Thanks for the guest post. You make some really good points about the induction of carcinogenesis and the hype about iPS and ESC-like phenotypes of cancer.

You asked if anyone has tried to do iPS from stem cells, so I wanted to point out this paper to you from Nature in October 2009 from Hans Scholer’s group at the Planck Institute [1]. They used NSCs to make iPSCs, and showed that they could get iPSCs with only one or two of the famous 4 factors (just Oct4 or Klf4 or Oct4 alone) and got ES-like cells with all the differentiation potential.

The ease by which adult stem cells can be induced to an immortal pluripotent state supports your hypothesis that cancer arises from progenitor cells, and not fully differentiated somatic cells. For, you could imagine, to achieve an ESC-like state, a differentiated cell might need 4 “hits” and an adult stem cell might only require 2. This difference of 2 hits, looking at it from the perspective of calculating the probability that a population of aspiring tumor cells could achieve the mutations, makes it many orders of magnitude more probable that tumors would arise from adult stem cells, with two fewer evolutionary barriers for the cancer to overcome.

[1]: Direct reprogramming of human neural stem cells by OCT4. Kim JB et al.