Keratin 6A is expressed at the invasive front and enhances the progression of colorectal cancer

Keratins are intermediate filament proteins in epithelial cells, and they are important for cytoskeletal organization. Keratin 6A (KRT6A), classified as a type II keratin, is normally expressed in stratified squamous epithelium and squamous cell carcinomas. Little is known about the expression and role of KRT6A in adenocarcinomas. We investigated the clinicopathological and molecular biological significance of KRT6A in colorectal adenocarcinoma. Immunostaining of our institution's colorectal adenocarcinoma cases demonstrated that KRT6A showed significantly stronger expression at the invasive front than the tumor center (p < 0.0001). The high-KRT6A-expression cases (n = 47) tended to have a high budding grade associated with significantly worse prognoses. A multivariate analysis revealed that the KRT6A expression status was an independent prognostic factor for overall survival (p = 0.0004), disease-specific survival (p = 0.0097) and progression-free survival (p = 0.0033). The correlation between KRT6A and patient prognoses was also validated in an external cohort from a published dataset. To determine the function of KRT6A in vitro, KRT6A was over-expressed in three colon cancer cell lines, DLD-1, SW620, and HCT 116. KRT6A overexpression increased migration and invasion in DLD-1, but did not in SW620 and HCT116. In three-dimensional sphere-forming culture, KRT6A expression enhanced the irregular protrusion around the spheroid in DLD-1. Our findings in the present study indicated that KRT6A expression is a valuable prognostic marker of colorectal cancer and KRT6A may be involved the molecular mechanism in the progression of invasive areas of colorectal cancer.

Delta/Notch-like Epidermal Growth Factor-Related Receptor (DNER), a Potential Prognostic Marker of Gastric Cancer Regulates Cell Survival and Cell Cycle Progression

Upregulation of the expression of Delta/notch-like epidermal growth factor-related receptor (DNER) and its oncogenic role have been reported in several cancers, including gastric, breast, and prostate cancers. This study aimed to investigate the oncogenic role of DNER and the mechanisms behind its oncogenic role in gastric cancer. Analysis of the RNASeq data of gastric cancer tissues obtained from the TCGA database revealed that the expression of DNER was associated with the pathology of advanced gastric cancer and the prognosis of patients. DNER expression was increased upon stem cell-enriching cancer spheroid culture. Knockdown of DNER expression inhibited cell proliferation and invasion, induced apoptosis, enhanced chemosensitivity, and decreased spheroid formation of SNU-638 gastric cancer cells. DNER silencing elevated the expression of p53, p21^cip/waf, and p27, and increased G₁ phase cells at the expense of S phase cells. Knockdown of p21^cip/waf expression in the DNER-silenced cells partially restored cell viability and S phase progression. DNER silencing also induced the apoptosis of SNU-638 cells. While both cleaved caspases-8 and 9 were detected in adherent cells, only cleaved caspase-8 was found to have increased in spheroid-cultured cells, suggesting a distinct activation pattern of caspase activation depending on the growth condition. Knockdown of p53 expression rescued the DNER-silenced cells from apoptosis and partially restored cell viability. In contrast, overexpression of the Notch intracellular domain (NICD) decreased the expression of p53, p21^cip/waf, and cleaved caspase-3 in DNER-silenced cells. Moreover, NICD expression fully reverted the cell viability reduction, arrest in the G₁ phase, and elevated apoptosis caused by DNER silencing, thereby suggesting activation of Notch signaling by DNER. Expression of a membrane-unbound mutant of mDNER also decreased cell viability and induced apoptosis. On the other hand, TGF-β signals were found to be involved in DNER expression in both adherent and spheroid-cultured cells. DNER could therefore be a link connecting TGF-β signaling to Notch signaling. Taken together, DNER regulates cell proliferation, survival, and invasive capacity of the gastric cancer cells through the activation of Notch signaling, which may facilitate tumor progression into an advanced stage. This study provides evidences suggesting that DNER could be a potential prognostic marker, a therapeutic target, and a drug candidate in the form of a cell-free mutant.

Effects of growth factor deprivation on MKN-45 spheroid cells

Background/aim

Serum and growth factor deprivation, a common cellular stressor in solid tumors, arises upon irradiation, chemotherapy, and antiangiogenesis. Spheroid body culture aims to enrich cancer stem cells by using low attachment conditions and some growth factors, such as basic fibroblast growth factor and epidermal growth factor to support the spheroid formation in serum-free spheroid culture. However, spheroid culture without any growth factors can imitate the tumor environment more realistically.In this study, we aimed to identify the effect of growth factor deprivation on the MKN-45 gastric cancer cell line in terms of stemness characteristics.

Materials and methods

The spheroids were obtained by culturing MKN-45 gastric cancer cells in low attachment conditions, and then spheroids were dissociated to obtain cells for further analyses. Self-renewal, multipotency, cellular transformation, invasiveness, chemoresistance, and the expression of stemness-related genes were analyzed using tumor spheroid formation assay, soft agar colony formation assay, transwell invasion assay, chemosensitivity assay, and quantitative RT-PCR assay, respectively.

Results

Fetal bovine serum and growth factor deprivation caused an increase in stemness markers of OCT4, NANOG, SOX2, MUC1, CD24 and CD90. Increasing functional aggressiveness-related properties, such as self-renewal, chemoresistance, and invasive ability, have also been observed in fetal bovine serum-growth factor-free conditions.

Conclusion

Growth factors may not be essential for spheroid culture to enrich cancer stem cells. The deprivation of both fetal bovine serum and growth factors also induces a more aggressive phenotype in MKN-45 cells; thus, it provides an opportunity for further studies targeting tumor cells.

Rapid Formation of Multicellular Spheroids in Boundary-Driven Acoustic Microstreams

3D cell spheroid culture has emerged as a more faithful recreation of cell growth environment compared to conventional 2D culture, as it can maintain tissue structures, physicochemical characteristics, and cell phenotypes. The majority of current spheroid formation methods are limited to a physical agglomeration of the desired cell type, and then relying on cell capacity to secrete extracellular matrix to form coherent spheroids. Hence, apart from being time-consuming, their success in leading to functional spheroid formation is also cell-type dependent. In this study, a boundary-driven acoustic microstreaming tool is presented that can simultaneously congregate cells and generate sturdy cell clusters through incorporating a bioadhesive such as collagen for rapid production of spheroids. The optimized mixture of type I collagen (0.42 mg mL^-1 ) and methylcellulose (0.4% w/v ) accelerates the coagulation of cell-matrix as fast as 10 s while avoiding their adhesion to the device, and thereby offering easy spheroid retrieval. The versatility of the platform is shown for the production of MDA-MB-231 and MCF-7 spheroids, multicellular spheroids, and composite spheroids made of cells and microparticles. The ability to produce densely packed spheroids embedded within a biomimetic extracellular matrix component, along with rapid formation and easy collection of spheroids render the proposed device a step in technology development required to realize potentials of 3D constructs such as building blocks for the emerging field of bottom-up tissue engineering.

Optimizing Conditions for Spheroid Formation of Dental Pulp Cells in Cell Culture

BACKGROUND/AIM

Spheroid formation is a well-known feature of stem/progenitor cells. Dental pulp cells (DPCs) cultured in serum-free medium can also form spheroids. However, the success rate varies largely depending on various factors. This study aimed to explore these factors and optimize the conditions.

MATERIALS AND METHODS

Primary DPCs were obtained from 6 wisdom teeth. Possible influencing factors including donor teeth, concentrations of the KnockOut Serum Replacement (KSR), seeding density (regarding surface and volume), passage and freezing were tested.

