The image on the cover of the July 1 issue of Biophysical Journal illustrates a circulating tumor cell forming membrane protrusions known as microtentacles. Microtentacles consist of parallel microtubule bundles that emerge from the microtubule organizing center within the cell body into the membrane protrusion. In our study, we investigated how microtubules generate the forces needed to drive membrane protrusions, specifically exploring how they can produce the force required to push the cell membrane outward.

We found that they polymerize against the cell membrane, and the resulting resistance from the deformed membrane creates a bending force at the microtubule tips that leads to curved microtentacles.

Microtentacles play a critical role in facilitating the reattachment of circulating tumor cells to blood vessel walls, a key step in the extravasation process, which enables tumor cells to leave the bloodstream and invade new tissues—a fundamental mechanism of metastasis. The length and curvature of microtentacles are both crucial parameters that determine the efficiency of the extravasation from the blood stream of circulating tumor cells.

Because metastasis remains one of the leading causes of cancer-related mortality, understanding these biomechanical mechanisms is essential for developing new therapeutic strategies that can limit or prevent metastatic spread.

To learn more about our research, visit http://www.lautenschlaeger.uni-saarland.de

— Lucina Kainka,  Reza Shaebani,  Kathi Kaiser,  Jonas Bosche, Ludger Santen, and  Franziska Lautenschläger