The extracellular topographical environment influences ovarian cancer cell behaviour

Surface roughness modulates EGFR signaling and stemness of triple-negative breast cancer cells

Introduction: Cancer stem cells (CSC), a major culprit of drug-resistant phenotypes and tumor relapse, represent less than 2 % of the bulk of TNBC cells, making them difficult to isolate, study, and thus, limiting our understanding of the pathogenesis of the disease. Current methods for CSC enrichment, such as 3D spheroid culture, genetic modification, and stem cell conditioning, are time consuming, expensive, and unsuitable for high-throughput assays. One way to address these limitations is to use topographical stimuli to enhance CSC populations in planar culture. Physical cues in the breast tumor microenvironment can influence cell behavior through changes in the mechanical properties of the extracellular matrix (ECM). In this study, we used topographical cues on polystyrene films to investigate their effect on the proteome and stemness of standard TNBC cell lines. Methods: The topographical polystyrene-based array was generated using razor printing and polishing methods. Proteome data were analyzed and enriched bioprocesses were identified using R software. Stemness was assessed measuring CD44, CD24 and ALDH markers using flow cytometry, immunofluorescence, detection assays, and further validated with mammosphere assay. EGF/EGFR expression and activity was evaluated using enzyme-linked immunosorbent assay (ELISA), immunofluorescence and antibody membrane array. A dose-response assay was performed to further investigate the effect of surface topography on the sensitivity of cells to the EGFR inhibitor. Results: Surface roughness enriched the CSC population and modulated epidermal growth factor receptor (EGFR) signaling activity in TNBC cells. Enhanced proliferation of MDA-MB-468 cells in roughness correlated with upregulation of the epidermal growth factor (EGF) ligand, which in turn corresponded with a 3-fold increase in the expression of EGFR and a 42% increase in its phosphorylation compared to standard smooth culture surfaces. The results also demonstrated that phenotypic changes associated with topographical (roughness) stimuli significantly decreased the drug sensitivity to the EGFR inhibitor gefitinib. In addition, the proportion of CD44+/CD24-/ALDH+ was enhanced on surface roughness in both MDA-MB-231 and MDA-MB-468 cell lines. We also demonstrated that YAP/TAZ activation decreased in a roughness-dependent manner, confirming the mechanosensing effect of the topographies on the oncogenic activity of the cells. Discussion: Overall, this study demonstrates the potential of surface roughness as a culture strategy to influence oncogenic activity in TNBC cells and enrich CSC populations in planar cultures. Such a culture strategy may benefit high-throughput screening studies seeking to identify compounds with broader tumor efficacy.

Ovarian Biomechanics: From Health to Disease

Biomechanics is a physical phenomenon which mainly related with deformation and movement of life forms. As a mechanical signal, it participates in the growth and development of many tissues and organs, including ovary. Mechanical signals not only participate in multiple processes in the ovary but also play a critical role in ovarian growth and normal physiological functions. Additionally, the involvement of mechanical signals has been found in ovarian cancer and other ovarian diseases, prompting us to focus on the roles of mechanical signals in the process of ovarian health to disease. This review mainly discusses the effects and signal transduction of biomechanics (including elastic force, shear force, compressive stress and tensile stress) in ovarian development as a regulatory signal, as well as in the pathological process of normal ovarian diseases and cancer. This review also aims to provide new research ideas for the further research and treatment of ovarian-related diseases.

Deciphering Biophysical Modulation in Ovarian Cancer Cells

It has been long known that the oncogenic extracellular environment plays an indispensable role in developing and nurturing cancer cell progression and in resistance to standard treatments. However, by how much the biophysical components of tumour extracellular environment contribute to these processes is uncertain. In particular, the topographic environment is scarcely explored. The biophysical modulation of cell behaviour is primarily facilitated through mechanotransduction-associated mechanisms, including focal adhesion and Rho/ROCK signalling. Dysregulation of these pathways is commonly observed in ovarian cancer and, therefore, biophysical modulation of these mechanisms may be of great importance to ovarian cancer development and progression. In this work, aspects of the biophysical environment were explored using a bioimprinting technique. The study showed that topography-mediated substrate sensing delayed cell attachment, however, cell-cell interactions overrode the effect of topography in some cell lines, such as OVCAR-5. Also, 3D topographical cues were shown to modulate the inhibition of focal adhesion and Rho signalling, which resulted in higher MAPK activity in cells on the bioimprints. It was revealed that c-Src is vital to the biophysical modulation of cell proliferation and inhibition of c-Src could downregulate biophysically modulated MAPK activity. This study provides evidence that the biophysical extracellular environment affects key intracellular mechanisms associated with tumourigenicity in ovarian cancer cells.

Extracellular biophysical environment: Guilty of being a modulator of drug sensitivity in ovarian cancer cells

The roles of the extracellular biophysical environment in cancer are barely studied. This study considers the possibility that cell-like topography of a cancer cell environment may influence chemo-responses. Here, a novel bioimprinting technique was employed to produce cell-like topography on the polystyrene substrates used for cell culture. In this work, we have shown that extracellular biophysical cues generated from the topography alter the chemosensitivity of ovarian cancer cells. The three-dimensionality of the bioimprinted surface altered the cell-surface interaction, which consequently modulated intracellular signalling and chemoresponses. Sensitivity to platinum was altered more than that to paclitaxel. The effect was largely mediated through the integrin/focal adhesion system and the Rho/ROCK pathway. Moreover, the results provided evidence that biophysical cues also modulate MAPK signalling associated with chemo-resistance in ovarian cancer. Therefore, the novel findings from of this study revealed for the first time that the effects of the biophysical environment, such as substrate topography, influences ovarian cancer cell responses to clinical drugs. These observations suggest that a full clinical understanding of ovarian cancer will include biophysical aspects of tumour microenvironment.