Co-culture of 3D tumor spheroids with fibroblasts as a model for epithelial-mesenchymal transition in vitro

Factors Determining Epithelial-Mesenchymal Transition in Cancer Progression

Epithelial-mesenchymal transition (EMT) is a process in which an epithelial cell undergoes multiple modifications, acquiring both morphological and functional characteristics of a mesenchymal cell. This dynamic process is initiated by various inducing signals that activate numerous signaling pathways, leading to the stimulation of transcription factors. EMT plays a significant role in cancer progression, such as metastasis and tumor heterogeneity, as well as in drug resistance. In this article, we studied molecular mechanisms, epigenetic regulation, and cellular plasticity of EMT, as well as microenvironmental factors influencing this process. We included both in vivo and in vitro models in EMT investigation and clinical implications of EMT, such as the use of EMT in curing oncological patients and targeting its use in therapies. Additionally, this review concludes with future directions and challenges in the wide field of EMT.

A vascularized breast cancer spheroid platform for the ranked evaluation of tumor microenvironment-targeted drugs by light sheet fluorescence microscopy

Targeting the supportive tumor microenvironment (TME) is an approach of high interest in cancer drug development. However, assessing TME-targeted drug candidates presents a unique set of challenges. We develop a comprehensive screening platform that allows monitoring, quantifying, and ranking drug-induced effects in self-organizing, vascularized tumor spheroids (VTSs). The confrontation of four human-derived cell populations makes it possible to recreate and study complex changes in TME composition and cell-cell interaction. The platform is modular and adaptable for tumor entity or genetic manipulation. Treatment effects are recorded by light sheet fluorescence microscopy and translated by an advanced image analysis routine in processable multi-parametric datasets. The system proved to be robust, with strong interassay reliability. We demonstrate the platform's utility for evaluating TME-targeted antifibrotic and antiangiogenic drugs side-by-side. The platform's output enabled the differential evaluation of even closely related drug candidates according to projected therapeutic needs.

Interrogating Matrix Stiffness and Metabolomics in Pancreatic Ductal Carcinoma Using an Openable Microfluidic Tumor-on-a-Chip

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a dense fibrotic stroma that contributes to aggressive tumor biology and therapeutic resistance. Current in vitro PDAC models lack sufficient optical and physical access for fibrous network visualization, in situ mechanical stiffness measurement, and metabolomic profiling. Here, we describe an openable multilayer microfluidic PDAC-on-a-chip platform that consists of pancreatic tumor cells (PTCs) and pancreatic stellate cells (PSCs) embedded in a 3D collagen matrix that mimics the stroma. Our system allows fibrous network visualization via reflected light confocal (RLC) microscopy, in situ mechanical stiffness testing using atomic force microscopy (AFM), and compartmentalized hydrogel extraction for PSC metabolomic profiling via mass spectrometry (MS) analysis. In comparing cocultures of gel-embedded PSCs and PTCs with PSC-only monocultures, RLC microscopy identified a significant decrease in pore size and corresponding increase in fiber density. In situ AFM indicated significant increases in stiffness, and hallmark characteristics of PSC activation were observed using fluorescence microscopy. PSCs in coculture also demonstrated localized fiber alignment and densification as well as increased collagen production. Finally, an untargeted MS study putatively identified metabolic contributions consistent with in vivo PDAC studies. Taken together, this platform can potentially advance our understanding of tumor-stromal interactions toward the discovery of novel therapies.

A Multi-Layer Breast Cancer Model to Study the Synergistic Effect of Photochemotherapy

Breast cancer is one of the most common cancers among women. The development of new and effective therapeutic approaches in the treatment of breast cancer is an important challenge in modern oncology. Two-dimensional (2D) cell cultures are most often used in the study of compounds with potential anti-tumor nature. However, it is necessary to develop advanced three-dimensional (3D) cell models that can, to some extent, reflect the physiological conditions. The use of miniature cancer-on-a-chip microfluidic systems can help to mimic the complex cancer microenvironment. In this report, we developed a 3D breast cancer model in the form of a cell multilayer, composed of stromal cells (HMF) and breast cancer parenchyma (MCF-7). The developed cell model was successfully used to analyze the effectiveness of combined sequential photochemotherapy, based on doxorubicin and meso-tetraphenylporphyrin. We proved that the key factor that allows achieving the synergistic effect of combination therapy are the order of drug administration to the cells and the sequence of therapeutic procedures. To the best of our knowledge, studies on the effectiveness of combination photochemotherapy depending on the sequence of the component drugs were performed for the first time under microfluidic conditions on a 3D multilayered model of breast cancer tissue.

Doxorubicin Activity Is Modulated by Traditional Herbal Extracts in a 2D and 3D Multicellular Sphere Model of Leukemia

The modulation of the tumor microenvironment by natural products may play a significant role in the response of tumor cells to chemotherapy. In this study, we evaluated the effect of extracts derived from P2Et (Caesalpinia spinosa) and Anamú-SC (Petiveria alliacea) plants, previously studied by our group, on the viability and ROS levels in the K562 cell line (Pgp- and Pgp+), endothelial cells (ECs, Eahy.926 cell line) and mesenchymal stem cells (MSC) cultured in 2D and 3D. The results show that: (a) the two botanical extracts are selective on tumor cells compared to doxorubicin (DX), (b) cytotoxicity is independent of the modulation of intracellular ROS for plant extracts, unlike DX, (c) the interaction with DX can be influenced by chemical complexity and the expression of Pgp, (d) the 3D culture shows a greater sensitivity of the tumor cells to chemotherapy, in co-treatment with the extracts. In conclusion, the effect of the extracts on the viability of leukemia cells was modified in multicellular spheroids with MSC and EC, suggesting that the in vitro evaluation of these interactions can contribute to the comprehension of the pharmacodynamics of the botanical drugs.

The characterization of the sensitive ovarian cancer cell lines A2780 and W1 in response to ovarian CAFs

PURPOSE

The cancer-associated fibroblasts (CAFs) are one of the most abundant components of the tumor microenvironment (TME). CAFs have been implicated in tumor progression, extracellular matrix (ECM) remodeling, and treatment resistance. Drug resistance is the primary limiting factor in achieving cures for patients with cancer, particularly ovarian cancer. Therefore, inhibiting CAFs can be an effective strategies for cancer treatment. In this research, we studied whether CAFs have an influence on drug-sensitive ovarian cancer cells to become more resistant. We examined the influence of CAFs on genes and proteins expression changes in sensitive ovarian cancer cells. We prepared a 3D co-culture to investigate the role of CAFs on cancer cell morphology.

METHODS

Here, we performed a detailed analysis of drug-sensitive ovarian cancer cell lines (A2780 and W1) and the influence of ovarian CAFs on the A2780 and W1 cells morphology, genes and proteins expression. The 2D and 3D cultures, genes expression analysis (TaqMan qPCR), and proteins expression (Western blot analysis) were assessed in this study.

RESULTS

We observed upregulation of ABCC5, CYP2C8, CYP2C9, and DHFR mRNA in cell lines supplemented by CAFs medium. We showed fibronectin overexpression and COL3A1 downregulation after supplementation with CAFs. Co-culturing with CAFs prevented the formation of spheroids in 3D conditions.

CONCLUSION

We demonstrated that the process of drug resistance in ovarian cancer cells is launched by CAFs. CAFs not only simulate cancer cells to produce drug transporters and specific enzymes production, but also remodel the TME to increase drug resistance. We believe that cancer progression and migration is due to the CAFs po-tumorigenic activity.

