Miércoles 24 de Agosto de 2005, Ip nº 123

Brain Cancer Linked to Stem Cells
Some types of brain cancer may start with specialized stem cells, researchers said in a report that could lead to new treatments for hard-to-treat brain tumors.

Studies in mice showed that certain incurable types of brain tumor may be initiated by the primitive stem cells, which are a kind of master cell for blood and tissue, they reported Monday.

"Continued research into the biology of adult stem cells will aid in the understanding of how cancers originate and develop and may lead to possible new therapies for treating aggressive, currently incurable brain tumors," said Dr. Luis Parada of the University of Texas Southwestern Medical Center in Dallas, who led the study.

Writing in the journal Cancer Cell, Parada and colleagues said their findings support evidence that so-called adult stem cells may play a role in the development of some forms of cancer.

Stem cells share some properties with cancer cells, including an ability to live a very long time without self-destructing, as a normal cell does as it ages.

Adult stem cells are already programmed to become certain types of tissue. For example, bone marrow stem cells make various kinds of blood cells such as white blood cells, and can also become muscle when directed properly.

Similarly, there are primitive liver cells and primitive brain cells. Some of these primitive brain cells may be predisposed to form tumors, Parada's team found.

They bred genetically engineered mice that lacked a gene called p53, known for its role in preventing tumors. It repairs the errors in DNA that can result in cancer.

The mice also had a mutated version of another tumor suppressor gene called NF1.

As these gene-engineered mice matured, they all developed brain tumors.

The researchers found that stem cells in a part of the brain called the subventricular zone gave rise to malignant astrocytoma cells in the genetically engineered mice.

Malignant astrocytoma, or glioma, is one of the most common types of brain tumor in adults.

"Our results challenge current dogma, which assumes that tumors of this type arise from glial cells located throughout the brain," Parada said in a statement.

This could help explain why these tumors are so hard to cure. Surgery and radiation therapy my remove the tumor, but the cancer could be replenishing itself from the stem cells, Parada said.


  16/08/2005. Reuters.