Using Cancer Treatment For Diseases Caused By Tapeworms
The team was able to map the genomes of tapeworms which indicated what existing drugs could provide effective treatment for the diseases; echinococcosis and cysticercosis - two potentially fatal neglected tropical diseases according to the World Health Organization (WHO).
Adult tapeworms can live in the gut for years without doing too much harm, however, the larvae they produce can cause very harmful effects in the host. They create cysts that grow for years, in time it is possible for the cysts to rupture, which can cause anaphylactic reactions or even death.
Other complications associated with tapeworms include blindness and epilepsy. A neuropeptide called Substance P is the cause of epileptic-like seizures.
Dr Matthew Berriman, senior author from the Wellcome Trust Sanger Institute, noted that the infections caused by tapeworms are just as much of a burden as malignant melanoma or multiple sclerosis in many parts of the world.
"These genome sequences are helping us to immediately identify new targets for much-needed drug treatment. In addition, exploring the parasites' full DNA sequences is driving our understanding of its complex biology, helping the research community to focus on the most effective drug candidates."
The researchers identified possible drug targets by identifying similarities between the pathogen genome sequence and the human host's DNA. Usually researchers looking for drug targets try to identify the differences between humans and the pathogen, however, in this case they looked for similarities, given that humans and tapeworms are evolutionary very similar.
After finding the similarities, the team was able to find which treatment options - already available - would be effective at treating the diseases.
In many ways these parasitic diseases are similar to cancer tumors - in the way they progress. Therefore, it's possible that some cancer treatments (involving the suppression of cell division and DNA replication) could work at treating the diseases.
In fact the researchers found that many of the most likely targets for drug treatment were the same targets as those of cancer chemotherapies.
Dr Berriman said: "Exploring the parasites' full DNA sequences is driving our understanding of its complex biology, helping the research community to focus on the most effective drug candidates."
In addition, they found that over time tapeworms lose the ability to synthesize the necessary fats for larvae development. The parasites scavenge their hosts for these fats instead, producing proteins that bind the fats, collecting them together.
Using current drugs to disrupt these proteins could be a viable treatment option.
Professor Klaus Brehm, co-author from the University of Würzburg, Germany, said:
"We have developed a new method to grow tapeworm cells in the laboratory and we're screening these cells against many of the potential drug treatments identified from the genomes. Given that so few successful treatment options are currently available, we hope that we will be able to identify and validate existing drug candidates, relieving the burden of this debilitating, overlooked disease."
The researchers also found out the reasons why other treatment options have been unsuccessful. For example, even though targeting the acetylcholinesterases has proved to be effective in treating fluke worms and malaria, in tapeworms it has little to no effect, this is because the production of acetylcholinesterases is very low in tapeworm cysts.
By assembling almost complete chromosomes of one tapeworm species, the team had numerous different drug targets to look at, enabling them to identify the ones that would work at treating the infections.
Professor Peter Hotez, Dean of the National School of Tropical Medicine at Baylor College of Medicine and Editor-in-Chief of PLoS Neglected Tropical Diseases, said:
"We need to take advantage of this genetic sequence data to find new and improved ways of coping with this problem that devastates much of the developed and developing world. Open access to these complete genomes will accelerate the pace in which we find alternative tools and treatments to combat tapeworm infections."
In a previous study, researchers found that a compound that has been used against tapeworm infection for the last six decades was effective against colon cancer metastasis in mice.
Written by Joseph Nordqvist
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