Adjusting Degree of Modification and Composition of gelAGE-Based Hydrogels Improves Long-Term Survival and Function of Primary Human Fibroblasts and Endothelial Cells in 3D Cultures

This study aimed to develop a suitable hydrogel-based 3D platform to support long-term culture of primary endothelial cells (ECs) and fibroblasts. Two hydrogel systems based on allyl-modified gelatin (gelAGE), G_1MM and G_2LH, were cross-linked via thiol-ene click reaction with a four-arm thiolated polyethylene glycol (PEG-4-SH). Compared to G_1MM, the G_2LH hydrogel was characterized by the lower polymer content and cross-linking density with a softer matrix and homogeneous and open porosity. Cell viability in both hydrogels was comparable, although the G_2LH-based platform supported better F-actin organization, cell-cell interactions, and collagen and fibronectin production. In co-cultures, early morphogenesis leading to tubular-like structures was observed within 2 weeks. Migration of fibroblasts out of spheroids embedded in the G_2LH hydrogels started after 5 days of incubation. Taken together, the results demonstrated that the G_2LH hydrogel fulfilled the demands of both ECs and fibroblasts to enable long-term culture and matrix remodeling.

Patient-derived spheroids and patient-derived organoids simulate evolutions of lung cancer

Cancer cells harbor many genetic mutations and gene expression profiles different from normal cells. Patient-derived cancer cells (PDCC) are preferred materials in cancer study. We established patient-derived spheroids (PDSs) and patient-derived organoids (PDOs) from PDCCs isolated from the malignant pleural effusion in 8 patients. The morphologies suggested that PDSs may be a model of local cancer extensions, while PDOs may be a model of distant cancer metastases. The gene expression profiles differed between PDSs and PDOs: Gene sets related to inflammatory responses and EMT were antithetically regulated in PDSs or in PDOs. PDSs demonstrated an attenuation of the pathways that contribute to the enhancement of transforming growth factor beta (TGF-β) induced epithelial mesenchymal transition (EMT), while PDOs demonstrated an attenuation of it. Taken together, PDSs and PDOs have differences in both the interaction to the immune systems and to the stroma. PDSs and PDOs will provide a model system that enable intimate investigation of the behavior of cancer cells in the body.

Evaluation of paclitaxel-loaded polymeric nanoparticles in 3D tumor model: impact of tumor stroma on penetration and efficacy

Since tumor stroma poses as a barrier to achieve efficacy of nanomedicines, it is essential to evaluate nano-chemotherapeutics in stroma-mimicking 3D models that reliably predict their behavior regarding these hurdles limiting efficacy. In this study, we evaluated the effect of paclitaxel-loaded polymeric micelles (PTX-PMCs) and polymeric nanoparticles (PTX-PNPs) in a tumor stroma-mimicking 3D in vitro model. PTX-PMCs (77 nm) based on a amphiphilic block copolymer of mPEG-b-p(HPMAm-Bz) and PTX-PNPs (159 nm) based on poly(lactic-co-glycolic acid) were prepared, which had an encapsulation efficiency (EE%) of 81 ± 15% and 45 ± 8%, respectively. 3D homospheroids of mouse 4T1 breast cancer cells and heterospheroids of NIH3T3 fibroblasts and 4T1 (5:1 ratio) were prepared and characterized with high content two-photon microscopy and immunostaining. Data showed an induction of epithelial-mesenchymal transition (α-SMA) in both homo- and heterospheroids, while ECM (collagen) deposition only in heterospheroids. Two-photon imaging revealed that both fluorescently labeled PMCs and PNPs penetrated into the core of homospheroids and only PMCs penetrated into heterospheroids. Furthermore, PTX-PMCs, PTX-PNPs, and free PTX induced cytotoxicity in tumor cells and fibroblasts grown as monolayer, but these effects were substantially reduced in 3D models, in particular in heterospheroids. Gene expression analysis showed that heterospheroids had a significant increase of drug resistance markers (Bcl2, Abgc2) compared to 2D or 3D monocultures. Altogether, this study shows that the efficacy of nanotherapeutics is challenged by stroma-induced poor penetration and development of resistant phenotype. Therefore, this tumor stroma-mimicking 3D model can provide an excellent platform to study penetration and effects of nanotherapeutics before in vivo studies.

EMT and Tumor Turning Point Analysis in 3D Spheroid Culture of HNSCC and Mesenchymal Stem Cells

The prognosis, metastasis, and behavior of head and neck squamous cancer cells are influenced by numerous factors concerning the tumor microenvironment, intercellular communication, and epithelial-to-mesenchymal transition (EMT). The aim of this study was to examine the codependent interaction of the mesenchymal stroma with head and neck squamous cell carcinoma (HNSCC) in a 3D spheroid structure. To simulate stroma-rich and -poor 3D tumor microenvironments, cells of the established cell SCC-040 were cultured with human mesenchymal stromal cells (MSCs), forming 3D stroma-tumor spheroids (STSs). STSs were compared to uniform spheroids of SCC-040 and MSC, respectively. The expressions of CD24, β-catenin, SNAI2, and ZEB2 were analyzed via RT-qPCR. The immunohistochemical expressions of E-cadherin, connexin 43, vimentin, and emmprin were analyzed, and protein expression pathways as well as Akt signaling were assessed via protein analysis. A promotive effect on the expressions of EMT markers ZEB2 (p = 0.0099), SNAI2 (p = 0.0352), and β-catenin (p = 0.0031) was demonstrated in STSs, as was the expression of Akt pathway proteins mTOR (p = 0.007), Erk1/2 (p = 0.0045), and p70 S6 Kinase (p = 0.0016). Our study demonstrated a change in genetic expression patterns early on in tumor development, indicating a tumor turning point.

Bench to Bedside: New Therapeutic Approaches with Extracellular Vesicles and Engineered Biomaterials for Targeting Therapeutic Resistance of Cancer Stem Cells

Cancer has recently been the second leading cause of death worldwide, trailing only cardiovascular disease. Cancer stem cells (CSCs), represented as tumor-initiating cells (TICs), are mainly liable for chemoresistance and disease relapse due to their self-renewal capability and differentiating capacity into different types of tumor cells. The intricate molecular mechanism is necessary to elucidate CSC's chemoresistance properties and cancer recurrence. Establishing efficient strategies for CSC maintenance and enrichment is essential to elucidate the mechanisms and properties of CSCs and CSC-related therapeutic measures. Current approaches are insufficient to mimic the in vivo chemical and physical conditions for the maintenance and growth of CSC and yield unreliable research results. Biomaterials are now widely used for simulating the bone marrow microenvironment. Biomaterial-based three-dimensional (3D) approaches for the enrichment of CSC provide an excellent promise for future drug discovery and elucidation of molecular mechanisms. In the future, the biomaterial-based model will contribute to a more operative and predictive CSC model for cancer therapy. Design strategies for materials, physicochemical cues, and morphology will offer a new direction for future modification and new methods for studying the CSC microenvironment and its chemoresistance property. This review highlights the critical roles of the microenvironmental cues that regulate CSC function and endow them with drug resistance properties. This review also explores the latest advancement and challenges in biomaterial-based scaffold structure for therapeutic approaches against CSC chemoresistance. Since the recent entry of extracellular vesicles (EVs), cell-derived nanostructures, have opened new avenues of investigation into this field, which, together with other more conventionally studied signaling pathways, play an important role in cell-to-cell communication. Thus, this review further explores the subject of EVs in-depth. This review also discusses possible future biomaterial and biomaterial-EV-based models that could be used to study the tumor microenvironment (TME) and will provide possible therapeutic approaches. Finally, this review concludes with potential perspectives and conclusions in this area.

