Navigation Links
Evidence Grows That Cancer Has Its Own Stem Cells

By Lisa Esposito
HealthDay Reporter

WEDNESDAY, Aug. 1 (HealthDay News) -- While scientists hotly debate the existence of cancer stem cells, three related new studies, all conducted on mice, provide some supporting evidence.

Stem cells are the foundation for healthy cell growth in the body. Some researchers believe that malignant stem cells also exist -- so-called cancer stem cells that generate tumors and resist treatment by simply re-growing afterward.

"Cancer stem cells are still controversial, but with progress in studies like these, it's less about whether they exist and more about 'what does this mean?'" said Dr. Max Wicha, director of the University of Michigan Comprehensive Cancer Center, who is familiar with the new findings.

Appearing online Aug. 1 in the journal Nature, one study involved mice with glioblastoma, the most common malignant brain tumor in adults and a particularly lethal cancer.

Researchers led by Luis Parada, a professor and chairman of developmental biology at University of Texas Southwestern Medical Center in Dallas, genetically engineered mice so they would develop glioblastoma.

Then they developed a "transgene" designed only to be active in stem cells in healthy adult brains. They marked this transgene with a green fluorescent protein so the researchers would see it wherever it appeared.

To this transgene they added a virus gene that would self-destruct if treated with the drug acyclovir.

Next, they put the transgene into the mice, which developed tumors. In every mouse, a subset of cells in the malignant brain tumor cells was green.

"The next obvious question was: Since the 'transgene' was designed to be active in stem cells, might these be stem cells?" Parada said.

The researchers gave the drug acyclovir to mice that had tumors. "And when we did that, the tumors stopped growing," he said.

The investigators also looked at "regular" cancer cells and found that those cells were not green. And while tumor cells divided, the green cells rested.

"That observation was reminiscent of a normal stem cell environment," Parada said. "If we go back to adult stem cells, the stem cells are mostly quiescent. That means they rarely divide."

In healthy brain tissue, he said, a few stem cells eventually enter the cell cycle, and give rise to progenitor cells that divide frequently before becoming neurons in the brain. The researchers wanted to show that cancer cells had a similar cycle.

Their next experiment was to apply the chemotherapy drug temozolomide to the tumor-ridden mice, which got rid of all the currently dividing tumor cells. But when the chemotherapy stopped, the tumors resumed cell division.

The cells not eradicated -- that were still giving rise to new cancer cells -- were the specially marked green cells that behave similarly to stem cells in healthy tissues.

In a final experiment, "we were able to give the mice temozolomide to get rid of the highly dividing cells, plus ganciclovir to get rid of the stem cells. And when we did that, the tumors were unable to form," Parada said.

Just what are the implications for human cancer?

"With a solid tumor that's formed by cancer stem cells in a hierarchical fashion, the critical cells to identify, understand and target with chemotherapy are the cancer stem cells," he said.

The research is still in early stages, Parada noted. "Now, knowing that these cells exist and being able to identify them inside of the tumors, we're trying to isolate them, purify them and study them in great detail," he added.

His caveat: Their work with glioblastoma may not apply to different kinds of cancers. "Each cancer has to be studied in this same way to determine if the cancers grow in this fashion or not," Parada said.

A second study in the same Nature issue investigated the growth of squamous skin cancer. By marking and tracing individual tumor cells in mice, researchers at the Free University of Brussels found a subset of tumor cells with properties similar to stem cells in normal tissue.

Meanwhile, a Dutch team looked at mouse intestinal tumors. In that study, published online Aug. 1 in the journal Science, researchers at University Medical Center Utrecht also found signs of what might be cancer stem cells.

However, scientists note that research with animals often fails to provide similar results in humans.

"It's interesting that all the studies came to the same conclusion with different types of cancer," said Wicha. "All use very elegant molecular tracing studies in mice."

Whereas previous studies were criticized for transplanting tumors from other sources into the mice being studied, he said these studies had the advantage of looking at the tumors in their natural environment.

Wicha said early clinical studies are already under way, using new drugs to directly target the cancer stem cells.

More information

Visit the U.S. National Cancer Institute to learn more about glioblastoma.

SOURCES: Luis F. Parada, Ph.D., professor and chairman of developmental biology, University of Texas Southwestern Medical Center, Dallas; Max S. Wicha, M.D., director, University of Michigan Comprehensive Cancer Center; Aug. 1, 2012, Nature, online; Aug. 1, 2012, Science, online

Copyright©2012 ScoutNews,LLC.
All rights reserved  

Related medicine news :

1. Researchers find evidence of banned antibiotics in poultry products
2. Report says new evidence could tip the balance in aspirin cancer prevention care
3. More Evidence Bilingualism Aids Thinking Skills
4. Novel biomarkers reveal evidence of radiation exposure
5. Antiretroviral treatment for preventing HIV infection: an evidence review for physicians
6. WSU study finds overwhelming evidence of hidden heart disease in hypertensive African-Americans
7. Study shows no evidence medical marijuana increases teen drug use
8. Study of Retired NFL Players Finds Evidence of Brain Damage
9. New evidence for link between obesity and circle of friends
10. Cochrane finds no reliable evidence on effectiveness of electric fans in heatwaves
11. Study Gives First Evidence That Adult Human Lungs Can Regrow
Post Your Comments:
Related Image:
Evidence Grows That Cancer Has Its Own Stem Cells
(Date:12/1/2015)... Angeles, CA (PRWEB) , ... December 01, 2015 , ... ... coalition of obesity groups has filed a discrimination claim against the U.S. Department of ... coverage in their Affordable Care Act (ACA) plans are breaking the clause in the ...
(Date:12/1/2015)... Fla. (PRWEB) , ... December 01, 2015 , ... ... number of leadless pacemakers in the U.S. and is the only hospital in ... from the largest clinical data presentation of transcatheter pacing patients were revealed recently ...
(Date:12/1/2015)... Houston, TX (PRWEB) , ... December 01, 2015 , ... ... owner of Vitenas Cosmetic Surgery, has been named by MedEsthetics magazine as the Best ... best of the best among the many elite aesthetic physicians honored by the industry ...
(Date:12/1/2015)... ... 2015 , ... Growth in medical payments per workers’ compensation claim in Louisiana ... and nonhospital care, according to a recent study by the Workers Compensation Research Institute ... found medical payments per claim with more than seven days of lost time continued ...
(Date:12/1/2015)... York, NY (PRWEB) , ... December 01, 2015 ... ... epidemic in the 1980s we have seen vast improvements in scientific research and ... made significant strides, providing increased hope and relief to those affected by HIV/AIDS. ...
Breaking Medicine News(10 mins):
(Date:12/1/2015)... VANCOUVER , Dec. 1, 2015 /PRNewswire/ ... Pharmaceuticals, Inc. (NASDAQ: OGXI ) announced today that ... the pre-planned interim futility analysis of the intent-to-treat (ITT) ... issues were identified by the DMC. Both the DMC ... results are expected in the second half of 2016, ...
(Date:12/1/2015)... -- As enforcement of the Food and Drug ... approaches, InfiniTrak announced today new partnerships ... looming FDA regulations. --> ... with State Pharmacy Associations, an independent pharmacist association, ... exclusively provide the InfiniTrak track-and-trace software solution to ...
(Date:12/1/2015)... ) ... "Medium Molecular Weight Polyisobutylene Market for Gum ... - Global Industry Analysis, Size, Share, Growth, ... report to their offering. --> ... the "Medium Molecular Weight Polyisobutylene Market ...
Breaking Medicine Technology: