Friday, January 15, 2010

How Sunlight Causes Skin Cells to Turn Cancerous

Study Could Point Way to Drugs to Fight Skin Cancer

MAYWOOD, Ill. -- Most skin cancers are highly curable, but require surgery that can be painful and scarring.

A new study by Loyola University Health System researchers could lead to alternative treatments that would shrink skin cancer tumors with drugs. The drugs would work by turning on a gene that prevents skin cells from becoming cancerous, said senior author Mitchell Denning, Ph.D.

The study was published Jan. 15, 2010 in the Journal of Biological Chemistry.

More than 1 million people in the United States are diagnosed with skin cancer each year. In the new study, researchers examined a type of skin cancer, called squamous cell carcinoma, that accounts for between 200,000 and 300,000 new cases per year.

Squamous cell carcinoma begins in the upper part of the epidermis, the top layer of the skin. Most cases develop on areas that receive lots of sun, such as the face, ear, neck, lips and backs of hands. There are various surgical treatments, including simple excision, curettage and electrodessication (scraping with a surgical tool and treating with an electric needle) and cryosurgery (freezing with liquid nitrogen). Removing large skin cancers can require skin grafts and be disfiguring.

Sunlight can damage a skin cell's DNA. Normally, a protein called protein kinase C (PKC) is activated in response to the damage. If the damage is too great to repair, the PKC protein directs the cell to die.

Healthy cells grow and divide in a cell-division cycle. At several checkpoints in this cycle, the cell stops to repair damaged DNA before progressing to the next step in the cycle. The new study found that the PKC gene is responsible for stopping the cell at the checkpoint just before the point when the cell divides. In squamous cell carcinoma, the PKC gene is turned off. The cell proceeds to divide without first stopping to repair its DNA, thus producing daughter tumor cells.

Denning said a class of drugs called protein kinase inhibitors potentially could shrink tumors by turning the PKC gene back on. Several such drugs have been approved by the Food and Drug Administration for other cancers. Denning is pursuing grant funding to test such drugs on animal models.

Denning is a professor in the Department of Pathology at Loyola University Chicago Stritch School of Medicine. The lead author of the study is Edward LaGory, a doctoral student at Stritch. A third co-author is Leonid Sitailo, Ph.D., a research assistant professor at Stritch.

About Loyola University Health System

Loyola University Health System (LUHS) is part of Trinity Health. Based in the western suburbs of Chicago, LUHS is a quaternary care system with a 61-acre main medical center campus, the 36-acre Gottlieb Memorial Hospital campus and more than 30 primary and specialty care facilities in Cook, Will and DuPage counties. Loyola University Medical Center’s campus is conveniently located in Maywood, 13 miles west of Chicago’s Loop and 8 miles east of Oak Brook, Ill. At the heart of the medical center campus is a 559-licensed-bed hospital that houses a Level 1 Trauma Center, a Burn Center and the Ronald McDonald® Children's Hospital of Loyola University Medical Center. Also on campus are the Cardinal Bernardin Cancer Center, Loyola Outpatient Center, Center for Heart & Vascular Medicine and Loyola Oral Health Center as well as Loyola University Chicago Stritch School of Medicine, Loyola University Chicago Marcella Niehoff School of Nursing and the Loyola Center for Fitness. Loyola's Gottlieb campus in Melrose Park includes the 255-licensed-bed community hospital, the Professional Office Building housing 150 private practice clinics, the Adult Day Care, the Gottlieb Center for Fitness, Loyola Center for Metabolic Surgery and Bariatric Care and the Loyola Cancer Care & Research at the Marjorie G. Weinberg Cancer Center at Melrose Park.

Trinity Health is a national Catholic health system with an enduring legacy and a steadfast mission to be a transforming and healing presence within the communities we serve. Trinity is committed to being a people-centered health care system that enables better health, better care and lower costs. Trinity Health has 88 hospitals and hundreds of continuing care facilities, home care agencies and outpatient centers in 21 states and 119,000 employees.