Discovery has implications for stem cell research and all types of cancer

MINNEAPOLIS / ST. PAUL (May 5, 2008)—Researchers at the Masonic Cancer Center, University of Minnesota may have discovered the Achilles' heel of leukemia, a disease that is often fatal in children and adults. Their finding is a major contribution toward resolving the long-standing medical controversy about which cells are the source of leukemias, cancer of the blood and bone marrow, and possibly other cancers.

An article about this laboratory discovery is published in the May issue of the journal Cancer Cell. This research study was sponsored with a grant from the National Cancer Institute.

"Determining whether more mature progenitor cells or the younger stem cells in the process of forming are at greatest risk for leukemia has been a research controversy for a long time," said John Kersey, M.D., pediatric cancer researcher at the Masonic Cancer Center and lead investigator on this study.

"We found that it is the young stem cells that are at greatest risk," said Kersey. "The young at-risk cells are extremely rare—less than one in 1,000 stem cells—but it is in that one cell that leukemia starts; that stem cell is the Achilles' heel of leukemias."

Kersey and his colleagues made this discovery in connection with acute leukemia, the most common childhood cancer. Current treatments cure more than 80 percent of children older than two years when diagnosed with ALL. That cure rate drops to much lower levels in infants who have leukemia caused by the cancer gene known as MLL-AF9.

For this laboratory study, Kersey and his colleagues Weili Chen and Ashish Kumar, M.D., Ph.D., used stem cells from young mice created to contain abnormal cells with the rearranged gene called MLL-AF9. The researchers sorted the candidate cells into the young stem cells or the more mature progenitor cells. They found that the young stem cells containing the MLL-AF9 gene were the ones that caused leukemia in the mice that is similar to the type that affects infants.

"We believe our finding has significance for all types of cancer because stem cells may be the Achilles' heel in most if not all human cancers," said Kersey. "It points out the critical need for research to better understand the complicated intricacies of stem cells and their potential for healing as well as harm."

The next step for Kersey and his laboratory team is to focus on how to block the pathway of the abnormal MLL-AF9 cancer gene from progressing into leukemia. He is hopeful that, within five years, strategies may be available to attack the MLL-AF9 and other cancer genes on the stem cell, and prevent or treat leukemia and other cancers.

Working with Kersey on this research study were Weili Chen, Ashish R. Kumar, Wendy A. Hudson, Quanzhi Li, Baolin Wu, Rodney A. Staggs, Erik A. Lund, and Thein N. Sam.

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The Masonic Cancer Center, University of Minnesota, is part of the University's Academic Health Center. It is a Comprehensive Cancer Center designated by the National Cancer Institute. For more information about the Masonic Cancer Center, call the information line at 612-624-2620 or toll-free in Minnesota, Iowa, Wisconsin, and the Dakotas at 1-888-CANCER MN (1-888-226-2376), or visit the Web at www.cancer.umn.edu.

Media contacts:

Masonic Cancer Center: Mary Lawson, Public Relations Director, 612-624-6165, 612-203-0819 (cell), mlawson@umn.edu

University of Minnesota Academic Health Center: Sara E. Buss, 612-626-7037