RESULTS

DPCs from all 6 donor teeth formed spheroids in serum-free medium. Number, size, and total area of spheroids varied among different donor teeth. Optimal concentration of the KSR and seeding densities also varied from tooth to tooth. Generally, high KSR and high cell density lead to better spheroid formation. However, very high KSR and cell density can also lead to cell death and the fusion of spheroids to irregular aggregates.

CONCLUSION

An initial setting can be recommended as: Serum-free MEM plus 10-15% KSR and seeding densities of 1-2×10⁵ cells/ml and 2×10⁵ cells/cm² These parameters provide a direction for optimizing the condition for obtaining spheroids from human DPCs.

TDO2 overexpression correlates with poor prognosis, cancer stemness, and resistance to cetuximab in bladder cancer

Background

Bladder cancer (BC) is the 10th most common cancer in the world. BC with muscle invasion results in a poor prognosis and is usually fatal. Cancer cell metabolism has an essential role in the development and progression of tumors. Expression of tryptophan 2,3‐dioxygenase (TDO2) is associated with tumor progression and worse survival in some other cancers. However, no studies have been performed to uncover the biofunctional roles of TDO2 in BC.

Aim

This study aim to investigate the clinicopathologic significance of TDO2 in BC.

Methods and results

TDO2 expression was evaluated by qRT‐PCR and immunohistochemistry in an integrated analysis with the Cancer Genome Atlas (TCGA) and other published datasets. TDO2 overexpression was significantly associated with T classification, N classification, and M classification, tumor stage, recurrence, and basal type, and with the expression of CD44 and aldehyde dehydrogenase 1 (ALDH1) in BC. High TDO2 expression correlated with poor outcome of BC patients. Using BC cell lines with knockdown and forced expression of TDO2, we found that TDO2 was involved in the growth, migration, and invasiveness of BC cells. Moreover, TDO2 was found to be crucial for spheroid formation in BC cells. Importantly, TDO2 promoted BC cells resistance to cetuximab through integration of the EGFR pathway.

Conclusion

Our results indicate that TDO2 might take an essential part in BC progression and could be a potential marker for targeted therapy in BC.

Expression and cell transformation activity of dynactin-associated protein isoforms

Overexpression of human dynactin-associated protein isoform a (dynAPa) transforms NIH3T3 cells. DynAPa is a single-pass transmembrane protein with a carboxy-terminal region exposed to the outside of cells. According to the NCBI RefSeq database, there may be two other splicing variants of the encoding gene (dynAPb and c). DynAPa and c differ in some amino-terminal residues (NH₂ -MVA in dynAPa and NH₂ -MEYQLL in dynAPc). DynAPb has the same amino-terminal residues as dynAPc, but lacks 55 residues in the intracellular region. All three isoforms have the same carboxy-terminal region, including the transmembrane domain. Expression of mRNAs of three splicing variants was found in human cancer cell lines ACHN and Caki-1. The subcellular localization and in vitro cell transformation ability of the three isoforms were examined using NIH3T3 cells overexpressing each respective isoform. All isoforms were found to be localized to the Golgi apparatus and plasma membrane, where the carboxy-terminal region was exposed to the outside of cells. Cell transformation was tested using focus formation due to loss of contact inhibition of cell proliferation, and colony formation was examined on soft agar and spheroid formation in ultralow U-bottomed wells. DynAPa robustly formed foci and colonies on soft agar and spheroid, whereas these abilities were considerably decreased for dynAPb and completely lost in dynAPc. These findings warrant dissection studies to identify the dynAP domain that is required for cell transformation.

Spheroid formation of human keratinocyte: Balancing between cell-substrate and cell-cell interaction

BACKGROUND

The formation of spheroids is tightly regulated by intrinsic cell-cell and cell-substrate interactions.

OBJECTIVE

The chitosan (CS)-coating was applied to investigate the driven force directed the spheroid formation.

METHODS

The effects of CS on cell functions were studied. Atomic force microscopy was employed to measure the cell- biomaterial interplay at single cell level.