TIMP-1-expressing breast tumor spheroids for the evaluation of drug penetration and efficacy

Abundance of stromal cells and extracellular matrix (ECM) is observed in breast cancer, acting as a barrier for drug penetration and presenting a key issue for developing efficient therapeutics. In this study, we aimed to develop a three-dimensional (3D) multicellular tumor model comprising cancer and stromal cells that could effectively mimic the drug resistance properties of breast cancer. Three different types of spheroid models were designed by co-culturing breast cancer cells (MDA-MB-231) with three different types of stromal cells: human adipose-derived stromal cells (hASCs), human bone marrow stromal cells, or human dermal fibroblasts. Compared with other models, in the hASC co-culture model, tissue inhibitor of metalloproteinases-1 (TIMP-1) was highly expressed and the activity of matrix metalloproteinases was decreased, resulting in a higher ECM deposition on the spheroid surfaces. This spheroid model showed less drug penetration and treatment efficacy than the other models. TIMP-1 silencing in hASCs reduced ECM protein expression and increased drug penetration and vulnerability. A quantitative structure-activity relationship study using multiple linear regression drew linear relationships between the chemical properties of drugs and experimentally determined permeability values. Drugs that did not match the drug-likeness rules exhibited lower permeability in the 3D tumor model. Taken together, our findings indicate that this 3D multicellular tumor model may be used as a reliable platform for efficiently screening therapeutics agents for solid tumors.

Novel Ex Vivo Models of Epithelial Ovarian Cancer: The Future of Biomarker and Therapeutic Research

Epithelial ovarian cancer (EOC) is a heterogenous disease associated with variations in presentation, pathology and prognosis. Advanced EOC is typified by frequent relapse and a historical 5-year survival of less than 30% despite improvements in surgical and systemic treatment. The advent of next generation sequencing has led to notable advances in the field of personalised medicine for many cancer types. Success in achieving cure in advanced EOC has however been limited, although significant prolongation of survival has been demonstrated. Development of novel research platforms is therefore necessary to address the rapidly advancing field of early diagnostics and therapeutics, whilst also acknowledging the significant tumour heterogeneity associated with EOC. Within available tumour models, patient-derived organoids (PDO) and explant tumour slices have demonstrated particular promise as novel ex vivo systems to model different cancer types including ovarian cancer. PDOs are organ specific 3D tumour cultures that can accurately represent the histology and genomics of their native tumour, as well as offer the possibility as models for pharmaceutical drug testing platforms, offering timing advantages and potential use as prospective personalised models to guide clinical decision-making. Such applications could maximise the benefit of drug treatments to patients on an individual level whilst minimising use of less effective, yet toxic, therapies. PDOs are likely to play a greater role in both academic research and drug development in the future and have the potential to revolutionise future patient treatment and clinical trial pathways. Similarly, ex vivo tumour slices or explants have also shown recent renewed promise in their ability to provide a fast, specific, platform for drug testing that accurately represents in vivo tumour response. Tumour explants retain tissue architecture, and thus incorporate the majority of tumour microenvironment making them an attractive method to re-capitulate in vivo conditions, again with significant timing and personalisation of treatment advantages for patients. This review will discuss the current treatment landscape and research models for EOC, their development and new advances towards the discovery of novel biomarkers or combinational therapeutic strategies to increase treatment options for women with ovarian cancer.

Mechanical transmission enables EMT cancer cells to drive epithelial cancer cell migration to guide tumor spheroid disaggregation

Cell phenotype heterogeneity within tumor tissue, especially which due to the emergence of epithelial-mesenchymal transition (EMT) in cancer cells, is associated with cancer invasion and metastasis. However, our understanding of the cellular mechanism(s) underlying the cooperation between EMT cell and epithelial cancer cell migration remains incomplete. Herein, heterotypic tumor spheroids containing both epithelial and EMT cancer cells were generated in vitro. We observed that EMT cells dominated the peripheral region of the self-organized heterotypic tumor spheroid. Furthermore, our results demonstrated that EMT cells could serve as leader cells to improve the collective migration efficiency of epithelial cancer cells and promote dispersion and invasion of the tumor spheroids, which was regulated by the force transition between EMT cells and epithelial cancer cells. Mechanistically, our data further suggest that force transmission is mediated by heterophilic N-cadherin/E-cadherin adhesion complexes between EMT and epithelial cancer cells. Impairment of N-cadherin/E-cadherin adhesion complex formation abrogated the ability of EMT cells to guide epithelial cancer cell migration and blocked the dispersion of tumor spheroids. Together, our data provide new insight into the mechanical interaction between epithelial and EMT cancer cells through heterophilic cadherin adhesion, which enables cooperative tumor cell migration, highlighting the role of EMT cells in tumor invasion.

Strategies for developing complex multi-component in vitro tumor models: Highlights in glioblastoma

In recent years, many research groups have begun to utilize bioengineered in vitro models of cancer to study mechanisms of disease progression, test drug candidates, and develop platforms to advance personalized drug treatment options. Due to advances in cell and tissue engineering over the last few decades, there are now a myriad of tools that can be used to create such in vitro systems. In this review, we describe the considerations one must take when developing model systems that accurately mimic the in vivo tumor microenvironment (TME) and can be used to answer specific scientific questions. We will summarize the importance of cell sourcing in models with one or multiple cell types and outline the importance of choosing biomaterials that accurately mimic the native extracellular matrix (ECM) of the tumor or tissue that is being modeled. We then provide examples of how these two components can be used in concert in a variety of model form factors and conclude by discussing how biofabrication techniques such as bioprinting and organ-on-a-chip fabrication can be used to create highly reproducible complex in vitro models. Since this topic has a broad range of applications, we use the final section of the review to dive deeper into one type of cancer, glioblastoma, to illustrate how these components come together to further our knowledge of cancer biology and move us closer to developing novel drugs and systems that improve patient outcomes.

Cancer-associated fibroblasts as cellular vehicles in endometrial cancer cell migration

Cell motility is a critical step in the metastasis cascade. However, the role of cancer-associated fibroblasts (CAFs) in facilitating endometrial cancer (EC) cell motility remains unclear. The present study aimed to investigate the role of CAFs in EC motility in a 3D environment. A co-culture model was established using an EC cell line (ECC-1) and CAFs on a Matrigel^® matrix and compared to the respective individual monocultures. It was demonstrated that endometrial CAFs increased the motility of the EC cell line, compared with the monoculture. Using live cell imaging, CAFs were observed to form cell projections that served as contact guidance for ECC-1 cell locomotion in the spheroid formation process. These effects were specific to CAFs, as fibroblasts isolated from benign endometrial tissue samples did not form cell projections. Molecular analysis revealed that RhoA/Rho-associated, coiled-coil containing protein kinase 1 (ROCK1) signaling activation partly contributed to CAF-mediated ECC-1 cell migration. The presence of Matrigel^® increased the mRNA expression of RhoA, and the mRNA and protein expression levels of its downstream effectors, ROCK1 and p-MLC, respectively, in the ECC-1 and CAF co-culture, as well as the ECC-1 and CAF monocultures. Interestingly, high phosphorylation levels of myosin light chain mediated the activation of RhoA/ROCK1 signaling in the ECC-1 and CAF co-culture. The ROCK1 inhibitor Y-27632 attenuated the motility of tumor cells in ECC-1 and CAF co-cultures. However, similar treatment led to a significant inhibition in the motility of the CAF monoculture, but not the ECC-1 monoculture. Moreover, tumor spheroid formation was inhibited due to a reduction in stress fiber formation in ECC-1 and CAF co-cultures. Altogether, these findings suggest that the regulation of the RhoA/ROCK1 signaling pathway is required for CAFs to serve as cellular vehicles in order for EC cells to migrate and form spheroids in a 3D environment.

