Minhee Ku

Mechanical remodeling of cancer cells plays a critical role in regulating invasive behavior, yet its quantitative relationship with therapeutic response remains insufficiently defined. Here, we systematically characterize drug‐induced mechanophenotype changes at the single‐cell level using an integrated nanomechanical profiling approach that combines atomic force microscopy‐based force mapping of fixed cells, high‐resolution imaging, and cytomorphometric analysis under room‐temperature conditions. Pharmacological perturbation induces pronounced cytoskeletal reorganization accompanied by increased cortical stiffness and surface roughness. Systemic multivariate analysis identifies 11 biophysical parameters associated with invasive capacity, with nucleus modulus, cytoskeletal network density, and cortical roughness emerging as dominant contributors. Dimensionality reduction (principal component analysis (PCA) and partial least squares discriminant analysis (PLS‐DA)) reveals a distinct mechanophenotype transition characterized by elevated stiffness and suppressed protrusive activity. Especially, reduced invasiveness correlates with increased cortical roughness and reorganization of perinuclear cytoskeletal structures, indicating that these features define a quantitative mechanical signature of phenotypic reprogramming. This integrated mechanical signature enables discrimination between invasive and noninvasive states at the single‐cell level. These results establish nanomechanical profiling as a quantitative framework for assessing drug‐induced phenotypic transitions and provide a complementary approach to conventional molecular assays for evaluating therapeutic response in cancer cells.

Radiation therapy induces DNA damage primarily through reactive oxygen species, leading to cancer cell apoptosis. However, intratumoral heterogeneity and spatial dose variations often result in the survival of polyploid giant cancer cells (PGCCs), a therapy-resistant subpopulation characterized by multinucleation, genetic instability, and stem-like features. Particularly in malignant breast cancer, PGCCs contribute to recurrence by adopting a dormant yet invasive phenotype. Despite their clinical relevance, reliable tools to identify or characterize these cells remain lacking. Here, we present a nanomechanical single-cell profiling platform that enables high-resolution mechanomics of radiation-induced PGCCs. Through integrated cytoskeletal imaging and nanoscale stiffness mapping, we identify a distinct mechanical dormancy state, marked by cortical actin remodeling, nuclear enlargement, and biomechanical stiffening. This dormant mechanotype is coupled with suppressed proliferation yet sustained expression of invasion-associated markers, representing a latent therapeutic threat. Our findings position mechanical dormancy as a mechanobiological hallmark of radiation resistance and propose a predictive framework for optimizing radiotherapy thresholds. This platform enables mechanotype-guided stratification and precision-targeted intervention in radiation-refractory cancer.

The dynamic rearrangement of the cellular cytoskeletal network and changes in cellular stiffness play crucial roles in the progression of malignant tumors, including those with invasive and metastatic traits. Despite the acknowledged connections, the inherent complexity of cancer and the various microenvironments that individual cells experience during treatment have hindered comprehensive investigations into therapeutic responses, particularly at the individual cell level. Notably, the emergence of large DNA damage-induced cells following radiotherapy in the challenging-to-treat triple-negative breast cancer (TNBC) subtype suggests potential concurrent alterations in cellular mechanics. This study dives into the complex interplay among radiation therapy, cytoskeletal architecture, and cellular stiffness at the level of individual cells. By utilizing atomic force microscopy (AFM) as a quantitative and non-invasive technique, we discerned how cancer cells respond to radiation treatment based on their cytoskeletal properties. Our findings revealed a clear correlation between radiation therapy and disruptions in cytoskeletal integrity, along with a simultaneous increase in cellular stiffness. These observed changes could potentially indicate impending cell death or a reduced tendency for metastasis. Building on these insights, we propose that assessing cytoskeletal features through AFM holds potential for tailoring personalized radiation therapy approaches, depending on the distinct responses exhibited by cancer cells post-treatment. This shift in approach, guided by mechanics, underscores the capacity to enhance treatment effectiveness while minimizing unintended damage. By shedding light on the intricate interplay between radiation-induced cellular responses and mechanical properties, this study lays the foundation for innovative strategies that leverage cytoskeletal attributes to customize and optimize therapeutic interventions for TNBC and potentially other malignancies. Citation Format: Minhee Ku, Jin Sung Kim, Woong Sub Koom, Jaemoon Yang. Single-cell analysis of dynamic remodeling of radiated TNBC cells [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr LB_B17.

Reprogramming of cellular metabolism is an important, emerging, and universal hallmark of cancer which has received considerable attention during the recent era of cancer research. Cancer cells show characteristic alterations in glucose metabolism in order to fulfill the needs of biosynthesis for tumor proliferation and growth. However, under certain circumstances such as invasion and metastasis, cancer cells are prone to metabolic stress and will require different strategies to meet the high energetic demand from cancer progression. From various metabolic rewiring mechanisms, cancer cells adopt other metabolic pathways with alternative nutrient sources. Therefore, targeting cancer metabolism holds promising but great challenge caused by the metabolic plasticity of cancer cells. This review will discuss characteristic cancer metabolism in detail with special focus on lipid metabolism which is gathering increasingly keen interest, in order to find novel therapeutic approaches to head and neck cancer. By understanding and exploiting the synthesis, oxidation, and storage of fatty acids, we could investigate potential strategies to block cancer proliferation and progression.