RESULTS

HaCaT cells shifted from their flattened sheet to a compact 3D spheroidal morphology when increasing CS-coating concentration. The proliferative capacity of HaCaT was preserved in the spheroid. The expression and activation of integrin β1 (ITGB1) were enhanced on CS modified surfaces, while the active to total ratio of ITGB1 was decreased. The adhesive force of a single HaCaT cell to the tissue culture plate (TCP) was 4.84±0.72 nN. It decreased on CS-coated surfaces as CS concentration increased, from 2.16±0.26 nN to 0.96±0.17 nN. The adhesive force between the single HaCaT cell to its neighbor cell increased as CS concentration increased, from 1.15±0.09 nN to 2.60±0.51 nN.

CONCLUSIONS

Conclusively, the decreased cell- substrate adhesion was the main driven force in the spheroid formation. This finding might serve as a design criterion for biomaterials facilitating the formation of epithelial spheroids.

One-Step Dip-Coating-Fabricated Core-Shell Silk Fibroin Rice Paper Fibrous Scaffolds for 3D Tumor Spheroid Formation

Bioscaffolds are important substrates for supporting three-dimensional (3D) cell cultures. Silk fibroin (SF) is an attractive biomaterial in tissue engineering because of its good biocompatibility and mechanical properties. Electrospinning is one of the most often used approaches to fabricate SF fibrous scaffolds; yet, this technique still faces many challenges, such as low yield, residual organic solvents, limited extensibility of fibers, and a lack of spatial control over pore size. To circumvent these limitations, a core-shell SF on rice paper (SF@RP) fibrous scaffold was fabricated using a mild one-step dip-coating method. The cellulose fiber matrix of RP is the physical basis of the 3D scaffold, whereas the SF coating on the cellulose fiber controls the adhesion/spreading of the cells. The results indicated that by tuning the secondary structure of SF on the surface of a SF@RP scaffold, the cell behavior on SF@RP could be tuned. Tumor spheroids can be formed on SF@RP scaffolds with a dominant random secondary structure, in contrast to cells adhering and spreading on SF@RP scaffolds with a higher ratio of β-sheet secondary structures. Direct culturing of breast cancer MDA-MB-231 and MCF-7, lung cancer A549, prostate cancer DU145, and liver cancer HepG2 cells could spontaneously lead to corresponding tumor spheroids on SF@RP. In addition, the physiological characteristics of HepG2 tumor spheroids were investigated, and the results showed that compared with HepG2 monolayer cells, CYP3A4, CYP1A1, and albumin gene expression levels in HepG2 cell spheres formed on SF@RP scaffolds were significantly higher. Moreover, these spheroids showed higher drug resistance. In summary, these SF@RP scaffolds prepared by the dip-coating method are biocompatible substrates for cell culture, especially for tumor cell spheroid formation.

Adjustable and Versatile 3D Tumor Spheroid Culture Platform with Interfacial Elastomeric Wells

Three-dimensional (3D) cell culture platforms have recently received a great deal of attention, as these systems are able to recapitulate the in vivo microenvironment of tissues or tumors. Herein, we describe adjustable and versatile elastomeric well structures for spheroid formation and their use for in situ analyses as a tunable 3D cell culture platform. Elastomeric spherical wells are fabricated using a one-step interfacial reaction between aqueous droplets on immiscible liquid polydimethylsiloxane (PDMS) without any template or expensive equipment. Because of their differing surface tensions, spherical wells are spontaneously formed on liquid PDMS with various sizes and curvatures that are easily controlled. Using arrays of these optimized wells, single tumor spheroids within each well were successfully formed at high efficiency (up to 97%) by coculturing tumor cells and fibroblasts to reflect the complex microenvironment of cancer tissue. Moreover, the tumor spheroids formed within the interfacial wells were directly applied for observing drug responses and monitoring reactive oxygen species (ROS) to investigate tumor cell responses to drugs or their 3D microenvironment. We believe that our proposed platform provides a significant contribution to the multimodal analyses of anticancer therapeutics and the tumor microenvironment.