The Microenvironment's Role in Mycosis Fungoides and Sézary Syndrome: From Progression to Therapeutic Implications

BACKGROUND

Mycosis fungoides (MF) and Sezary Syndrome (SS) are the most common cutaneous T-cell lymphomas. It has been hypothesized that the interaction between the immune system, cutaneous cells, and neoplastic elements may play a role in MF/SS pathogenesis and progression.

METHODS

This paper aims to revise in a narrative way our current knowledge of the microenvironment's role in MF/SS.

RESULTS AND CONCLUSIONS

Literature data support a possible implication of microenvironment cells in MF/SS pathogenesis and progression, opening up new therapeutic avenues.

Crosstalk between oral squamous cell carcinoma cells and cancer-associated fibroblasts via the TGF-β/SOX9 axis in cancer progression

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TGF-β1 secreted from CAFs promote the migration and invasion of OSCC cells.

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CAFs upregulate SOX9 expression of OSCC cells, possibly through inducing EMT.

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The presence of CAFs is correlated with SOX9 expression in the invasive cancer nests.

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The TGF-β/SOX9 axis between CAFs and OSCC cells facilitates cancer progression.

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Targeting the TGF-β/SOX9 axis could be a potential novel target for OSCC.

Cancer-associated fibroblasts (CAFs) have important roles in promoting cancer development and progression. We previously reported that high expression of sex-determining region Y (SRY)-box9 (SOX9) in oral squamous cell carcinoma (OSCC) cells was positively correlated with poor prognosis. This study developed three-dimensional (3D) in vitro models co-cultured with OSCC cells and CAFs to examine CAF-mediated cancer migration and invasion in vitro and in vivo. Moreover, we performed an immunohistochemical analysis of alpha-smooth muscle actin and SOX9 expression in surgical specimens from 65 OSCC patients. The results indicated that CAFs promote cancer migration and invasion in migration assays and 3D in vitro models. The invading OSCC cells exhibited significant SOX9 expression and changes in the expression of epithelial–mesenchymal transition (EMT) markers, suggesting that SOX9 promotes EMT. TGF-β1 signalling inhibition reduced SOX9 expression and cancer invasion in vitro and in vivo, indicating that TGF-β1-mediated invasion is dependent on SOX9. In surgical specimens, the presence of CAFs was correlated with SOX9 expression in the invasive cancer nests and had a significant impact on regional recurrence. These findings demonstrate that CAFs promote cancer migration and invasion via the TGF-β/SOX9 axis.

Leveraging advances in immunopathology and artificial intelligence to analyze in vitro tumor models in composition and space

Cancer is the leading cause of death worldwide. Unfortunately, efforts to understand this disease are confounded by the complex, heterogenous tumor microenvironment (TME). Better understanding of the TME could lead to novel diagnostic, prognostic, and therapeutic discoveries. One way to achieve this involves in vitro tumor models that recapitulate the in vivo TME composition and spatial arrangement. Here, we review the potential of harnessing in vitro tumor models and artificial intelligence to delineate the TME. This includes (i) identification of novel features, (ii) investigation of higher-order relationships, and (iii) analysis and interpretation of multiomics data in a (iv) holistic, objective, reproducible, and efficient manner, which surpasses previous methods of TME analysis. We also discuss limitations of this approach, namely inadequate datasets, indeterminate biological correlations, ethical concerns, and logistical constraints; finally, we speculate on future avenues of research that could overcome these limitations, ultimately translating to improved clinical outcomes.

3D Cancer Models: Depicting Cellular Crosstalk within the Tumour Microenvironment

The tumour microenvironment plays a critical role in tumour progression and drug resistance processes. Non-malignant cell players, such as fibroblasts, endothelial cells, immune cells and others, interact with each other and with the tumour cells, shaping the disease. Though the role of each cell type and cell communication mechanisms have been progressively studied, the complexity of this cellular network and its role in disease mechanism and therapeutic response are still being unveiled. Animal models have been mainly used, as they can represent systemic interactions and conditions, though they face recognized limitations in translational potential due to interspecies differences. In vitro 3D cancer models can surpass these limitations, by incorporating human cells, including patient-derived ones, and allowing a range of experimental designs with precise control of each tumour microenvironment element. We summarize the role of each tumour microenvironment component and review studies proposing 3D co-culture strategies of tumour cells and non-malignant cell components. Moreover, we discuss the potential of these modelling approaches to uncover potential therapeutic targets in the tumour microenvironment and assess therapeutic efficacy, current bottlenecks and perspectives.

The transformation of cancer-associated fibroblasts: Current perspectives on the role of TGF-β in CAF mediated tumor progression and therapeutic resistance

Over the last few years, the Transforming growth factor- β (TGF-β) has been significantly considered as an effective and ubiquitous mediator of cell growth. The cytokine, TGF-β is being increasingly recognized as the most potent inducer of cancer cell initiation, differentiation, migration as well as progression through both the SMAD-dependent and independent pathways. There is growing evidence that supports the role of secretory cytokine TGF-β as a crucial mediator of tumor-stroma crosstalk. Contextually, the CAFs are the prominent component of tumor stroma that helps in tumor progression and onset of chemoresistance. The interplay between the CAFs and the tumor cells through the paracrine signals is facilitated by cytokine TGF-β to induce the malignant progression. Here in this review, we have dissected the most recent advancements in understanding the mechanisms of TGF-β induced CAF activation, their multiple origins, and most importantly their role in conferring chemoresistance. Considering the pivotal role of TGF-β in tumor perogression and associated stemness, it is one the proven clinical targets We have also included the clinical trials going on, targeting the TGF-β and CAFs crosstalk with the tumor cells. Ultimately, we have underscored some of the outstanding issues that must be deciphered with utmost importance to unravel the successful strategies of anti-cancer therapies.

Parallel and large-scale antitumor investigation using stable chemical gradient and heterotypic three-dimensional tumor coculture in a multi-layered microfluidic device

BACKGROUND

Cancer has been responsible for a large number of human deaths in the 21st century. Establishing a controllable, biomimetic, and large-scale analytical platform to investigate the tumor-associated pathophysiological and preclinical events, such as oncogenesis and chemotherapy, is necessary.

METHODS AND RESULTS

This study presents antitumor investigation in a parallel, large-scale, and tissue-mimicking manner based on well-constructed chemical gradients and heterotypic three-dimensional (3D) tumor cocultures using a multifunction-integrated device. The integrated microfluidic device was engineered to produce a controllable and steady chemical gradient by manipulative optimization. Array-like and size-homogeneous production of heterotypic 3D tumor cocultures with in vivo-like features, including similar tumor-stromal composition and functional phenotypic gradients of metabolic activity and viability, was successfully established. Furthermore, temporal, parallel, and high-throughput analyses of tumor behaviors in different antitumor stimulations were performed in a device based on the integrated operations involving gradient generation and coculture.

