Navigation Links
Researchers Hone in on Cancer Stem Cells for Melanoma
Date:1/16/2008

For the first time, researchers say targeting these units can slow down tumor growth

WEDNESDAY, Jan. 16 (HealthDay News) -- Melanoma has joined the list of cancers that can arise from a rare population of primordial cancer stem cells, Harvard researchers report.

Even more importantly, the scientists demonstrated for the first time that targeting these cells can slow down the growth of a tumor.

"The findings validate for the first time the potential therapeutic utility of the cancer stem cell concept," explained study author Markus Frank. "To my knowledge, cancer stem cells have not been specifically targeted to date via a prospective molecular marker."

Frank and his colleagues were interested in a particular protein called ABCB5, which is expressed on the surface of some progenitor skin cells and has been shown to confer cancer drug resistance to melanoma.

Hypothesizing that the pool of ABCB5-positive cells could include cancer stem cells, the researchers separated human melanoma cells based on whether or not they expressed ABCB5, transplanted both types of cells into mice, and monitored their ability to form tumors.

Fourteen of 23 mice injected with ABCB5-positive cells developed tumors, compared to one of 23 mice injected with cells that did not express the protein.

When a mixture of both types of cells were injected into mice, the authors found the ABCB5-positive cells were more likely to fuel tumors, and they exhibited stem cell-like properties -- that is, they divided to form both the bulk of the tumor and to regenerate the stem cells themselves.

Those findings -- that a stem cell subpopulation appears to contain the ability to reconstitute a tumor -- have been observed before in colon, brain, breast and pancreatic cancers, among others, albeit using a different cellular protein. However, the Harvard researchers added a novel twist: They showed both that ABCB5 expression correlated with disease severity, and that treatment of mice with an antibody directed against ABCB5 halted growth of existing tumors and inhibited the formation of new cancers.

Dr. Jeremy Rich, a cancer stem cell researcher at Duke University Medical Center, said, "The exciting thing is they have done things others haven't, which is to ask what is the impact of the marker on disease. First, there is an increase in ABCB5 levels as malignancy increases, and second, if you block its function with an antibody, you slow the growth of these tumors."

The results were published in the Jan. 17 issue of Nature.

According to the American Cancer Society, there were an estimated 108,230 new cases of melanoma in 2007 and 8,110 deaths.

The cancer stem cell hypothesis posits that tumors (like other noncancerous tissues) derive from a small population of primitive cells, which can divide and differentiate to form both the bulk of the cancer, and also more stem cells. Because most chemotherapeutic agents kill off the tumor cells, but leave the stem cells unscathed, the cancers return and metastasize.

The bottom line, according to the researchers, is that anti-cancer strategies need to be overhauled to kill off these stem cells.

Previous cancer stem cell studies have focused on the protein CD133. But it is not clear whether CD133 plays a role in stem cell behavior. According to Rich, such markers have sometimes been compared to the stripes painted on race cars: They do not make the car go faster, but they do help to identify it.

"This time, they have found a marker that is very interesting, because it looks like it may make the car go faster," he noted.

Also interesting, Frank noted, is the potential involvement of ABCB5 in mediating the cancer's resistance to chemotherapeutic agents.

"The findings establish a direct relationship between cancer stem cells, cancer progression, and chemoresistance in a human solid malignancy," Frank said. "This is a relationship that has been invoked often, but these findings provide first evidence of such a direct link."

But first more work needs to be done characterizing these cells. The cancer stem cells identified in this study are very rare; the authors estimated they represent about one in 1 million melanoma cells overall, and about one in 100,000 ABCB5-positive cells.

In other words, Rich explained, the researchers have not so much identified the cancer stem cells, as they have narrowed the search.

"They know the ZIP code of the cancer stem cell, but the full identity remains yet to be discovered," he said.

More information

For more on melanoma, visit the American Academy of Dermatology.



SOURCES: Markus H. Frank, M.D., assistant professor, pediatrics, Harvard Medical School, Boston; Jeremy N. Rich, M.D., associate professor, Department of Medicine, and assistant professor, Departments of Neurobiology and Surgery, Duke University Medical Center, Durham, N.C.; Jan. 17, 2008, Nature


'/>"/>
Copyright©2008 ScoutNews,LLC.
All rights reserved  

Related medicine news :

1. Anyone can save a life: Penn researchers lead national efforts to improve CPR quality
2. Researchers find new way to block destructive rush of immune cells
3. U of M researchers create beating heart in laboratory
4. Researchers challenge previous findings regarding widely used asthma treatment
5. UT Health Science Center researchers decoding saliva to detect breast cancer
6. Protein power: Researchers trigger insulin production in diabetic mice
7. Researchers use neuroimaging to study ESP
8. UGA researchers receive $9 million in grants to study barriers to effective addiction treatment
9. Researchers seek to make cavity-causing bacteria self-destruct
10. Human factors researchers test voting systems for seniors that can improve voting accuracy and speed
11. New research tools are too complex for easy answers, researchers say
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Researchers Hone in on Cancer Stem Cells for Melanoma
(Date:6/27/2016)... Lafayette, California (PRWEB) , ... ... ... a pioneer in the patient payment industry today announced its strategic partnership ... and health system workflows. , The two companies’ proven, proprietary technology combine ...
(Date:6/26/2016)... ... June 27, 2016 , ... Quality metrics are proliferating in cancer ... they remain in the eye of the beholder, according to experts who offered insights ... American Journal of Managed Care. For the full issue, click here . , ...
(Date:6/26/2016)... North Carolina (PRWEB) , ... June 26, 2016 , ... ... release of a new product that was developed to enhance the health of felines. ... for centuries. , The two main herbs in the PawPaws Cat Kidney Support ...
(Date:6/25/2016)... ... June 25, 2016 , ... ... and applications at AcademyHealth’s Annual Research Meeting June 26-28, 2016, at the Hynes ... important health care topics including advance care planning, healthcare costs and patient and ...
(Date:6/25/2016)... ... June 25, 2016 , ... "With 30 hand-drawn hand gesture animations, ... Christina Austin - CEO of Pixel Film Studios. , ProHand Cartoon’s package transforms ... Final Cut Pro X . Simply select a ProHand generator and drag it above ...
Breaking Medicine News(10 mins):
(Date:6/23/2016)... , June 23, 2016  MedSource announced today ... its e-clinical software solution of choice.  This latest ... possible value to their clients by offering a ... preferred relationship establishes nowEDC as the EDC platform ... MedSource,s full-service clients.  "nowEDC has long been a ...
(Date:6/23/2016)... Any dentist who has made an implant supported ... Many of them do not even offer this as a ... laboratory costs involved. And those who ARE able to offer ... high cost that the majority of today,s patients would not ... Zadeh , founder of Dental Evolutions Inc. and inventor of ...
(Date:6/23/2016)... startling report released today, National Safety Council research shows ... plan to eliminate prescription opioid overdoses. Prescription Nation ... the worst drug crisis in recorded U.S. history, assigned a "Making ... , New Mexico , Tennessee ... states, three – Michigan , Missouri ...
Breaking Medicine Technology: