Quantifying Breast Cancer-Driven Fiber Alignment and Collagen Deposition in Primary Human Breast Tissue

Collagen architecture in triple negative breast cancer

This study evaluated collagen properties in TNBC samples collected from different racial groups to determine the presence of variance in matrix architecture. African American (AA) breast cancer patients have a significantly higher mortality rate and nearly a three-fold increased prevalence of triple negative breast cancer (TNBC) when compared to Caucasian (C) patients. The extracellular matrix region surrounding tumors contains abundant collagen fibers, and these fibers undergo remodeling throughout cancer progression, promote metastasis, and impede treatment response. High mammographic density, commonly known as dense breast tissue, is hypothesized to be more prevalent in AA women and characterized by increased collagen deposition and associated with more aggressive cancers. The aim of this research was to investigate fibrillar collagen architecture in TNBC samples from AA and C patients using two-photon microscopy with second harmonic generation (SHG), an intrinsic optical signal produced by fibrillar collagen. Twenty tissue regions per tumor sample were randomly selected for SHG microscopy, and image processing was conducted using the Fiji macro TWOMBLI to quantify mesoscopic fibrillar morphological properties and nanoscopic fibrillar properties with the Forward-Backward SHG ratio. Compared to the images from C tumor samples, those from AA samples exhibited a significant increase in parameters including fiber area, total length, and number of endpoints and branchpoints, but had decreased lacunarity. Collagen microstructure, including fibril arrangement and packing density, did not significantly differ between the groups. These results illustrate that the TNBC samples analyzed from AA patients may have macrostructural collagen characteristics associated with aggressive phenotype tumor formation.

Matrix stiffening from collagen fibril density and alignment modulates YAP-mediated T-cell immune suppression

T-cells are essential components of the immune system, adapting their behavior in response to the mechanical environments they encounter within the body. In pathological conditions like cancer, the extracellular matrix (ECM) often becomes stiffer due to increased density and alignment of collagen fibrils, which can have a significant impact on T-cell function. In this study, we explored how these ECM properties-density and fibrillar alignment-affect T-cell behavior using three-dimensional (3D) collagen matrices that mimic these conditions. Our results show that increased matrix stiffness, whether due to higher density or alignment, significantly suppresses T-cell activation, reduces cytokine production, and limits proliferation, largely through enhanced YAP signaling. Individually, matrix alignment appears to lower actin levels in activated T-cells and changes migration behavior in both resting and activated T-cells, an effect not observed in matrices with randomly oriented fibrils. Notably, inhibiting YAP signaling was able to restore T-cell activation and improve immune responses, suggesting a potential strategy to boost the effectiveness of immunotherapy in stiff ECM environments. Overall, this study provides new insights into how ECM characteristics influence T-cell function, offering potential avenues for overcoming ECM-induced immunosuppression in diseases such as cancer.

Tension directs cancer cell migration over fiber alignment through energy minimization

Cell migration during many fundamental biological processes including metastasis requires cells to traverse tissue with heterogeneous mechanical cues that direct migration as well as determine force and energy requirements for motility. However, the influence of discrete structural and mechanical cues on migration remains challenging to determine as they are often coupled. Here, we decouple the pro-invasive cues of collagen fiber alignment and tension to study their individual impact on migration. When presented with both cues, cells preferentially travel in the axis of tension against fiber alignment. Computational and experimental data show applying tension perpendicular to alignment increases potential energy stored within collagen fibers, lowering requirements for cell-induced matrix deformation and energy usage during migration compared to motility in the direction of fiber alignment. Energy minimization directs migration trajectory, and tension can facilitate migration against fiber alignment. These findings provide a conceptual understanding of bioenergetics during migration through a fibrous matrix.

Epithelial-Mesenchymal Plasticity and Epigenetic Heterogeneity in Cancer

The tumor microenvironment comprises various cell types and experiences dynamic alterations in physical and mechanical properties as cancer progresses. Intratumoral heterogeneity is associated with poor prognosis and poses therapeutic challenges, and recent studies have begun to identify the cellular mechanisms that contribute to phenotypic diversity within tumors. This review will describe epithelial-mesenchymal (E/M) plasticity and its contribution to phenotypic heterogeneity in tumors as well as how epigenetic factors, such as histone modifications, histone modifying enzymes, DNA methylation, and chromatin remodeling, regulate and maintain E/M phenotypes. This review will also report how mechanical properties vary across tumors and regulate epigenetic modifications and E/M plasticity. Finally, it highlights how intratumoral heterogeneity impacts therapeutic efficacy and provides potential therapeutic targets to improve cancer treatments.

Decellularized extracellular matrix-based bioengineered 3D breast cancer scaffolds for personalized therapy and drug screening

Breast cancer (BC) is the second deadliest cancer after lung cancer. Similar to all cancers, it is also driven by a 3D microenvironment. The extracellular matrix (ECM) is an essential component of the 3D tumor micro-environment, wherein it functions as a scaffold for cells and provides metabolic support. BC is characterized by alterations in the ECM. Various studies have attempted to mimic BC-specific ECMs using artificial materials, such as Matrigel. Nevertheless, research has proven that naturally derived decellularized extracellular matrices (dECMs) are superior in providing the essential in vivo-like cues needed to mimic a cancer-like environment. Developing in vitro 3-D BC models is not straightforward and requires extensive analysis of the data established by researchers. For the benefit of researchers, in this review, we have tried to highlight all developmental studies that have been conducted by various scientists so far. The analysis of the conclusions drawn from these studies is also discussed. The advantages and drawbacks of the decellularization methods employed for generating BC scaffolds will be covered, and the review will shed light on how dECM scaffolds help develop a BC environment. The later stages of the article will also focus on immunogenicity issues arising from decellularization and the origin of the tissue. Finally, this review will also discuss the biofabrication of matrices, which is the core part of the bioengineering process.

Using Microfluidics to Align Matrix Architecture and Generate Chemokine Gradients Promotes Directional Branching in a Model of Epithelial Morphogenesis

The mechanical cue of fiber alignment plays a key role in the development of various tissues in the body. The ability to study the effect of these stimuli in vitro has been limited previously. Here, we present a microfluidic device capable of intrinsically generating aligned fibers using the microchannel geometry. The device also features tunable interstitial fluid flow and the ability to form a morphogen gradient. These aspects allow for the modeling of complex tissues and to differentiate cell response to different stimuli. To demonstrate the abilities of our device, we incorporated luminal epithelial cysts into our device and induced growth factor stimulation. We found the mechanical cue of fiber alignment to play a dominant role in cell elongation and the ability to form protrusions was dependent on cadherin-3. Together, this work serves as a springboard for future potential with these devices to answer questions in developmental biology and complex diseases such as cancers.

Assessing the impact of extracellular matrix fiber orientation on breast cancer cellular metabolism

The extracellular matrix (ECM) is a dynamic and complex microenvironment that modulates cell behavior and cell fate. Changes in ECM composition and architecture have been correlated with development, differentiation, and disease progression in various pathologies, including breast cancer [1]. Studies have shown that aligned fibers drive a pro-metastatic microenvironment, promoting the transformation of mammary epithelial cells into invasive ductal carcinoma via the epithelial-to-mesenchymal transition (EMT) [2]. The impact of ECM orientation on breast cancer metabolism, however, is largely unknown. Here, we employ two non-invasive imaging techniques, fluorescence-lifetime imaging microscopy (FLIM) and intensity-based multiphoton microscopy, to assess the metabolic states of cancer cells cultured on ECM-mimicking nanofibers in a random and aligned orientation. By tracking the changes in the intrinsic fluorescence of nicotinamide adenine dinucleotide and flavin adenine dinucleotide, as well as expression levels of metastatic markers, we reveal how ECM fiber orientation alters cancer metabolism and EMT progression. Our study indicates that aligned cellular microenvironments play a key role in promoting metastatic phenotypes of breast cancer as evidenced by a more glycolytic metabolic signature on nanofiber scaffolds of aligned orientation compared to scaffolds of random orientation. This finding is particularly relevant for subsets of breast cancer marked by high levels of collagen remodeling (e.g. pregnancy associated breast cancer), and may serve as a platform for predicting clinical outcomes within these subsets [3-6].

Cyclic Stretching Triggers Cell Orientation and Extracellular Matrix Remodeling in a Periodontal Ligament 3D In Vitro Model

During orthodontic tooth movement (OTM), the periodontal ligament (PDL) plays a crucial role in regulating the tissue remodeling process. To decipher the cellular and molecular mechanisms underlying this process in vitro, suitable 3D models are needed that more closely approximate the situation in vivo. Here, a customized bioreactor is developed that allows dynamic loading of PDL-derived fibroblasts (PDLF). A collagen-based hydrogel mixture is optimized to maintain structural integrity and constant cell growth during stretching. Numerical simulations show a uniform stress distribution in the hydrogel construct under stretching. Compared to static conditions, controlled cyclic stretching results in directional alignment of collagen fibers and enhances proliferation and spreading ability of the embedded PDLF cells. Effective force transmission to the embedded cells is demonstrated by a more than threefold increase in Periostin protein expression. The cyclic stretch conditions also promote extensive remodeling of the extracellular matrix, as confirmed by increased glycosaminoglycan production. These results highlight the importance of dynamic loading over an extended period of time to determine the behavior of PDLF and to identify in vitro mechanobiological cues triggered during OTM-like stimulus. The introduced dynamic bioreactor is therefore a useful in vitro tool to study these mechanisms.

