Effect of compression on tumor fluidity and invasion.

Uncontrolled growth of tumor cells in confined spaces leads to the accumulation of compressive stresses within the tumor. In this study, we developed a 3D in vitro model to study tumor spheroids under mechanical compression. Breast tumor spheroids of MDA-MB-231 cells were prepared and suspended in a dense 3D collagen matrix. A constant compressive load was then applied to them. The dynamics of tumor spheroids and cells within the spheroid were imaged and analyzed. Spheroid morphology and single-cell motility parameters were studied. We found that the spheroids under compression exhibit more dynamic shape changes in contrast to control. More importantly, compression promoted tumor invasion.