Thursday, July 22, 2004

Linda McKasson, of Hawaii Biotech in Aiea, looks over a vial of carotenoid derivatives, solids that are dissolved for analysis in cancer research.

UH finds link
in stopping
tumor growth

In a major discovery, chemicals
that give vegetables their color
show cancer-fighting properties

Pigments that give yellow, red and green vegetables their colors stop tumors from growing and can prevent cancer by keeping cells "talking" to each other, University of Hawaii cancer researchers have discovered.

People who eat large amounts of these vegetables tend to have a lower risk of cancer and heart and eye diseases, said Dr. John Bertram, professor of cell and molecular biology at the John A. Burns School of Medicine and Cancer Research Center.

University of Hawaii Reporting on his group's research yesterday at the BioScience 2004 conference in Glasgow, Scotland, Bertram said the study found the pigments, called carotenoids, increased activity of a molecule called connexin 43.

The molecule forms small channels between cells and connects nearly all cells in the body, he said. Cells exchange nutrients through the channels and many signals responsible for normal cellular growth.

But most tumor cells have lost the ability to communicate and become isolated from normal cells, according to reports on his work by BioScience, BBC News and

Treating normal mouse cells with carotenoids improved communication in the cells and prevented cancer-causing chemicals from forming cancer, Bertram said.

Communication between cells also was restored when three types of human tumors were treated with carotenoids. The cells behaved more normally in cultures and when grown in laboratory animals, he said.

Marc Goodman, Cancer Research Center of Hawaii researcher, said that "one of the hallmarks of cancer is unregulated growth," when cancer cells are no longer getting appropriate signals to stop growing.

He said Bertram has shown chemicals such as carotenoids help to regulate growth by ensuring there is communication between cells. As a result, he said, there is "tremendous potential" for types of carotenoids not only to prevent cancer, but to augment cancer therapy.

Bertram advises eating carotenoid-rich vegetables and fruits and is collaborating with Hawaii Biotech Inc. to develop easily absorbed carotenoid tablets for use to prevent cancer, liver and eye disease and damage to the heart.

David Watumull, president and chief executive officer of the biopharmaceutical company in Aiea, said data on three species of animals shows new carotenoids being developed can prevent proliferation of cancer cells and prevent damage during or after cardiovascular procedures such as angioplasty.

Bertram said in Glasgow that the researchers looked at five or six carotenoids, and they all appear able to restore communication between cells.

He also found that activity of connexin 43 molecules could be increased by retinoids, another cancer preventive agent derived from vitamin A, especially when combined with carotenoids.

"This is a new mechanism whereby tumor growth can be interrupted," he reported. "Connexin 43 may be a potential new target for cancer treatment."

He said carotenoids and retinoids might stop cancers from forming by keeping cells communicating. "Prevention is always better than the cure, and prevention of cancer should be a priority goal for health care professionals."

Studies were presented to the conference showing up to 70 percent of human cancer is preventable and 40 percent could be associated with diet.

Carotenoid tablets are available, but they do not dissolve well in water and are not easily absorbed in the body, Bertram said.

The new versions he has developed with Hawaii Biotech are water-dispersible and up to 100 times more effective in cell cultures, mostly because of better absorption, he said.

Rapid and more complete absorption of carotenoids taken by mouth "could offer a significant advantage in future cancer prevention studies," he said.

Watumull said Hawaii Biotech is in preclinical stages of development, looking at manufacturing new compounds according to U.S. Food and Drug Administration standards. Human clinical trials on the new tablets will be done in about a year, he said.

"You will absorb our compounds better and have the right kind for the disease you are at risk for, because different ones (carotenoids) accumulate in different tissues." he said. "There may be one best for cardiovascular disease and a different one for prostate cancer."

Cancer Research Center of Hawaii
UH John A. Burns School of Medicine
BioScience 2004

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