Abstract 1513: Morphological analysis of compressed nuclei reveals conserved irregularities of different cell types

Abstract Solid tumors such as mammary and brain exert compressive forces on the surrounding host tissue over the course of tumor expansion. However, how these forces impact neighboring peritumoral cells remains poorly understood. In this study, we used an in vitro transwell compression device to evaluate the effect of compression on mouse fibroblasts and human astrocytes, the most abundant stromal cell types in the breast and brain peritumor, respectively. Strikingly, we noticed that compression altered nuclear morphology in the two cell types. We then utilized an unsupervised machine-learning clustering algorithm to determine the relative abundance of various nuclear geometries present in both groups. We found that compressed nuclei predominantly exhibited diverse morphologies, including circular, elongated, and kidney bean-like shapes. In contrast, uncompressed nuclei were morphologically homogeneous, with most maintaining a canonical circular or elliptical shape. We validated these observations using ImageJ, showing that compressed nuclei possessed significantly lower circularity, roundness, and solidity, while displaying significantly higher eccentricity compared to uncompressed nuclei. Because fibroblasts and astrocytes share analogous roles, we sought to determine whether these observed differences were recapitulated in functionally distinct cell types such as immune cells. Surprisingly, murine macrophages exhibited the same predominant shape modes and similar quantitative differences in shape factors seen in the stromal cells. Furthermore, we performed nuclear morphometric analysis to numerically characterize the relative irregularity of compressed nuclei in astrocytes based on the calculation of a nuclear irregularity index (NII). Our analysis revealed that the NII of compressed nuclei is significantly higher than their uncompressed counterparts while the nuclear area in both groups was similar. Among 7 morphological categories, uncompressed nuclei were classified as “normal” while compressed nuclei were classified as “irregular.” These findings suggest that compressed nuclei may either be undergoing mitotic catastrophe or another nuclear damaging event rather than acquire aberrant morphologies due to mechanically induced senescence or apoptosis. In fact, we were able to demonstrate in preliminary live-dead cell imaging experiments that these morphologies are captured in compressed live cells. Altogether, these results indicate that compression appears to induce morphological changes that are conserved in distinct cell types. Citation Format: Julian Najera, Bianca Batista, Triston Acher, Meenal Datta. Morphological analysis of compressed nuclei reveals conserved irregularities of different cell types [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1513.