Sentinel lymph node (SLN) biopsy has gained attention as a method of minimizing the extent of neck dissection with a similar survival rate as elective neck dissection in oral cancer. Indocyanine green (ICG) imaging is widely used in the field of surgical oncology. Real-time ICG-guided SLN imaging has been widely used in minimally invasive surgeries for various types of cancers. Here, we provide an overview of conventional SLN biopsy and ICG-guided SLN mapping techniques for oral cancer. Although ICG has many strengths, it still has limitations regarding its potential use as an ideal compound for SLN mapping. The development of novel fluorophores and imaging technology is needed for accurate identification of SLNs, which will allow precision surgery that would reduce morbidities and increase patient survival.

Microcapsules with molecule‐selective permeation are appealing as microreactors, capsule‐type sensors, drug and cell carriers, and artificial cells. To accomplish molecular size‐ and charge‐selective permeation, regular size of pores and surface charges have been formed in the membranes. However, it remains an important challenge to provide advanced regulation of transmembrane transport. Here, smart microcapsules are designed that provide molecular polarity‐ and temperature‐dependent permeability. With capillary microfluidic devices, water‐in‐oil‐in‐water (W/O/W) double‐emulsion drops are prepared, which serve as templates to produce microcapsules. The oil shell is composed of two monomers and dodecanol, which turns to a polymeric framework whose continuous voids are filled with dodecanol upon photopolymerization. One of the monomers provides mechanical stability of the framework, whereas the other serves as a compatibilizer between growing polymer and dodecanol, preventing macrophase separation. Above melting point of dodecanol, molecules that are soluble in the molten dodecanol are selectively allowed to diffuse across the shell, where the rate of transmembrane transport is strongly influenced by partition coefficient. The rate is drastically lowered for temperatures below the melting point. This molecular polarity‐ and temperature‐dependent permeability renders the microcapsules potentially useful as drug carriers for triggered release and contamination‐free microreactors and microsensors.

Polydiacetylene-based nanoparticles have been developed as nanocarriers for various bio-applications. However, how nanocarriers enter the cell environment and affect cell viability has not yet been considerably explored. In this study, polydiacetylene-based nanoliposomes (nanosomes) were electrostatically complexed with rhodamine fluorophores. Based on real-time cell imaging and cell viability assessment, the most highly polymerized nanosomes were found to be less toxic to cells. Moreover, it was revealed that the rhodamine/polydiacetylene nanosome complex dissociates at cell environment, the polydiacetylene nanosome penetrates into cells, as suggested by the fluorescence observed in confocal microscopy images.

Epidermal growth factor receptor (EGFR) overexpression is common in head and neck squamous cell carcinoma. Targeted therapy specifically directed towards EGFR has been an area of keen interest in head and neck cancer research, as EGFR is potentially an integration point for convergent signaling. Despite the latest advancements in cancer diagnostics and therapeutics against EGFR, the survival rates of patients with advanced head and neck cancer remain disappointing due to anti-EGFR resistance. This review article will discuss recent multilateral efforts to discover and validate actionable strategies that involve signaling pathways in heterogenous head and neck cancer and to overcome anti-EGFR resistance in the era of precision medicine. Particularly, this review will discuss in detail the issue of cancer metabolism, which has recently emerged as a novel mechanism by which head and neck cancer may be successfully controlled according to different perspectives.

The aim of this study was the development of a human epidermal growth factor receptor 2 (HER2)-targetable contrast agent for magnetic resonance imaging (MRI) with a high magnetic sensitivity. An anti-HER2 aptamer-modified magnetic nanosensitizer (Apt(HER2)-MNS) was prepared by conjugation with 5'-thiol-modified aptamers and maleimidylated magnetic nanocrystals (MNCs). The physicochemical characteristics and targeting ability of Apt(HER2)-MNS were confirmed, and the binding affinity (K-d) onto HER2 protein of Apt(HER2)-MNS was 0.57 +/- 0.26 nM. In vivo MRI contrast enhancement ability was also verified at HER2+ cancer cell (NIH3T6.7)-xenograft mouse models (n = 3) at 3T clinical MRI instrument. The control experiment was carried out using non-labeled MNCs. The results indicated that up to 150% contrast enhancement was achieved at the tumor region in the T2-weighted MR images after the injection of the Apt(HER2)-MNS agent in mice that received the NIH3T6.7 cells.

Biophysical properties are intimately connected to metastatic functions and aggressiveness in cancers. Especially, cellular stiffness is regarded as a biomarker for the understanding of metastatic potential and drug sensitivity. Here, protease‐mediated changes of cortical stiffness are identified due to the deformation of cytoskeleton alignment at a cortex. For the past few decades, membrane type 1‐matrix metalloproteinase (MT1‐MMP) has been well known as a kernel protease enriched in podosomes during metastasis for extracellular matrix degradation. However, the biophysical significance of MT1‐MMP expressing cancer cells is still unknown. Therefore, the nanomechanics of cancer cells is analyzed by a nanoindentation using a microsphere‐attached cantilever of atomic force microscopy (AFM). In conclusion, the results suggest that MT1‐MMP has contributed as a key regulator in cytoskeletal deformation related with cancer metastasis. Particularly, the AFM‐based nanoindentation system for the monitoring of cortical nanomechanics will be crucial to understand molecular networks in cancers.