The freshwater polyp Hydra is a cnidarian, a simple multicellular organism that has been around for over 600 million years and plays a key role in early animal evolution.
Summary: Can cancer ever be completely defeated? Researchers have now reached a sobering conclusion: “cancer is as old as multi-cellular life on Earth and will probably never be completely eradicated,” says one expert, following his latest research results. The researchers have now achieved an impressive understanding of the roots of cancer, providing proof that tumors indeed exist in primitive and evolutionary old animals.
The causes of tumors are the so-called cancer genes. As from when evolution started producing tumors is an issue that the scientists Tomislav Domazet-Lošo and Diethard Tautz from the Max Planck Institute for Evolutionary Biology in Plön have been investigating for several years, using bio-informational methods and databases that they have developed in-house. “During the search for the origin of the cancer gene, we unexpectedly made a discovery in the ancient group of animals,” explains Domazet-Lošo. He is one of the authors of the present study and is currently working at the Ruder Boškovic Institute and the Catholic University of Croatia in Zagreb. “Our data predicted that the first multi-cellular animals already had most of the genes which can cause cancer in humans.” What was missing until now was, on the one hand, evidence that these animals can actually suffer from tumors and, on the other, the molecular understanding of the mechanisms of tumor formation in these simple animals.
According to the research team led by Bosch, the findings of primordial tumors in Hydra are a breakthrough step in that direction: “Our research reconfirms that primordial animals such as Hydra polyps provide an enormous amount of information to help us understand such complex problems as ‘cancer’. Our study also makes it unlikely that the ‘War on Cancer’ proclaimed in the 1970s can ever be won. However, knowing your enemy from it origins is the best way to fight it, and win many battles,” says Bosch.
Here’s the abstract:
The molecular nature of tumours is well studied in vertebrates, although their evolutionary origin remains unknown. In particular, there is no evidence for naturally occurring tumours in pre-bilaterian animals, such as sponges and cnidarians. This is somewhat surprising given that recent computational studies have predicted that most metazoans might be prone to develop tumours. Here we provide first evidence for naturally occurring tumours in two species of Hydra. Histological, cellular and molecular data reveal that these tumours are transplantable and might originate by differentiation arrest of female gametes. Growth of tumour cells is independent from the cellular environment. Tumour-bearing polyps have significantly reduced fitness. In addition, Hydra tumours show a greatly altered transcriptome that mimics expression shifts in vertebrate cancers. Therefore, this study shows that spontaneous tumours have deep evolutionary roots and that early branching animals may be informative in revealing the fundamental mechanisms of tumorigenesis. (paywall)
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