ScienceDaily (June 20, 2012) -- Researchers at Oregon State University
have for the first time traced the actions of a known carcinogen in cooked
meat to its complex biological effects on microRNA and cancer stem cells.
The findings are part of a growing awareness of the role of epigenetics
in cancer, or the ways in which gene expression and cell behavior can be
changed even though DNA sequence information is unaltered.
scientists also found that consumption of spinach can partially offset the
damaging effects of the carcinogen. In tests with laboratory animals, it cut
the incidence of colon tumors almost in half, from 58 percent to 32 percent.
The research at OSU's Linus Pauling Institute was recently reported in the
journal Molecular Nutrition and Food Research, in work supported by the
National Institutes of Health.
"Cancer development is a complex,
multi-step process, with damaged cells arising through various means," said
Mansi Parasramka, a postdoctoral scholar with LPI. "This study showed that
alterations of microRNAs affect cancer stem cell markers in colon cancer
"MicroRNAs are very small factors that do very big things
in cells," she said.
Traditionally, cancer was thought to be caused by
changes in DNA sequence, or mutations, that allowed for uncontrolled cell
growth. That's still true. However, there's also increasing interest in the
role played by epigenetics, in which such factors as diet, environmental
toxins, and lifestyle affect the expression of genes -- not just in cancer,
but also cardiovascular disease, diabetes, and neurological disorders.
Included in this epigenetic equation is the formation of microRNAs --
once thought to be "junk DNA" -- which researchers were at a loss to
understand. It's now known that they influence which areas of DNA get
expressed or silenced.
There are hundreds of microRNAs, and the OSU
scientists monitored 679 in their experiments. When they don't work right,
bad things can happen, including abnormal gene expression leading to cancer.
"Recent research is showing that microRNAs are one of the key epigenetic
mechanisms regulating cellular functions in normal and diseased tissues,"
said Rod Dashwood, the Helen P. Rumbel Professor for Cancer Prevention and
director of LPI's Cancer Chemoprotection Program.
mutations which are permanent genetic changes in DNA," he said, "the good
news about epigenetics and microRNA alterations is that we may be able to
restore normal cell function, via diet and healthy life style choices, or
even drug treatments."
Epigenetics essentially makes every person
biologically unique, Dashwood said, a product of both their genetics and
their environment. That includes even identical twins.
of the new study should lead to advances in understanding microRNAs, their
effects on cancer stem cells, and the regulatory processes disrupted in
disease development, the OSU scientists said. This might lead one day to
tailored or "patient specific" therapies for cancer, Dashwood said.
The above story is reprinted from
materials provided by Oregon State
Note: Materials may be edited for content and
length. For further information, please contact the source cited above.
Mansi A. Parasramka, W. Mohaiza Dashwood, Rong
Wang, Amir Abdelli, George S. Bailey, David E. Williams, Emily Ho, Roderick
H. Dashwood. MicroRNA profiling of carcinogen-induced rat colon tumors and
the influence of dietary spinach. Molecular Nutrition & Food Research, 2012;