Characterization of ascites-derived aldehyde dehydrogenase-positive ovarian cancer stem cells isolated from Leghorn chickens

Leghorn chickens are used as a preclinical model of ovarian cancer as they develop epithelial ovarian adenocarcinoma spontaneously at a very high frequency. Ovarian cancer is the most lethal disease among all gynecological malignancies in women. A small proportion of ovarian cancer stem cells are responsible for drug resistance and relapse of ovarian cancer. The objectives of this study are to isolate ovarian cancer stem cells from ascites of Leghorn chickens that spontaneously developed ovarian cancer and to determine their invasiveness, spheroid formation in three-dimensional culture devoid of extracellular matrix over several months. Ovarian cancer cells obtained from ascites were subjected to ALDEFLOUR assay that measures aldehyde dehydrogenase (ALDH) activity to separate ALDH1⁺ and ALDH1^- cells by fluorescence-activated cell sorting. The cells were cultured using serum-free media for up to 6 mo in ultra-low attachment plates. Invasiveness of ALDH1⁺ and ALDH1^- cells was determined by Matrigel invasion assay. Cellular uptake of acetylated low-density lipoprotein was evaluated. A small proportion (<4.75%) of ovarian cancer cells isolated from ascites were found to be ALDH1⁺ cells. ALDH1⁺ cells formed a greater number of spheroids and were also highly invasive in extracellular matrix compared to ALDH1^- cells. Several spheroids developed 0.1- to 1-mm-long capillary-like tubules connecting other spheroids, thus forming a complex network that underwent remodeling over several months. Cells in the spheroids incorporated acetylated low-density lipoprotein suggestive of scavenger receptor activity. In summary, ALDH1⁺ ovarian cancer stem cells isolated from ascites of chickens appear to be invasive and form spheroids with complex networks of tubules reminiscent of vascular mimicry. Understanding the structure and function of spheroids and tubular network would provide valuable insight into the biology of ovarian cancer and improve poultry health.

Triptolide inhibits CD133+ /CD44+ colon cancer stem cell growth and migration through triggering apoptosis and represses epithelial-mesenchymal transition via downregulating expressions of snail, slug, and twist

High recurrence and metastatic behavior patterns are the most important reasons for the failure of treatment strategies in patients with colon cancer. Cancer stem cells (CSCs), which are considered root of cancer, are thought to be associated with therapy resistance, relapse, and metastasis, and, therefore, targeting CSCs rather than the bulk population may be an effective approach. In cancer studies, there is an increasing interest in close friendship between epithelial-mesenchymal transition (EMT) and CSCs. Triptolide (TPL) isolated from Chinese herb Tripterygium wilfordii has important effects on the prevention of migration and metastasis as well as cytotoxic effect against cancer cells. The potential lethal efficacy of TPL on CSCs that is highly resistant to the drug is an unsolved mystery. Fundamentally, the present study basically aims to find answers to two questions: (a) is it possible to target colon CSCs with TPL? and (b) what are the mechanisms underlying TPL's potential to eliminate CSCs? Cytotoxic effects of TPL on CSCs were evaluated by WST-1 and Muse count and viability assays. Apoptosis assay and cell-cycle analysis were performed to investigate the inhibitory effect of TPL. Moreover, the effects of TPL on spheroid formation capacity, migration, and EMT processes, which are associated with CSC phenotype, were also investigated. The results revealed that TPL triggered cell death and apoptosis and altered cell cycle distribution. Moreover, TPL significantly reduced the snail slug and twist expressions associated with EMT. TPL has been shown to be effective in colon CSCs by in vitro experiments, and it might be a highly effective agent against colon cancer has been implicated in need of supporting in vivo and clinical studies.