Imaging and quantification of the tumor microenvironment of triple negative breast cancer using TPEF and scanning laser optical tomography

Triple-negative breast cancer is an aggressive subtype of breast cancer that has a poor five-year survival rate. The tumor's extracellular matrix is a major compartment of its microenvironment and influences the proliferation, migration and the formation of metastases. The study of such dependencies requires methods to analyze the tumor matrix in its native form. In this work, the limits of SHG-microscopy, namely limited penetration depth, sample size and specificity, are addressed by correlative three-dimensional imaging. We present the combination of scanning laser optical tomography (SLOT) and multiphoton microscopy, to depict the matrix collagen on different scales. Both methods can be used complementarily to generate full-volume views and allow for in-depth analysis. Additionally, we explore the use of SHG as a contrast mechanism for complex samples in SLOT. It was possible to depict the overall collagen structure and specific fibers using marker free imaging on different scales. An appropriate sample preparation enables the fixation of the structures while simultaneously conserving the fluorescence of antibody staining. We find that SHG is a suitable contrast mechanism to depict matrix collagen even in complex samples and using SLOT. The insights presented here shall further facilitate the study of the tumor extracellular matrix by correlative 3d imaging.

Quantitative collagen analysis using second harmonic generation images for the detection of basal cell carcinoma with ex vivo multiphoton microscopy

Basal cell carcinoma (BCC) is the most common skin cancer, and its incidence is rising. Millions of benign biopsies are performed annually for BCC diagnosis, increasing morbidity, and healthcare costs. Non-invasive in vivo technologies such as multiphoton microscopy (MPM) can aid in diagnosing BCC, reducing the need for biopsies. Furthermore, the second harmonic generation (SHG) signal generated from MPM can classify and prognosticate cancers based on extracellular matrix changes, especially collagen type I. We explored the potential of MPM to differentiate collagen changes associated with different BCC subtypes compared to normal skin structures and benign lesions. Quantitative analysis such as frequency band energy analysis in Fourier domain, CurveAlign and CT-FIRE fibre analysis was performed on SHG images from 52 BCC and 12 benign lesions samples. Our results showed that collagen distribution is more aligned surrounding BCCs nests compared to the skin's normal structures (p < 0.001) and benign lesions (p < 0.001). Also, collagen was orientated more parallelly surrounding indolent BCC subtypes (superficial and nodular) versus those with more aggressive behaviour (infiltrative BCC) (p = 0.021). In conclusion, SHG signal from type I collagen can aid not only in the diagnosis of BCC but could be useful for prognosticating these tumors. Our initial results are limited to a small number of samples, requiring large-scale studies to validate them. These findings represent the groundwork for future in vivo MPM for diagnosis and prognosis of BCC.

Epiploic Adipose Tissue (EPAT) in Obese Individuals Promotes Colonic Tumorigenesis: A Novel Model for EPAT-Dependent Colorectal Cancer Progression

The obesity epidemic is associated with increased colorectal cancer (CRC) risk and progression, the mechanisms of which remain unclear. In obese individuals, hypertrophic epiploic adipose tissue (EPAT), attached to the colon, has unique characteristics compared to other fats. We hypothesized that this understudied fat could serve as a tumor-promoting tissue and developed a novel microphysiological system (MPS) for human EPAT-dependent colorectal cancer (CRC-MPS). In CRC-MPS, obese EPAT, unlike lean EPAT, considerably attracted colon cancer HT29-GFP cells and enhanced their growth. Conditioned media (CM) from the obese CRC-MPS significantly increased the growth and migration of HT29 and HCT116 cells (p < 0.001). In HT29 cells, CM stimulated differential gene expression (hOEC₈₆₇) linked to cancer, tumor morphology, and metabolism similar to those in the colon of high-fat-diet obese mice. The hOEC₈₆₇ signature represented pathways found in human colon cancer. In unsupervised clustering, hOEC₈₆₇ separated transcriptomes of colon cancer samples from normal with high significance (PCA, p = 9.6 × 10^-11). These genes, validated in CM-treated HT29 cells (p < 0.05), regulate the cell cycle, cancer stem cells, methylation, and metastasis, and are similarly altered in human colon cancer (TCGA). These findings highlight a tumor-promoting role of EPAT in CRC facilitated with obesity and establishes a platform to explore critical mechanisms and develop effective treatments.

Unusual Suspects: Bone and Cartilage ECM Proteins as Carcinoma Facilitators

The extracellular matrix (ECM) is the complex three-dimensional network of fibrous proteins and proteoglycans that constitutes an essential part of every tissue to provide support for normal tissue homeostasis. Tissue specificity of the ECM in its topology and structure supports unique biochemical and mechanical properties of each organ. Cancers, like normal tissues, require the ECM to maintain multiple processes governing tumor development, progression and spread. A large body of experimental and clinical evidence has now accumulated to demonstrate essential roles of numerous ECM components in all cancer types. Latest findings also suggest that multiple tumor types express, and use to their advantage, atypical ECM components that are not found in the cancer tissue of origin. However, the understanding of cancer-specific expression patterns of these ECM proteins and their exact roles in selected tumor types is still sketchy. In this review, we summarize the latest data on the aberrant expression of bone and cartilage ECM proteins in epithelial cancers and their specific functions in the pathogenesis of carcinomas and discuss future directions in exploring the utility of this selective group of ECM components as future drug targets.