A study published in Developmental Cell reveals that sustained mechanical pressure within tumors can activate a self-destruct process in invasive cancer cells, potentially curbing their ability to metastasize. The research highlights a previously unknown link between physical forces in tumors and necroptosis, a specific type of programmed cell death, offering insights into how cancer cells respond to prolonged confinement.
Cancer cells must handle dense environments while invading nearby tissues and entering the bloodstream. Some achieve this via the mesenchymal-to-amoeboid transition (MAT), shifting from an elongated, adhesive movement style to a more compact, adaptable shape that enables them to pass through tight spaces. This adaptation helps them adjust to their surroundings.
Investigating the Effects of Mechanical Pressure
To explore how mechanical pressure impacts cancer cells, researchers under Liming Sun, PhD, created a lab setup that mirrored aspects of the three-dimensional tumor microenvironment. Unlike standard two-dimensional cell cultures, this system subjected cancer cells to ongoing confinement while restricting their surface adhesion. This configuration enabled the study of mechanical pressure effects.
The findings exposed an unexpected weakness. While cancer cells first adapted to confinement by increasing mobility, extended exposure triggered necroptosis, leading to membrane rupture and cell death. The team linked this response to a signaling cascade involving three proteins: PIEZO1, STAT1, and MLKL. This pathway is central to the mechanism.
A Natural “Braking Mechanism” Against Metastasis
PIELO1, which detects mechanical stress, activated STAT1, boosting MLKL production—a protein that sparks necroptosis, a type of programmed cell death. Remarkably, this occurred without RIPK3, an enzyme usually necessary to start this death process. The researchers term this pathway a “natural ‘braking mechanism’” capable of eliminating highly invasive cancer cells. This mechanism may curb metastasis.
When scientists genetically removed MLKL, cancer cells managed to endure confinement and sustain their mobility. These surviving cells might represent groups with enhanced metastatic potential. Examination of human tumor samples corroborated this, revealing that less aggressive areas of breast tumors exhibited higher MLKL levels, whereas colorectal cancer cells at the invasive fronts of liver metastases displayed lower MLKL expression compared to cells in matched primary tumors. MLKL expression varied across tumor types.
These findings suggest that MLKL expression might serve as a marker to identify cancers with higher metastatic risk. They also point to a therapeutic angle: reactivating or strengthening this cell-death pathway, possibly in combination with current cancer therapies. However, the research is still in preclinical stages, and additional studies are necessary to assess whether this pathway can be safely utilized in patients. Further investigation is needed to fully explore the mechanism’s potential.
