Matrix stiffness induces epithelial-mesenchymal transition and promotes chemoresistance in pancreatic cancer cells

Matrix Stiffness Contributes to Cancer Progression by Regulating Transcription Factors

Simple Summary

Matrix stiffness is recognized as a critical factor in cancer progression. Recent studies have shown that matrix stiffening is caused by the accumulation, contraction, and crosslinking of the extracellular matrix by cancer and stromal cells. Cancer and stromal cells respond to matrix stiffness, which determines the phenotypes of these cells. In addition, matrix stiffness activates and/or inactivates specific transcription factors in cancer and stromal cells to regulate cancer progression. In this review, we discuss the mechanisms of cancer stiffening and progression that are regulated by transcription factors responding to matrix stiffness.

Abstract

Matrix stiffness is critical for the progression of various types of cancers. In solid cancers such as mammary and pancreatic cancers, tumors often contain abnormally stiff tissues, mainly caused by stiff extracellular matrices due to accumulation, contraction, and crosslinking. Stiff extracellular matrices trigger mechanotransduction, the conversion of mechanical cues such as stiffness of the matrix to biochemical signaling in the cells, and as a result determine the cellular phenotypes of cancer and stromal cells in tumors. Transcription factors are key molecules for these processes, as they respond to matrix stiffness and are crucial for cellular behaviors. The Yes-associated protein (YAP)/transcriptional coactivator with PDZ-binding motif (TAZ) is one of the most studied transcription factors that is regulated by matrix stiffness. The YAP/TAZ are activated by a stiff matrix and promotes malignant phenotypes in cancer and stromal cells, including cancer-associated fibroblasts. In addition, other transcription factors such as β-catenin and nuclear factor kappa B (NF-κB) also play key roles in mechanotransduction in cancer tissues. In this review, the mechanisms of stiffening cancer tissues are introduced, and the transcription factors regulated by matrix stiffness in cancer and stromal cells and their roles in cancer progression are shown.

The Role of SMAD4 Inactivation in Epithelial-Mesenchymal Plasticity of Pancreatic Ductal Adenocarcinoma: The Missing Link?

Simple Summary

Pancreatic ductal adenocarcinoma (PDAC) is currently one of the deadliest cancers. Despite the progress that has been made in the research of patient care and the understanding of pancreatic cancer, the survival rate remains mediocre. SMAD4, a tumor-suppressor gene, is specifically inactivated in 50–55% of pancreatic cancers. The role of SMAD4 protein loss in PDAC remains controversial, but seems to be associated with worse overall survival and metastasis. Here, we review the function of SMAD4 inactivation in the context of a specific biological process called epithelial–mesenchymal transition, as it has been increasingly associated with tumor formation, metastasis and resistance to therapy. By improving our understanding of these molecular mechanisms, we hope to find new targets for therapy and improve the care of patients with PDAC.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) presents a five-year survival rate of 10% and its incidence increases over the years. It is, therefore, essential to improve our understanding of the molecular mechanisms that promote metastasis and chemoresistance in PDAC, which are the main causes of death in these patients. SMAD4 is inactivated in 50% of PDACs and its loss has been associated with worse overall survival and metastasis, although some controversy still exists. SMAD4 is the central signal transducer of the transforming growth factor-beta (TGF-beta) pathway, which is notably known to play a role in epithelial–mesenchymal transition (EMT). EMT is a biological process where epithelial cells lose their characteristics to acquire a spindle-cell phenotype and increased motility. EMT has been increasingly studied due to its potential implication in metastasis and therapy resistance. Recently, it has been suggested that cells undergo EMT transition through intermediary states, which is referred to as epithelial–mesenchymal plasticity (EMP). The intermediary states are characterized by enhanced aggressiveness and more efficient metastasis. Therefore, this review aims to summarize and analyze the current knowledge on SMAD4 loss in patients with PDAC and to investigate its potential role in EMP in order to better understand its function in PDAC carcinogenesis.

p53 Signaling on Microenvironment and Its Contribution to Tissue Chemoresistance

Chemoresistance persists as a significant, unresolved clinical challenge in many cancer types. The tumor microenvironment, in which cancer cells reside and interact with non-cancer cells and tissue structures, has a known role in promoting every aspect of tumor progression, including chemoresistance. However, the molecular determinants of microenvironment-driven chemoresistance are mainly unknown. In this review, we propose that the TP53 tumor suppressor, found mutant in over half of human cancers, is a crucial regulator of cancer cell-microenvironment crosstalk and a prime candidate for the investigation of microenvironment-specific modulators of chemoresistance. Wild-type p53 controls the secretion of factors that inhibit the tumor microenvironment, whereas altered secretion or mutant p53 interfere with p53 function to promote chemoresistance. We highlight resistance mechanisms promoted by mutant p53 and enforced by the microenvironment, such as extracellular matrix remodeling and adaptation to hypoxia. Alterations of wild-type p53 extracellular function may create a cascade of spatial amplification loops in the tumor tissue that can influence cellular behavior far from the initial oncogenic mutation. We discuss the concept of chemoresistance as a multicellular/tissue-level process rather than intrinsically cellular. Targeting p53-dependent crosstalk mechanisms between cancer cells and components of the tumor environment might disrupt the waves of chemoresistance that spread across the tumor tissue, increasing the efficacy of chemotherapeutic agents.

Towards an integrative understanding of cancer mechanobiology: calcium, YAP, and microRNA under biophysical forces

An increasing number of studies have demonstrated the significant roles of the interplay between microenvironmental mechanics in tissues and biochemical-genetic activities in resident tumor cells at different stages of tumor progression. Mediated by molecular mechano-sensors or -transducers, biomechanical cues in tissue microenvironments are transmitted into the tumor cells and regulate biochemical responses and gene expression through mechanotransduction processes. However, the molecular interplay between the mechanotransduction processes and intracellular biochemical signaling pathways remains elusive. This paper reviews the recent advances in understanding the crosstalk between biomechanical cues and three critical biochemical effectors during tumor progression: calcium ions (Ca²⁺), yes-associated protein (YAP), and microRNAs (miRNAs). We address the molecular mechanisms underpinning the interplay between the mechanotransduction pathways and each of the three effectors. Furthermore, we discuss the functional interactions among the three effectors in the context of soft matter and mechanobiology. We conclude by proposing future directions on studying the tumor mechanobiology that can employ Ca²⁺, YAP, and miRNAs as novel strategies for cancer mechanotheraputics. This framework has the potential to bring insights into the development of novel next-generation cancer therapies to suppress and treat tumors.

