Scientists have identified a gene that helps protect mice against intestinal
tumours, although it may also play a role in spreading breast cancer, according
to a study published on
Thursday.


http://www.sciencedaily.com/images/2005/01/050111121148.jpg


Despite the gene’s
Jekyll-and-Hyde personality, the discovery may one day lead to drugs that boost
resistance to cancer in humans, said the study, which appears in the journal
Nature. Researchers led by Roger Reeves at Johns Hopkins University in
Baltimore, Maryland, showed that the gene Ets2 acts as a tumour suppressor in
rodents afflicted with the human equivalent of Down’s
syndrome.


The finding settles a
decades-old debate about whether this inherited disorder confers protection
against cancerous tumours. Establishing this connection was, in fact, the
starting point for a clever series of experiments using genetically modified
mice that eventually led to
Ets2.


Down’s syndrome, which
occurs in approximately one in 800 live births, retards physical and
intellectual development. Persons with the syndrome have an extra chromosome in
their genetic code — 47 rather than 46, due to an additional 21st
chromosome.


Reeves and his
colleagues began by cross-breeding rodents carrying the three copies of
chromosome 21 with another set of gene-altered mice designed to develop
intestinal cancer. Compared to normal mice, the offspring produced far fewer
tumours, and the cancers that did appear were smaller, the study
showed.


Further breeding
experiments led to a third mutant mouse which expressed the minimal genetic
changes needed to produce Down’s syndrome, and this allowed Reeves to narrow
down the precious anti-tumour source to a mere 33 genes.

Via Times of India