Using Algae in Anti-Cancer Drugs Could Cut Costs
Biologists have engineered a new designer drug paving the way for larger quantities at lower prices.
-- by Suzanne Boothby
UC San Diego biologists have succeeded in genetically engineering algae to produce a new “designer” cancer drug.
After seven years of work, researchers found that Chlamydomonas reinhardtii, a green algae used widely in biology labs as a genetic model organism, can produce a wide range of human therapeutic proteins.
Their discovery, published in the online issue of The Proceedings of the National Academy of Sciences this week, creates new potential for making these and other “designer” proteins in larger quantities and at lower prices than can currently be made from mammalian cells. Also, the algae is abundant, resilient, and efficient at folding complex proteins.
“Because we can make the exact same drug in algae, we have the opportunity to drive down the price down dramatically,” said Stephen Mayfield, a professor of biology at UC San Diego and director of the San Diego Center for Algae Biotechnology or SD-CAB, a consortium of research institutions that is also working to develop new biofuels from algae.
The algae proteins would have two functions—one contains an antibody, which can find and attach to a cancer cell and another that contains a toxin that kills the bound cancer cells. Pharmaceutical companies now create these fusion proteins in a more complicated, two-step process using Chinese hamster cells. But the algae version is identical and could be produced for a fraction of the price, according to the scientists.
The Expert Take
This new method could be used to make novel complex drugs to treat cancer or other human diseases in new ways.
"You can't make these drugs in bacteria, because bacteria are incapable of folding these proteins into these complex, three-dimensional shapes," says Mayfield. "And you can't make these proteins in mammalian cells because the toxin would kill them."
Mayfield first got a hint about the potential of algae while working with it to develop a malaria vaccine.
“What the development of the malarial vaccine showed us was that algae could produce proteins that were really complex structures, containing lots of disulfide bonds that would still fold into the correct three-dimensional structures," he said. "Antibodies were the first sophisticated proteins we made. But the malarial vaccine is complex, with disulfide bonds that are pretty unusual. So once we made that, we were convinced we could make just about anything in algae."
The nutrient-rich properties of algae, and particularly chlorella, a unicellular green algae, have been praised by the holistic world for years as a supplement to help fight cancer.
"Chlorella…contains the highest chlorophyll level per ounce of any plant, as well as protein (nearly 58 percent), carbohydrates, all of the B vitamins, vitamins C and E, amino acids (including all nine essential ones), enzymes, and rare trace minerals," wrote Phyllis A. Balch In Prescription for Dietary Wellness.
Source and Method
Mayfield said producing this particular fusion protein was straightforward because it involved fusing two domains—one to recognize and bind to cancer cells and another to kill them.
He suspects in the future this same method could be used to engineer algae to produce more complex proteins with multiple domains.
The future looks bright for algae proteins that can create designer drugs made less expensively than current models.
“At some point you can start thinking about medicine the same way we think about assembling a computer, combining different modules with specific purposes,” Mayfield said. “We can produce a protein that has one domain that targets the kind of cell you want to impact, and another domain that specifies what you want the cell to do."
A 2007 study also found potential in algae’s ability to fight disease. A compound, called cryptophycin 1, held so much promise as an anti-cancer drug that organic chemists worked to make a synthetic form of the compound in large enough quantities for clinical trials.