Investigating the mechanics of cancer tissue - my MSc thesis in 3 minutes скачать в хорошем качестве

Investigating the mechanics of cancer tissue - my MSc thesis in 3 minutes

Work conducted at the University of Bern (Institute of Cell Biology) in the laboratory of Prof. Olivier Pertz. Thesis abstract: Breast cancer is among the most prevalent epithelial malignancies and is frequently driven by mutations in the PIK3CA gene. These mutations result in constitutive activation of the PI3K/AKT pathway, which promotes oncogenic phenotypes through enhanced cell survival, proliferation, and metabolic reprogramming. While the PI3K signaling crosstalk with the MAPK/ERK pathway is well established, recent in vitro findings from our laboratory suggest that oncogenic PI3K signaling may also disrupt mechanotransduction, an integrated set of signaling pathways by which cells convert mechanical cues from their environment into biochemical responses. Altered mechanical signaling is increasingly recognized as a contributor to cancer progression, yet the mechanisms by which oncogenic PI3K mutations impact this process remain poorly understood. In this study, we investigated how optogenetically induced mechanical perturbations affect downstream ERK signaling dynamics in breast epithelial monolayers, comparing responses between PIK3CA H1047R mutant and wild-type MCF10A cells. Conventional genetic and pharmacological perturbations lack the precision to resolve complex, dynamic signaling events. Thus, tools that provide spatiotemporal control of signaling and mechanics are therefore essential for dissecting how oncogenic PI3K mutations rewire cellular responses. To this end, we modularized several optogenetic actuators, optoLARG, optoMYPT1 and optoShroom3, using the Mammalian Toolkit (MTK), which enabled the reuse of common genetic elements and the rapid assembly of customizable gene circuits. Among these tools, optoLARG was selected as the most robust and reliable actuator to control cellular contractility. This system was then used to achieve precise spatiotemporal activation of RhoA-mediated contractility in MCF10A mammary epithelial cells, both wildtype and PIK3CA H1047R mutant. Despite persistent challenges related to the long-term stability of optoLARG transgene expression, ultimately preventing reliable side-by-side comparison of mutant and wild-type cells, we show that light-induced contraction of PIK3CA mutant epithelia elicits wavelike ERK propagation, a phenomenon commonly seen in migrating cells. This response occurs in both confluent monolayers and subconfluent colonies, suggesting that mutant cells possess heightened sensitivity to mechanical cues, which can promote spontaneous cell displacement. Furthermore, functional binning of single-cell responses revealed distinct ERK dynamics: mechanical stretch enhanced ERK activity, whereas contraction suppressed it. While these results are broadly consistent with previous reports, the finding that contraction deactivates ERK remains comparatively underexplored. Together, these observations reinforce the concept that mechanical perturbations shape downstream ERK activity and point to a mechanistic link between oncogenic PI3K signaling, altered force sensing, and dysregulated mitogenic signaling, offering new insight into how mechanical dysfunction may contribute to the early stages of breast epithelial malignancy.