Mechanisms of Cisplatin Resistance in HPV Negative Head and Neck Squamous Cell Carcinomas

Head and neck squamous cell carcinomas (HNSCCs) are the eighth most common cancers worldwide. While promising new therapies are emerging, cisplatin-based chemotherapy remains the gold standard for advanced HNSCCs, although most of the patients relapse due to the development of resistance. This review aims to condense the different mechanisms involved in the development of cisplatin resistance in HNSCCs and highlight future perspectives intended to overcome its related complications. Classical resistance mechanisms include drug import and export, DNA repair and oxidative stress control. Emerging research identified the prevalence of these mechanisms in populations of cancer stem cells (CSC), which are the cells mainly contributing to cisplatin resistance. The use of old and new CSC markers has enabled the identification of the characteristics within HNSCC CSCs predisposing them to treatment resistance, such as cell quiescence, increased self-renewal capacity, low reactive oxygen species levels or the acquisition of epithelial to mesenchymal transcriptional programs. In the present review, we will discuss how cell intrinsic and extrinsic cues alter the phenotype of CSCs and how they influence resistance to cisplatin treatment. In addition, we will assess how the stromal composition and the tumor microenvironment affect drug resistance and the acquisition of CSCs' characteristics through a complex interplay between extracellular matrix content as well as immune and non-immune cell characteristics. Finally, we will describe how alterations in epigenetic modifiers or other signaling pathways can alter tumor behavior and cell plasticity to induce chemotherapy resistance. The data generated in recent years open up a wide range of promising strategies to optimize cisplatin therapy, with the potential to personalize HNSCC patient treatment strategies.

Biophysical and biochemical attributes of hybrid epithelial/mesenchymal phenotypes

The Epithelial-Mesenchymal Transition (EMT) is a biological phenomenon associated with explicit phenotypic and molecular changes in cellular traits. Unlike the earlier-held popular belief of it being a binary process, EMT is now thought of as a landscape including diverse hybrid E/M phenotypes manifested by varying degrees of the transition. These hybrid cells can co-express both epithelial and mesenchymal markers and/or functional traits, and can possess the property of collective cell migration, enhanced tumor-initiating ability, and immune/targeted therapy-evasive features, all of which are often associated with worse patient outcomes. These characteristics of the hybrid E/M cells have led to a surge in studies that map their biophysical and biochemical hallmarks that can be helpful in exploiting their therapeutic vulnerabilities. This review discusses recent advances made in investigating hybrid E/M phenotype(s) from diverse biophysical and biochemical aspects by integrating live cell-imaging, cellular morphology quantification and mathematical modelling, and highlights a set of questions that remain unanswered about the dynamics of hybrid E/M states.

A microenvironment-inspired synthetic three-dimensional model for pancreatic ductal adenocarcinoma organoids

Experimental in vitro models that capture pathophysiological characteristics of human tumours are essential for basic and translational cancer biology. Here, we describe a fully synthetic hydrogel extracellular matrix designed to elicit key phenotypic traits of the pancreatic environment in culture. To enable the growth of normal and cancerous pancreatic organoids from genetically engineered murine models and human patients, essential adhesive cues were empirically defined and replicated in the hydrogel scaffold, revealing a functional role of laminin-integrin α3/α6 signalling in establishment and survival of pancreatic organoids. Altered tissue stiffness-a hallmark of pancreatic cancer-was recapitulated in culture by adjusting the hydrogel properties to engage mechano-sensing pathways and alter organoid growth. Pancreatic stromal cells were readily incorporated into the hydrogels and replicated phenotypic traits characteristic of the tumour environment in vivo. This model therefore recapitulates a pathologically remodelled tumour microenvironment for studies of normal and pancreatic cancer cells in vitro.

The case for cancer-associated fibroblasts: essential elements in cancer drug discovery?

Although cancer-associated fibroblasts (CAFs) have gained increased attention for supporting cancer progression, current CAF-targeted therapeutic options are limited and failing in clinical trials. As the largest component of the tumor microenvironment (TME), CAFs alter the biochemical and physical structure of the TME, modulating cancer progression. Here, we review the role of CAFs in altering drug response, modifying the TME mechanics and the current models for studying CAFs. To provide new perspectives, we highlight key considerations of CAF activity and discuss emerging technologies that can better address CAFs; and therefore, increase the likelihood of therapeutic efficacy. We argue that CAFs are crucial components of the cancer drug discovery pipeline and incorporating these cells will improve drug discovery success rates.

Spontaneous formation and spatial self-organization of mechanically induced mesenchymal-like cells within geometrically confined cancer cell monolayers

There is spatiotemporal heterogeneity in cell phenotypes and mechanical properties in tumor tissues, which is associated with cancer invasion and metastasis. It is well-known that exogenous growth factors like transforming growth factor (TGF)-β, can induce epithelial-mesenchymal transition (EMT)-based phenotypic transformation and the formation of EMT patterning on geometrically confined monolayers with mechanics heterogeneity. In the absence of exogenous TGF-β stimulation, however, whether geometric confinement-caused mechanics heterogeneity of cancer cell monolayers alone can trigger the EMT-based phenotypic heterogeneity still remains mysterious. Here, we develop a micropattern-based cell monolayer model to investigate the regulation of mechanics heterogeneity on the cell phenotypic switch. We reveal that mechanics heterogeneity itself is enough to spontaneously induce the emergence of mesenchymal-like phenotype and asymmetrical activation of TGF-β-SMAD signaling. Spatiotemporal dynamics of patterned cell monolayers with mesenchymal-like phenotypes is essentially regulated by tissue-scale cell behaviors like proliferation, migration as well as heterogeneous cytoskeletal contraction. The inhibition of cell contraction abrogates the asymmetrical TGF-β-SMAD signaling activation level and the emergence of mesenchymal-like phenotype. Our work not only sheds light on the key regulation of mechanics heterogeneity caused by spatially geometric confinement on regional mesenchymal-like phenotype of cancer cell monolayers, but highlights the key role of biophysical/mechanical cues in triggering phenotypic switch.

Stromal architecture directs early dissemination in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDA) is an extremely metastatic and lethal disease. Here, in both murine and human PDA, we demonstrate that extracellular matrix architecture regulates cell extrusion and subsequent invasion from intact ductal structures through tumor-associated collagen signatures (TACS). This results in early dissemination from histologically premalignant lesions and continual invasion from well-differentiated disease, and it suggests TACS as a biomarker to aid in the pathologic assessment of early disease. Furthermore, we show that pancreatitis results in invasion-conducive architectures, thus priming the stroma prior to malignant disease. Analysis in potentially novel microfluidic-derived microtissues and in vivo demonstrates decreased extrusion and invasion following focal adhesion kinase (FAK) inhibition, consistent with decreased metastasis. Thus, data suggest that targeting FAK or strategies to reengineer and normalize tumor microenvironments may have roles not only in very early disease, but also for limiting continued dissemination from unresectable disease. Likewise, it may be beneficial to employ stroma-targeting strategies to resolve precursor diseases such as pancreatitis in order to remove stromal architectures that increase risk for early dissemination.

Precise Diagnosis and Therapy of Bone Cancer Using Near-Infrared Lights

Bone is a preferred site for both primary and metastasis tumors. Current diagnosis of osteopathia typically relies on noninvasive skeleton radiography technology. However, due to the limited resolution of ionizing radiation, accurate diagnosis and effective identification impairment areas are still lacking. Near-infrared (NIR) bioimaging, especially in the NIR-II (1000-1700 nm) regions, can provide high sensitivity and spatiotemporal resolution bioimaging compared to the conventional radiography. Thus, NIR bioimaging affords intraoperative visualization and imaging-guided surgery, aiming to overcome challenges associated with theranostics of osteopathia and bone tumors. The present review aimed to summarize the latest evidence on the use of NIR probes for the targeting bone imaging. We further highlight the recent advances in bone photoX (X presents thermal, dynamic, and immuno) therapy through NIR probes, in particular combination with other customized therapeutic agents could provide high-efficiency treatment for bone tumors.

Metabolic reprogramming by driver mutation-tumor microenvironment interplay in pancreatic cancer: new therapeutic targets

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers globally with a mortality rate exceeding 95% and very limited therapeutic options. A hallmark of PDAC is its acidic tumor microenvironment, further characterized by excessive fibrosis and depletion of oxygen and nutrients due to poor vascularity. The combination of PDAC driver mutations and adaptation to this hostile environment drives extensive metabolic reprogramming of the cancer cells toward non-canonical metabolic pathways and increases reliance on scavenging mechanisms such as autophagy and macropinocytosis. In addition, the cancer cells benefit from metabolic crosstalk with nonmalignant cells within the tumor microenvironment, including pancreatic stellate cells, fibroblasts, and endothelial and immune cells. Increasing evidence shows that this metabolic rewiring is closely related to chemo- and radioresistance and immunosuppression, causing extensive treatment failure. Indeed, stratification of human PDAC tumors into subtypes based on their metabolic profiles was shown to predict disease outcome. Accordingly, an increasing number of clinical trials target pro-tumorigenic metabolic pathways, either as stand-alone treatment or in conjunction with chemotherapy. In this review, we highlight key findings and potential future directions of pancreatic cancer metabolism research, specifically focusing on novel therapeutic opportunities.

Single-cell tracking reveals super-spreading brain cancer cells with high persistence

Cell migration is a fundamental characteristic of vital processes such as tissue morphogenesis, wound healing and immune cell homing to lymph nodes and inflamed or infected sites. Therefore, various brain defect diseases, chronic inflammatory diseases as well as tumor formation and metastasis are associated with aberrant or absent cell migration. We embedded multicellular brain cancer spheroids in Matrigel™ and utilized single-particle tracking to extract the paths of cells migrating away from the spheroids. We found that - in contrast to local invasion - single cell migration is independent of Matrigel™ concentration and is characterized by high directionality and persistence. Furthermore, we identified a subpopulation of super-spreading cells with >200-fold longer persistence times than the majority of cells. These results highlight yet another aspect of cell heterogeneity in tumors.

Targeting Tumor-Stromal Interactions in Pancreatic Cancer: Impact of Collagens and Mechanical Traits

Pancreatic ductal adenocarcinoma (PDAC) has one of the worst outcomes among cancers with a 5-years survival rate of below 10%. This is a result of late diagnosis and the lack of effective treatments. The tumor is characterized by a highly fibrotic stroma containing distinct cellular components, embedded within an extracellular matrix (ECM). This ECM-abundant tumor microenvironment (TME) in PDAC plays a pivotal role in tumor progression and resistance to treatment. Cancer-associated fibroblasts (CAFs), being a dominant cell type of the stroma, are in fact functionally heterogeneous populations of cells within the TME. Certain subtypes of CAFs are the main producer of the ECM components of the stroma, with the most abundant one being the collagen family of proteins. Collagens are large macromolecules that upon deposition into the ECM form supramolecular fibrillar structures which provide a mechanical framework to the TME. They not only bring structure to the tissue by being the main structural proteins but also contain binding domains that interact with surface receptors on the cancer cells. These interactions can induce various responses in the cancer cells and activate signaling pathways leading to epithelial-to-mesenchymal transition (EMT) and ultimately metastasis. In addition, collagens are one of the main contributors to building up mechanical forces in the tumor. These forces influence the signaling pathways that are involved in cell motility and tumor progression and affect tumor microstructure and tissue stiffness by exerting solid stress and interstitial fluid pressure on the cells. Taken together, the TME is subjected to various types of mechanical forces and interactions that affect tumor progression, metastasis, and drug response. In this review article, we aim to summarize and contextualize the recent knowledge of components of the PDAC stroma, especially the role of different collagens and mechanical traits on tumor progression. We furthermore discuss different experimental models available for studying tumor-stromal interactions and finally discuss potential therapeutic targets within the stroma.

Inhibition of matrix stiffness relating integrin β1 signaling pathway inhibits tumor growth in vitro and in hepatocellular cancer xenografts

Background

Cancer development is strictly correlated to composition and physical properties of the extracellular matrix. Particularly, a higher matrix stiffness has been demonstrated to promote tumor sustained growth. Our purpose was to explore the role of matrix stiffness in liver cancer development.

Methods

The matrix stiffness of tumor tissues was determined by atomic force microscopy (AFM) analysis. In vitro, we used a tunable Polyacrylamide (PA) hydrogels culture system for liver cancer cells culture. The expression level of integrin β1, phosphorylated FAK, ERK1/2, and NF-κB in SMMC-7721 cells was measured by western blotting analysis. We performed MTT, colony formation and transwell assay to examine the tumorigenic and metastatic potential of SMMC-7721 cells cultured on the tunable PA hydrogels. SMMC-7721 cancer xenografts were established to explore the anticancer effects of integrin inhibitors.

Results

Our study provided evidence that liver tumor tissues from metastatic patients possessed a higher matrix stiffness, when compared to the non-metastatic group. Liver cancer cells cultured on high stiffness PA hydrogels displayed enhanced tumorigenic potential and migrative properties. Mechanistically, activation of integrin β1/FAK/ ERK1/2/NF-κB signaling pathway was observed in SMMC-7721 cells cultured on high stiffness PA hydrogels. Inhibition of ERK1/2, FAK, and NF-κB signaling suppressed the pro-tumor effects induced by matrix stiffness. Combination of chemotherapy and integrin β1 inhibitor suppressed the tumor growth and prolonged survival time in hepatocellular cancer xenografts.

Conclusion

A higher matrix stiffness equipped tumor cells with enhanced stemness and proliferative characteristics, which was dependent on the activation of integrin β1/FAK/ERK1/2/NF-κB signaling pathway. Blockade of integrin signals efficiently improved the outcome of chemotherapy, which described an innovative approach for liver cancer treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08982-3.

The amoeboid state as part of the epithelial-to-mesenchymal transition programme

Cell migration is essential for many biological processes, while abnormal cell migration is characteristic of cancer cells. Epithelial cells become motile by undergoing epithelial-to-mesenchymal transition (EMT), and mesenchymal cells increase migration speed by adopting amoeboid features. This review highlights how amoeboid behaviour is not merely a migration mode but rather a cellular state - within the EMT spectra - by which cancer cells survive, invade and colonise challenging microenvironments. Molecular biomarkers and physicochemical triggers associated with amoeboid behaviour are discussed, including an amoeboid associated tumour microenvironment. We reflect on how amoeboid characteristics support metastasis and how their liabilities could turn into therapeutic opportunities.

3D Collagen-Nanocellulose Matrices Model the Tumour Microenvironment of Pancreatic Cancer

Three-dimensional (3D) cancer models are invaluable tools designed to study tumour biology and new treatments. Pancreatic ductal adenocarcinoma (PDAC), one of the deadliest types of cancer, has been progressively explored with bioengineered 3D approaches by deconstructing elements of its tumour microenvironment. Here, we investigated the suitability of collagen-nanocellulose hydrogels to mimic the extracellular matrix of PDAC and to promote the formation of tumour spheroids and multicellular 3D cultures with stromal cells. Blending of type I collagen fibrils and cellulose nanofibres formed a matrix of controllable stiffness, which resembled the lower profile of pancreatic tumour tissues. Collagen-nanocellulose hydrogels supported the growth of tumour spheroids and multicellular 3D cultures, with increased metabolic activity and matrix stiffness. To validate our 3D cancer model, we tested the individual and combined effects of the anti-cancer compound triptolide and the chemotherapeutics gemcitabine and paclitaxel, resulting in differential cell responses. Our blended 3D matrices with tuneable mechanical properties consistently maintain the growth of PDAC cells and its cellular microenvironment and allow the screening of anti-cancer treatments.

The PDAC Extracellular Matrix: A Review of the ECM Protein Composition, Tumor Cell Interaction, and Therapeutic Strategies

Pancreatic ductal adenocarcinoma (PDAC) is notorious for a dense fibrotic stroma that is interlaced with a collagen-based extracellular matrix (ECM) that plays an important role in tumor biology. Traditionally thought to only provide a physical barrier from host responses and systemic chemotherapy, new studies have demonstrated that the ECM maintains biomechanical and biochemical properties of the tumor microenvironment (TME) and restrains tumor growth. Recent studies have shown that the ECM augments tumor stiffness, interstitial fluid pressure, cell-to-cell junctions, and microvascularity using a mix of biomechanical and biochemical signals to influence tumor fate for better or worse. In addition, PDAC tumors have been shown to use ECM-derived peptide fragments as a nutrient source in nutrient-poor conditions. While collagens are the most abundant proteins found in the ECM, several studies have identified growth factors, integrins, glycoproteins, and proteoglycans in the ECM. This review focuses on the dichotomous nature of the PDAC ECM, the types of collagens and other proteins found in the ECM, and therapeutic strategies targeting the PDAC ECM.

Pancreatic Ductal Adenocarcinoma: Preclinical in vitro and ex vivo Models

Pancreatic ductal adenocarcinoma (PDAC) is one of the most overlooked cancers despite its dismal median survival time of 6 months. The biggest challenges in improving patient survival are late diagnosis due to lack of diagnostic markers, and limited treatment options due to almost complete therapy resistance. The past decades of research identified the dense stroma and the complex interplay/crosstalk between the cancer- and the different stromal cells as the main culprits for the slow progress in improving patient outcome. For better ex vivo simulation of this complex tumor microenvironment the models used in PDAC research likewise need to become more diverse. Depending on the focus of the investigation, several in vitro and in vivo models for PDAC have been established in the past years. Particularly, 3D cell culture such as spheroids and organoids have become more frequently used. This review aims to examine current PDAC in vitro models, their inherent limitations, and their successful implementations in research.

Channeling the Force: Piezo1 Mechanotransduction in Cancer Metastasis

Cancer metastasis is one of the leading causes of death worldwide, motivating research into identifying new methods of preventing cancer metastasis. Recently there has been increasing interest in understanding how cancer cells transduce mechanical forces into biochemical signals, as metastasis is a process that consists of a wide range of physical forces. For instance, the circulatory system through which disseminating cancer cells must transit is an environment characterized by variable fluid shear stress due to blood flow. Cancer cells and other cells can transduce physical stimuli into biochemical responses using the mechanosensitive ion channel Piezo1, which is activated by membrane deformations that occur when cells are exposed to physical forces. When active, Piezo1 opens, allowing for calcium flux into the cell. Calcium, as a ubiquitous second-messenger cation, is associated with many signaling pathways involved in cancer metastasis, such as angiogenesis, cell migration, intravasation, and proliferation. In this review, we discuss the roles of Piezo1 in each stage of cancer metastasis in addition to its roles in immune cell activation and cancer cell death.

Matrix stiffness drives stromal autophagy and promotes formation of a protumorigenic niche

Increased stiffness of solid tissues has long been recognized as a diagnostic feature of several pathologies, most notably malignant diseases. In fact, it is now well established that elevated tissue rigidity enhances disease progression and aggressiveness and is associated with a poor prognosis in patients as documented, for instance, for lung fibrosis or the highly desmoplastic cancer of the pancreas. The underlying mechanisms of the interplay between physical properties and cellular behavior are, however, not very well understood. Here, we have found that switching culture conditions from soft to stiff substrates is sufficient to evoke (macro) autophagy in various fibroblast types. Mechanistically, this is brought about by stiffness-sensing through an Integrin αV-focal adhesion kinase module resulting in sequestration and posttranslational stabilization of the metabolic master regulator AMPKα at focal adhesions, leading to the subsequent induction of autophagy. Importantly, stiffness-induced autophagy in stromal cells such as fibroblasts and stellate cells critically supports growth of adjacent cancer cells in vitro and in vivo. This process is Integrin αV dependent, opening possibilities for targeting tumor-stroma crosstalk. Our data thus reveal that the mere change in mechanical tissue properties is sufficient to metabolically reprogram stromal cell populations, generating a tumor-supportive metabolic niche.

Bioengineered 3D models of human pancreatic cancer recapitulate in vivo tumour biology

Patient-derived in vivo models of human cancer have become a reality, yet their turnaround time is inadequate for clinical applications. Therefore, tailored ex vivo models that faithfully recapitulate in vivo tumour biology are urgently needed. These may especially benefit the management of pancreatic ductal adenocarcinoma (PDAC), where therapy failure has been ascribed to its high cancer stem cell (CSC) content and high density of stromal cells and extracellular matrix (ECM). To date, these features are only partially reproduced ex vivo using organoid and sphere cultures. We have now developed a more comprehensive and highly tuneable ex vivo model of PDAC based on the 3D co-assembly of peptide amphiphiles (PAs) with custom ECM components (PA-ECM). These cultures maintain patient-specific transcriptional profiles and exhibit CSC functionality, including strong in vivo tumourigenicity. User-defined modification of the system enables control over niche-dependent phenotypes such as epithelial-to-mesenchymal transition and matrix deposition. Indeed, proteomic analysis of these cultures reveals improved matrisome recapitulation compared to organoids. Most importantly, patient-specific in vivo drug responses are better reproduced in self-assembled cultures than in other models. These findings support the use of tuneable self-assembling platforms in cancer research and pave the way for future precision medicine approaches.

