Marine Biotechnologists Treat Cancer With Mud-loving Ocean Bacteria
November 1, 2007 — Biomedicine scientists identified and sequenced the genes of a bacteria called Salinispora tropica. It produces anti-cancer compounds and can be found in ocean sediments off the Bahamas. A product called salinosporamide A has shown promise treating a bone marrow cancer called multiple myeloma, as well as solid tumors.
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It's estimated that over 1.4 million Americans will be diagnosed with cancer this year, and for more than 500,000 it will be fatal. But now, scientists have found a new weapon against it. The ocean! You run in it ... play in it ... splash in it ... but what's found at the bottom of it can kill cancer!
"This bacteria makes a really potent anti cancer agent," Bradley Moore, Ph.D., marine biochemist at Scripps Institution of Oceanography in San Diego, Calf., told Ivanhoe.
The bacterium was discovered in 1991, but just recently researchers at the Scripps Institution of Oceanography unlocked the genomic sequence, revealing this bacteria's cancer fighting potential.
"That's how new drugs are discovered. We really have to go out there and grow bacteria, look at the genomes," Dr. Moore said. "What we've recently been able to do is take the enzymes out of the cell, put them in a test tube, and then play God and manipulate these enzymes and make new chemistry."
And make new drugs. "There's a major search underway for better drugs to treat cancer and one way to find these new medicines is to look to nature," Paul Jensen, Ph.D., associate research scientist at Scipps Institution of Oceanography, told Ivanhoe.
And unlike most of the drugs used to fight cancer today -- this bacterium is not found on land.
"When you look at a globe ... there's more blue than there is land," said Dr. Moore.
Revealing that our oceans maybe an even more valuable resource than we realize. A clinical trial is already underway. A San Diego pharmaceutical company is using it to treat patients that have a form of bone marrow cancer -- and it could soon be tested to treat other cancers.
The American Geophysical Union and The American Society for Microbiology contributed to the information contained in the TV portion of this report.
BACKGROUND: Researchers at the Scripps Institution of Oceanography have discovered bacteria in mud from the Bahamas with the potential to help fight cancer. Now that the bacteria's genome has been successfully sequenced, that information is now being used by a pharmaceutical company to treat bone marrow cancer patients.
ABOUT THE BACTERIA: The bacteria known as Salinispora tropica is related to the Streptomyces genus, a land-based group of bacteria considered to be the kinds of antibiotic-producing organisms. First discovered in 1991 in shallow ocean sediment off the Bahamas, it took several years to successfully sequence Salinispora's genome, revealing that this mud-dwelling bacteria produces natural antibiotics and anti-cancer products. Researchers found that 10% of the bacteria's genome is dedicated to producing molecules for antibiotics and anti-cancer agents, compared to only 6% to 8% of most organisms' genomes. The decoding opens the door to a broad range of possibilities for isolating and adapting potent molecules the marine organism naturally employs for chemical defense, scavenging for nutrients, and communication in its ocean environment. One compound, salinosporamide A, is currently in human clinical trials for treating multiple myeloma, a cancer of plasma cells in bone marrow, as well as for treating solid tumors.
SEQUENCING ABCs: Genome sequencing is figuring out the order of DNA nucleotides, or bases, in a genome: the building blocks that make up an organism's DNA. The entire genome can't be sequenced at once because DNA sequencing methods can only handle short stretches of DNA at a time. So scientists break the DNA into small pieces, sequence those, and then reassemble the pieces into the proper order to sequence the entire genome. There are two ways of doing this. The "clone-by-clone" approach involves breaking the genome into chunks, called clones, each about 150,000 base pairs long, then using genome mapping techniques to figure where each belongs in the genome. Next they cut the clones into smaller, overlapping pieces of about 500 base pairs each, sequence those pieces, and use the overlaps to reconstruct the sequence of the entire clone.
An alternative strategy, called the "whole-genome shotgun method," involves breaking the genome into small pieces, sequencing them, and then reassembling the pieces into the full genome. The clone-by-clone approach is more reliable, but slow and time-consuming. The shotgun method is faster, but it can be extremely difficult to accurately put together so many tiny pieces of sequence all at once Neither of these approaches proved sufficient to completely solve the Salinispora tropica genomic puzzle, however. Instead, information about the natural chemistry of the organism helped close the sequencing gap.
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