LINC00311 promotes cancer stem-like properties by targeting miR-330-5p/TLR4 pathway in human papillary thyroid cancer

Growing evidence has suggested that long noncoding RNAs (lncRNAs) play an essential role in the progression of papillary thyroid cancer (PTC). LncRNA LINC00311 was found to be able to regulate many cellular process in several diseases. However, the function and regulatory mechanism of LINC00311 remains unclear in PTC. In the present study, the results showed that the expression of LINC00311 was upregulated in PTC tissues and cells. Furthermore, knockdown of LINC00311 dramatically suppressed spheroid formation, proliferation, migration, and invasion in PTC cells in vitro. Mechanistic investigations revealed that LINC00311 was negatively correlated with the expression of miR‐330‐5p, meanwhile, TLR4 was a direct target of miR‐330‐5p. In addition, rescue assays further determined that LINC00311 contributed to the progression of PTC through regulating TLR4 expression. Taken together, these findings indicated that LINC00311 could promote cancer stem‐like properties by targeting miR‐330‐5p/TLR4 pathway in PTC.

A Human Liver-on-a-Chip Platform for Modeling Nonalcoholic Fatty Liver Disease

The liver possesses a unique microenvironment with a complex internal vascular system and cell-cell interactions. Nonalcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease, and although much effort has been dedicated to building models to target NAFLD, most in vitro systems rely on simple models failing to recapitulate complex liver functions. Here, an in vitro system is presented to study NAFLD (steatosis) by coculturing human hepatocellular carcinoma (HepG2) cells and umbilical vein endothelial cells (HUVECs) into spheroids. Analysis of colocalization of HepG2-HUVECs along with the level of steatosis reveals that the NAFLD pathogenesis could be better modeled when 20% of HUVECs are presented in HepG2 spheroids. Spheroids with fat supplements progressed to the steatosis stage on day 2, which could be maintained for more than a week without being harmful for cells. Transferring spheroids onto a chip system with an array of interconnected hexagonal microwells proves helpful for monitoring functionality through increased albumin secretions with HepG2-HUVEC interactions and elevated production of reactive oxygen species for steatotic spheroids. The reversibility of steatosis is demonstrated by simply stopping fat-based diet or by antisteatotic drug administration, the latter showing a faster return of intracellular lipid levels to the basal level.

miR-590-3p Targets Cyclin G2 and FOXO3 to Promote Ovarian Cancer Cell Proliferation, Invasion, and Spheroid Formation

Ovarian cancer is the leading cause of death from gynecological cancers. MicroRNAs (miRNAs) are small, non-coding RNAs that interact with the 3' untranslated region (3' UTR) of target genes to repress their expression. We have previously reported that miR-590-3p promoted ovarian cancer growth and metastasis, in part by targeting Forkhead box A (FOXA2). In this study, we further investigated the mechanisms by which miR-590-3p promotes ovarian cancer development. Using luciferase reporter assays, real-time PCR, and Western blot analyses, we demonstrated that miR-590-3p targets cyclin G2 (CCNG2) and Forkhead box class O3 (FOXO3) at their 3' UTRs. Silencing of CCNG2 or FOXO3 mimicked, while the overexpression of CCNG2 or FOXO3 reversed, the stimulatory effect of miR-590-3p on cell proliferation and invasion. In hanging drop cultures, the overexpression of mir-590 or the transient transfection of miR-590-3p mimics induced the formation of compact spheroids. Transfection of the CCNG2 or FOXO3 plasmid into the mir-590 cells resulted in the partial disruption of the compact spheroid formation. Since we have shown that CCNG2 suppressed β-catenin signaling, we investigated if miR-590-3p regulated β-catenin activity. In the TOPFlash luciferase reporter assays, mir-590 increased β-catenin/TCF transcriptional activity and the nuclear accumulation of β-catenin. Silencing of β-catenin attenuated the effect of mir-590 on the compact spheroid formation. Taken together, these results suggest that miR-590-3p promotes ovarian cancer development, in part by directly targeting CCNG2 and FOXO3.

