Cancer-Causing Mutation May Be Due to Poison
Consumption of a poison produced by a South African fungus may cause high rates of liver cancer found in many areas of the world, says a Harvard Medical School hepatologist.
Assistant Professor of Medicine Dr. Mehmet Ozturk and his associates at the Massachusetts General Hospital (MGH) have isolated the poison, known as aflatoxin B, which causes a DNA sequence mutation common to many cancers.
A correlative study of tumor-suppression gene p53 demonstrated that tumor samples contained the same mutation.
Strong evidence for aflatoxin's role in liver cancer appeared when researchers found that in four out of five DNA sequences examined, one amino acid, guanine, was converted to anther, thymine. The poison had previously been demonstrated to cause guanine to mutate to thymine in the liver. Hepatitis B, which is another cause of liver cancer, does not cause this same mutation.
This evidence was further supported by studies by Ozturk and independent researchers in China and Japan. In Japan, where hepatitis B exists but there are no aflatoxins, no specific p53 mutations were observed.
Ozturk said last week that he and his team would like to correlate the research with epidemiological studies and to use the findings to try to understand the function of p53.
"We would like to demonstrate that aflatoxin can cause the p53 mutation," he said. "This would be direct proof that aflatoxin is a carcinogen."
Animals Make Use of Medicinal Plants
Humans are not alone in using medications to treat illnesses, one Harvard professor has found. Monkeys, bears and elephants utilize natural drugs to fight disease.
While studying chimpanzees in Tanzania 20 years ago, Professor of Anthropology Richard W. Wrangham discovered several plants, used medicinally by the animals. One such plant contains an oil that kills bacteria, fungi and parasitic worms. Another is an effective antibiotic, and a third induces labor or abortion.
Wrangham reported his findings to members of the American Association for the Advancement of Science (AASA) at the association's annual meeting this month. The anthropologist also told members that an oil he discovered kills cancer cells that are particularly resistant to drugs.
The researcher was joined in his efforts by phytochemist Eloy Rodriguez of University of California, Irvine, who analyzed the chemical composition of the leaves. Rodriguez told the AASA that the oil found in one plant, a relative of the sunflower, has also been shown to be effective against breast, lung and colon cancer tumors.
Wrangham's work took him from Tanzania to Uganda searching for species of animals which utilize plants for medicinal purposes. One drug, nicknamed a 'bear balm,' is used by bears to discourage ticks and a fungus similar to athlete's foot.
Drug companies are currently looking into possible uses of the plants, but widespread acceptance is at least a decade away, Wrangham said last week. Researchers are investigating one of the compounds as a pesticide against nematodes.
The discovery of these animals is particularly important, he said, because they can act as a guide for future searches for useful plants.
The anthropologist said that scientists are still trying to establish that the chimpanzees benefit from the plants they use.
"What people are trying to do is follow chimpanzees and see whether or not their conditions improve because of their intake," he said.