Joined: 16 Mar 2004
|Posted: Fri Sep 05, 2008 3:39 pm Post subject: Take a Dive into Anti-Cancer Waters
|Take a Dive into Anti-Cancer Waters
It’s the bane of swimming pool owners. And every year for as long as anyone cares to remember, the midsummer heat has produced a blight of blue-green algae in Hartbeespoort Dam, turning a water playground into a pea-soup pond. Polluted rivers flowing into the dam from Johannesburg and Pretoria are responsible for the toxic smelly scum that motorists see at the dam wall.
South Africans are familiar with algae in their swimming pools, rivers and dams, but few realise that life on earth would not have existed without it.
Algae — or cyanobacteria, to use the proper scientific term — were the original and only life form on this planet from about 3.6 billion years ago. We owe our DNA to them.
Also, because they consumed vast amounts of carbon-dioxide and produced oxygen to fill the atmosphere, they created the conditions for many new forms of life to flourish, including humans. What the world needs right now in the age of global warming is a similar planet-wide pump to remove CO2 from the air and give us back our life-sustaining oxygen.
Cyanobacteria are particularly well equipped to penetrate other living cells as they have a very simple structure. They lack their own cell nucleus, and throughout evolution have readily exchanged biological information across membrane boundaries.
Now two independent teams of US scientists have discovered that certain types of blue-green algal bloom found in the South Pacific contain a powerful anti-cancer agent. If a normal-sized swimming pool full of cancer cells were treated with only three milligrams of the agent — about the weight of a grain of rice — it would kill all of the cancer cells.
A paper published online in Proceedings of the National Academy of Science recently announced the findings of a group of San Diego medical researchers and pharmacologists.
“We are excited because we have discovered a structurally unique and highly potent cancer-fighting compound,” said Dr Dwayne Stupack, an Associate Professor of Pathology at the Moores Cancer Centre at the University of California. “We envision it will be perfect for emerging technology, particularly nanotechnology, which is being developed to target cancerous tumors without toxic side effects.”
The collaborative team was spearheaded by Dr Dennis Carson, Professor of Medicine at the university. The active agent, ScA compound, was found in a type of cyanobacteria known as “mermaid’s hair”, gathered in the sea off Fiji by the laboratory of William Gerwick at Scripps Institution of Oceanography.
Stupack said the blood vessels that feed tumors are especially sensitive to ScA. Blood vessel formation is inhibited by the ScA, which activates a “death pathway” and so destroys the dangerous cells. The agent also has a direct impact on tumour cell growth.
There is strong competition amongst research laboratories throughout the world to source new therapies from ancient reserves of plant and animal life. A study of algae in a recent issue of ACS Chemical Biology independently announced that the green gunk could become cancer-fighting gold.
The team led by University of Michigan Life Sciences Institute research professor David Sherman and researcher Zachary Beck isolated an organic compound from algae that has the potential to create a promising anti-cancer drug with low-level side effects.
The real achievement was to synthesise the compound, cryptophycin 1, in large enough quantities for clinical trials. Sherman says it was extremely difficult to extract and use the native blue-green algae for high-level production using traditional approaches.
Making synthetic compounds from natural models is vital for drug development. But cryptophycins present more of a challenge than penicillin and tetracycline which lend themselves easily to synthetic copying. Sherman’s team managed to isolate an entire set of biosynthetic genes and key enzymes to manufacture the broad class of cryptophycin products.
Much excitement is stirring in scientific circles over the blue-green algal discoveries. It is ironic that it has taken the cutting-edge molecular biology of the 21st century to uncover the life-sustaining potential of the world’s oldest organisms. In general, bacteria that make up blue-green algae are by no means friendly to humankind. A 2003 department of water affairs clean-up plan for Hartbeespoort Dam warned that the algal scum could be toxic. Technicians pumping it over the dam wall to a safe dry area had to wear protective respirators and clothing.
But the bacteria have special qualities that more evolved forms of life lack. According to bio-visionary author Howard Bloom, whose book The Global Brain deals with networking in the universe, the primitive structure of cyanobacteria made it easy for them to exchange genes and survive in hostile environments.
Cyanobacteria are classed as prokaryotes, the earliest and simplest cells on earth, organisms whose genetic material is not enclosed by a nucleus. The later eukaryotes make up the more advanced forms of life like ourselves. These contain a nucleus and organelles surrounded by a cell membrane, all of which tend to limit the open sharing of information with other nearby cells.
The difference between prokaryotes and eukaryotes, says Bloom, is that the former are better networkers. In the heyday of prokaryotes Planet Earth was covered by a dense mat of networking organisms whose strengths are a model for global information exchange today.
In medical science, cyanobacteria are proving to be a source of large numbers of novel organic compounds with unique structures that lend themselves to molecular therapies. Drug development is moving towards highly specific design that targets troublesome genes and viruses in our bodies.
The networking strengths of algae are a positive force in the struggle to beat inherited and invasive diseases.
The more we learn about cancer, the clearer it becomes that genetics, viruses and the environment play a role in the development of tumours. It was logical for scientists to search for natural products like blue-green algae that can unlock cell pathways.
The San Diego team’s cancer find is a direct product of this philosophy. They say the structure of the ScA compound is well suited to nanotechnology . The ScA “incorporates spontaneously” into molecule-sized nanoparticles, important for the kind of targeted combination therapy being developed to treat cancer.