Sponges against cancer

Deep under the sea, there's a battle of life and death going on, with no holds barred. Sponges and other marine animals which cannot move around might seem to be defenceless against predators. Yet nothing is further from the truth. These animals produce biologically active chemical substances which provide them with an effective defence against their enemies.

Because sponges are specialized in chemical warfare, they store numerous substances which, it now appears, could be very useful for humans too. Some of these substances can help combat diseases, including cancer and the Aids virus. At the beginning of this year, for example, American researchers discovered a substance called batzelline in a glass sponge off the coast of Florida. Batzelline seems highly promising for combating pancreatic cancer. It suddenly seems that there's a lot more to a sponge than a bath aid.

Chemical weapon arsenal

The idea of using chemical substances obtained from animals as medicine has been around since the nineteen nineties. And sponges are good candidates. With around fifteen thousand species, all busy keeping their chemical weapon arsenal up to date, the potential for medicine is enormous. It is not for nothing that a massive three quarters of the patented anti-cancer substances and about thirty percent of potential new natural medicines come from sponges.

Professor Rene Wijffels of the Bioprocess technology chair group at the Wageningen University has been doing research for about ten years on how medicines from sponges can be produced sustainably and efficiently. 'In about ten percent of sponges there are substances that are toxic for cells, and are therefore a possible basis for medicines', he says. 'So there's a very high hit rate with sponges, and that makes them attractive as research subjects.'

Race

So for Wijffels, the discovery of a spectacular substance such as batzelline is no surprise. 'Throughout evolution, sponges had to defend themselves against invasion by cells trying to overrun them, which makes an effect on the cell division of enemy cells a logical defence mechanism', explains Wijffels. 'To prevent them becoming the victims of friendly fire, the substances must be selective and pick off the enemy only.' The success of batzelline is not unique. Sponges have also been discovered which produced substances that attack bacteria and viruses.

Wijffels is working with a few medicinal sponge species from the Mediterranean Sea which contain substances that work against psoriasis (a skin disease), cancer and bacteria. The aim is to breed sponges and thus eventually to produce sustainable medicines. 'Occasionally we rent a house on the coast and set up a temporary laboratory', Wijffels says. 'That guarantees you fresh seawater and fresh sponges.' But the group is also screening new sponge species.

'At the moment there is a race for the places that haven't been researched yet', says Wijffels. 'We are now planning a big screening project in the Red Sea, together with Dr. Shirley Pomponi of the Harbor Branch Oceanographic Institution in Florida. As yet, little is known about the sponge species there, in contrast to the Mediterranean, which has been thoroughly combed.' Wijffels wants to start with this project in the Spring of 2010. At present there is funding for one aio, but Wijffels hopes to get two or three on the job. Because the Red Sea species have by no means all been identified, a taxonomist will go along as well. Success takes an element of luck, but ' you also have to push a bit for that', says the Process technologist.

A nutritious soup

Wijffels thinks it is theoretically possible to synthesize the bioactive sponge molecules, but it would be difficult and expensive, as the molecules are extremely expensive. So there are very many stages to go through before you reach the end product. For this reason, science is still dependent on the sponges themselves. But catching and processing sponges is not so clever, ecologically or financially speaking. Breeding them is a better option.

Wijffels thinks the most promising approach is production with sponge cell lines, getting them to produce the desired molecules under optimal conditions. However, it is not easy to breed and keep sponge cells in a bioreactor to achieve a controlled production of biologically active substances. In this research, too, Wijffels works with the Harbor Branch Oceanographic Institution.

It seems such a simple job. You catch, or rather pick, a sponge, isolate the cells, chuck them into a nutritious soup and then breed the cells in a bioreactor. And hope that the sponge cells do what is expected of them: divide and produce medicines. But the sponges did not collaborate and refused to give away their secrets. 'Even though sponges are such simple creatures, it is amazingly difficult to breed them', explains Wijffels. Very little is known still about their growth and metabolism, and farming sponges is surprisingly difficult. In spite of their simple structure, they seem to make big demands of their environment. So it will be a while before the sponge cell production line is up and running. 'It doesn't go that fast', says Wijffels.

Provided by Wageningen University