CONCLUSION

This achievement holds great potential for applications in the establishment of multifunctional tumor platforms to perform tissue-biomimetic neoplastic research and therapy assessment in the fields of oncology, bioengineering, and drug discovery.

Self-Assembling Polypeptide Hydrogels as a Platform to Recapitulate the Tumor Microenvironment

Simple Summary

The tumor microenvironment is characterized by increased tissue stiffness, low (acidic) pH, and elevated temperature, all of which contribute to the development of cancer. Improving our in vitro models of cancer, therefore, requires the development of cell culture platforms that can mimic these microenvironmental properties. Here, we study a new biomaterial composed of short amino acid chains that self-assemble into a fibrous hydrogel network. This material enables simultaneous and independent tuning of substrate rigidity, extracellular pH, and temperature, allowing us to mimic both healthy tissues and the tumor microenvironment. We used this platform to study the effect of these conditions on pancreatic cancer cells and found that high substrate rigidity and low pH promote proliferation and survival of cancer cells and activate important signaling pathways associated with cancer progression.

Abstract

The tumor microenvironment plays a critical role in modulating cancer cell migration, metabolism, and malignancy, thus, highlighting the need to develop in vitro culture systems that can recapitulate its abnormal properties. While a variety of stiffness-tunable biomaterials, reviewed here, have been developed to mimic the rigidity of the tumor extracellular matrix, culture systems that can recapitulate the broader extracellular context of the tumor microenvironment (including pH and temperature) remain comparably unexplored, partially due to the difficulty in independently tuning these parameters. Here, we investigate a self-assembled polypeptide network hydrogel as a cell culture platform and demonstrate that the culture parameters, including the substrate stiffness, extracellular pH and temperature, can be independently controlled. We then use this biomaterial as a cell culture substrate to assess the effect of stiffness, pH and temperature on Suit2 cells, a pancreatic cancer cell line, and demonstrate that these microenvironmental factors can regulate two critical transcription factors in cancer: yes-associated protein 1 (YAP) and hypoxia inducible factor (HIF-1A).

Co-culturing multicellular tumor models: Modeling the tumor microenvironment and analysis techniques

Advances in two-dimensional (2D) and three-dimensional (3D) cell culture over the last 10 years have led to the development of a plethora of methods for cultivating tumor models. More recently, cellular co-cultures have become a suitable testbed. The first portion of this review focuses on co-culturing methods that have been developed in recent years utilizing the multicellular tumor spheroid model. The latter portion describes techniques that are used to analyze the proteomes of mono- or co-cultured tumor models, with a focus on mass spectrometry (MS)-based analyses. Protein profiles are important indicators of the tumor heterogeneity. Therefore, there is a specific focus within this review on analysis by MS and MS imaging methods evaluating the proteomic profiles of 2D and 3D co-cultures. While these models are incredibly important for biological research, so far, they have not been widely explored on the proteomic level. With this review, we aim to introduce these systems to an analytical audience, with the goal of highlighting MS as an underutilized tool for proteomic analysis of tumor models.

Development of a Decellularized Porcine Esophageal Matrix for Potential Applications in Cancer Modeling

Many decellularized extracellular matrix-derived whole organs have been widely used in studies of tissue engineering and cancer models. However, decellularizing porcine esophagus to obtain decellularized esophageal matrix (DEM) for potential biomedical applications has not been widely investigated. In this study a modified decellularization protocol was employed to prepare a porcine esophageal DEM for the study of cancer cell growth. The cellular removal and retention of matrix components in the porcine DEM were fully characterized. The microstructure of the DEM was observed using scanning electronic microscopy. Human esophageal squamous cell carcinoma (ESCC) and human primary esophageal fibroblast cells (FBCs) were seeded in the DEM to observe their growth. Results show that the decellularization process did not cause significant loss of mechanical properties and that blood ducts and lymphatic vessels in the submucosa layer were also preserved. ESCC and FBCs grew on the DEM well and the matrix did not show any toxicity to cells. When FBS and ESCC were cocultured on the matrix, they secreted more periostin, a protein that supports cell adhesion on matrix. This study shows that the modified decellularization protocol can effectively remove the cell materials and maintain the microstructure of the porcine esophageal matrix, which has the potential application of studying cell growth and migration for esophageal cancer models.

Recent Advances in Three-Dimensional Multicellular Spheroid Culture and Future Development

Three-dimensional multicellular spheroids (MCSs) have received extensive attention in the field of biomedicine due to their ability to simulate the structure and function of tissues in vivo more accurately than traditional in vitro two-dimensional models and to simulate cell-cell and cell extracellular matrix (ECM) interactions. It has become an important in vitro three-dimensional model for tumor research, high-throughput drug screening, tissue engineering, and basic biology research. In the review, we first summarize methods for MCSs generation and their respective advantages and disadvantages and highlight the advances of hydrogel and microfluidic systems in the generation of spheroids. Then, we look at the application of MCSs in cancer research and other aspects. Finally, we discuss the development direction and prospects of MCSs.

Progression-Mediated Changes in Mitochondrial Morphology Promotes Adaptation to Hypoxic Peritoneal Conditions in Serous Ovarian Cancer

Ovarian cancer is the deadliest gynecological cancer in women, with a survival rate of less than 30% when the cancer has spread throughout the peritoneal cavity. Aggregation of cancer cells increases their viability and metastatic potential; however, there are limited studies that correlate these functional changes to specific phenotypic alterations. In this study, we investigated changes in mitochondrial morphology and dynamics during malignant transition using our MOSE cell model for progressive serous ovarian cancer. Mitochondrial morphology was changed with increasing malignancy from a filamentous network to single, enlarged organelles due to an imbalance of mitochondrial dynamic proteins (fusion: MFN1/OPA1, fission: DRP1/FIS1). These phenotypic alterations aided the adaptation to hypoxia through the promotion of autophagy and were accompanied by changes in the mitochondrial ultrastructure, mitochondrial membrane potential, and the regulation of reactive oxygen species (ROS) levels. The tumor-initiating cells increased mitochondrial fragmentation after aggregation and exposure to hypoxia that correlated well with our previously observed reduced growth and respiration in spheroids, suggesting that these alterations promote viability in non-permissive conditions. Our identification of such mitochondrial phenotypic changes in malignancy provides a model in which to identify targets for interventions aimed at suppressing metastases.

TGFβ Signaling in the Tumor Microenvironment

Transforming growth factor beta (TGFβ) is a pleiotropic growth factor. Under normal physiological conditions, TGFβ maintains homeostasis in mammalian tissues by restraining the growth of cells and stimulating apoptosis. However, the role of TGFβ signaling in the carcinogenesis is complex. TGFβ acts as a tumor suppressor in the early stages of disease and as a tumor promoter in its later stages where cancer cells have been relieved from TGFβ growth controls. Overproduction of TGFβ by cancer cells lead to a local fibrotic and immune-suppressive microenvironment that fosters tumor growth and correlates with invasive and metastatic behavior of the cancer cells. Here, we present an overview of the complex biology of the TGFβ family, and we discuss the roles of TGFβ signaling in carcinogenesis and how this knowledge is being leveraged to develop TGFβ inhibition therapies against the tumor.