TAZ enhances mammary cell proliferation in 3D culture through transcriptional regulation of IRS1

WW domain-containing transcriptional regulator 1 (TAZ) is a transcriptional co-activator and effector of the Hippo signaling pathway. In certain breast cancer subtypes, Hippo signaling is dysregulated leading to activation of TAZ and altered expression of TAZ transcriptional targets. Over the past decade, we and others have found that TAZ transcriptionally regulates genes that affect multiple aspects of breast cancer cell behaviour. However, while cancer cell-intrinsic oncogenic functions of TAZ have emerged, less is known about whether TAZ might also contribute to tumourigenesis by sensitizing tumour cells to factors present in the tumour microenvironment or in systemic circulation. Here, we show that TAZ directly regulates the expression of insulin receptor substrate 1 (IRS1) in breast cancer cells. TAZ or IRS1 overexpression induces a similar proliferative transformation phenotype in MCF10A mammary epithelial cells. TAZ enhances IRS1 mRNA, protein levels and downstream signaling in MCF10A. Mechanistically, TAZ interacts with the IRS1 promoter through the TEAD family of transcription factors and enhances its activity. Critically, TAZ-induced IRS1 upregulation contributes to the proliferation of TAZ-overexpressing MCF10A in 3-dimensional (3D) Matrigel culture. Therefore, we offer compelling evidence that TAZ regulates signaling through the insulin pathway in breast cancer cells. These findings highlight an additional mechanism by which TAZ may promote breast cancer tumourigenesis and progression by modulating cancer cell responses to exogenously produced factors.

Re-purposing of curcumin as an anti-metastatic agent for the treatment of epithelial ovarian cancer: in vitro model using cancer stem cell enriched ovarian cancer spheroids

Malignant epithelial ovarian cancer (EOC) spheroids high frequently are detected in the malignant ascites of the patients with the extensive peritoneal metastasis of ovarian cancer, which represent a significant obstacle to efficacious treatment. Clinical data also suggested that EOC spheroids play a putative role in the development of chemoresistance. Since standard surgery and conventional chemotherapy is the only available treatment, there is an urgent need to identify a more effective therapeutic strategy. Recent studies demonstrated that curcumin exerts an anticancer effect in a variety of human cancers including ovarian cancer. This study evaluates anti-peritoneal metastasis and chemoresistance of curcumin related to the EOC spheroids. In this study, we confirm that the high invasive EOC cells forming the spheroids express a high level of a cancer stem cell (CSC) marker, aldehyde dehydrogenase 1 family member A1 (ALDH1A1), which was significantly down-regulated by curcumin treatment. Curcumin treatment markedly enhances the sensitivity of EOC spheroids to cisplatin in a dose-dependent manner. Our experiments provided evidence that curcumin could abolish the sphere-forming capacity of EOC cells in a dose-dependent manner. Moreover, curcumin substantially suppressed the growth of the pre-existed EOC spheroids, inhibited the adhesion of EOC spheroids to ECM as well as the invasion of EOC spheroids to the mesothelial monolayers. We propose to re-purpose curcumin as anti-metastatic and chemoresistant agent for EOC management in combination with conventional regimen. Further preclinical studies are necessary to validate the anti-cancer effect of curcumin in patients with EOC.

miR-509-3p is clinically significant and strongly attenuates cellular migration and multi-cellular spheroids in ovarian cancer

