Emergent in vitro Cancer Tumor Hypoxia and K-Core Collapse*

We have developed a oxygen-permeable thin film containing a platinum-porphyrin phosphorescent dye whose excited state is quenched by O2. The dye phosphorescence intensity is a function of oxygen concentration over at least 3 orders of magnitude, when used in a microfabricated 3D ecology we get time and space resolved hypoxia of a PC3 cancer colony. The cancer colony when enclosed generates its own emergent hypoxia due to metabolism to the remarkably low level of 0.01 or lower normoxia and can maintain this for several days. However, the extremely low self-induced hypoxia and acidosis seems to generate a collective response of the cells consisting of polyploidal giant cells with strong interconnects. This ``k-core” interactive colony ultimately reaches a tipping point and collapses.