University at Buffalo - The State University of New York

Published: November 18, 2004

By LOIS BAKER
Contributing Editor

Light—its absence, as well as the particular properties of one of its spectra—may form the basis for promising new treatments for breast cancer.

UB chemists and epidemiologists are delving into the effects of light on tumor development and tumor destruction through several new studies with grants totaling more than $1.3 million from the U.S. Department of Defense (DOD).

The most far-reaching investigation is an examination of the role of melatonin, a hormone produced during darkness, as a predictor of breast-cancer development. Abnormally low levels of melatonin are thought to increase the risk of breast cancer. Coincidentally, breast-cancer rates in Western industrialized nations, where plentiful electricity allows people to be active throughout the night, are 10 times higher than in less affluent countries.

"The theory that prolonged exposure to light during the night is a risk factor for breast cancer is supported by results from several studies of women who do night shift work, such as nurses and flight attendants," said Paola Muti, principal investigator on the new study and professor of social and preventive medicine in the School of Public Health and Health Professions.

"Moreover, studies conducted in cell cultures and in animals have shown consistently that melatonin has anti-cancer properties, perhaps by strengthening the immune system and reducing cell proliferation and free-radical production," Muti said. "But few studies have assessed directly the relation of melatonin production to breast-cancer incidence."

In her study, funded by a $471,000 grant from the DOD, Muti will measure a marker of melatonin levels in urine samples from 10,788 healthy women who took part in an Italian breast-cancer study that began in 1987. She will compare melatonin levels in women in the study who have remained healthy with levels in women who developed breast cancer between the study's start and 2004.

"This study will be able to indicate whether melatonin levels may predict the occurrence of breast cancer," Muti said.

Taking advantage of the properties of certain light wave lengths, a group of UB chemists are studying ways to increase the effectiveness of photodynamic therapy, or PDT, to treat breast cancer. Photodynamic therapy, which was developed by scientists at Roswell Park Cancer Institute, employs red-spectrum light to activate a light-sensitive chemical, called a photosensitizer, that accumulates specifically in cancer cells. When exposed to this light spectrum, the activated chemical destroys the cancer cells.

Youngjae You, research assistant professor in the Department of Chemistry, College of Arts and Sciences, is developing a new generation of photosensitizers that bind to a specific receptor on breast-cancer cells, making the treatment more effective.

In another project, David Donnelly, research assistant in the Department of Chemistry, is developing a photosensitizer that is a more efficient absorber of light and will respond to light of longer wave lengths that can reach deeper tumors without damaging surrounding healthy tissue. The new photosensitizer could decrease the long-term skin sensitivity to natural light following PDT, which is a drawback of current photosensitizers.

Michael Detty, professor of chemistry, is studying ways to use PDT to damage or inactivate a protein that removes anticancer drugs from breast-cancer cells, diminishing the effectiveness of chemotherapy. He cites a recent study showing that 68 percent of breast tumors with low expression of the protein responded to chemotherapy, while only 17 percent of tumors with high expression responded to chemotherapy.

Detty is working to develop a chemical that binds to the protein, which then can be combined with a photosensitizer and exposed to red light. PDT will damage the protein, allowing chemotherapy to be more effective.

The PDT research projects are supported by U.S. DOD grants totaling $591,284.

In yet another approach to treating breast cancer, Jamie Heimburg, doctoral student in the Department of Microbiology and Immunology, is conducting preliminary research on a potential target for a vaccine that, if successful, could prevent breast-tumor cells from spreading and may boost immune-system response to cancer cells.

Marcia Boehmke, research assistant professor in the School of Nursing, is concerned with the stress breast-cancer diagnosis and treatment creates in women's lives. She is developing the first instrument to identify symptoms of distress following cancer therapy, with the goal of recognizing, addressing and managing the life-long consequences of breast-cancer treatment.

These two projects are funded by a total of $289,721 from the DOD.