- WASHINGTON (Reuters) -- A
cloning experiment may show that the body itself has the ability to reverse
cancer, U.S.-based researchers said on Saturday.
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- They cloned mouse embryos from a melanoma skin cancer
cell, and created healthy adult mice using some of the cloned cancer cells,
showing that malignancy is not the inevitable fate of a cancer cell.
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- "This settles a principal biological question,"
said Dr. Rudolf Jaenisch of the Whitehead Institute at the Massachusetts
Institute of Technology, one of the country's leading experts in cloning.
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- He said while the genetic elements of cancer cannot be
reversed, the epigenetics -- how the genes are actually turned on and off
-- can be.
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- The finding, published in the journal Genes and Development,
point to a new way to treat cancer, said Lynda Chin of the Dana-Farber
Cancer Institute and Harvard Medical School, who worked on the study.
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- "Drugs that target the cancer epigenome may prove
to be a key therapeutic opportunity for diverse cancers," she said
in a statement. In other words, it might be possible to silence a cancer
gene.
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- Cancer begins when certain genes mutate, or when a certain,
inherited version of a gene somehow gets turned on.
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- This can happen through various so-called epigenetic
processes -- when other molecules in a cell affect genes without actually
altering the sequence of DNA.
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- In the experiment, Konrad Hochedlinger and Robert Blelloch,
both researchers in Jaenisch's lab, took the nucleus from a melanoma cell
and injected it into a hollowed-out mouse egg cell.
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- This started the egg growing as if it had been fertilized
by sperm.
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- They did not allow this embryonic mouse to develop, but
harvested from it embryonic stem cells -- immature cells that have the
potential to become any cell in the body at all.
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- They put these stem cells into healthy mouse blastocysts
-- very early embryos only a few days old. Some of these developed into
healthy, normal mice.
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- "It's important to note that the stem cells from
the cloned melanoma were incorporated into most, if not all, tissues of
adult mice, showing that they can develop into normal, healthy cells,"
Blelloch said.
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- They included skin pigmentation cells, immune cells and
connective tissue.
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- This could only have happened if the cancer cells had
lost their malignant qualities, at least temporarily, the researchers said.
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- But when certain cancer-related genes in these mice were
activated, they developed malignant tumors at a much faster rate than normal
mice, the researchers added.
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- Many researchers want to try similar experiments with
human cancer cells, but the administration of President Bush forbids the
use of federal funds for such study because it would involve the creation
of what is technically a human embryo.
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