Simple plant cell morphologies, such as cylindrical shoot cells, are determined by the extensibility pattern of the primary cell wall, which is thought to be largely dominated by cellulose microfibrils, but the mechanism leading to more complex shapes, such as the interdigitated patterns in the epidermis of many eudicotyledon leaves, is much less well understood. Details about the manner in which cell wall polymers at the periclinal wall regulate the morphogenetic process in epidermal pavement cells and mechanistic information about the initial steps leading to the characteristic undulations in the cell borders are elusive. Here, we used genetics and recently developed cell mechanical and imaging methods to study the impact of the spatio-temporal dynamics of cellulose and homogalacturonan pectin distribution during lobe formation in the epidermal pavement cells of Arabidopsis (Arabidopsis thaliana) cotyledons. We show that nonuniform distribution of cellulose microfibrils and demethylated pectin coincides with spatial differences in cell wall stiffness but may intervene at different developmental stages. We also show that lobe period can be reduced when demethyl-esterification of pectins increases under conditions of reduced cellulose crystallinity. Our data suggest that lobe initiation involves a modulation of cell wall stiffness through local enrichment in demethylated pectin, whereas subsequent increase in lobe amplitude is mediated by the stress-induced deposition of aligned cellulose microfibrils. Our results reveal a key role of noncellulosic polymers in the biomechanical regulation of cell morphogenesis.

Ascites refers to the abnormal accumulation of fluid in the peritoneum resulting from an underlying pathology, such as metastatic cancer. Among all cancers, advanced-stage epithelial ovarian cancer is most frequently associated with the production of malignant ascites and is the leading cause of death from gynecologic malignancies. Despite decades of evidence showing that the accumulation of peritoneal fluid portends the poorest outcomes for cancer patients, the role of malignant ascites in promoting metastasis and therapy resistance remains poorly understood. This review summarizes the current understanding of malignant ascites, with a focus on ovarian cancer. The first section provides an overview of heterogeneity in ovarian cancer and the pathophysiology of malignant ascites. Next, analytical methods used to characterize the cellular and acellular components of malignant ascites, as well the role of these components in modulating cell biology, are discussed. The review then provides a perspective on the pressures and forces that tumors are subjected to in the presence of malignant ascites and the impact of physical stress on therapy resistance. Treatment options for malignant ascites, including surgical, pharmacological and photochemical interventions are then discussed to highlight challenges and opportunities at the interface of drug discovery, device development and physical sciences in oncology.

A key reason for the persistently grim statistics associated with metastatic ovarian cancer is resistance to conventional agents, including platinum-based chemotherapies. A major source of treatment failure is the high degree of genetic and molecular heterogeneity, which results from significant underlying genomic instability, as well as stromal and physical cues in the microenvironment. Ovarian cancer commonly disseminates via transcoelomic routes to distant sites, which is associated with the frequent production of malignant ascites, as well as the poorest prognosis. In addition to providing a cell and protein-rich environment for cancer growth and progression, ascitic fluid also confers physical stress on tumors. An understudied area in ovarian cancer research is the impact of fluid shear stress on treatment failure. Here, we investigate the effect of fluid shear stress on response to platinum-based chemotherapy and the modulation of molecular pathways associated with aggressive disease in a perfusion model for adherent 3D ovarian cancer nodules. Resistance to carboplatin is observed under flow with a concomitant increase in the expression and activation of the epidermal growth factor receptor (EGFR) as well as downstream signaling members mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK) and extracellular signal-regulated kinase (ERK). The uptake of platinum by the 3D ovarian cancer nodules was significantly higher in flow cultures compared to static cultures. A downregulation of phospho-focal adhesion kinase (p-FAK), vinculin, and phospho-paxillin was observed following carboplatin treatment in both flow and static cultures. Interestingly, low-dose anti-EGFR photoimmunotherapy (PIT), a targeted photochemical modality, was found to be equally effective in ovarian tumors grown under flow and static conditions. These findings highlight the need to further develop PIT-based combinations that target the EGFR, and sensitize ovarian cancers to chemotherapy in the context of flow-induced shear stress. Keywords: ovarian cancer; epidermal growth factor receptor (EGFR); mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK); extracellular signal-regulated kinase (ERK); chemoresistance; fluid shear stress; ascites; perfusion model; photoimmunotherapy (PIT); photodynamic therapy (PDT); carboplatin J. Clin. Med. 2020, 9, 924 3 of 27 anatomical structures [4,[27][28][29][30]]. An area that remains understudied is the effect of fluid shear stress on response to chemotherapy and the modulation of molecular pathways associated with aggressive disease [11,16,17,31]. J. Clin. Med. 2020, 9, x FOR PEER REVIEW 3 of 27 Figure 1. (A) A schematic of ovarian cancer metastases involving tumor cells or clusters (yellow) shedding from a primary site and disseminating along ascitic currents of peritoneal fluid (green arrows) in the abdominal cavity. Ovarian cancer typically disseminates in four common abdominopelvic sites: (1) cul-de-sac (an extension of the peritoneal cavity between the r...

