"SUPER" CANCER STEM CELLS FOUND IN LIVER CANCER

HONG KONG (Reuters) Jul 07 - 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, scheduled for publication 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.
These cancer stem cells bear the surface protein 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 tumors, spread and be drug resistant. If we inhibit the function of STAT3, we block the function of cancer stem cells."
In a murine model, Ng and colleagues found that liver cancer enriched with CD24 cancer stem cells was resistant to chemotherapy.
The researchers 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% chance of cancer recurrence in the first year after surgery, compared to 21% recurrence in those with low CD24 count.
Those with a high CD24 count had an 80% chance of their cancer spreading, compared to 32% in patients with a low CD24 count.
Ten percent of China's population carries 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.
SOURCE: http://bit.ly/4kkpZ6
Cell Stem Cell 2011.