Cincinnati--Findings from a team of researchers led by Yuri
Nikiforov, MD, PhD, assistant professor of pathology and laboratory
medicine, University of Cincinnati (UC) College of Medicine, provide
scientists a better understanding of the genetic mechanism of cancer
development following radiation exposure, as reported in the October 6
issue of Science magazine.
The cancers they are studying have chromosomal rearrangements.
Chromosomal rearrangements are mutations formed by breakage and
abnormal fusion of two chromosomal regions. Each of us normally carries
23 chromosomes or chains of genes linked together. For decades,
scientists wondered why two genes located separately in the nucleus of
certain cells fuse together to form a rearrangement after radiation
exposure. "In this paper we show that such rearrangements in gene
segments may occur in humans because the two genes are very close in
location to each other," says Nikiforov. The proximity predisposes the
DNA, which has been damaged by ionizing radiation or by other
gene-altering agents, to form a rearrangement.
Nikiforov came to
the U.S. from Belarus, a country just north of Chernobyl that was most
severely affected by radioactive fall-out after the Chernobyl Nuclear
Plant disaster in 1986. Since the early 1990s, Nikiforov and his
colleagues have studied thyroid cancer in children exposed to radiation
from Chernobyl. Their most recent efforts focused on investigating how
radiation exposure causes chromosomal rearrangements. These
rearrangements often lead to the development of various cancers such as
leukemia, thyroid, and many others.
This study is an important
contribution to medical science since it describes a fundamental
mechanism of how chromosomes exposed to radiation will change. This
knowledge may lead to a better understanding of how a broad range of
cancers originate, especially those arising after radiation exposure.
In the long term, this may result in the development of new therapeutic
strategies aimed at protecting human cells from the development of
chromosomal rearrangements and subsequent cancer after radiation
One of the referees for the prestigious Science
magazine, said in his review of Nikiforov's paper, "The results are
striking, interesting, and potentially quite important. It has been a
long-standing puzzle that ionizing radiation acts comparatively
uniformly on different parts of the genome, but some common
cancer-associated chromosomal rearrangements are very specific. This
paper supplies perhaps the clearest evidence to date that geometric
proximity of different genes in the nucleus is part of the answer."