Friday, August 3, 2012

Some Cancers May Have Stem Cells

Experiments with mice are looking into the possibility of cancer stem cells. Though stem cells are the basis for growing healthy cells in the human body, there are researchers who think malignant stem cells exist as well. It is speculated that these cancer stem cells create tumors and can grow back after resisting treatment. Lisa Esposite of HealthDay reports that three experiments with mice indicate the progress made in this area.

One study, reported in the August 1st edition of Nature, involves mice with glioblastoma, a lethal malignant brain tumor. A gene was developed that is only active in healthy adult brains and market it with a florescent protein so it could be observed. A specific virus gene was added – one that self-destructs if treated with acyclovir, a drug.

The transgene was placed in mice engineered to develop glioblastoma, and for every mouse, part of the malignant brain tumor cells were green Then the mice with tumors were given acyclovir – and the tumors stopped growing.

In another experiment, the drug temozolomide was given to mice with tumors. The drug got rid of all currently dividing tumor cells – but when the therapy stopped, the cells resumed dividing. The tumors marked with green to show they behave similar to stem cells were not eradicated.
In a third experiment, temozolomide was administered to eliminate highly dividing cells and ganciclovir was also administered to get rid of stem cells. When both drugs were used, tumors were unable to form.

So the theory has been formed that for a solid tumor formed by cancer stem cells in a hierarchical fashion, it is critical to provide themotherapy to the cancer stem cells, a researcher has noted. This research is in its early stages and is not applicable to cancers other than glioblastoma.
Another study in the same issue of Nature found that, in Brussels, a subset of tumor cells in mice with squamous skin cancer seemed to function in a manner similar to the stem cells of normal tissue.

And Dutch researchers examining the intestinal tumors of mice, in a study found in the August 1st issue of Science, found indications of possible cancer stem cells.

Unlike some earlier studies, the research above has been examining tumors in their natural environment (not tumors transplanted into the animals). Some studies are already under way to target new drugs to cancer stem cells.

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