Scientists achieve breakthrough in tumour study

Updated: May 07, 2010, 00:00 AM IST

Washington: Scientists have developed
a powerful new technique for analysing the genome of single
tumour cells, a key breakthrough which they claim would help
doctors to identify dangerous tumour cells from small samples.

"Tumours are complex populations of cells and they are
not limited to the tumour mass itself. By the time a tumour is
discovered there are almost certainly thousands of tumour
cells in the circulation or hiding in places like bone marrow.

"The breakthrough here is that we have proven the
concept of identifying tumour cells in very small samples and
profiling them to see whether they are dangerous," Dr James
Hicks, who led a team at Cold Spring Harbour Laboratory, said.

A major focus of cancer treatment at present is
determining how aggressively to treat patients as methods for
early cancer detection improve. The opportunity to use similar
techniques to study the basic biology of tumour growth is more
academic, but no less important aspect.

The technique developed at Cold Spring Harbor focuses
on "copy number variation" in cancer cells. These are changes
to the expected number of copies of large sections of DNA. For
example, genes that were thought always to occur in two copies
per cell might be found in one, three or more copies.

Dr Hicks said: "Most solid tumours, especially breast,
lung, liver, bladder and prostate, exhibit varying degrees of
chromosomal rearrangement.

"As cells progress from normal state where there
are two copies of each chromosome, to become more cancer-like,
they tend to accumulate more and more rearrangements that can
be seen as copy number changes.

"The genetic history of a tumour cell is written in
its DNA and much of that information can be extracted from its
copy number profile."