treated Hydra, these analyses propose a link between hyTCTP1, hyTCTP2 and epithelial cell proliferation. Additional functional analyses regarding the regulation of cell death must be performed to unravel the roles of hyTCTP1 and hyTCTP2 in epithelial Hydra.