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<DIV>From <A
href="http://www.eurekalert.org/pub_releases/2003-12/sjcr-nwt121203.php">EurekAlert</A>:
Investigators at <A href="http://www.stjude.org/">St. Jude Children's Research
Hospital</A> have discovered a new way that an enzyme crucial to the cell's
ability to decode genes and duplicate chromosomes can be turned into a poison
inside cancer cells. The discovery is an important step toward designing a new
class of anti-cancer drugs. Such drugs might be given with an existing agent
that also targets this enzyme, creating a one-two punch against both solid
tumors and leukemia, according to the researchers. <BR>The enzyme, called
Topoisomerase 1 (Top 1), is crucial to the cell's ability to unwind the DNA of
chromosomes and separate the two strands making up a giant molecule. This
activity permits the cell to transcribe (decode) specific genes or to make a
copy of the entire chromosome. Duplication of chromosomes is critical to the
process called mitosis, or cell division. After the cell divides, each daughter
cell receives a copy of the entire set of duplicated chromosomes. Modifying Top
1 so it became locked onto the DNA molecule was enough to cause cell death.
<BR>This differs from the way a currently used anti-cancer drug, camptothecin
(CPT), works. CPT works only during the part of the cell's life cycle called S
phase, when the cell synthesizes duplicate chromosomes. Because the new strategy
can work whether the cell is in S phase or just decoding a single gene, a drug
based on this approach could be particularly versatile.</DIV></BODY></HTML>