Mesenchymal Lineage Heterogeneity Underlies Non-Redundant Functions of Pancreatic Cancer-Associated Fibroblasts

Cancer-associated fibroblast (CAF) heterogeneity is increasingly appreciated, but the origins and functions of distinct CAF subtypes remain poorly understood. The abundant and transcriptionally diverse CAF population in pancreatic ductal adenocarcinoma (PDAC) is thought to arise from a common cell of origin, pancreatic stellate cells (PSCs), with diversification resulting from cytokine and growth factor gradients within the tumor microenvironment. Here we analyzed the differentiation and function of PSCs during tumor progression in vivo. Contrary to expectations, we found that PSCs give rise to a numerically minor subset of PDAC CAFs. Targeted ablation of PSC-derived CAFs within their host tissue revealed non-redundant functions for this defined CAF population in shaping the PDAC microenvironment, including production of specific extracellular matrix components and tissue stiffness regulation. Together, these findings link stromal evolution from distinct cells of origin to transcriptional heterogeneity among PDAC CAFs, and demonstrate unique functions for CAFs of a defined cellular origin.

The Role of Cancer-Associated Fibroblasts in Cancer Invasion and Metastasis

Cancer-associated fibroblasts (CAFs) play a key role in cancer progression by contributing to extracellular matrix (ECM) deposition and remodeling, extensive crosstalk with cancer cells, epithelial-to-mesenchymal transition (EMT), invasion, metastasis, and therapy resistance. As metastasis is a main reason for cancer-related deaths, it is crucial to understand the role of CAFs in this process. Colorectal cancer (CRC) is a heterogeneous disease and lethality is especially common in a subtype of CRC with high stromal infiltration. A key component of stroma is cancer-associated fibroblasts (CAFs). To provide new perspectives for research on CAFs and CAF-targeted therapeutics, especially in CRC, we discuss the mechanisms, crosstalk, and functions involved in CAF-mediated cancer invasion, metastasis, and protection. This summary can serve as a framework for future studies elucidating these roles of CAFs.

Parallels between the extracellular matrix roles in developmental biology and cancer biology

Interaction of a tumor with its microenvironment is an emerging field of investigation, and the crosstalk between cancer cells and the extracellular matrix is of particular interest, since cancer patients with abundant and stiff extracellular matrices display a poorer prognosis. At the post-juvenile stage, the extracellular matrix plays predominantly a structural role by providing support to cells and tissues; however, during development, matrix proteins exert a plethora of diverse signals to guide the movement and determine the fate of pluripotent cells. Taking a closer look at the communication between the extracellular matrix and cells of a developing body may bring new insights into cancer biology and identify cancer weaknesses. This review discusses parallels between the extracellular matrix roles during development and tumor growth.

Recapitulating the Cancer Microenvironment Using Bioprinting Technology for Precision Medicine

The complex and heterogenous nature of cancer contributes to the development of cancer cell drug resistance. The construction of the cancer microenvironment, including the cell-cell interactions and extracellular matrix (ECM), plays a significant role in the development of drug resistance. Traditional animal models used in drug discovery studies have been associated with feasibility issues that limit the recapitulation of human functions; thus, in vitro models have been developed to reconstruct the human cancer system. However, conventional two-dimensional and three-dimensional (3D) in vitro cancer models are limited in their ability to emulate complex cancer microenvironments. Advances in technologies, including bioprinting and cancer microenvironment reconstruction, have demonstrated the potential to overcome some of the limitations of conventional models. This study reviews some representative bioprinted in vitro models used in cancer research, particularly fabrication strategies for modeling and consideration of essential factors needed for the reconstruction of the cancer microenvironment. In addition, we highlight recent studies that applied such models, including application in precision medicine using advanced bioprinting technologies to fabricate biomimetic cancer models. Furthermore, we discuss current challenges in 3D bioprinting and suggest possible strategies to construct in vitro models that better mimic the pathophysiology of the cancer microenvironment for application in clinical settings.

Induction of cellular senescence in fibroblasts through β1-integrin activation by tenascin-C-derived peptide and its protumor effect

Tenascin-C is upregulated during inflammation and tumorigenesis, and its expression level is correlated with a poor prognosis in several malignancies. Nevertheless, the substantial role of tenascin-C in cancer progression is poorly understood. Previously, we found that a peptide derived from tenascin-C, termed TNIIIA2, acts directly on tumor cells to activate β1-integrin and induce malignant progression. Here, we show that β1-integrin activation by TNIIIA2 in human fibroblasts indirectly contributes to cancer progression through the induction of cellular senescence. Prolonged treatment of fibroblasts with TNIIIA2 induced cellular senescence, as characterized by the suppression of cell growth and the induction of senescence-associated-β-galactosidase and p16^INK4a expression. The production of reactive oxygen species and subsequent DNA damage were responsible for the TNIIIA2-induced senescence of fibroblasts. Interestingly, peptide FNIII14, which inactivates β1-integrin, inhibited fibroblast senescence induced not only by TNIIIA2 but also by H₂O₂, suggesting that β1-integrin activation plays a critical role in the induction of senescence in fibroblasts. Moreover, TNIIIA2-induced senescent fibroblasts secreted heparin-binding epidermal growth factor-like growth factor (HB-EGF), which caused preneoplastic epithelial HaCaT cells to acquire malignant properties, including colony-forming and focus-forming abilities. Thus, our study demonstrates that tenascin-C-derived peptide TNIIIA2 induces cellular senescence in fibroblasts through β1-integrin activation, causing cancer progression via the secretion of humoral factors such as HB-EGF.

Engineering hydrogels for personalized disease modeling and regenerative medicine

Technological innovations and advances in scientific understanding have created an environment where data can be collected, analyzed, and interpreted at scale, ushering in the era of personalized medicine. The ability to isolate cells from individual patients offers tremendous promise if those cells can be used to generate functional tissue replacements or used in disease modeling to determine optimal treatment strategies. Here, we review recent progress in the use of hydrogels to create artificial cellular microenvironments for personalized tissue engineering and regenerative medicine applications, as well as to develop personalized disease models. We highlight engineering strategies to control stem cell fate through hydrogel design, and the use of hydrogels in combination with organoids, advanced imaging methods, and novel bioprinting techniques to generate functional tissues. We also discuss the use of hydrogels to study molecular mechanisms underlying diseases and to create personalized in vitro disease models to complement existing pre-clinical models. Continued progress in the development of engineered hydrogels, in combination with other emerging technologies, will be essential to realize the immense potential of personalized medicine. STATEMENT OF SIGNIFICANCE: In this review, we cover recent advances in hydrogel engineering strategies with applications in personalized medicine. Specifically, we focus on material systems to expand or control differentiation of patient-derived stem cells, and hydrogels to reprogram somatic cells to pluripotent states. We then review applications of hydrogels in developing personalized engineered tissues. We also highlight the use of hydrogel systems as personalized disease models, focusing on specific examples in fibrosis and cancer, and more broadly on drug screening strategies using patient-derived cells and hydrogels. We believe this review will be a valuable contribution to the Special Issue and the readership of Acta Biomaterialia will appreciate the comprehensive overview of the utility of hydrogels in the developing field of personalized medicine.

