by Kristen Philipkoski
Wired
Researchers have discovered cells that continually replenish leukemia tumors. Killing these infinitely renewing cells could be key to halting the disease.
A genetic mutation causes the leukemia cells to divide out of control and allows tumors to grow, according to research published in the Aug. 12 issue of the New England Journal of Medicine. Previously, no one knew the exact identity of these cells.
Isolating these so-called cancer stem cells paves the way for creation of drugs to target them. Specifically destroying leukemia's stem cells -- the source of the cancer -- could eliminate the disease better than treatments that randomly kill cancer cells.
The work provides opportunities for pharmaceutical companies to investigate drugs that could inhibit the development of cancer stem cells, said Irving Weissman, a stem-cell researcher at Stanford who contributed to the study.
The study focused on the stem cells that lead to chronic myelogenous leukemia. In recent years, researchers have discovered several similar stem cells, including those behind acute myeloma leukemia, two brain cancers and breast cancer. Finding cancers' stem cells is a rapidly growing area of research, Weissman said, and it will be a main focus of the Institute of Cancer and Stem Cell Biology, which he heads at Stanford. The institute was established in December 2002 through an anonymous $12 million donation.
Cancer stem cells make up only a tiny number of the total cancer cells in a leukemia patient, which makes the cells next to impossible to find. In order to grow a larger number of them, the researchers took samples from healthy patients and from patients with chronic myelogenous leukemia. They separated the various types of leukemia cancer cells into separate dishes to find which ones could replenish themselves -- an indication that they are likely cancer stem cells. Further tests confirmed they had found the cells they were looking for.
The promise of this line of research can only be realized, Weissman said, by studying adult stem cells as well as embryonic stem cells, which are controversial because an early embryo is destroyed when researchers remove stem cells from it. While in this study volunteers could provide samples, that won't be the case for all types of disease. An alternative is to take the stem cells from embryos that carry a genetic defect for specific diseases.
"There are whole areas of tissues you can't get at, but which human embryonic stem cells almost certainly will develop daily," Weissman said.
Scientists at the Reproductive Genetics Institute, a private clinic in Chicago, are also studying stem cells to discover the origins of disease. They have isolated 12 new stem-cell lines from genetically flawed human embryos, providing stem cells that will specifically develop seven diseases, including two forms of muscular dystrophy, thalassemia, Fanconi anemia, fragile X syndrome, Marfan syndrome and a type of neurofibromatosis. Couples undergoing in vitro fertilization donated the embryos after the clinic performed prenatal genetic screening.
The Chicago clinic funded the research privately. President Bush declared on Aug. 9, 2001, that only research on existing stem-cell lines would qualify for federal funding. He said at the time that 64 stem-cell lines were available. Today, the National Institutes of Health lists 21 lines that are available for federal funding.
Wired
Researchers have discovered cells that continually replenish leukemia tumors. Killing these infinitely renewing cells could be key to halting the disease.
A genetic mutation causes the leukemia cells to divide out of control and allows tumors to grow, according to research published in the Aug. 12 issue of the New England Journal of Medicine. Previously, no one knew the exact identity of these cells.
Isolating these so-called cancer stem cells paves the way for creation of drugs to target them. Specifically destroying leukemia's stem cells -- the source of the cancer -- could eliminate the disease better than treatments that randomly kill cancer cells.
The work provides opportunities for pharmaceutical companies to investigate drugs that could inhibit the development of cancer stem cells, said Irving Weissman, a stem-cell researcher at Stanford who contributed to the study.
The study focused on the stem cells that lead to chronic myelogenous leukemia. In recent years, researchers have discovered several similar stem cells, including those behind acute myeloma leukemia, two brain cancers and breast cancer. Finding cancers' stem cells is a rapidly growing area of research, Weissman said, and it will be a main focus of the Institute of Cancer and Stem Cell Biology, which he heads at Stanford. The institute was established in December 2002 through an anonymous $12 million donation.
Cancer stem cells make up only a tiny number of the total cancer cells in a leukemia patient, which makes the cells next to impossible to find. In order to grow a larger number of them, the researchers took samples from healthy patients and from patients with chronic myelogenous leukemia. They separated the various types of leukemia cancer cells into separate dishes to find which ones could replenish themselves -- an indication that they are likely cancer stem cells. Further tests confirmed they had found the cells they were looking for.
The promise of this line of research can only be realized, Weissman said, by studying adult stem cells as well as embryonic stem cells, which are controversial because an early embryo is destroyed when researchers remove stem cells from it. While in this study volunteers could provide samples, that won't be the case for all types of disease. An alternative is to take the stem cells from embryos that carry a genetic defect for specific diseases.
"There are whole areas of tissues you can't get at, but which human embryonic stem cells almost certainly will develop daily," Weissman said.
Scientists at the Reproductive Genetics Institute, a private clinic in Chicago, are also studying stem cells to discover the origins of disease. They have isolated 12 new stem-cell lines from genetically flawed human embryos, providing stem cells that will specifically develop seven diseases, including two forms of muscular dystrophy, thalassemia, Fanconi anemia, fragile X syndrome, Marfan syndrome and a type of neurofibromatosis. Couples undergoing in vitro fertilization donated the embryos after the clinic performed prenatal genetic screening.
The Chicago clinic funded the research privately. President Bush declared on Aug. 9, 2001, that only research on existing stem-cell lines would qualify for federal funding. He said at the time that 64 stem-cell lines were available. Today, the National Institutes of Health lists 21 lines that are available for federal funding.