Emergence of spatio-temporal variations in chemotherapeutic drug efficacy: in-vitro and in-Silico 3D tumour spheroid studies

Background

The mechanisms of action and efficacy of cisplatin and paclitaxel at cell population level are well studied and documented, however the localized spatio-temporal effects of the drugs are less well understood. We explore the emergence of spatially preferential drug efficacy resulting from variations in mechanisms of cell-drug interactions.

Methods

3D spheroids of HeLa-C3 cells were treated with drugs, cisplatin and paclitaxel. This was followed by sectioning and staining of the spheroids to track the spatio-temporal apoptotic effects of the drugs. A mechanistic drug-cell interaction model was developed and simulated to analyse the localized efficacy of these drugs.

Results

The outcomes of drug actions on a local cell population was dependant on the interactions between cell repair probability, intracellular drug concentration and cell’s mitosis phase. In spheroids treated with cisplatin, drug induced apoptosis is found to be scattered throughout the volume of the spheroids. In contrast, effect of paclitaxel is found to be preferentially localized along the periphery of the spheroids. Combinatorial treatments of cisplatin and paclitaxel result in varying levels of cell apoptosis based on the scheduling strategy.

Conclusions

The preferential action of paclitaxel can be attributed to the cell characteristics of the peripheral population. The model simulations and experimental data show that treatments initiated with paclitaxel are more efficacious due to the cascading of spatial effects of the drugs.

A review of manufacturing capabilities of cell spheroid generation technologies and future development

Spheroid culture provides cells with a three-dimensional environment that can better mimic physiological conditions compared to monolayer culture. Technologies involved in the generation of cell spheroids are continuously being innovated to produce spheroids with enhanced properties. In this paper, we review the manufacturing capabilities of current cell spheroid generation technologies. We propose that spheroid generation technologies should enable tight and robust process controls to produce spheroids of consistent and repeatable quality. Future technology development for the generation of cell spheroids should look into improvement in process control, standardization, scalability and monitoring, in addition to advanced methods of spheroid transfer and characterization.

Ritchie A, Onion D, Clarke PA, Allegrucci C, Grabowska AM. A 3D Heterotypic Breast Cancer Model Demonstrates a Role for Mesenchymal Stem Cells in Driving a Proliferative and Invasive Phenotype

Previous indirect 2D co-culture studies have demonstrated that mesenchymal stem cells (MSCs) promote breast cancer (BC) progression through secretion of paracrine factors including growth factors, cytokines and chemokines. In order to investigate this aspect of the tumour microenvironment in a more relevant 3D co-culture model, spheroids incorporating breast cancer cells (BCCs), both cell lines and primary BCCs expanded as patient-derived xenografts, and MSCs were established. MSCs in co-cultures were shown to enhance proliferation of estrogen receptor (ER)/progesterone receptor (PR)-positive BCCs. In addition, co-culture resulted in downregulation of E-cadherin in parallel with upregulation of the epithelial-mesenchymal transition (EMT)-relation transcription factor, SNAIL. Cytoplasmic relocalization of ski-related novel protein N (SnON), a negative regulator of transforming growth factor-beta (TGF-β) signalling, and of β-catenin, involved in a number of pathways including Wnt signalling, was also observed in BCCs in co-cultures in contrast to monocultures. In addition, the β-catenin inhibitor, 3-[[(4-methylphenyl)sulfonyl]amino]-benzoic acid methyl ester (MSAB), mediated reduced growth and invasion in the co-cultures. This study highlights the potential role for SnON as a biomarker for BC invasiveness, and the importance of interactions between TGF-β and Wnt signalling, involving SnON. Such pathways may contribute towards identifying possible targets for therapeutic intervention in BC patients.

Integrin alpha-5 silencing leads to myofibroblastic differentiation in IPF-derived human lung fibroblasts

Background and objective:

The term ‘fibroblast’ covers a heterogeneous cell population in idiopathic pulmonary fibrosis (IPF). The fibroblasts are considered as main effector cells, because they promote disease progression by releasing exaggerated amounts of extracellular matrix proteins and modifying cell microenvironment. As IPF-derived human lung fibroblasts (IPF-HLFs) were shown to express higher levels of integrin alpha-5 (ITGA5) than normal derived HLFs (N-HLFs), we explored the importance of ITGA5 to IPF progression.

Methods:

IPF-HLF and N-HLF primary cultures were established. ITGA5 was silenced by specific small interfering RNA (siRNA)s and its effects on cell phenotype (e.g. cell number, size, cell death, migration) and gene expression (e.g. RNA sequencing, quantitative polymerase chain reaction [qPCR], western blot and immunofluorescence) were tested. Specific integrin expression was evaluated in IPF patient formalin-fixed paraffin embedded sections by immunohistochemistry (IHC).

Results:

ITGA5-silencing resulted in reduced IPF-HLF proliferation rates and cell migration (p < 0.05), as well as elevated cell death. transforming growth factor beta (TGF-β) targets (e.g. Fibronectin (FN1), Matrix metalloproteinase 2 (MMP2), TGFB1) were surprisingly elevated following ITGA5 silencing (p < 0.05). N-HLFs, however, were only slightly affected. Interestingly, ITGA5-silenced cells differentiated into myofibroblasts (e.g. elevated alpha-smooth muscle actin [αSMA], collagen1a, large cell size). RNA-sequencing revealed that following differentiation on 3D-Matrigel for 24 h, ITGA5 levels are reduced while integrin alpha-8 (ITGA8) are elevated in IPF-HLFs. This was confirmed in IPF patients, in which ITGA5 was mainly found in fibroblastic foci, while ITGA8 was mostly observed in old fibrous tissue in the same patient.

Conclusions:

ITGA5 expression facilitates a more aggressive proliferative phenotype. Downregulation of this integrin results in myofibroblastic differentiation, which is accompanied by elevated ITGA8. Specific targeting could present a therapeutic benefit.

A novel pancreatic tumour and stellate cell 3D co-culture spheroid model

BACKGROUND

Pancreatic ductal adenocarcinoma is a devastating disease with poor outcome, generally characterized by an excessive stroma component. The purpose of this study was to develop a simple and reproducible in vitro 3D-assay employing the main constituents of pancreatic ductal adenocarcinoma, namely pancreatic stellate and cancer cells.

METHOD

A spheroid assay, directly co-culturing human pancreatic stellate cells with human pancreatic tumour cells in 3D was established and characterized by electron microscopy, immunohistochemistry and real-time RT-PCR. In order to facilitate the cell type-specific crosstalk analysis by real-time RT-PCR, we developed a novel in vitro 3D co-culture model, where the participating cell types were from different species, human and mouse, respectively. Using species-specific PCR primers, we were able to investigate the crosstalk between stromal and cancer cells without previous cell separation and sorting.

RESULTS

We found clear evidence for mutual influence, such as increased proliferation and a shift towards a more mesenchymal phenotype in cancer cells and an activation of pancreatic stellate cells towards the myofibroblast phenotype. Using a heterospecies approach, which we coined virtual sorting, confirmed the findings we made initially in the human-human spheroids.

CONCLUSIONS

We developed and characterized different easy to set up 3D models to investigate the crosstalk between cancer and stroma cells for pancreatic cancer.

