Microbeams found to have unexpected results on cancer cells

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Microbeams found to have unexpected results on cancer cells

 

03.12.2003

http://www.nzherald.co.nz/storydisplay.cfm?storyID=3537342 & thesection=news & t

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LONDON - Scientists testing the effects of microbeams have discovered that

targeting just a few cells can cause massive destruction to other diseased

cells.

 

Scientists at Cancer Research UK have dubbed it the " bystander effect "

because the cancer cells zapped by the microbeams not only die but send out

suicide signals to other abnormal cells, telling them to self-destruct.

 

" We used to assume that the only way to kill cancer cells with radiotherapy

was to hit every one of the cells in the tumour with a fatal dose of

radiation, " said Dr Kevin Prise, of the charity's Gray Cancer Institute in

southern England.

 

" Now we're finding that it's possible to hit just a handful of cells with

much lower doses and let the cells' natural suicide machinery do the rest. "

 

The findings could have important implications for improving the

effectiveness of radiotherapy for cancer sufferers because hitting just one

cell with the microbeam, which launches streams of helium ions a thousandth

of a millimetre wide, has an effect on so many other cells.

 

Prise and his colleagues, who reported their findings in the journal Cancer

Research, tested microbeams in the laboratory on brain-cancer cells that

were highly resistant to conventional radiotherapy. Although they targeted

the beam at a single cell, it had an impact and triggered a significant

proportion of other cells to commit suicide in a process known as apoptosis.

 

Cancer develops when abnormal cells do not self-destruct but continue

dividing and form tumours.

 

" If we could enhance the bystander effect within tumours, we could develop

much more effective systems of radiotherapy, perhaps using lower doses to

reduce side effects, " Prise said.

 

" But of course it also means that even very low doses of radiation may be

doing more damage to normal cells than we'd thought, so we'll have to look

for ways of protecting healthy tissue more effectively. "

 

An estimated 50 per cent of patients diagnosed with cancer would benefit

from radiotherapy, which kills cancerous cells with tight beams of

radiation.

 

The scientists said the bystander effect is linked to a molecule called

nitric oxide which plays a role in cell suicide. Nitric oxide seems to be

important in sending out suicide signals in cells when they are hit by

radiation.

 

" Making sure that there are high amounts of the molecule produced within

tumours may be essential to optimise the bystander effect and improve

treatments, " Prise said.

 

" We also think the mechanisms involved in the bystander effect might be

different in healthy and cancerous tissue, so it might be possible to

develop drugs that protect normal tissue from radiotherapy while leaving

cancer cells more vulnerable. "

 

- NZPA

 

Herald Feature: Health