Abstract 6224: Drop-like deformation of nuclei in cancer patient tissue
Authors: Dubell Christina R. , Wang Ting-Ching , Singh Ishita , Rosen Daniel G. , Chakraborty Saptarshi , Lele Tanmay P. 
Published: March 2024

In this study, we investigated nuclear deformations in cancer tissues and their clinical relevance to diagnostics.

Introduction: Cancers are graded by pathologists examining biopsy slides stained with hematoxylin and eosin for factors including nuclear atypia, which can include features like lobules, invaginations, large nuclear size, and prominent nucleoli. While the importance of nuclear atypia has been known for centuries, its cause remains unclear. Nuclear shaping has been studied extensively in vitro, leading to the liquid drop model of nuclear shaping, which states that nuclear shape changes can occur due to excess area in the form of wrinkles or folds in the lamina. When the lamina becomes fully taut, the nucleus reaches a limiting steady shape. Wrinkles allow the nuclear shape to mirror the cell shape such as in invading cancer cells. The applicability of this model to nuclei in cancer tissues from human patients is untested. Here, tissues were stained for nuclear lamina proteins to test for the presence of excess area in the lamina. Diagnostic relevance of the drop model was assessed by quantitative Fourier analysis of high-resolution images of lamin-stained nuclei.

Methods: Deidentified patient tissues from breast, colon, head and neck, and skin were immunostained for lamin B1 and imaged at high resolution (60X, 1.5 NA). Nuclei were then roughly segmented by the deep learning program Cellpose, followed by segmentation with a custom approach that sensitively detects micron-scale variations in the laminar contour. An Elliptical Fourier Analysis was performed to quantify nuclear irregularity by describing nuclear shape with a series of elliptical harmonics. More irregular nuclei are described by larger Fourier coefficients at higher frequencies.

Results: Folds and wrinkles in the nuclear lamina were observed in healthy tissue from all four tissue types studied, indicating the presence of excess area in the lamina. The presence of irregular nuclear shape including wrinkling/folds in the lamina was quantified with the Elliptical Fourier Coefficient (EFC) ratio. Posterior probability analysis related EFC ratio to tumor grade to assess the clinical value of the excess area found in the nuclear lamina. This revealed cancer-type dependent trends between EFC ratio and tumor grade.

Conclusions: Observations of wrinkling/folds in the nuclear lamina in healthy and cancerous tissue are consistent with the liquid drop model of nuclear deformation. Quantification of nuclear lamina wrinkling with the EFC ratio, along with other nuclear shape parameters, can be a powerful approach for computer-based, explainable, clinical grading. Our findings reveal a fundamental principle of nuclear deformation in cancer tissues and suggest a new approach for improving the accuracy in cancer grading.

Citation Format: Christina R. Dubell, Ting-Ching Wang, Ishita Singh, Daniel G. Rosen, Saptarshi Chakraborty, Tanmay P. Lele. Drop-like deformation of nuclei in cancer patient tissue [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6224.