Could
scientists have discovered the clue to what makes prostate
cancer grow? That’s the suggestion being made by researchers at
York University, who have found the cells that appear to “drive”
prostate cancer by ordering surrounding cells to turn malignant,
and have been able to grow these cells in the laboratory. This
raises the possibility that pharmaceutical companies could
develop treatments to kill the offending “ parent” cells.
The “parent” cells are actually stem cells.
Healthy stem cells act as the building blocks of life, giving
rise to a range of cells responsible for regenerating our
organs, tissues and red blood cells. Now cancer specialists say
that stem cells may play a leading role in prostate cancer, too.
This week scientists at the Yorkshire Cancer
Research Unit, led by Professor Norman Maitland and Dr Anne
Collins, both biologists, have reported that cancer stem cells
work in a similar way to healthy stem cells. Writing in the
American journal Cancer Research, they say that
although only 0.1 per cent of the cells they took from prostate
tumours were cancer stem cells, this small number had been able
to direct other, lesser cells to develop into “colonies” of
tumours four times their own number.
This is “groundbreaking” work, according to
Jack Schalken, professor of experimental urology at Radboud
University in the Netherlands. He says: “Identifying the cancer
stem cell is the most important element: stem cells feed the
whole repertoire of cancer cells that complete the tumour.”
Hing Leung, professor of urological oncology
at Newcastle University, says that the concept of cancer stem
cells is “the equivalent of finding the ‘engine room’ that
drives cancer to grow, spread and resist treatment such as
chemotherapy and radiotherapy”. He adds: “Finding such stem
cells is like looking for a very small needle in a rapidly
growing haystack. This study has identified the first ‘hints’
that such novel stem cells do exist in prostate cancer.
“This is likely to open up new avenues to
understand better the underlying biology of cancer. It may also
highlight ‘drugable’ targets for developing better medicine.”
Professor Maitland explains that most cancer
treatments try to kill off the bulk of tumour cells, leaving
behind a stem cell population. But if you can kill the roots,
“you kill the cancer for good”.
Professor Schalken suggests that Professor
Maitland’s work will be the catalyst for treatments that may, in
time, have a similar impact to the development of hormone
therapy in the 1950s. Until then, the only treatment for
prostate cancer was surgery.
Professor Maitland is cautious about when a
treatment might become available but believes that cyclopamine,
a drug undergoing human trials in the US, could be “a ready-made
therapy” because it has been shown to reduce tumours, possibly
by preventing stem cells from communicating with surrounding
cells.
Until now the drug has been used blind, says
Professor Maitland. Researchers have not been able to target it
at the cancer stem cells, which can mean that it has the
potential to kill the normal, healthy stem cells that renew our
bodies. This is clearly a problem because without stem cells
organs such as the liver would shrivel up.
Both professors are wary of raising false
hopes, but Professor Maitland suggests that at a time when
treatments are developed more and more quickly, an effective
treatment could be only years away.
Chris Hiley, head of research at the Prostate
Cancer Charity, says: “The research and discoveries in prostate
cancer stem cells are exciting.
“There is usually the fear that scientists can
overstate their findings, but Professor Maitland is a very
measured researcher and is clued up about making his findings
relevant for patients suffering with prostate cancer. It is very
promising.”
