| HONG KONG, July 7
HONG KONG, July 7 Liver cancers are embedded
with a type of super cancer stem cells that make them resistant
to chemotherapy, spread to other body parts and stage a comeback
even after they are surgically removed, researchers in Hong Kong
reported on Thursday.
The discovery, published this week in the journal Cell Stem
Cell, is important because it means experts can target these
stem cells in their fight against liver cancer, a major blight
in China and southeast Asia.
These cancer stem cells have a unique surface protein called
CD24 and patients with high counts of CD24 tend to have poorer
chances of survival, said lead researcher Irene Ng, pathology
professor and director of the State Key Laboratory for Liver
Research at the University of Hong Kong.
"CD24 is like a button, a switch on some cancer stem cells.
Once they are switched on, they activate a protein in the cell
called STAT3," Ng told a news conference.
Her colleague Terence Lee said: "STAT3 goes into the nucleus
of the cells and carries out its functions, which are to form
tumours, spread and be drug resistant. If we inhibit the
function of STAT3, we block the function of cancer stem cells."
Stem cells are master cells found throughout the body and
they are special because they can transform into different cell
types and multiply and self-renew.
Liver cancer stem cells are therefore troublesome because
they are responsible for growing tumours, making them spread,
drug-resistant and so hardy that they recur even after they have
been surgically removed.
In their experiment, Ng and colleagues found that mice that
were implanted with liver cancer enriched with CD24 cancer stem
cells were resistant to chemotherapy.
They then injected two colonies of liver cancer cells - one
with CD24 stem cells and the other without - into separate parts
of the liver of the same mouse.
"That part of the liver with CD24 cancer stem cells grew
cancer and the cancer spread to the lungs. But not the other
part of the liver without CD24 cancer stem cells," Lee said.
They went back to human liver cancer patients and found that
those with high concentrations of CD24 had a 67 percent chance
of cancer recurrence in the first year after surgery, compared
to 21 percent recurrence in those with low CD24 count.
Those with high CD24 count had a 80 percent chance of their
cancer spreading to other body parts, compared to 32 percent
chance of spreading in patients with low D24 count.
Ten percent of China's population carry the hepatitis B
virus, a key cause of liver cancer. There are 500,000 new cases
of liver cancer worldwide a year, over 50 percent in China.
(Editing by Sanjeev Miglani)
(Created by Ee-lyn Tan)