The Role of Tumor Microenvironment in Chemoresistance: 3D Extracellular Matrices as Accomplices

Cell and extracellular matrix interaction models in benign mesothelial and malignant pleural mesothelioma cells in 2D and 3D in-vitro

Malignant pleural mesothelioma (MPM) is an aggressive tumour that grows in the pleural cavity. MPM spheroids released in the pleural fluid can form new tumour foci. Cell-cell, cell-extracellular matrix (ECM) interactions in 2D and 3D impact malignant cell behaviour during cell adhesion, migration, proliferation and epithelial-mesenchymal transition (EMT). In this study, epithelioid, biphasic and sarcomatoid MPM cell types as well as benign mesothelial cells were tested with regards to the above phenotypes. Fibronectin (FN) and homologous cell-derived extracellular matrix (hcd-ECM) treated substratum differentially affected the above phenotypes. 3D MPM spheroid invasion was higher in FN-collagen matrices in the epithelioid and biphasic cells, while 3D cell cultures of epithelioid and sarcomatoid MPM cells in FN-collagen showed a higher contractility compared to hcd-ECM-collagen. Cell aggregates demonstrated invasive behaviour in hcd-ECM matrices alone. Our results suggest that ECM and the dimensionality affect malignant cell behaviour during cell culture studies.

What Is the Storage Effect, Why Should It Occur in Cancers, and How Can It Inform Cancer Therapy?

Intratumor heterogeneity is a feature of cancer that is associated with progression, treatment resistance, and recurrence. However, the mechanisms that allow diverse cancer cell lineages to coexist remain poorly understood. The storage effect is a coexistence mechanism that has been proposed to explain the diversity of a variety of ecological communities, including coral reef fish, plankton, and desert annual plants. Three ingredients are required for there to be a storage effect: (1) temporal variability in the environment, (2) buffered population growth, and (3) species-specific environmental responses. In this article, we argue that these conditions are observed in cancers and that it is likely that the storage effect contributes to intratumor diversity. Data that show the temporal variation within the tumor microenvironment are needed to quantify how cancer cells respond to fluctuations in the tumor microenvironment and what impact this has on interactions among cancer cell types. The presence of a storage effect within a patient’s tumors could have a substantial impact on how we understand and treat cancer.

Overexpressed COL5A1 is correlated with tumor progression, paclitaxel resistance, and tumor-infiltrating immune cells in ovarian cancer

Ovarian cancer (OC) remains the leading cause of cancer-related death among gynecological cancers. The present study examined the role of collagen type V alpha 1 (COL5A1) and the characteristics of COL5A1 as an oncogenic protein in OC. The association of COL5A1 with paclitaxel (PTX)-resistance and stemness in OC was also studied and the multidatabase and big data analyses of the prognostic value, coexpression network, genetic alterations, and tumor-infiltrating immune cells of COL5A1 were elucidated. We found that COL5A1 expression was high in OC cells and tissues. Knockdown of COL5A1 inhibited the proliferation and migration of OC cells. Further study also showed that COL5A1 was overexpressed in PTX-resistant OC cells compared to respective PTX-sensitive cells. Additionally, COL5A1 was more enriched in OC stem cell-like cells. Silencing COL5A1 expression decreased the OC cell resistance to PTX and inhibited the ability of OC-spheroid formation. Survival analysis predicted that the elevated COL5A1 expression was associated with a worse survival outcome and correlated to the tumor stage of OC patients. The estimating relative subsets of RNA transcripts (CIBERSORT) algorithm analysis also unveiled the correlation of several tumor-infiltrating immune cells with the expression of COL5A1. Taken together, our data demonstrate that COL5A1 is a biomarker to predict OC progression and PTX-resistance and represents a promising target for OC treatment.

Adaptive Mechanisms of Tumor Therapy Resistance Driven by Tumor Microenvironment

Cancer is a disease which frequently has a poor prognosis. Although multiple therapeutic strategies have been developed for various cancers, including chemotherapy, radiotherapy, and immunotherapy, resistance to these treatments frequently impedes the clinical outcomes. Besides the active resistance driven by genetic and epigenetic alterations in tumor cells, the tumor microenvironment (TME) has also been reported to be a crucial regulator in tumorigenesis, progression, and resistance. Here, we propose that the adaptive mechanisms of tumor resistance are closely connected with the TME rather than depending on non-cell-autonomous changes in response to clinical treatment. Although the comprehensive understanding of adaptive mechanisms driven by the TME need further investigation to fully elucidate the mechanisms of tumor therapeutic resistance, many clinical treatments targeting the TME have been successful. In this review, we report on recent advances concerning the molecular events and important factors involved in the TME, particularly focusing on the contributions of the TME to adaptive resistance, and provide insights into potential therapeutic methods or translational medicine targeting the TME to overcome resistance to therapy in clinical treatment.

Proteinaceous Hydrogels for Bioengineering Advanced 3D Tumor Models

The establishment of tumor microenvironment using biomimetic in vitro models that recapitulate key tumor hallmarks including the tumor supporting extracellular matrix (ECM) is in high demand for accelerating the discovery and preclinical validation of more effective anticancer therapeutics. To date, ECM-mimetic hydrogels have been widely explored for 3D in vitro disease modeling owing to their bioactive properties that can be further adapted to the biochemical and biophysical properties of native tumors. Gathering on this momentum, herein the current landscape of intrinsically bioactive protein and peptide hydrogels that have been employed for 3D tumor modeling are discussed. Initially, the importance of recreating such microenvironment and the main considerations for generating ECM-mimetic 3D hydrogel in vitro tumor models are showcased. A comprehensive discussion focusing protein, peptide, or hybrid ECM-mimetic platforms employed for modeling cancer cells/stroma cross-talk and for the preclinical evaluation of candidate anticancer therapies is also provided. Further development of tumor-tunable, proteinaceous or peptide 3D microtesting platforms with microenvironment-specific biophysical and biomolecular cues will contribute to better mimic the in vivo scenario, and improve the predictability of preclinical screening of generalized or personalized therapeutics.

Hydrogels to engineer tumor microenvironments in vitro

Illustration of engineered hydrogel to recapitulate aspects of the tumor microenvironment.

