Project description:The molecular nature of malignant tumors is well studied in vertebrates, while their evolutionary origin remains unknown. In particular, there is no evidence for naturally occurring malignant tumors in pre-bilaterian animals, such as sponges and cnidarians. This is somewhat surprising given that recent computational studies have predicted that all metazoans are prone to develop tumors. Here we provide first evidence for naturally occurring tumors in Hydra oligactis. Histological, cellular and molecular data reveal that these tumors are transplantable and caused by differentiation arrest of female gametes. Growth of tumor cells is independent from the cellular environment. Tumor bearing polyps have significantly reduced fitness. In addition, Hydra tumors show a greatly altered transcriptome that mimics expression shifts in vertebrate cancers. Therefore, this study shows, that invasive tumors have deep roots in animal phylogeny, and that early branching animals may be informative in revealing the fundamental mechanisms of tumorigenesis. We compared four samples of Hydra oligactis tumor-bearing animals to three samples of female polyps undergoing oogenesis and six samples of female asexual control polyps
Project description:The molecular nature of malignant tumors is well studied in vertebrates, while their evolutionary origin remains unknown. In particular, there is no evidence for naturally occurring malignant tumors in pre-bilaterian animals, such as sponges and cnidarians. This is somewhat surprising given that recent computational studies have predicted that all metazoans are prone to develop tumors. Here we provide first evidence for naturally occurring tumors in Hydra oligactis. Histological, cellular and molecular data reveal that these tumors are transplantable and caused by differentiation arrest of female gametes. Growth of tumor cells is independent from the cellular environment. Tumor bearing polyps have significantly reduced fitness. In addition, Hydra tumors show a greatly altered transcriptome that mimics expression shifts in vertebrate cancers. Therefore, this study shows, that invasive tumors have deep roots in animal phylogeny, and that early branching animals may be informative in revealing the fundamental mechanisms of tumorigenesis.
Project description:Head regeneration in Hydra requires the transformation of gastric tissue into a head organizer that produces a head activator and a head inhibitor. Here we report the decipherment of a long-standing question in developmental biology, the identification of the transcription factor Sp5 as a key head inhibitory component. We show that Sp5 has an apical to basal graded expression pattern in intact Hydra, its expression is induced upon Wnt/β-catenin signaling activation and when knocked-down triggers the formation of multiple heads and axes in homeostatic and regenerative conditions. Our data indicate that Sp5 acts in a feed-forward loop to robustly regulate its own expression and that Sp5 prevents head formation by repressing the Wnt3 promoter. This Sp5 mediated Wnt antagonism is conserved and was invented early in metazoan evolution to set up axial patterning.
Project description:Head regeneration in Hydra requires the transformation of gastric tissue into a head organizer that produces a head activator and a head inhibitor. Here we report the decipherment of a long-standing question in developmental biology, the identification of the transcription factor Sp5 as a key head inhibitory component. We show that Sp5 has an apical to basal graded expression pattern in intact Hydra, its expression is induced upon Wnt/β-catenin signaling activation and when knocked-down triggers the formation of multiple heads and axes in homeostatic and regenerative conditions. Our data indicate that Sp5 acts in a feed-forward loop to robustly regulate its own expression and that Sp5 prevents head formation by repressing the Wnt3 promoter. This Sp5 mediated Wnt antagonism is conserved and was invented early in metazoan evolution to set up axial patterning.