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.

Substrate Stiffness Modulates the Growth, Phenotype, and Chemoresistance of Ovarian Cancer Cells

Mechanical factors in the tumor microenvironment play an important role in response to a variety of cellular activities in cancer cells. Here, we utilized polyacrylamide hydrogels with varying physical parameters simulating tumor and metastatic target tissues to investigate the effect of substrate stiffness on the growth, phenotype, and chemotherapeutic response of ovarian cancer cells (OCCs). We found that increasing the substrate stiffness promoted the proliferation of SKOV-3 cells, an OCC cell line. This proliferation coincided with the nuclear translocation of the oncogene Yes-associated protein. Additionally, we found that substrate softening promoted elements of epithelial-mesenchymal transition (EMT), including mesenchymal cell shape changes, increase in vimentin expression, and decrease in E-cadherin and β-catenin expression. Growing evidence demonstrates that apart from contributing to cancer initiation and progression, EMT can promote chemotherapy resistance in ovarian cancer cells. Furthermore, we evaluated tumor response to standard chemotherapeutic drugs (cisplatin and paclitaxel) and found antiproliferation effects to be directly proportional to the stiffness of the substrate. Nanomechanical studies based on atomic force microscopy (AFM) have revealed that chemosensitivity and chemoresistance are related to cellular mechanical properties. The results of cellular elastic modulus measurements determined by AFM demonstrated that Young's modulus of SKOV-3 cells grown on soft substrates was less than that of cells grown on stiff substrates. Gene expression analysis of SKOV-3 cells showed that mRNA expression can be greatly affected by substrate stiffness. Finally, immunocytochemistry analyses revealed an increase in multidrug resistance proteins, namely, ATP binding cassette subfamily B member 1 and member 4 (ABCB1 and ABCB4), in the cells grown on the soft gel resulting in resistance to chemotherapeutic drugs. In conclusion, our study may help in identification of effective targets for cancer therapy and improve our understanding of the mechanisms of cancer progression and chemoresistance.

Mammographic features are associated with cardiometabolic disease risk and mortality

AIMS

In recent years, microcalcifications identified in routine mammograms were found to be associated with cardiometabolic disease in women. Here, we aimed to systematically evaluate the association of microcalcifications and other mammographic features with cardiometabolic disease risk and mortality in a large screening cohort and to understand a potential genetic contribution.

METHODS AND RESULTS

This study included 57 867 women from a prospective mammographic screening cohort in Sweden (KARMA) and 49 583 sisters. Cardiometabolic disease diagnoses and mortality and medication were extracted by linkage to Swedish population registries with virtually no missing data. In the cardiometabolic phenome-wide association study, we found that a higher number of microcalcifications were associated with increased risk for multiple cardiometabolic diseases, particularly in women with pre-existing cardiometabolic diseases. In contrast, dense breasts were associated with a lower incidence of cardiometabolic diseases. Importantly, we observed similar associations in sisters of KARMA women, indicating a potential genetic overlap between mammographic features and cardiometabolic traits. Finally, we observed that the presence of microcalcifications was associated with increased cardiometabolic mortality in women with pre-existing cardiometabolic diseases (hazard ratio and 95% confidence interval: 1.79 [1.24-2.58], P = 0.002) while we did not find such effects in women without cardiometabolic diseases.

CONCLUSIONS

We found that mammographic features are associated with cardiometabolic risk and mortality. Our results strengthen the notion that a combination of mammographic features and other breast cancer risk factors could be a novel and affordable tool to assess cardiometabolic health in women attending mammographic screening.

Erlotinib Promotes Ligand-Induced EGFR Degradation in 3D but Not 2D Cultures of Pancreatic Ductal Adenocarcinoma Cells

The epithelial growth factor receptor (EGFR) is a tyrosine kinase receptor that participates in many biological processes such as cell proliferation. In addition, EGFR is overexpressed in many epithelial cancers and therefore is a target for cancer therapy. Moreover, EGFR responds to lots of stimuli by internalizing into endosomes from where it can be recycled to the membrane or further sorted into lysosomes where it undergoes degradation. Two-dimensional cell cultures have been classically used to study EGFR trafficking mechanisms in cancer cells. However, it has been widely demonstrated that in 2D cultures cells are exposed to a non-physiological environment as compared to 3D cultures that provide the normal cellular conformation, matrix dimensionality and stiffness, as well as molecular gradients. Therefore, the microenvironment of solid tumors is better recreated in 3D culture models, and this is why they are becoming a more physiological alternative to study cancer physiology. Here, we develop a new model of EGFR internalization and degradation upon erlotinib treatment in pancreatic ductal adenocarcinoma (PDAC) cells cultured in a 3D self-assembling peptide scaffold. In this work, we show that treatment with the tyrosine kinase inhibitor erlotinib promotes EGFR degradation in 3D cultures of PDAC cell lines but not in 2D cultures. We also show that this receptor degradation does not occur in normal fibroblast cells, regardless of culture dimensionality. In conclusion, we demonstrate not only that erlotinib has a distinct effect on tumor and normal cells but also that pancreatic ductal adenocarcinoma cells respond differently to drug treatment when cultured in a 3D microenvironment. This study highlights the importance of culture systems that can more accurately mimic the in vivo tumor physiology.

The Extracellular Matrix in Pancreatic Cancer: Description of a Complex Network and Promising Therapeutic Options

The stroma is a relevant player in driving and supporting the progression of pancreatic ductal adenocarcinoma (PDAC), and a large body of evidence highlights its role in hindering the efficacy of current therapies. In fact, the dense extracellular matrix (ECM) characterizing this tumor acts as a natural physical barrier, impairing drug penetration. Consequently, all of the approaches combining stroma-targeting and anticancer therapy constitute an appealing option for improving drug penetration. Several strategies have been adopted in order to target the PDAC stroma, such as the depletion of ECM components and the targeting of cancer-associated fibroblasts (CAFs), which are responsible for the increased matrix deposition in cancer. Additionally, the leaky and collapsing blood vessels characterizing the tumor might be normalized, thus restoring blood perfusion and allowing drug penetration. Even though many stroma-targeting strategies have reported disappointing results in clinical trials, the ECM offers a wide range of potential therapeutic targets that are now being investigated. The dense ECM might be bypassed by implementing nanoparticle-based systems or by using mesenchymal stem cells as drug carriers. The present review aims to provide an overview of the principal mechanisms involved in the ECM remodeling and of new promising therapeutic strategies for PDAC.

