mellowsong
11-05-09, 09:49 AM
What I like about this is the fact that they used concentrations that could actually be found in real life.
Exposure to arsenic causes human stem cells to transform into cancer cells, report researchers who studied the cells in a laboratory. People in certain regions of the world are exposed to high levels of arsenic through drinking water tainted by the naturally-occurring element. The results of this new study may explain why arsenic is associated with several human cancers, including prostrate cancer in men.
Context
Stem cells (http://stemcells.nih.gov/info/basics/) are unique because they are able to divide endlessly. Both types of stem cells – embryonic and adult – can give rise to either more stem cells or can develop into other types of cells.
Embryonic stem cells are found in developing embryos and can form into many kinds of cells. Some can give rise to an entire animal. Others can give rise to more than 200 different cell types.
Adult stem cells are rare and act to repair and maintain the tissue where they originate. They are found in small clusters in virtually all tissues but make up only a very small fraction of that tissue. They give rise to fewer cell types than embryonic stem cells and can generally withstand most toxic insults. For example, hematopoetic stem cells are located in bone marrow and can become red, white or any type of blood cell.
Cancer cells differ (http://www.cancerhelp.org.uk/about-cancer/what-is-cancer/cells/the-cancer-cell) from normal cells in several key ways. They divide uncontrollably; they ignore other cell signals; they remain detached from other cells; and they do not mature and specialize. Mounting evidence suggests that normal stem cells may give rise to cancer stem cells, which then go through unregulated division to become full blown tumors (Pardal et al. 2003 (http://www.environmentalhealthnews.org/ehs/newscience/arsenic-makes-good-cells-go-bad#Pardal); Reya et al. 2001 (http://www.environmentalhealthnews.org/ehs/newscience/arsenic-makes-good-cells-go-bad#reya)).
Arsenic occurs naturally. It is widely distributed in water, food, air and soil due to natural and human activities. Volcanic ash fallout, the weathering of arsenic-containing mineral and ores, and human activities – such as applying pesticides that contain the metalloid – contribute to the arsenic in the environment.
Arsenic commonly contaminates groundwater throughout the world and is a significant pollution problem for many drinking water supplies. It causes kidney, bladder and several other cancers in lab animals (Waalkes et al. 2008 (http://www.environmentalhealthnews.org/ehs/newscience/arsenic-makes-good-cells-go-bad#waalkes09)). In people, exposure is associated with prostate, urinary tract and other types of cancers (Benbrahim-Tallaa and Wallkes 2008 (http://www.environmentalhealthnews.org/ehs/newscience/arsenic-makes-good-cells-go-bad#benbraham08)). Although it is not known how arsenic induces cancers, recent animal research suggests prebirth exposure may predispose certain cells to become cancerous.
What did they do?
Human adult stem cells from the prostate were exposed to arsenic in the laboratory. Concentrations were environmentally relevant, meaning the concentrations are at a level that could be seen under natural conditions.
The stem cells were exposed to the arsenic for up to 18 weeks. Researchers examined the exposed prostate stem cells and observed changes.
They also injected some of the exposed cells into mice and watched for cancer development in the tissues during the next six months.
What did they find?
By 18 weeks of exposure to arsenic, the prostate stem cells rapidly transformed into what appeared to be malignant cancerous stem cells. The ductal structures that are typical of normal stem cell function grew faster and had more branching in the treated cells when compared to the normal untreated stem cells.
When transplanted into mice, the arsenic-exposed cells rapidly developed into invasive and aggressive tumors in as little as two to three weeks. More than 40 percent of the mice developed cancer within six months. Cancer did not develop in the mice injected with untreated stem cells.
In addition, the activity of a key gene known to suppress tumor formation decreased in cells treated with arsenic. The decrease coincided with increased gene activity that controls cell division.
What does it mean?
Studies with lab animals have shown arsenic to cause cancer, but those types of studies cannot be done with humans. In people, arsenic has been linked with certain cancers, including prostate cancer. This type of association is not proof that arsenic is causing the cancer.
This study provides strong evidence that arsenic could indeed be a causal factor in the development of prostate cancer. The results identify a mechanism for how this could happen with human cells.
This study substantiates the growing body of scientific literature that indicates arsenic contributes to the development of human cancers. The authors say their results provide "compelling evidence that the metalloid can act directly upon a human stem/progenitor population to initiate formation of cancer stem-like cells and provides unique insights into the very earliest period of arsenic carcinogenesis."
Prostate cancer is the second most common cancer in American men. About 1 in 6 men will be diagnosed with prostate cancer in his lifetime.
