- Growing cancer cells are found to be stem cells
- A perfect storm of DNA mutation, damage to tissue and
stem cell activation lead to cancer.
- Infant stem cell is less likely to form cancer
There have always been ongoing
debates about the significance of stem cells
in increasing the risk for cancer
while some sections of the
scientific community support environmental risk factors in the propagation of
Researchers from The
University of Cambridge and St Jude's Children's hospital have carried out an
extensive study which confirms that stem cells contribute to the origin of various
types of cancer in mice.
‘Retinoic acid blocks or slows cancer development by activating a type of immune cell called a CD8 T cell.’
Stem cells are
progenitor cells that grow and develop into many different types of cells
during early stages of life. They are also found in certain tissues in the body
where they serve as internal cells for repair. Every time a stem cell divides,
it forms more stem cells or it divides into specialized cells.
Some scientists believe that the ability of
stem cells to generate could be the triggering factor for the development of
The study's senior
author, Dr. Richard Gilbertson who was the director at St. Jude scientific and
Comprehensive Cancer Center and currently the director of the Cancer Research
UK Cancer Center at Cambridge University says "The chance accrual of random
mistakes in cell DNA likely plays an important role in generating cancer; but
whether this has to happen in specific cell types, such as stem cells, and
precisely how other factors such as environmental carcinogens contribute to
cancer is unclear.
Indeed, an argument has
raged across the scientific community for some years now - some say cancer is
'bad luck' because mutations arise by chance in stem cells, while others argue
environmental carcinogens are more important. This disagreement has arisen
largely from the use of different mathematical models to look at existing human
cancer and stem cell data, from which it is extremely difficult to tease out
the impact of individual factors. Therefore, we tested these different opinions
in actual experimental models that looked at the individual components that
might drive cancer."
Factors that Signal Cancer Stem Cells
Cancer cells grow like
normal cells, mimicking the growth and differentiation of stem cells.
the Activity of Cells
- Tumor cells like stem cells can grow and mature
extensively, some of them mature into transit amplifying cells.
- The transit amplifying cells divide for a specific
number of time before they differentiate into specialized cells.
- The cells that differentiate into specialized cells do
not divide and do not further assist in the growth of the tumor.
A marker molecule called
Prom 1 was used to identify the activity of cells in the various tissues of
mice. In certain tissues, these marker cells were mature and did not divide but
in certain other tissues they were active stem cells. Dr. Liqin Zhu who is the
first author of the study and a research associated at St. Jude's says "By
following these Prom1+ cells in all the major organs in mice through their
lifetime journey we were able to identify in which organs these cells were
actively dividing stem cells."
Once the activity of
these marker cells was identified in the whole body of mice, mutations were
introduced into these cells. Dr. Zhu adds "This approach does away with
the need for carcinogens, removing them from the cancer equation and allowing
us to test if the generative capacity of stem cells influenced cancer risk."
The researchers spent 7 years studying the spread of the cells and the
development of cancer.
The study shows that
stem cells are required for the generative capacity of tumor cells. However,
the research shows that stem cells can be woken up to form cancer. For example,
when the liver is damaged it can wake up the stem cells, increasing the risk
The researchers conclude
that a perfect storm needs to occur for cancer to form and develop, the perfect
Stem Cells in Children Less Likely to Form Cancers
- Mutations in the DNA
- Stem cell function
- Damage to the tissue
The scientists also
showed that stem cells in young animals were less likely to develop into cancer
cells when compared with adult stem cells. This could be due to the fact that
stem cells in children have an innate resistant to the development of cancer.
Dr. Zhu further adds
"If this biology were to hold true in humans, then it may explain why
cancer rates are many-fold lower in children than adults, despite the fact that
childhood cancers accrue significant numbers of mutations that alter proteins,
and the growth rates of organs peak in childhood."
The findings of the
study provide crucial evidence about the growth and spread of tumors that will
pave the way for a better treatment module.
- Stem Cell Basics - (http://stemcells.nih.gov/info/basics/pages/basics1.aspx)
- Cancer - A Disease of the Stem Cells - (http://www.eurostemcell.org/factsheet/cancer-disease-stem-cells)