Photodynamic Therapy for Pancreatic Ductal Adenocarcinoma

Simple Summary

Pancreatic ductal adenocarcinoma (PDAC) is among the most lethal of human cancers. Numerous clinical trials evaluating various combinations of chemotherapy and targeted agents and radiotherapy have failed to provide meaningful improvements in survival. A growing number of studies however have indicated that photodynamic therapy (PDT) may be a viable approach for treatment of some pancreatic tumors. PDT, which uses light to activate a photosensitizing agent in target tissue, has seen widespread adoption primarily for dermatological and other applications where superficial light delivery is relatively straightforward. Advances in fiber optic light delivery and dosimetry however have been leveraged to enable PDT even for challenging internal sites, including the pancreas. The aim of this article is to help inform future directions by reviewing relevant literature on the basic science, current clinical status, and potential challenges in the development of PDT as a treatment for PDAC.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is among the most lethal of human cancers. Clinical trials of various chemotherapy, radiotherapy, targeted agents and combination strategies have generally failed to provide meaningful improvement in survival for patients with unresectable disease. Photodynamic therapy (PDT) is a photochemistry-based approach that enables selective cell killing using tumor-localizing agents activated by visible or near-infrared light. In recent years, clinical studies have demonstrated the technical feasibility of PDT for patients with locally advanced PDAC while a growing body of preclinical literature has shown that PDT can overcome drug resistance and target problematic and aggressive disease. Emerging evidence also suggests the ability of PDT to target PDAC stroma, which is known to act as both a barrier to drug delivery and a tumor-promoting signaling partner. Here, we review the literature which indicates an emergent role of PDT in clinical management of PDAC, including the potential for combination with other targeted agents and RNA medicine.

Regulation of Extracellular Matrix Production in Activated Fibroblasts: Roles of Amino Acid Metabolism in Collagen Synthesis

Cancer associated fibroblasts (CAFs) are a major component of the tumour microenvironment in most tumours, and are key mediators of the response to tissue damage caused by tumour growth and invasion, contributing to the observation that tumours behave as 'wounds that do not heal'. CAFs have been shown to play a supporting role in all stages of tumour progression, and this is dependent on the highly secretory phenotype CAFs develop upon activation, of which extracellular matrix (ECM) production is a key element. A collagen rich, stromal ECM has been shown to influence tumour growth and metastasis, exclude immune cells and impede drug delivery, and is associated with poor prognosis in many cancers. CAFs also extensively remodel their metabolism to support cancer cells, however, it is becoming clear that metabolic rewiring also supports intrinsic functions of activated fibroblasts, such as increased ECM production. In this review, we summarise how fibroblasts metabolically regulate ECM production, focussing on collagen production, at the transcriptional, translational and post-translational level, and discuss how this can provide possible strategies for effectively targeting CAF activation and formation of a tumour-promoting stroma.

Tissue Architecture Influences the Biological Effectiveness of Boron Neutron Capture Therapy in In Vitro/In Silico Three-Dimensional Self-Assembly Cell Models of Pancreatic Cancers

Simple Summary

Boron neutron capture therapy (BNCT) is becoming one of the most promising radiotherapies for aggressive cancers, but the detailed cellular mechanisms of BNCT remain largely underexplored. Solid tumors are composed of heterogeneous cell populations, which create a 3-dimensional complicated microenvironment for tumor progression. To recapture the influences of the microenvironment on BNCT efficacy, we applied a self-assembly 3D cell culture system with two different types of pancreatic cancer cells. In contrast to previous findings with γ-ray exposure, we found that the 3D architecture of pancreatic tumor can facilitate the susceptibility of cancer cells to BNCT, as compared to 2D tissue structure; a computer simulation model was established to further confirm this unexpected finding. These outcomes can contribute to better understanding of the radiobiology of BNCT, and the developed models may facilitate the recent development in personalized radiotherapy.

Abstract

Pancreatic cancer is a leading cause of cancer death, and boron neutron capture therapy (BNCT) is one of the promising radiotherapy techniques for patients with pancreatic cancer. In this study, we evaluated the biological effectiveness of BNCT at multicellular levels using in vitro and in silico models. To recapture the phenotypic characteristic of pancreatic tumors, we developed a cell self-assembly approach with human pancreatic cancer cells Panc-1 and BxPC-3 cocultured with MRC-5 fibroblasts. On substrate with physiological stiffness, tumor cells self-assembled into 3D spheroids, and the cocultured fibroblasts further facilitated the assembly process, which recapture the influence of tumor stroma. Interestingly, after 1.2 MW neutron irradiation, lower survival rates and higher apoptosis (increasing by 4-fold for Panc-1 and 1.5-fold for BxPC-3) were observed in 3D spheroids, instead of in 2D monolayers. The unexpected low tolerance of 3D spheroids to BNCT highlights the unique characteristics of BNCT over conventional radiotherapy. The uptake of boron-containing compound boronophenylalanine (BPA) and the alteration of E-cadherin can partially contribute to the observed susceptibility. In addition to biological effects, the probability of induced α-particle exposure correlated to the multicellular organization was speculated to affect the cellular responses to BNCT. A Monte Carlo (MC) simulation was also established to further interpret the observed survival. Intracellular boron distribution in the multicellular structure and related treatment resistance were reconstructed in silico. Simulation results demonstrated that the physical architecture is one of the essential factors for biological effectiveness in BNCT, which supports our in vitro findings. In summary, we developed in vitro and in silico self-assembly 3D models to evaluate the effectiveness of BNCT on pancreatic tumors. Considering the easy-access of this 3D cell-assembly platform, this study may not only contribute to the current understanding of BNCT but is also expected to be applied to evaluate the BNCT efficacy for individualized treatment plans in the future.

Dynamic extracellular matrix stiffening induces a phenotypic transformation and a migratory shift in epithelial cells

Soft tissue tumors, including breast cancer, become stiffer throughout disease progression. This increase in stiffness has been shown to correlate to malignant phenotype and epithelial-to-mesenchymal transition (EMT) in vitro. Unlike current models, utilizing static increases in matrix stiffness, our group has previously created a system that allows for dynamic stiffening of an alginate-matrigel composite hydrogel to mirror the native dynamic process. Here, we utilize this system to evaluate the role of matrix stiffness on EMT and metastasis both in vitro and in vivo. Epithelial cells were seen to lose normal morphology and become protrusive and migratory after stiffening. This shift corresponded to a loss of epithelial markers and gain of mesenchymal markers in both the cell clusters and migrated cells. Furthermore, stiffening in a murine model reduced tumor burden and increased migratory behavior prior to tumor formation. Inhibition of FAK and PI3K in vitro abrogated the morphologic and migratory transformation of epithelial cell clusters. This work demonstrates the key role extracellular matrix stiffening has in tumor progression through integrin signaling and, in particular, its ability to drive EMT-related changes and metastasis.

