The noise and the KISS in the cancer stem cells niche.

There is a persistent controversy regarding the frequency of cancer stem cells (CSCs) in solid tumors. Initial studies indicated that these cells had a frequency ranging from 0.0001% to 0.1% of total cells. Recent studies have shown that this does not seem to be always the case. Some of these studies have indicated a frequency of 40%. Through a simple population dynamics model, we studied the effects of stochastic noise and cellular plasticity in the minimal path size of a cancer stem cells population, similar to what is done in what is sometimes called the Kierstead-Skellam-Slobodkin (KISS) Size analysis. We show that the possibility of large variations in the results obtained in the experiments may be a consequence of the different conditions under which the different experiments are submitted, specifically regarding the effective cell niche size where stem cells are transplanted. We also show the possibility of a noise induced transition where the stationary probability distribution of the CSC population can present bimodality.