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Source: ONE News
Researchers have found an unexpected genetic mutation that
causes a rare type of early childhood cancer, and said it
represents a whole new mechanism for the development of
cancer.
They found that children with a rare, aggressive form of lung
cancer called pleuropulmonary blastoma, or PPB, are born with a
mutation in DICER1, itself a master controller gene that helps
regulate other genes.
In addition, they found children with PPB have normal-looking cells
in their lungs that appear to cause neighboring cells to turn
cancerous.
"This mutation tells us how embryos and foetuses and young children
maldevelop - how something goes wrong," Dr Jack Priest, research
director of the International PPB Registry in Minnesota, said in a
telephone interview.
"It's a bigger story than PPB. It suggests a completely novel
cancer induction," Priest added.
PPB is so rare that it is only diagnosed in 10 to 20 children every
year in the United States and 50 to 60 globally.
Identified and treated early, it has a 90% cure rate, but
doctors rarely expect to find lung cancer in newborns or young
children.
If not treated correctly, children only have about a 40% chance of
survival.
The researchers told a meeting of the American Association for
Cancer Research in Denver that the finding may or may not shed
light on adult cancers, but it provides insight into the mechanisms
underlying some early childhood cancers.
"Some of these children were born with PPB," Priest said.
He said one child in the study had evidence before birth of
tell-tale cysts in the lungs in an ultrasound done before
birth.
Dr Ashley Hill of Children's National Medical Center in Washington
and colleagues analyzed DNA samples from 49 people in four
families.
About 40% of cases of PPB are found in children, whose families
have a history of some kind of cancer, suggesting an inherited
genetic cause.
They were surprised to find the mutation in DICER1, which is named
for its function chopping up large molecules into smaller molecules
called microRNAs that help regulate other genes.
The people with the DICER1 mutations had the defect in every cell
of the body, but Hill found something else unusual.
Seemingly normal lung cells, which carried an even more severe
form of the mutation, were apparently causing neighbouring cells to
go haywire and form tumours.
"The cell, because it is screwed up, is inducing cancer in
neighbouring cells. That has never been seen before," Priest
said.
The next step is to try to develop a test for the DICER1 mutation that can be used to see if children born to high-risk families carry it, and thus are at high risk themselves, Priest said.