Manipulating the Tumor Microenvironment in Tumor Organoids Induces Phenotypic Changes and Chemoresistance

Tumors comprised a tightly surrounded tumor microenvironment, made up of non-cellular extracellular matrix (ECM) and stromal cells. Although treatment response is often attributed to tumor heterogeneity, progression and malignancy are profoundly influenced by tumor cell interactions with the surrounding ECM. Here, we used a tumor organoid model, consisting of hepatic stellate cells (HSCs) embedded in collagen type 1 (Col1) and colorectal cancer cell (HCT-116) spheroids, to determine the relationship between the ECM architecture, cancer cell malignancy, and chemoresistance. Exogenous transforming growth factor beta (TGF-β) used to activate the HSCs increased the remodeling and bundling of Col1 in the ECM around the cancer spheroid. A dense ECM architecture inhibited tumor cell growth, reversed their mesenchymal phenotype, preserved stem cell population, and reduced chemotherapy response. Overall, our results demonstrate that controlled biofabrication and manipulation of the ECM in tumor organoids results enables studying tumor cell-ECM interactions and better understand tumor cell response to chemotherapies.

Targeting Notch in oncology: the path forward

Notch signalling is involved in many aspects of cancer biology, including angiogenesis, tumour immunity and the maintenance of cancer stem-like cells. In addition, Notch can function as an oncogene and a tumour suppressor in different cancers and in different cell populations within the same tumour. Despite promising preclinical results and early-phase clinical trials, the goal of developing safe, effective, tumour-selective Notch-targeting agents for clinical use remains elusive. However, our continually improving understanding of Notch signalling in specific cancers, individual cancer cases and different cell populations, as well as crosstalk between pathways, is aiding the discovery and development of novel investigational Notch-targeted therapeutics.

Cell-Derived Extracellular Matrix for Tissue Engineering and Regenerative Medicine

Cell-derived extracellular matrices (CD-ECMs) captured increasing attention since the first studies in the 1980s. The biological resemblance of CD-ECMs to their in vivo counterparts and natural complexity provide them with a prevailing bioactivity. CD-ECMs offer the opportunity to produce microenvironments with costumizable biological and biophysical properties in a controlled setting. As a result, CD-ECMs can improve cellular functions such as stemness or be employed as a platform to study cellular niches in health and disease. Either on their own or integrated with other materials, CD-ECMs can also be utilized as biomaterials to engineer tissues de novo or facilitate endogenous healing and regeneration. This review provides a brief overview over the methodologies used to facilitate CD-ECM deposition and manufacturing. It explores the versatile uses of CD-ECM in fundamental research and therapeutic approaches, while highlighting innovative strategies. Furthermore, current challenges are identified and it is accentuated that advancements in methodologies, as well as innovative interdisciplinary approaches are needed to take CD-ECM-based research to the next level.

Cancer Stem Cell Markers in Relation to Patient Survival Outcomes: Lessons for Integrative Diagnostics and Next-Generation Anticancer Drug Development

Solid tumors display a complex biology that requires a multipronged treatment strategy. Most anticancer interventions, including chemotherapy, are currently unable to prevent treatment resistance and relapse. In general, therapeutics target cancer cells and overlook the tumor microenvironment (TME) and the presence of cancer stem cells (CSCs) with self-renewal and tumorigenic abilities. CSCs have been postulated to play key roles in tumor initiation, progression, therapy resistance, and metastasis. Hence, CSC markers have been suggested as diagnostics to forecast cancer prognosis as well as molecular targets for new-generation cancer treatments, especially in resistant disease. We report here original findings on expression and prognostic significance of CSC markers in several cancers. We examined and compared the transcriptional expression of CSC markers (ABCB1, ABCG2, ALDH1A1, CD24, CD44, CD90, CD133, CXCR4, EPCAM, ICAM1, and NES) in tumor tissues versus the adjacent normal tissues using publicly available databases, The Cancer Genome Atlas and Gene Expression Profiling Interactive Analysis. We found that CSC transcriptional markers were, to a large extent, expressed in higher abundance in solid tumors such as colon, lung, pancreatic, and esophageal cancers. On the other hand, no CSC marker in our analysis was expressed in the same pattern in all cancers, while individual CSC marker expression, alone, was not significantly associated with overall patient survival. Innovation in next-generation cancer therapeutics and diagnostics ought to combine CSC markers as well as integrative diagnostics that pool knowledge from CSCs and other TME components and cancer cells.

Acute, reproductive, and developmental toxicity of essential oils assessed with alternative in vitro and in vivo systems

Essential oils (EOs) have attracted increased interest for different applications such as food preservatives, feed additives and ingredients in cosmetics. Due to their reported variable composition of components, they might be acutely toxic to humans and animals in small amounts. Despite the necessity, rigorous toxicity testing in terms of safety evaluation has not been reported so far, especially using alternatives to animal models. Here, we provide a strategy by use of alternative in vitro (cell cultures) and in vivo (Caenorhabditis elegans, hen’s egg test) approaches for detailed investigation of the impact of commonly used rosemary, citrus and eucalyptus essential oil on acute, developmental and reproductive toxicity as well as on mucous membrane irritation. In general, all EOs under study exhibited a comparable impact on measured parameters, with a slightly increased toxic potential of rosemary oil. In vitro cell culture results indicated a concentration-dependent decrease of cell viability for all EOs, with mean IC₅₀ values ranging from 0.08 to 0.17% [v/v]. Similar results were obtained for the C. elegans model when using a sensitized bus-5 mutant strain, with a mean LC₅₀ value of 0.42% [v/v]. In wild-type nematodes, approximately tenfold higher LC₅₀ values were detected. C. elegans development and reproduction was already significantly inhibited at concentrations of 0.5% (wild-type) and 0.1% (bus-5) [v/v] of EO, respectively. Gene expression analysis revealed a significant upregulation of xenobiotic and oxidative stress genes such as cyp-14a3, gst-4, gpx-6 and sod-3. Furthermore, all three EOs under study showed an increased short-time mucous membrane irritation potential, already at 0.5% [v/v] of EO. Finally, GC–MS analysis was performed to quantitate the relative concentration of the most prominent EO compounds. In conclusion, our results demonstrate that EOs can exhibit severe toxic properties, already at low concentrations. Therefore, a detailed toxicological assessment is highly recommended for each EO and single intended application.

Identification of Mutations Related to Cisplatin-Resistance and Prognosis of Patients With Lung Adenocarcinoma

Background: Lung adenocarcinoma (LUAD) is the most common histologic type of non-small cell lung cancer (NSCLC; approximately 60%), and platinum-based chemotherapy is the cornerstone of the treatment for patients with LUAD. However, a considerable number of patients experience tumor recurrence after developing cisplatin (cis-diamminedichloroplatinum(II) or CDDP) resistance. Therefore, it is particularly important to screen primary CDDP-resistant LUAD patient populations, which can maximize the clinical benefits for these patients. Methods: Data for 61 LUAD cell lines were downloaded from the Genomics of Drug Sensitivity in Cancer (GDSC) database to screen for mutations related to CDDP susceptibility, and we conducted whole-exome sequencing (WES) of tumors from 45 LUAD patients from Zhujiang Hospital of Southern Medical University. Subsequently, the clinical prognostic value of these mutations was verified by using The Cancer Genome Atlas (TCGA)-LUAD cohort and our cohort (n = 45). Results: Based on drug sensitivity data for the GDSC-LUAD cell lines and survival analysis of the cohorts TCGA-LUAD and Local-LUAD, we found only one gene (GREB1) with mutations related to decreased CDDP sensitivity as well as worse overall survival (OS) and progression-free survival (PFS) [OS: log-rank p = 0.038, hazard ratio (HR; 95% confidence interval (95% CI)): 2.19 (0.73-6.55); PFS: log-rank p = 0.001; HR: 4.65, 95% CI: 1.18-18.37]. The GREB1-mutant (GREB1-MT) group had a higher frequency of gene mutations. Additionally, gene set enrichment analysis (GSEA) and single-sample GSEA (ssGSEA) suggested reduced accumulation of intracellular drugs in the GREB1-MT group, in addition to increased drug efflux and enhanced DNA damage repair and intracellular detoxification. Conclusion: This study found that GREB1 mutations may mediate the primary resistance and clinical prognosis of LUAD patients undergoing treatment with CDDP. Further functional analysis showed that GREB1 mutations are related to the known mechanism of CDDP resistance. These results suggest that GREB1 mutations are potential biomarkers for screening of CDDP resistance among LUAD patients.

A WEE1 family business: regulation of mitosis, cancer progression, and therapeutic target

The inhibition of the DNA damage response (DDR) pathway in the treatment of cancer has recently gained interest, and different DDR inhibitors have been developed. Among them, the most promising ones target the WEE1 kinase family, which has a crucial role in cell cycle regulation and DNA damage identification and repair in both nonmalignant and cancer cells. This review recapitulates and discusses the most recent findings on the biological function of WEE1/PKMYT1 during the cell cycle and in the DNA damage repair, with a focus on their dual role as tumor suppressors in nonmalignant cells and pseudo-oncogenes in cancer cells. We here report the available data on the molecular and functional alterations of WEE1/PKMYT1 kinases in both hematological and solid tumors. Moreover, we summarize the preclinical information on 36 chemo/radiotherapy agents, and in particular their effect on cell cycle checkpoints and on the cellular WEE1/PKMYT1-dependent response. Finally, this review outlines the most important pre-clinical and clinical data available on the efficacy of WEE1/PKMYT1 inhibitors in monotherapy and in combination with chemo/radiotherapy agents or with other selective inhibitors currently used or under evaluation for the treatment of cancer patients.

Nanomedicine and chemotherapeutics drug delivery: challenges and opportunities

Cancer is considered as one of the biggest threats to humans worldwide. Researchers suggest that tumour is not just a single mass, it comprises cancerous cells surrounded by noncancerous cells such as immune cells, adipocytes and cancer stem cells (CSCs) in the extracellular matrix (ECM) containing distinct components such as proteins, glycoproteins and enzymes; thus tumour microenvironment (TME) is partially complex. Multiple interactions happen in the dynamic microenvironment (ME) lead to an acidic, hypoxic and stiff ME that is considered as one of the major contributors to cancer progression and metastasis. Furthermore, TME involves in drug resistance mechanisms and affects enhanced permeability and retention (EPR) in tumours. In such a scenario, the first step to accomplish satisfying results is the identification and recognition of this ME. Then designing proper drug delivery systems can perform selectively towards cancerous cells. In this way, several targeting and stimuli/enzyme responsive drug delivery systems have been designed. More importantly, it is necessary to design a drug delivery system that can penetrate deeper into the tumours, efficiently and selectively. Various drug delivery systems such as exosomes and size-switchable nanocarriers (NCs) could decrease side effects and increase tumour treatment results by selective accumulation in tumours. In this review, TME features, current drug delivery approaches, challenges and promising strategies towards cancer treatment are discussed.

Advances in Therapeutic Targeting of Cancer Stem Cells within the Tumor Microenvironment: An Updated Review

Despite great strides being achieved in improving cancer patients' outcomes through better therapies and combinatorial treatment, several hurdles still remain due to therapy resistance, cancer recurrence and metastasis. Drug resistance culminating in relapse continues to be associated with fatal disease. The cancer stem cell theory posits that tumors are driven by specialized cancer cells called cancer stem cells (CSCs). CSCs are a subpopulation of cancer cells known to be resistant to therapy and cause metastasis. Whilst the debate on whether CSCs are the origins of the primary tumor rages on, CSCs have been further characterized in many cancers with data illustrating that CSCs display great abilities to self-renew, resist therapies due to enhanced epithelial to mesenchymal (EMT) properties, enhanced expression of ATP-binding cassette (ABC) membrane transporters, activation of several survival signaling pathways and increased immune evasion as well as DNA repair mechanisms. CSCs also display great heterogeneity with the consequential lack of specific CSC markers presenting a great challenge to their targeting. In this updated review we revisit CSCs within the tumor microenvironment (TME) and present novel treatment strategies targeting CSCs. These promising strategies include targeting CSCs-specific properties using small molecule inhibitors, immunotherapy, microRNA mediated inhibitors, epigenetic methods as well as targeting CSC niche-microenvironmental factors and differentiation. Lastly, we present recent clinical trials undertaken to try to turn the tide against cancer by targeting CSC-associated drug resistance and metastasis.

Physical Cues in the Microenvironment Regulate Stemness-Dependent Homing of Breast Cancer Cells

Tissue-specific microenvironmental factors contribute to the targeting preferences of metastatic cancers. However, the physical attributes of the premetastatic microenvironment are not yet fully characterized. In this research, we develop a transwell-based alginate hydrogel (TAH) model to study how permeability, stiffness, and roughness of a hanging alginate hydrogel regulate breast cancer cell homing. In this model, a layer of physically characterized alginate hydrogel is formed at the bottom of a transwell insert, which is placed into a matching culture well with an adherent monolayer of breast cancer cells. We found that breast cancer cells dissociate from the monolayer and home to the TAH for continual growth. The process is facilitated by the presence of rich serum in the upper chamber, the increased stiffness of the gel, as well as its surface roughness. This model is able to support the homing ability of MCF-7 and MDA-MB-231 cells drifting across the vertical distance in the culture medium. Cells homing to the TAH display stemness phenotype morphologically and biochemically. Taken together, these findings suggest that permeability, stiffness, and roughness are important physical factors to regulate breast cancer homing to a premetastatic microenvironment.

Esophageal Microenvironment: From Precursor Microenvironment to Premetastatic Niche

Esophageal cancer (EC) is the sixth most deadly cancer, and its incidence is still increasing year by year. Although the researches on the molecular mechanisms of EC have been widely carried out and incremental progress has been made, its overall survival rate is still low. There is cumulative evidence showing that the esophageal microenvironment plays a vital role in the development of EC. In precancerous lesions of the esophagus, high-risk environmental factors can promote the development of precancerous lesions by inducing the production of inflammatory factors and the recruitment of immune cells. In the tumor microenvironment, tumor-promoting cells can inhibit anti-tumor immunity and promote tumor progression through a variety of pathways, such as bone marrow-derived suppressor cells (MDSCs), tumor-associated fibroblasts (CAFs), and regulatory T cells (Tregs). The formation of extracellular hypoxia and acidic microenvironment and the change of extracellular matrix stiffness are also important factors affecting tumor progression and metastasis. Simultaneously, primary tumor-derived cytokines and bone marrow-derived immune cells can also promote the formation of pre-metastasis niche of EC lymph nodes, which are beneficial to EC lymph node metastasis. Further research on the specific mechanism of these processes in the occurrence, development, and metastasis of each EC subtype will support us to grasp the overall pre-cancerous prevention, targeted treatment, and metastatic assessment of EC.

Expression Changes and Impact of the Extracellular Matrix on Etoposide Resistant Human Retinoblastoma Cell Lines

Retinoblastoma (RB) represents the most common malignant childhood eye tumor worldwide. Several studies indicate that the extracellular matrix (ECM) plays a crucial role in tumor growth and metastasis. Moreover, recent studies indicate that the ECM composition might influence the development of resistance to chemotherapy drugs. The objective of this study was to evaluate possible expression differences in the ECM compartment of the parental human cell lines WERI-RB1 (retinoblastoma 1) and Y79 and their Etoposide resistant subclones via polymerase chain reaction (PCR). Western blot analyses were performed to analyze protein levels. To explore the influence of ECM molecules on RB cell proliferation, death, and cluster formation, WERI-RB1 and resistant WERI-ETOR cells were cultivated on Fibronectin, Laminin, Tenascin-C, and Collagen IV and analyzed via time-lapse video microscopy as well as immunocytochemistry. We revealed a significantly reduced mRNA expression of the proteoglycans Brevican, Neurocan, and Versican in resistant WERI-ETOR compared to sensitive WERI-RB1 cells. Also, for the glycoproteins α1-Laminin, Fibronectin, Tenascin-C, and Tenascin-R as well as Collagen IV, reduced expression levels were observed in WERI-ETOR. Furthermore, a downregulation was detected for the matrix metalloproteinases MMP2, MMP7, MMP9, the tissue-inhibitor of metalloproteinase TIMP2, the Integrin receptor subunits ITGA4, ITGA5 and ITGB1, and all receptor protein tyrosine phosphatase β/ζ isoforms. Downregulation of Brevican, Collagen IV, Tenascin-R, MMP2, TIMP2, and ITGA5 was also verified in Etoposide resistant Y79 cells compared to sensitive ones. Protein levels of Tenascin-C and MMP-2 were comparable in both WERI cell lines. Interestingly, Fibronectin displayed an apoptosis-inducing effect on WERI-RB1 cells, whereas an anti-apoptotic influence was observed for Tenascin-C. Conversely, proliferation of WERI-ETOR cells was enhanced on Tenascin-C, while an anti-proliferative effect was observed on Fibronectin. In WERI-ETOR, cluster formation was decreased on the substrates Collagen IV, Fibronectin, and Tenascin-C. Collectively, we noted a different ECM mRNA expression and behavior of Etoposide resistant compared to sensitive RB cells. These findings may indicate a key role of ECM components in chemotherapy resistance formation of RB.

Resistance to drugs and cell death in cancer stem cells (CSCs)

Human cancers emerge from cancer stem cells (CSCs), which are resistant to cancer chemotherapeutic agents, radiation, and cell death. Moreover, autophagy provides the cytoprotective effect which contributes to drug resistance in these cells. Furthermore, much evidence shows that CSCs cause tumor initiation, progression, metastasis, and cancer recurrence. Various signaling pathways including the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR), maternal embryonic leucine zipper kinase (MELK), NOTCH1, and Wnt/β-catenin as well as the CSC markers maintain CSC properties. Several mechanisms including overexpression of ABC multidrug resistance transporters, a deficiency in mitochondrial-mediated apoptosis, upregulation of c-FLIP, overexpression of anti-apoptotic Bcl-2 family members and inhibitors of apoptosis proteins (IAPs), and PI3K/AKT signaling contribute to enhancing resistance to chemotherapeutic drugs and cell death induction in CSCs in various cancers. Studying such pathways may help provide detailed understanding of CSC mechanisms of resistance to chemotherapeutic agents and apoptosis and may lead to the development of effective therapeutics to eradicate CSCs.

Shaping Up the Tumor Microenvironment With Cellular Fibronectin

Normal tissue homeostasis and architecture restrain tumor growth. Thus, for a tumor to develop and spread, malignant cells must overcome growth-repressive inputs from surrounding tissue and escape immune surveillance mechanisms that curb cancer progression. This is achieved by promoting the conversion of a physiological microenvironment to a pro-tumoral state and it requires a constant dialog between malignant cells and ostensibly normal cells of adjacent tissue. Pro-tumoral reprogramming of the stroma is accompanied by an upregulation of certain extracellular matrix (ECM) proteins and their cognate receptors. Fibronectin (FN) is one such component of the tumor matrisome. This large multidomain glycoprotein dimer expressed over a wide range of human cancers is assembled by cell-driven forces into a fibrillar array that provides an obligate scaffold for the deposition of other matrix proteins and binding sites for functionalization by soluble factors in the tumor microenvironment. Encoded by a single gene, FN regulates the proliferation, motile behavior and fate of multiple cell types, largely through mechanisms that involve integrin-mediated signaling. These processes are coordinated by distinct isoforms of FN, collectively known as cellular FN (as opposed to circulating plasma FN) that arise through alternative splicing of the FN1 gene. Cellular FN isoforms differ in their solubility, receptor binding ability and spatiotemporal expression, and functions that have yet to be fully defined. FN induction at tumor sites constitutes an important step in the acquisition of biological capabilities required for several cancer hallmarks such as sustaining proliferative signaling, promoting angiogenesis, facilitating invasion and metastasis, modulating growth suppressor activity and regulating anti-tumoral immunity. In this review, we will first provide an overview of ECM reprogramming through tumor-stroma crosstalk, then focus on the role of cellular FN in tumor progression with respect to these hallmarks. Last, we will discuss the impact of dysregulated ECM on clinical efficacy of classical (radio-/chemo-) therapies and emerging treatments that target immune checkpoints and explore how our expanding knowledge of the tumor ECM and the central role of FN can be leveraged for therapeutic benefit.

A Soft Mechanical Phenotype of SH-SY5Y Neuroblastoma and Primary Human Neurons Is Resilient to Oligomeric Aβ(1-42) Injury

Aggregated amyloid beta (Aβ) is widely reported to cause neuronal dystrophy and toxicity through multiple pathways: oxidative stress, disrupting calcium homeostasis, and cytoskeletal dysregulation. The neuro-cytoskeleton is a dynamic structure that reorganizes to maintain cell homeostasis in response to varying soluble and physical cues presented from the extracellular matrix (ECM). Due this relationship between cell health and the ECM, we hypothesize that amyloid toxicity may be directly influenced by physical changes to the ECM (stiffness and dimensionality) through mechanosensitive pathways, and while previous studies demonstrated that Aβ can distort focal adhesion signaling with pathological consequences, these studies do not address the physical contribution from a physiologically relevant matrix. To test our hypothesis that physical cues can adjust Aβ toxicity, SH-SY5Y human neuroblastoma and primary human cortical neurons were plated on soft and stiff, 2D polyacrylamide matrices or suspended in 3D collagen gels. Each cell culture was exposed to escalating concentrations of oligomeric or fibrillated Aβ(1-42) with MTS viability and lactate dehydrogenase toxicity assessed. Actin restructuring was further monitored in live cells by atomic force microscopy nanoindentation, and our results demonstrate that increasing either matrix stiffness or exposure to oligomeric Aβ promotes F-actin polymerization and cell stiffening, while mature Aβ fibrils yielded no apparent cell stiffening and minor toxicity. Moreover, the rounded, softer mechanical phenotype displayed by cells plated onto a compliant matrix also demonstrated a resilience to oligomeric Aβ as noted by a significant recovery of viability when compared to same-dosed cells plated on traditional tissue culture plastic. This recovery was reproduced pharmacologically through inhibiting actin polymerization with cytochalasin D prior to Aβ exposure. These studies indicate that the cell-ECM interface can modify amyloid toxicity in neurons and the matrix-mediated pathways that promote this protection may offer unique targets in amyloid pathologies like Alzheimer's disease.

Taking a Full Snapshot of Cancer Biology: Deciphering the Tumor Microenvironment for Effective Cancer Therapy in the Oncology Clinic

A bottleneck that is hindering therapeutics innovation in cancers is the current lack of integration of what we have learned in tumor biology as well as the tumor microenvironment (TME). This is because tumors are complex tissues composed of cancer cells, stromal cells, and the extracellular matrix (ECM). Although genetic alterations might cause the initial uncontrolled growth, resistance to apoptosis in cancer cells and stromal cells play additional key roles within the TME and thus influence tumor initiation, progression, therapy resistance, and metastasis. Therapies targeting cancer cells are usually insufficient when the stromal component of the TME causes therapy resistance. For innovation in cancer treatment and to take a full snapshot of cancer biology, anticancer drug design must, therefore, target both cancer cells and the stromal component. This expert review critically examines the TME components such as cancer-associated fibroblasts and ECM that can be reprogrammed to create a tumor-suppressive environment, thereby aiding in tumor treatment. Better cancer experimental models that mimic the TME such as tumor spheroids, microfluidics, three dimensional (3D) bioprinted models, and organoids will allow deeper investigations of the TME complexity and can lead to the translation of basic tumor biology to effective cancer treatments. Ultimately, innovative cancer treatments and, by extension, improvement in cancer patients' outcomes will emerge from combinatorial drug development strategies targeting both cancer cells and stromal components of the TME. Combinatorial treatment strategies can take the form of chemotherapy and radiotherapy (targeting tumor cells and stromal components) and immunotherapy that is able to regulate immune responses against tumor cells. This expert review thus addresses a previously neglected knowledge gap in cancer drug design and development by broadening the focus in cancer biology to TME so as to empower disruptive health care innovations in the oncology clinic.

Routine Optical Clearing of 3D-Cell Cultures: Simplicity Forward

Three-dimensional cell cultures, such as spheroids and organoids, serve as increasingly important models in fundamental and applied research and start to be used for drug screening purposes. Optical tissue clearing procedures are employed to enhance visualization of fluorescence-stained organs, tissues, and three-dimensional cell cultures. To get a more systematic overview about the effects and applicability of optical tissue clearing on three-dimensional cell cultures, we compared six different clearing/embedding protocols on seven types of spheroid- and chip-based three-dimensional cell cultures of approximately 300 μm in size that were stained with nuclear dyes, immunofluorescence, cell trackers, and cyan fluorescent protein. Subsequent whole mount confocal microscopy and semi-automated image analysis were performed to quantify the effects. Quantitative analysis included fluorescence signal intensity and signal-to-noise ratio as a function of z-depth as well as segmentation and counting of nuclei and immunopositive cells. In general, these analyses revealed five key points, which largely confirmed current knowledge and were quantified in this study. First, there was a massive variability of effects of different clearing protocols on sample transparency and shrinkage as well as on dye quenching. Second, all tested clearing protocols worked more efficiently on samples prepared with one cell type than on co-cultures. Third, z-compensation was imperative to minimize variations in signal-to-noise ratio. Fourth, a combination of sample-inherent cell density, sample shrinkage, uniformity of signal-to-noise ratio, and image resolution had a strong impact on data segmentation, cell counts, and relative numbers of immunofluorescence-positive cells. Finally, considering all mentioned aspects and including a wish for simplicity and speed of protocols - in particular, for screening purposes - clearing with 88% Glycerol appeared to be the most promising option amongst the ones tested.

Esophageal Cancer Development: Crucial Clues Arising from the Extracellular Matrix

In the last years, the extracellular matrix (ECM) has been reported as playing a relevant role in esophageal cancer (EC) development, with this compartment being related to several aspects of EC genesis and progression. This sounds very interesting due to the complexity of this highly incident and lethal tumor, which takes the sixth position in mortality among all tumor types worldwide. The well-established increase in ECM stiffness, which is able to trigger mechanotransduction signaling, is capable of regulating several malignant behaviors by converting alteration in ECM mechanics into cytoplasmatic biochemical signals. In this sense, it has been shown that some molecules play a key role in these events, particularly the different collagen isoforms, as well as enzymes related to its turnover, such as lysyl oxidase (LOX) and matrix metalloproteinases (MMPs). In fact, MMPs are not only involved in ECM stiffness, but also in other events related to ECM homeostasis, which includes ECM remodeling. Therefore, the crucial role of distinct MMPs isoform has already been reported, especially MMP-2, -3, -7, and -9, along EC development, thus strongly associating these proteins with the control of important cellular events during tumor progression, particularly in the process of invasion during metastasis establishment. In addition, by distinct mechanisms, a vast diversity of glycoproteins and proteoglycans, such as laminin, fibronectin, tenascin C, galectin, dermatan sulfate, and hyaluronic acid exert remarkable effects in esophageal malignant cells due to the activation of oncogenic signaling pathways mainly involved in cytoskeleton alterations during adhesion and migration processes. Finally, the wide spectrum of interactions potentially mediated by ECM may represent a singular intervention scenario in esophageal carcinogenesis natural history and, due to the scarce knowledge on the cellular and molecular mechanisms involved in EC development, the growing body of evidence on ECM’s role along esophageal carcinogenesis might provide a solid base to improve its management in the future.

A new three-dimensional glass scaffold increases the in vitro maturation efficiency of buffalo (Bubalus bubalis) oocyte via remodelling the extracellular matrix and cell connection of cumulus cells

At present, many three-dimensional (3D) culture systems have been reported, improving the oocyte quality of in vitro maturation (IVM), yet the mechanism still needs to be further explored. Here we examined the effects of a new self-made 3D glass scaffold on buffalo oocyte maturation; meanwhile, the underlying mechanism on buffalo oocyte maturation was also detected. Compared to the two-dimensional (2D) glass dish culture, results revealed that the 3D culture can improve the first polar body rate of oocytes, subsequent cleavage and blastocysts rate of parthenogenetic activation embryos (p < .05). The extracellular matrix-related proteins COL1A1, COL2A1, COL3A1, FN and cell connection-related proteins N-cadherin, E-cadherin, GJA1 were found higher in cumulus cells of 3D culture. Moreover, in cumulus cells, proteins of the PI3K/AKT pathway reported being regulated by FN and E-cadherin including PI3K P85 and p-AKT were also higher in 3D culture. Furthermore, proapoptosis proteins P53, BAX, caspase-3 were lower in both cumulus cells and oocytes in 3D culture, while proteins PCNA and BCL2 showed the opposite result. Results also showed that the apoptosis was inhibited, and the proliferation was enhanced in cumulus cells of 3D culture. Finally, the cumulus expansion-related genes HAS2, CD44, HMMR, PTX3, PTGS2 were found higher in cumulus cells of 3D culture. Taken together, the 3D culture could promote oocyte maturation by regulating proteins correlated with the ECM, cell connection and PI3K/AKT pathway, inhibiting the apoptosis of cumulus cells and oocytes, enhancing the proliferation of cumulus cells and the cumulus expansion.

Tumor Microenvironment - Selective Pressures Boosting Cancer Progression

In 2018, 9.6 million deaths from cancer were estimated, being this disease the second leading cause of death worldwide. Notwithstanding all the efforts developed in prevention, diagnosis and new treatment approaches, chemoresistance seems to be inevitable, leading to cancer progression, recurrence and affecting the outcome of the disease. As more and more evidence support that cancer is an evolutionary and ecological process, this concept is rarely applied in the clinical context. In fact, cancer cells emerge and progress within an ecological niche - the tumor microenvironment - that is shared with several other cell types and that is continuously changing. Therefore, the tumor microenvironment imposes several selective pressures on cancer cells such as acidosis, hypoxia, competition for space and resources, immune predation and anti-cancer therapies, that cancer cells must be able to adapt to or will face extinction.In here, the role of the tumor microenvironment selective pressures on cancer progression will be discussed, as well as the targeting of its features/components as strategies to fight cancer.

Epigenetic mechanisms driving tumor supportive microenvironment differentiation and function: a role in cancer therapy?