Biology uses diffusible oxidants to perform functions that range from signaling to matrix assembly, and these oxidation chemistries offer surprising selectivities. Here, we report that mediated electrochemistry can access the richness of such oxidation chemistries. Specifically, we use electrodeimposed voltage inputs to locally-generate oxidized mediators that can diffuse into polymer solutions and induce the formation of covalent bonds for the deposition and functionalization of hydrogels at the electrode surface. Depending on the mediator's redox potential (E 0 ), it is possible to "gate" the voltage inputs to target specific residues (e.g. thiols or amines) and oxidation chemistries. Further, mediators of varying E 0 offer different reactivities and thus allow control of reaction-diffusion rates to modulate This article is protected by copyright. All rights reserved. 2 the hydrogel's crosslink density and mechanical properties. Importantly, this mediated oxidation can be performed under physiologically-relevant conditions to preserve labile biological functionalities (e.g., cell viability and protein function). Finally, we demonstrate that protein fusion tags can be engineered to have "targetable" amino acid residues that enable protein function to be oxidativelyconjugated to electrodeposited hydrogels. In summary, mediated electrochemistry can engage orthogonal oxidation chemistries to create functionalized matrices and thus mediated electrochemistry should add important capabilities to the electrofabrication toolbox.Received: ((will be filled in by the editorial staff))Revised: ((will be filled in by the editorial staff))

Introduction-The mechanical interaction between cells and their microenvironment is emerging as an important determinant of cancer progression and sensitivity to treatment, including in ovarian cancer (OvCa). However, current technologies limit mechanical analysis in 3D culture systems. Brillouin Confocal Microscopy is an optical non-contact method to assess the mechanical properties of biological materials. Here, we validate the ability of this technology to assess the mechanical properties of 3D tumor nodules. Methods-OvCa cells were cultured in 3D using two established methods: (1) overlay cultures on Matrigel; (2) spheroids in ultra-low attachment plates. To alter the mechanical state of these tumors, nodules were immersed in PBS with varying levels of sucrose to induce osmotic stress. Next, nodule mechanical properties were measured by Brillouin microscopy and validated with standard stressstrain tests: Atomic Force Microscopy (AFM) and a parallel plate compression device (Microsquisher). Finally, the nodules were treated with a chemotherapeutic commonly used to manage OvCa, carboplatin, to determine treatment-induced effects on tumor mechanical properties. Results-Brillouin microscopy allows mechanical analysis with limited penetration depth (~92 lm for Matrigel method;~54 lm for low attachment method). Brillouin microscopy metrics displayed the same trends as the corresponding ''gold-standard'' Young's moduli measured with stress-strain methods when the osmolality of the medium was increased. Nodules treated with carboplatin showed a decrease in Brillouin frequency shift. Conclusion-This validation study paves the way to evaluate the mechanics of 3D nodules, with micron-scale three-dimensional resolution and without contact, thus extending the experimental possibilities.