Investigating TNS4 in the Colorectal Tumor Microenvironment Using 3D Spheroid Models of Invasion

TNS4 (Tensin 4 or Cten) is a putative oncogene in colorectal cancer (CRC) with a role in regulating cell adhesion, motility, invasion, and epithelial to mesenchymal transition (EMT). The objective is to study the role of TNS4 in CRC using more realistic models of the tumor microenvironment. CRC cells expressing TdTomato protein and shTNS4/shLUC hairpin oligos are grown in 3D spheroids with and without cancer-associated fibroblasts (CAFs). Adhesiveness to collagen I and CAFs is assessed in 2D and cell proliferation, volume, and invasion are assessed in 3D conditions. The role of TNS4 knockdown in gefitinib chemosensitivity and epidermal growth factor receptor (EGFR) and Ras protein levels are also tested. In general, TNS4 knockdown increases cell proliferation in cell lines producing compact spheroids. The addition of CAFs in spheroids supports CRC cell proliferation, whereas CAFs themselves do not proliferate, but increases ECM degradation. TNS4 knockdown reduces adhesiveness and 3D invasion and disrupts EGFR signaling which results in increased sensitivity to Gefitinib. In conclusion, in a 3D spheroid model, TNS4 inhibits cell proliferation and promotes cell invasion into the ECM, possibly by adhesion to the ECM and stromal cells. TNS4 knockdown enhances sensitivity to the EGFR inhibitor gefitinib and may be helpful for Kirsten ras oncogene homolog mutant CRC patients.

A TRACER culture invasion assay to probe the impact of cancer associated fibroblasts on head and neck squamous cell carcinoma cell invasiveness

Cancer associated fibroblasts (CAFs) are a major cellular component of the tumour stroma and have been shown to promote tumour cell invasion and disease progression. CAF-cancer cell interactions are bi-directional and occur via both soluble factor dependent and extracellular matrix (ECM) remodelling mechanisms, which are incompletely understood. Previously we developed the Tissue Roll for Analysis of Cellular Environment and Response (TRACER), a novel stacked paper tumour model in which cells embedded in a hydrogel are infiltrated into a porous cellulose scaffold that is then rolled around an aluminum core to generate a multi-layered 3D tissue. Here, we use the TRACER platform to explore the impact of CAFs derived from three different patients on the invasion of two head and neck squamous cell carcinoma (HNSCC) cell lines (CAL33 and FaDu). We find that co-culture with CAFs enhances HNSCC tumour cell invasion into an acellular collagen layer in TRACER and this enhanced migration occurs independently of proliferation. We show that CAF-enhanced invasion of CAL33 cells is driven by a soluble factor independent mechanism, likely involving CAF mediated ECM remodelling via matrix metalloprotenases (MMPs). Furthermore, we find that CAF-enhanced tumour cell invasion is dependent on the spatial pattern of collagen density within the culture. Our results highlight the utility of the co-culture TRACER platform to explore soluble factor independent interactions between CAFs and tumour cells that drive increased tumour cell invasion.

Organotypic breast tumor model elucidates dynamic remodeling of tumor microenvironment

Fibroblasts are a critical component of tumor microenvironments and associate with cancer cells physically and biochemically during different stages of the disease. Existing cell culture models to study interactions between fibroblasts and cancer cells lack native tumor architecture or scalability. We developed a scalable organotypic model by robotically encapsulating a triple negative breast cancer (TNBC) cell spheroid within a natural extracellular matrix containing dispersed fibroblasts. We utilized an established CXCL12 - CXCR4 chemokine-receptor signaling in breast tumors to validate our model. Using imaging techniques and molecular analyses, we demonstrated that CXCL12-secreting fibroblasts have elevated activity of RhoA/ROCK/myosin light chain-2 pathway and rapidly and significantly contract collagen matrices. Signaling between TNBC cells and CXCL12-producing fibroblasts promoted matrix invasion of cancer cells by activating oncogenic mitogen-activated protein kinase signaling, whereas normal fibroblasts significantly diminished TNBC cell invasiveness. We demonstrated that disrupting CXCL12 - CXCR4 signaling using a molecular inhibitor significantly inhibited invasiveness of cancer cells, suggesting blocking of tumor-stromal interactions as a therapeutic strategy especially for cancers such as TNBC that lack targeted therapies. Our organotypic tumor model mimics native solid tumors, enables modular addition of different stromal cells and extracellular matrix proteins, and allows high throughput compound screening against tumor-stromal interactions to identify novel therapeutics.

Characterization and printability of Sodium alginate -Gelatin hydrogel for bioprinting NSCLC co-culture

3D bioprinting improves orientation of in vitro tumor models by offering layer by layer positioning of cancer cells and cancer associated fibroblasts (CAFs) which can replicate tumor microenvironment. Aim of this study was to develop a sodium alginate -gelatin (SA-GL) hydrogel by optimizing rheological parameters to print non-small cell lung cancer (NSCLC) patient derived xenograft (PDX) cells and lung CAFs co-cultures. SA-GL hydrogels were prepared, and rheological properties were evaluated. Both the cells were mixed with the hydrogel and printed using INKREDIBLE bioprinter. Hydrogels prepared with 3.25% and 3.5% (w/v) SA and 4% (w/v) GL showed higher printability and cell viability. A significant decline in viscosity with shear rate was observed in these hydrogels suggesting the shear thinning property of hydrogels. Spheroid size distribution after 15 days was in the diameter range of 50-1100 µm. Up-regulation of vimentin, α-SMA and loss of E-cadherin in co-culture spheroids confirmed cellular crosstalk. This study demonstrates that rheological optimization of SA-GL hydrogel enhances printability and viability of NSCLC PDX and CAF co-culture which allows 3D co-culture spheroid formation within the printed scaffold. Therefore, this model can be used for studying high throughput drug screening and other pre-clinical applications.

Gradient-sized control of tumor spheroids on a single chip

Multicellular tumor spheroids are attracting more attention as a physiologically relevant in vitro tumor model for biomedical research. The size of spheroids is one of the critical parameters related to drug penetration and cellular responses. It remains challenging to generate a large number of gradient-sized spheroids in one culture vessel. Here, a liquid-dome method was used to simultaneously produce more than 200 gradient-sized spheroids on an agarose chip. Surface tension effect was used to modulate the liquid spatial distribution and achieve a range of spheroid sizes. MCF-7 cells formed multiple spheroids on the chips for concept validation. It showed that different configurations of the liquid domes exhibited different levels of size control. Relative to the smallest spheroids in the configuration, hemispheric and square domes produced spheroids up to 3.4 and 12.8-fold larger in area, respectively. In addition, the co-culture of MCF-7 and fibroblasts helped to elucidate the tendency of fibroblasts towards the spheroid center. Other size-dependent behaviors were profiled; larger spheroids behaved differently from smaller spheroids in terms of spheroid growth, drug penetration and cellular responses. This method breaks the boundary between the preparation of gradient-sized spheroids and significant time/labour demand. It can be useful for drug screening and in vitro tumor modelling.

Cancer-Associated Fibroblasts in Undifferentiated Nasopharyngeal Carcinoma: A Putative Role for the EBV-Encoded Oncoprotein, LMP1

Undifferentiated nasopharyngeal carcinoma (NPC) is 100% associated with Epstein–Barr virus (EBV) infection, and biopsies display variable levels of expression of the viral oncoprotein, latent membrane protein 1 (LMP1). Emerging evidence suggests an important role for cancer-associated fibroblasts (CAFs) in the NPC tumour microenvironment, yet the interaction between the virus, its latent gene products and the recruitment and activation of CAFs in the NPC tumour stroma remains unclear. This short review will discuss the current evidence for the importance of CAFs in NPC pathogenesis and outline a putative role for the EBV-encoded oncoprotein, LMP1, in governing tumour–stromal interactions.

