Turning Stem Cells Into Cancer

An interesting new paper (Open Access, click away!!!) exploring the cancer stem cell hypothesis, describing to my knowledge the first transgenic cancer model to be derived by specifically targeting a normal stem cell population. The Spanish group of Maria Perez-Caro et al. show that they can induce chronic myeloid leukemia (CML) in mice by introducing the infamous bcr-abl oncogene (a gene encoding an aberrent fusion protein known to drive the human disease), specifically into Sca1+ normal hematopoietic stem cells.

They go on to use the model to investigate an important corollary of the cancer stem cell hypothesis, which postulates that residual CSCs are responsible for disease remission during/following therapy. They show that their CML mice cannot be cured with the bcr-abl targeted inhibitor STI571/Gleevec, whereas ablation of the Sca1+ stem cell compartment is sufficient to eliminate the disease. Therapeutically speaking they cheated a bit here by simply engineering a suicide gene into the oncogene cassette, but it's a start. It would be nice to see whether a therapeutically relevant approach to CSC depletion (ie anti-Sca-1 MAb) would also be able to eliminate the disease in their model.

Depleted Uranium and Cancer: What Does The Science Say?

After reading this news story mentioned on a Digg post (Digg my comment) which suggested that an American Gulf War veteran's cancer had been caused by exposure to depleted Uranium, I was interested to see what the science had to say. The use of high-density depleted Uranium in armor-piercing ammuntition and armor by American, British and NATO forces has been the subject of much controversy. Critics cite it as a cause of cancer in troops exposed on the battlefied, and a hazardous environmental pollutant for local residents. Actually, quite a few studies have been done to investigate this matter, most of them by various European countries falling outside the influence of the so-called American "military industrial complex". Here's what they say:

• A Danish study published September 2006 examined cancer incidence in 14,000 of that countries veterans who had been deployed in the Balkans as part of the UN force. Contrary to previous speculations, no increased incidence of leukemia or testicular cancer was found amongst veterans in comparison to the overall Danish population.

• A similar study of 9000 Swedish Balkan veterans showed no increased incidence of leukemias or testicular cancer.

• A UK study comparing cancer incidences of 50,000 British veterans of the 1991 gulf-war to 50,000 control servicemen who had not been deployed showed no increased risk.

• United Nations Environment Programme scientists have measured soil samples from known sites of artillery impact in Kosovo. Although radioactivity was increased slightly above background, counts were well within safe bounds and one expert declared the soil emitted so little radiation that it would be safe to eat.

What's the bottom line? Studies have been done and so far there seems to be no evidence linking depleted Uranium use to cancer. Of course, cancer is a slow-developing disease and continued follow-up studies will be necessary to determine if incidences are affected decades from now. So while human beings firing armor-piercing ammo at each other while littering the environment with heavy metals and explosives (ie war) should probably be considered as something that is bad for human health, it doesn't seem to make a difference whether you're firing lead or depleted Uranium. Can't we all just settle our differences over a little LAN party?