Ovarian cancer presents as an aggressive, advanced stage cancer with widespread metastases that depend primarily on multicellular spheroids in the peritoneal fluid. To identify new druggable pathways related to metastatic progression and spheroid formation, we integrated microRNA and mRNA sequencing data from 293 tumors from The Cancer Genome Atlas (TCGA) ovarian cancer cohort. We identified miR-509-3p as a clinically significant microRNA that is more abundant in patients with favorable survival in both the TCGA cohort (P = 2.3E–3), and, by in situ hybridization (ISH), in an independent cohort of 157 tumors (P < 1.0E–3). We found that miR-509-3p attenuated migration and disrupted multi-cellular spheroids in HEYA8, OVCAR8, SKOV3, OVCAR3, OVCAR4 and OVCAR5 cell lines. Consistent with disrupted spheroid formation, in TCGA data miR-509-3p's most strongly anti-correlated predicted targets were enriched in components of the extracellular matrix (ECM). We validated the Hippo pathway effector YAP1 as a direct miR-509-3p target. We showed that siRNA to YAP1 replicated 90% of miR-509-3p-mediated migration attenuation in OVCAR8, which contained high levels of YAP1 protein, but not in the other cell lines, in which levels of this protein were moderate to low. Our data suggest that the miR-509-3p/YAP1 axis may be a new druggable target in cancers with high YAP1, and we propose that therapeutically targeting the miR-509-3p/YAP1/ECM axis may disrupt early steps in multi-cellular spheroid formation, and so inhibit metastasis in epithelial ovarian cancer and potentially in other cancers.

Neuroaxonal Dystrophy in a Flock of Pied Imperial Pigeons (Ducula bicolor)

Five juvenile pied imperial pigeons (Ducula bicolor) presented with neurological signs including torticollis, ataxia and poor flying ability. All were humanely destroyed and submitted for post-mortem examination. Microscopically, the most significant findings were in the brain and spinal cord. Spheroid formation was evident within the medulla, pons, diencephalon, cortical grey and subcortical white matter, spinal cord white and grey matter and the granular and molecular cell layers of the cerebellum. There was no evidence of associated inflammation. Immunohistochemistry revealed positive labelling within the spheroids for S100 axons and phosphorylated neurofilaments including SMI31, neurofilament cocktail and microtubule-associated protein 2. Transmission electron microscopy confirmed the light microscopical findings of frequent axonal spheroids. These results are consistent with neuroaxonal dystrophy, which has not been described previously in pigeons. This highlights the importance of considering neuroaxonal dystrophy in juvenile birds with neurological signs. A genetic basis is suspected in this group.

Segmentation and tracking of stem cells in time lapse microscopy to quantify dynamic behavioral changes during spheroid formation

Dynamic behavior of stem cells during in vitro development is diverse. Previous cell tracking studies have focused more on cell proliferation than on cell aggregation. However, the enhancement of cell proliferation in association with cell aggregation has been reported. In a previous study, we also demonstrated that the aggregation of adult human mesenchymal stem cells to form three-dimensional (3D) cellular spheroids helped maintain the expression of stemness marker genes in the cells. However, the dynamic behavioral changes triggered by spheroid formation remain to be investigated. A scheme of image processing techniques is proposed to meet this need. A hybrid-thresholding technique was first developed for efficient segmentation of cell clusters, after which a cell tracking method based on pair-matching with topological constraints was designed. Two morphological indices were derived to track the timing of 3D spheroid formation during the cellular aggregation process. Five cell motility indices measured from single cells and 3D spheroids were then compared. After confirmation of more than 90% correspondence between the results obtained by manual tracking and the proposed methods, an analysis of cellular behavior reveals a significant increase in motility in association with spheroid formation, consistent with a previous report that used a gene expression approach. This study proposed a systematic image analysis method to quantify the dynamic behavior of stem cells for stemness evaluation during cell culturing in vitro. Results demonstrated the validity of the developed platform in investigation of the dynamic behavior of cell aggregation in stem cell cultures in vitro.

Switchable water-adhesive, superhydrophobic palladium-layered silicon nanowires potentiate the angiogenic efficacy of human stem cell spheroids

A switchable water-adhesive, super-hydrophobic nanowire surface is developed for the formation of functional stem cell spheroids. The sizes of hADSC spheroids are readily controllable on the surface. Our surface increases cell-cell and cell-matrix interaction, which improves viability and paracrine secretion of the spheroids. Accordingly, the hADSC spheroids produced on the surface exhibit significantly enhanced angiogenic efficacy.