Nanopillar-guided subnuclear deformations in tumor cells

• Main Author: Zeng, Yongpeng
• Other Authors: Zhao Wenting
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Nanotechnology
• Online Access: https://hdl.handle.net/10356/156207
• Institution: Nanyang Technological University

Subnuclear shape irregularities, including folding and grooves of the nuclear envelope, function as a routine marker in the diagnosis and prognosis of many cancer types and show strong correlation with diverse pathological alterations. However, their assessment is primarily relying on qualitative visual inspection due to the small feature size and random distribution that are extremely difficult to be quantified using conventional technology. Consequently, lack of tool for providing quantitative evaluation of such irregularities becomes a significant bottleneck for precise cancer grading and the related fundamental studies. In this thesis, we developed a novel nanopillar-based assay to easily locate and subsequently quantitative characterization for subnuclear irregularities in cancer cells, thereby improving the precision of distinguishing malignancy for cancer diagnosis and drug screening, as well as enabling a new angle to investigate the molecular mechanism underlying the formation and regulation of subnuclear irregularities in cancer cells. This goal was pursued in three steps as detailed in three chapters from Chapter 2 to 4. In the first step in Chapter 2, we established the methodology of applying nanopillar arrays for the effective guidance and characterization of subnuclear shape irregularities in breast cancer cells. Distinct guided subnuclear features further enable quantitative differentiation of cancer cells with varying malignancies. Optimal nanopillar dimensions for malignancy differentiation have been determined. This method has been demonstrated to probe the heterogeneity within a mixed population of both low- and high-malignant cells and even within the same cell line. In addition, the differential anti-cancer drug response in low- and high-malignant cells has been revealed using this assay. In the second step in Chapter 3, the prevalence of this assay across different cancer types has been demonstrated. Nanopillar-enabled evaluation of subnuclear irregularities enables heterogeneity evaluation among individual neuroblastoma cells. The heterogeneity within neuroblastoma cells is found to strongly correlate with metastatic potential, thus holding a promise for precise risk stratification. Furthermore, this assay is able to assess drug response at single-cell level. In the third step in Chapter 4, we explored the underlying mechanism of the subnuclear irregularities through nanopillar guidance. Coupled with computer-based systematic analysis of subnuclear features on nanopillars, we developed a comprehensive characterization matrix to afford a minute characterization of the subnuclear irregularities. The impact of a wide spectrum of cellular modulators of the irregularities has been analyzed by the characterization matrix, where critical regulators such as contractility and nuclear lamina mechanics have been identified. Besides, an analysis pipeline has been proposed to provide quantitative comparison among different regulators. In summary, we developed a nanopillar-based tool for quantitatively assessment of subnuclear irregularities in cancer cells. We believe this tool constitutes a novel and powerful system for precise malignancy evaluation and elucidating nuclear biology from a new angle.