Stroma-Rich Co-Culture Multicellular Tumor Spheroids as a Tool for Photoactive Drugs Screening

Conventional 3D multicellular tumor spheroids of head and neck squamous cell carcinoma (HNSCC) consisting exclusively of cancer cells have some limitations. They are compact cell aggregates that do not interact with their extracellular milieu, thus suffering from both insufficient extracellular matrix (ECM) deposition and absence of different types of stromal cells. In order to better mimic in vivo HNSCC tumor microenvironment, we have constructed a 3D stroma-rich in vitro model of HNSCC, using cancer-associated MeWo skin fibroblasts and FaDu pharynx squamous cell carcinoma. The expression of stromal components in heterospheroids was confirmed by immunochemical staining. The generated co-culture FaDu/MeWo spheroids were applied to study penetration, distribution and antitumor efficacy of photoactive drugs such as Temoporfin and Chlorin e6 used in the photodynamic therapy flow cytometry and fluorescence microscopy techniques. We also investigated the distribution of photodiagnostic agent Indocyanine Green. We demonstrated that the presence of stroma influences the behavior of photoactive drugs in different ways: (i) No effect on Indocyanine Green distribution; (ii) lower accumulation of Chlorin e6; (iii) better penetration and PDT efficiency of Temoporfin. Overall, the developed stroma-rich spheroids enlarge the arsenal of in vitro pre-clinical models for high-throughput screening of anti-cancer drugs.

Morphological and Molecular Changes in Juvenile Normal Human Fibroblasts Exposed to Simulated Microgravity

The literature suggests morphological alterations and molecular biological changes within the cellular milieu of human cells, exposed to microgravity (µg), as many cell types assemble to multicellular spheroids (MCS). In this study we investigated juvenile normal human dermal fibroblasts (NHDF) grown in simulated µg (s-µg) on a random positioning machine (RPM), aiming to study changes in cell morphology, cytoskeleton, extracellular matrix (ECM), focal adhesion and growth factors. On the RPM, NHDF formed an adherent monolayer and compact MCS. For the two cell populations we found a differential regulation of fibronectin, laminin, collagen-IV, aggrecan, osteopontin, TIMP-1, integrin-β₁, caveolin-1, E-cadherin, talin-1, vimentin, α-SM actin, TGF-β₁, IL-8, MCP-1, MMP-1, and MMP-14 both on the transcriptional and/or translational level. Immunofluorescence staining revealed only slight structural changes in cytoskeletal components. Flow cytometry showed various membrane-bound proteins with considerable variations. In silico analyses of the regulated proteins revealed an interaction network, contributing to MCS growth via signals mediated by integrin-β₁, E-cadherin, caveolin-1 and talin-1. In conclusion, s-µg-conditions induced changes in the cytoskeleton, ECM, focal adhesion and growth behavior of NHDF and we identified for the first time factors involved in fibroblast 3D-assembly. This new knowledge might be of importance in tissue engineering, wound healing and cancer metastasis.

Targeting of activated fibroblasts for imaging and therapy

Tumors form a complex environment consisting of a variety of non-malignant cells. Especially cancer-associated fibroblasts have been shown to have an important role for different aspects of malignant tumors such as migration, metastasis, resistance to chemotherapy and immunosuppression. Therefore, a targeting of these cells may be useful for both imaging and therapy. In this respect, an interesting target is the fibroblast activation protein (FAP) which is expressed in activated fibroblasts, but not in quiescent fibroblasts, giving the opportunity to use this membrane-anchored enzyme as a target for radionuclide-based approaches for diagnosis and treatment of tumors and for the diagnosis of non-malignant disease associated with a remodelling of the extracellular matrix.

Bi-layer blood vessel mimicking microfluidic platform for antitumor drug screening based on co-culturing 3D tumor spheroids and endothelial layers

Two-dimensional (2D) cell culture is not ideal for traditional drug screening, because 2D culture does not accurately mimic the physiological microenvironment of tumor cells. Thus, a drug-screening system which more closely mimics the microenvironment of in vivo tumors is necessary. Here, we present a biomimicking bilayer microfluidic device that can facilitate antitumor drug screening. The microfluidic device consists of two polydimethylsiloxane (PDMS) pieces with channels which are separated by a semipermeable membrane to allow water, oxygen, and nutrition supply, while preventing cell migration. The channels embedded on the two PDMS pieces overlap each other over a long distance to ensure a larger exchange area to mimic the blood vessel-tumor model. High concentrations of endothelial cells (EC) are first seeded onto the membrane through the apical channel, and after a two-day culture, a confluent EC monolayer forms. Tumor spheroid-laden Matrigel is then seeded into the basal channel. After the Matrigel is cured, the device is ready for drug testing. Paclitaxel is used as the model drug for testing. Confocal microscopy and ImageJ are used to assess the efficacy of different concentrations of paclitaxel, and optical coherence tomography (OCT) is employed to determine the tumor volumetric change after the drug treatment. The results indicate that the proposed bilayer microfluidic device in combination with confocal and OCT optical characterization provide an efficient platform for antitumor drug testing.

A Review of Self-Expanding Esophageal Stents for the Palliation Therapy of Inoperable Esophageal Malignancies

Esophageal cancer is a very deadly disease, killing more than 15,000 people in the United States annually. Almost 400,000 new cases happen in the worldwide every year. More than 50% esophageal cancer patients are diagnosed at an advanced stage when they need an esophageal stent to open the blocked esophagus for feeding and drinking. Esophageal stents have evolved in stages over the years. Current clinically used stents commonly include stainless steel or nitinol self-expandable metallic stent (SEMS) and self-expandable plastic stent (SEPS). There are many choices of different types of stents and sizes, with fierce competition among manufacturers. However, current stent technology, whether uncovered, partially covered, fully covered SEMS or SEPS, has their own advantages to solve the dysphagia, stricture, and fistula problems, but they also cause some clinical complications. The ideal stent remains elusive. New 3D printing technique may bring new promising potential to manufacturing personalized esophageal stents. Drug-eluting stents could be the new avenue to do more than just pry open a stricture or cover a defect in the esophageal lumen, a possibility of proving local anticancer therapy simultaneously. Additionally, the lack of esophageal cancer animal models also hinders the progress of stent development. This paper reviews these topics for a comprehensive understanding of this field. In a conclusion, the ultimate goal of the future esophageal stent would have multifunction to treat the underlying conditions and restore esophageal function to near normal.

Preclinical Organotypic Models for the Assessment of Novel Cancer Therapeutics and Treatment

The immense costs in both financial terms and preclinical research effort that occur in the development of anticancer drugs are unfortunately not matched by a substantial increase in improved clinical therapies due to the high rate of failure during clinical trials. This may be due to issues with toxicity or lack of clinical effectiveness when the drug is evaluated in patients. Currently, much cancer research is driven by the need to develop therapies that can exploit cancer cell adaptations to conditions in the tumor microenvironment such as acidosis and hypoxia, the requirement for more-specific, targeted treatments, or the exploitation of 'precision medicine' that can target known genomic changes in patient DNA. The high attrition rate for novel anticancer therapies suggests that the preclinical methods used in screening anticancer drugs need improvement. This chapter considers the advantages and disadvantages of 3D organotypic models in both cancer research and cancer drug screening, particularly in the areas of targeted drugs and the exploitation of genomic changes that can be used for therapeutic advantage in precision medicine.