If arsenic is contributing to the incidence of cancer in humans as this study suggests, this highlights a compelling reason to reconsider the use of arsenic in pesticides and other products that contribute to environmental(article cut off here)
http://www.environmentalhealthnews.org/ehs/newscience/arsenic-makes-good-cells-go-bad/
Exposure to arsenic causes human stem cells to transform into cancer cells, report researchers who studied the cells in a laboratory. People in certain regions of the world are exposed to high levels of arsenic through drinking water tainted by the naturally-occurring element. The results of this new study may explain why arsenic is associated with several human cancers, including prostrate cancer in men.
Context
Stem cells (http://stemcells.nih.gov/info/basics/) are unique because they are able to divide endlessly. Both types of stem cells – embryonic and adult – can give rise to either more stem cells or can develop into other types of cells.
Embryonic stem cells are found in developing embryos and can form into many kinds of cells. Some can give rise to an entire animal. Others can give rise to more than 200 different cell types.
Adult stem cells are rare and act to repair and maintain the tissue where they originate. They are found in small clusters in virtually all tissues but make up only a very small fraction of that tissue. They give rise to fewer cell types than embryonic stem cells and can generally withstand most toxic insults. For example, hematopoetic stem cells are located in bone marrow and can become red, white or any type of blood cell.
Cancer cells differ (http://www.cancerhelp.org.uk/about-cancer/what-is-cancer/cells/the-cancer-cell) from normal cells in several key ways. They divide uncontrollably; they ignore other cell signals; they remain detached from other cells; and they do not mature and specialize. Mounting evidence suggests that normal stem cells may give rise to cancer stem cells, which then go through unregulated division to become full blown tumors (Pardal et al. 2003 (http://www.environmentalhealthnews.org/ehs/newscience/arsenic-makes-good-cells-go-bad#Pardal); Reya et al. 2001 (http://www.environmentalhealthnews.org/ehs/newscience/arsenic-makes-good-cells-go-bad#reya)).
Arsenic occurs naturally. It is widely distributed in water, food, air and soil due to natural and human activities. Volcanic ash fallout, the weathering of arsenic-containing mineral and ores, and human activities – such as applying pesticides that contain the metalloid – contribute to the arsenic in the environment.
Arsenic commonly contaminates groundwater throughout the world and is a significant pollution problem for many drinking water supplies. It causes kidney, bladder and several other cancers in lab animals (Waalkes et al. 2008 (http://www.environmentalhealthnews.org/ehs/newscience/arsenic-makes-good-cells-go-bad#waalkes09)). In people, exposure is associated with prostate, urinary tract and other types of cancers (Benbrahim-Tallaa and Wallkes 2008 (http://www.environmentalhealthnews.org/ehs/newscience/arsenic-makes-good-cells-go-bad#benbraham08)). Although it is not known how arsenic induces cancers, recent animal research suggests prebirth exposure may predispose certain cells to become cancerous.
What did they do?
Human adult stem cells from the prostate were exposed to arsenic in the laboratory. Concentrations were environmentally relevant, meaning the concentrations are at a level that could be seen under natural conditions.
The stem cells were exposed to the arsenic for up to 18 weeks. Researchers examined the exposed prostate stem cells and observed changes.
They also injected some of the exposed cells into mice and watched for cancer development in the tissues during the next six months.
What did they find?
By 18 weeks of exposure to arsenic, the prostate stem cells rapidly transformed into what appeared to be malignant cancerous stem cells. The ductal structures that are typical of normal stem cell function grew faster and had more branching in the treated cells when compared to the normal untreated stem cells.
When transplanted into mice, the arsenic-exposed cells rapidly developed into invasive and aggressive tumors in as little as two to three weeks. More than 40 percent of the mice developed cancer within six months. Cancer did not develop in the mice injected with untreated stem cells.
In addition, the activity of a key gene known to suppress tumor formation decreased in cells treated with arsenic. The decrease coincided with increased gene activity that controls cell division.
What does it mean?
Studies with lab animals have shown arsenic to cause cancer, but those types of studies cannot be done with humans. In people, arsenic has been linked with certain cancers, including prostate cancer. This type of association is not proof that arsenic is causing the cancer.
This study provides strong evidence that arsenic could indeed be a causal factor in the development of prostate cancer. The results identify a mechanism for how this could happen with human cells.
This study substantiates the growing body of scientific literature that indicates arsenic contributes to the development of human cancers. The authors say their results provide "compelling evidence that the metalloid can act directly upon a human stem/progenitor population to initiate formation of cancer stem-like cells and provides unique insights into the very earliest period of arsenic carcinogenesis."
Prostate cancer is the second most common cancer in American men. About 1 in 6 men will be diagnosed with prostate cancer in his lifetime.
If arsenic is contributing to the incidence of cancer in humans as this study suggests, this highlights a compelling reason to reconsider the use of arsenic in pesticides and other products that contribute to environmental(article cut off here)
http://www.environmentalhealthnews.org/ehs/newscience/arsenic-makes-good-cells-go-bad/