The tumor microenvironment (TME) plays a central role in tumor development and drug resistance. Within TME, the stromal cell subset, called cancer-associated fibroblasts, is a heterogeneous population originating from poorly characterized precursors. Since cancer-associated fibroblasts do not acquire somatic mutations, other mechanisms like epigenetic regulation, could be involved in the development of these cells and in the acquisition of tumor supportive phenotypes. Moreover, such epigenetic modulations have been correlated to the emergence of an immunosuppressive microenvironment facilitating tumor evasion. These findings underline the need to deepen our knowledge on epigenetic mechanisms driving TME development and function, and to understand the impact of epigenetic drugs that could be used in future to target both tumor cells and their TME.

Development and Evaluation of Paclitaxel-Loaded Aerosol Nanocomposite Microparticles and Their Efficacy Against Air-Grown Lung Cancer Tumor Spheroids

Paclitaxel (as intravenous Taxol) is one of the most applied chemotherapeutics used for the treatment of lung cancer. This project involves the development of a dry powder nanocomposite microparticle (nCmP) aerosol containing PTX-loaded nanoparticles (NP) to be delivered via a dry powder inhaler to the lungs for the treatment of non-small cell lung cancer (NSCLC). Nanoparticles were formulated by a single emulsion and solvent evaporation method, producing smooth, neutral PTX NP of approximately 200 nm in size. PTX nCmP were obtained via spray drying PTX NP with mannitol, producing amorphous wrinkled particles that demonstrated optimal aerosol deposition for in vitro pulmonary delivery. Free PTX, PTX NP, and PTX nCmP were evaluated in vitro in both 2D monolayers and 3D multicellular spheroids (MCS). PTX NP enhanced cytotoxicity when compared to pure drug in the 2D evaluation. However, on a liquid culture 3D tumor spheroid model, PTX NP and pure PTX showed similar efficacy in growth inhibition of MCS. The PTX nCmP formulation had a comparable cytotoxicity impact on MCS compared with free PTX. Finally, PTX nCmP were evaluated in an air-grown 3D MCS platform that mimics the pulmonary environment, representing a new model for the assessment of dry powder formulations.

The clinical significance of collagen family gene expression in esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is a subtype of esophageal cancer with high incidence and mortality. Due to the poor 5-year survival rates of patients with ESCC, exploring novel diagnostic markers for early ESCC is emergent. Collagen, the abundant constituent of extracellular matrix, plays a critical role in tumor growth and epithelial-mesenchymal transition. However, the clinical significance of collagen genes in ESCC has been rarely studied. In this work, we systematically analyzed the gene expression of whole collagen family in ESCC, aiming to search for ideal biomarkers.

METHODS

Clinical data and gene expression profiles of ESCC patients were collected from The Cancer Genome Atlas and the gene expression omnibus databases. Bioinformatics methods, including differential expression analysis, survival analysis, gene sets enrichment analysis (GSEA) and co-expression network analysis, were performed to investigate the correlation between the expression patterns of 44 collagen family genes and the development of ESCC.

RESULTS

A total of 22 genes of collagen family were identified as differentially expressed genes in both the two datasets. Among them, COL1A1, COL10A1 and COL11A1 were particularly up-regulated in ESCC tissues compared to normal controls, while COL4A4, COL6A5 and COL14A1 were notably down-regulated. Besides, patients with low COL6A5 expression or high COL18A1 expression showed poor survival. In addition, a 7-gene prediction model was established based on collagen gene expression to predict patient survival, which had better predictive accuracy than the tumor-node-metastasis staging based model. Finally, GSEA results suggested that collagen genes might be tightly associated with PI3K/Akt/mTOR pathway, p53 pathway, apoptosis, cell cycle, etc.

CONCLUSION

Several collagen genes could be potential diagnostic and prognostic biomarkers for ESCC. Moreover, a novel 7-gene prediction model is probably useful for predicting survival outcomes of ESCC patients. These findings may facilitate early detection of ESCC and help improves prognosis of the patients.

Recent Trends in Decellularized Extracellular Matrix Bioinks for 3D Printing: An Updated Review

The promise of regenerative medicine and tissue engineering is founded on the ability to regenerate diseased or damaged tissues and organs into functional tissues and organs or the creation of new tissues and organs altogether. In theory, damaged and diseased tissues and organs can be regenerated or created using different configurations and combinations of extracellular matrix (ECM), cells, and inductive biomolecules. Regenerative medicine and tissue engineering can allow the improvement of patients' quality of life through availing novel treatment options. The coupling of regenerative medicine and tissue engineering with 3D printing, big data, and computational algorithms is revolutionizing the treatment of patients in a huge way. 3D bioprinting allows the proper placement of cells and ECMs, allowing the recapitulation of native microenvironments of tissues and organs. 3D bioprinting utilizes different bioinks made up of different formulations of ECM/biomaterials, biomolecules, and even cells. The choice of the bioink used during 3D bioprinting is very important as properties such as printability, compatibility, and physical strength influence the final construct printed. The extracellular matrix (ECM) provides both physical and mechanical microenvironment needed by cells to survive and proliferate. Decellularized ECM bioink contains biochemical cues from the original native ECM and also the right proportions of ECM proteins. Different techniques and characterization methods are used to derive bioinks from several tissues and organs and to evaluate their quality. This review discusses the uses of decellularized ECM bioinks and argues that they represent the most biomimetic bioinks available. In addition, we briefly discuss some polymer-based bioinks utilized in 3D bioprinting.

The role of collagen in cancer: from bench to bedside

Collagen is the major component of the tumor microenvironment and participates in cancer fibrosis. Collagen biosynthesis can be regulated by cancer cells through mutated genes, transcription factors, signaling pathways and receptors; furthermore, collagen can influence tumor cell behavior through integrins, discoidin domain receptors, tyrosine kinase receptors, and some signaling pathways. Exosomes and microRNAs are closely associated with collagen in cancer. Hypoxia, which is common in collagen-rich conditions, intensifies cancer progression, and other substances in the extracellular matrix, such as fibronectin, hyaluronic acid, laminin, and matrix metalloproteinases, interact with collagen to influence cancer cell activity. Macrophages, lymphocytes, and fibroblasts play a role with collagen in cancer immunity and progression. Microscopic changes in collagen content within cancer cells and matrix cells and in other molecules ultimately contribute to the mutual feedback loop that influences prognosis, recurrence, and resistance in cancer. Nanoparticles, nanoplatforms, and nanoenzymes exhibit the expected gratifying properties. The pathophysiological functions of collagen in diverse cancers illustrate the dual roles of collagen and provide promising therapeutic options that can be readily translated from bench to bedside. The emerging understanding of the structural properties and functions of collagen in cancer will guide the development of new strategies for anticancer therapy.

New Insights into Mechanisms of Cisplatin Resistance: From Tumor Cell to Microenvironment

Although cisplatin has been a pivotal chemotherapy drug in treating patients with various types of cancer for decades, drug resistance has been a major clinical impediment. In general, cisplatin exerts cytotoxic effects in tumor cells mainly through the generation of DNA-platinum adducts and subsequent DNA damage response. Accordingly, considerable effort has been devoted to clarify the resistance mechanisms inside tumor cells, such as decreased drug accumulation, enhanced detoxification activity, promotion of DNA repair capacity, and inactivated cell death signaling. However, recent advances in high-throughput techniques, cell culture platforms, animal models, and analytic methods have also demonstrated that the tumor microenvironment plays a key role in the development of cisplatin resistance. Recent clinical successes in combination treatments with cisplatin and novel agents targeting components in the tumor microenvironment, such as angiogenesis and immune cells, have also supported the therapeutic value of these components in cisplatin resistance. In this review, we summarize resistance mechanisms with respect to a single tumor cell and crucial components in the tumor microenvironment, particularly focusing on favorable results from clinical studies. By compiling emerging evidence from preclinical and clinical studies, this review may provide insights into the development of a novel approach to overcome cisplatin resistance.

ERK is a Pivotal Player of Chemo-Immune-Resistance in Cancer

The extracellular signal-related kinases (ERKs) act as pleiotropic molecules in tumors, where they activate pro-survival pathways leading to cell proliferation and migration, as well as modulate apoptosis, differentiation, and senescence. Given its central role as sensor of extracellular signals, ERK transduction system is widely exploited by cancer cells subjected to environmental stresses, such as chemotherapy and anti-tumor activity of the host immune system. Aggressive tumors have a tremendous ability to adapt and survive in stressing and unfavorable conditions. The simultaneous resistance to chemotherapy and immune system responses is common, and ERK signaling plays a key role in both types of resistance. In this review, we dissect the main ERK-dependent mechanisms and feedback circuitries that simultaneously determine chemoresistance and immune-resistance/immune-escape in cancer cells. We discuss the pros and cons of targeting ERK signaling to induce chemo-immune-sensitization in refractory tumors.

Polyphenols as Immunomodulatory Compounds in the Tumor Microenvironment: Friends or Foes?

Polyphenols are natural antioxidant compounds ubiquitously found in plants and, thus, ever present in human nutrition (tea, wine, chocolate, fruits and vegetables are typical examples of polyphenol-rich foods). Widespread evidence indicate that polyphenols exert strong antioxidant, anti-inflammatory, anti-microbial and anti-cancer activities, and thus, they are generally regarded to as all-purpose beneficial nutraceuticals or supplements whose use can only have a positive influence on the body. A closer look to the large body of results of years of investigations, however, present a more complex scenario where polyphenols exert different and, sometimes, paradoxical effects depending on dose, target system and cell type and the biological status of the target cell. Particularly, the immunomodulatory potential of polyphenols presents two opposite faces to researchers trying to evaluate their usability in future cancer therapies: on one hand, these compounds could be beneficial suppressors of peri-tumoral inflammation that fuels cancer growth. On the other hand, they might suppress immunotherapeutic approaches and give rise to immunosuppressive cell clones that, in turn, would aid tumor growth and dissemination. In this review, we summarize knowledge of the immunomodulatory effects of polyphenols with a particular focus on cancer microenvironment and immunotherapy, highlighting conceptual pitfalls and delicate cell-specific effects in order to aid the design of future therapies involving polyphenols as chemoadjuvants.

Three-Dimensional Organoids in Cancer Research: The Search for the Holy Grail of Preclinical Cancer Modeling

Most solid tumors become therapy resistant and will relapse, with no durable treatment option available. One major impediment to our understanding of cancer biology and finding innovative approaches to cancer treatment stems from the lack of better preclinical tumor models that address and explain tumor heterogeneity and person-to-person differences in therapeutic and toxic responses. Past cancer research has been driven by inadequate in vitro assays utilizing two-dimensional monolayers of cancer cells and animal models. Additionally, animal models do not truly mimic the original human tumor, are time consuming, and usually costly. New preclinical models are needed for innovation in cancer translational research. Hence, it is time to welcome the three-dimensional (3D) organoids: self-organizing cells grown in 3D culture systems mimicking the parent tissues from which the primary cells originate. The 3D organoids offer deeper insights into the crucial cellular processes in tissue and organ formation and pathological processes. Generation of near-perfect physiological microenvironments allow 3D organoids to couple with gene editing tools, such as the clustered regularly interspersed short palindromic repeat (CRISPR)/CRISPR-associated 9 and the transcription activator-like effector nucleases to model human diseases, offering distinct advantages over current models. We explain in this expert review that through recapitulating patients' normal and tumor tissues, organoid technology can markedly advance personalized medicine and help reveal once hidden aspects of cancers. The use of defined tissue- or organ-specific matrices, among other factors, will likely allow organoid technology to realize its potential in innovating many fields of life sciences.

Chemoresistance and the Self-Maintaining Tumor Microenvironment

The progression of cancer is associated with alterations in the tumor microenvironment, including changes in extracellular matrix (ECM) composition, matrix rigidity, hypervascularization, hypoxia, and paracrine factors. One key malignant phenotype of cancer cells is their ability to resist chemotherapeutics, and elements of the ECM can promote chemoresistance in cancer cells through a variety of signaling pathways, inducing changes in gene expression and protein activity that allow resistance. Furthermore, the ECM is maintained as an environment that facilitates chemoresistance, since its constitution modulates the phenotype of cancer-associated cells, which themselves affect the microenvironment. In this review, we discuss how the properties of the tumor microenvironment promote chemoresistance in cancer cells, and the interplay between these external stimuli. We focus on both the response of cancer cells to the external environment, as well as the maintenance of the external environment, and how a chemoresistant phenotype emerges from the complex signaling network present.