Cancer stem cell chemoresistance

Hong Kong, China -

It is known that similar to normal tissue, cancer tissue has differentiated cells, and stem cells. The stem cells contribute to, and maintain, the tumor mass. Since numerous properties of stem cells are becoming elucidated, such as markers (CD133) and specific characteristics (rhodamine 123 efflux), these properties are being used to purify cancer stem cells and to study their characteristics.

In a recent study (Ma et al. CD133 HCC cancer stem cells confer chemoresistance by preferential expression of the Akt/PKB survival pathway. Oncogene. 2007 Sep 24) human liver cancer stem cells were isolated by expression of CD133 and implanted into immune compromized mice. It was demonstrated that only implanted cells which had CD133 expression were resistant to doxorubicin and 5-FU chemotherapy whereas cells lacking CD133 were sensitive. Furthermore, the investigators found that the cancer stem cells had higher expression of Akt/PKB as well as the Bcl-2 pathway. When investigators blocked the Akt/PKB pathway through administration of a chemical inhibitor they could increase susceptibility of the tumor stem cells to chemotherapy.

This study supports the notion that cancer scientists have to start focusing more and more on cancer stem cells and also suggests that the overall lack of clinical translation of cancer treatments could be due to not understanding cancer stem cell biology.