Biomimetic stiffening of cell-laden hydrogels via sequential thiol-ene and hydrazone click reactions

Hydrogels with dynamically tunable crosslinking are invaluable for directing stem cell fate and mimicking a stiffening matrix during fibrosis or tumor development. The increases in matrix stiffness during tissue development are often accompanied by the accumulation of extracellular matrices (e.g., collagen, hyaluronic acid (HA)), a phenomenon that has received little attention in the development of dynamic hydrogels. In this contribution, we present a gelatin-based cell-laden hydrogel system capable of being dynamically stiffened while accumulating HA, a key glycosaminoglycans (GAG) increasingly deposited by stromal cells during tumor progression. Central to this strategy is the synthesis of a dually-modified gelatin macromer - gelatin-norbornene-carbohydrazide (GelNB-CH), which is susceptible to both thiol-norbornene photopolymerization and hydrazone click chemistry. We demonstrate that the crosslinking density of cell-laden thiol-norbornene hydrogels can be dynamically tuned via simple incubation with aldehyde-bearing macromers (e.g., oxidized dextran (oDex) or oHA). The GelNB-CH hydrogel system is highly cytocompatible, as demonstrated by in situ encapsulation of pancreatic cancer cells (PCC) and cancer-associated fibroblasts (CAF). This unique dynamic stiffening scheme provides a platform to study tandem accumulation of HA and elevation in matrix stiffness in the pancreatic tumor microenvironment. STATEMENT OF SIGNIFICANCE: Hydrogels permitting on-demand and secondary crosslinking are ideal for mimicking a stiffening tumor microenvironment (TME). However, none of the current dynamic hydrogels account for both stiffening and accumulation of hyaluronic acid (HA), a major extracellular matrix component increasingly deposited in tumor stromal tissues, including pancreatic ductal adenocarcinoma (PDAC). The current work addresses this gap by developing a dynamic hydrogel system capable of simultaneously increasing stiffness and HA accumulation. This is achieved by a new gelatin macromer permitting sequential thiol-norbornene (for primary network crosslinking) and hydrazone click chemistry (for bioinert or biomimetic stiffening with oxidized dextran (oDex) or oHA, respectively). The results of this study provide new insights into how dynamically changing physicochemical matrix properties guide cancer cell fate processes.

The functional cross talk between cancer cells and cancer associated fibroblasts from a cancer mechanics perspective

The function of biological tissues in health and disease is regulated at cellular level and is highly influenced by the physical microenvironment, through the interaction of forces between cells and ECM, which are perceived through mechanosensing pathways. In cancer, both chemical and physical signaling cascades and their interactions are involved during cell-cell and cell-ECM communications to meet requirements of tumor growth. Among stroma cells, cancer associated fibroblasts (CAFs) play key role in tumor growth and pave the way for cancer cells to initiate metastasis and invasion to other tissues, and without recruitment of CAFs, the process of cancer invasion is dysfunctional. This is through an intense chemical and physical cross talks with tumor cells, and interactive remodeling of ECM. During such interaction CAFs apply traction forces and depending on the mechanical properties, deform ECM and in return receive physical signals from the micromechanical environment. Such interaction leads to ECM remodeling by manipulating ECM structure and its mechanical properties. The results are in form of deposition of extra fibers, stiffening, rearrangement and reorganization of fibrous structure, and degradation which are due to a complex secretion and expression of different markers triggered by mechanosensing of tumor cells, specially CAFs. Such events define cancer progress and invasion of cancer cells. A systemic knowledge of chemical and physical factors provides a holistic view of how cancer process and enhances the current treatment methods to provide more diversity among targets that involves tumor cells and ECM structure.

Collagen XI alpha 1 chain, a potential therapeutic target for cancer

Extracellular matrix (ECM) plays an important role in the progression of cancer. Collagen is the most abundant component in ECM, and it is involved in the biological formation of cancer. Although type XI collagen is a minor fibrillar collagen, collagen XI alpha 1 chain (COL11A1) has been found to be upregulated in a variety of cancers including ovarian cancer, breast cancer, thyroid cancer, pancreatic cancer, non-small-cell lung cancer, and transitional cell carcinoma of the bladder. High levels of COL11A1 usually predict poor prognosis, while COL11A1 is related to angiogenesis, invasion, and drug resistance of cancer. However, little is known about the specific mechanism by which COL11A1 regulates tumor progression. Here, we have organized and summarized the recent developments regarding elucidation of the relationship between COL11A1 and various cancers, as well as the interaction between COL11A1 and intracellular signaling pathways. In addition, we have selected therapeutic agents targeting COL11A1. All these indicate the possibility of using COL11A1 as a target for cancer treatment.

Recent advances in regenerative medicine strategies for cancer treatment

Cancer stands as one of the most leading causes of death worldwide, while one of the most significant challenges in treating it is revealing novel alternatives to predict, diagnose, and eradicate tumor cell growth. Although various methods, such as surgery, chemotherapy, and radiation therapy, are used today to treat cancer, its mortality rate is still high due to the numerous shortcomings of each approach. Regenerative medicine field, including tissue engineering, cell therapy, gene therapy, participate in cancer treatment and development of cancer models to improve the understanding of cancer biology. The final intention is to convey fundamental and laboratory research to effective clinical treatments, from the bench to the bedside. Proper interpretation of research attempts helps to lessen the burden of treatment and illness for patients. The purpose of this review is to investigate the role of regenerative medicine in accelerating and improving cancer treatment. This study examines the capabilities of regenerative medicine in providing novel cancer treatments and the effectiveness of these treatments to clarify this path as much as possible and promote advanced future research in this field.

Machine learning reveals mesenchymal breast carcinoma cell adaptation in response to matrix stiffness

Epithelial-mesenchymal transition (EMT) and its reverse process, mesenchymal-epithelial transition (MET), are believed to play key roles in facilitating the metastatic cascade. Metastatic lesions often exhibit a similar epithelial-like state to that of the primary tumour, in particular, by forming carcinoma cell clusters via E-cadherin-mediated junctional complexes. However, the factors enabling mesenchymal-like micrometastatic cells to resume growth and reacquire an epithelial phenotype in the target organ microenvironment remain elusive. In this study, we developed a workflow using image-based cell profiling and machine learning to examine morphological, contextual and molecular states of individual breast carcinoma cells (MDA-MB-231). MDA-MB-231 heterogeneous response to the host organ microenvironment was modelled by substrates with controllable stiffness varying from 0.2kPa (soft tissues) to 64kPa (bone tissues). We identified 3 distinct morphological cell types (morphs) varying from compact round-shaped to flattened irregular-shaped cells with lamellipodia, predominantly populating 2-kPa and >16kPa substrates, respectively. These observations were accompanied by significant changes in E-cadherin and vimentin expression. Furthermore, we demonstrate that the bone-mimicking substrate (64kPa) induced multicellular cluster formation accompanied by E-cadherin cell surface localisation. MDA-MB-231 cells responded to different substrate stiffness by morphological adaptation, changes in proliferation rate and cytoskeleton markers, and cluster formation on bone-mimicking substrate. Our results suggest that the stiffest microenvironment can induce MET.

Translating complexity and heterogeneity of pancreatic tumor: 3D in vitro to in vivo models

Pancreatic ductal adenocarcinoma (PDAC) is an extremely aggressive type of cancer with an overall survival rate of less than 7-8%, emphasizing the need for novel effective therapeutics against PDAC. However only a fraction of therapeutics which seemed promising in the laboratory environment will eventually reach the clinic. One of the main reasons behind this low success rate is the complex tumor microenvironment (TME) of PDAC, a highly fibrotic and dense stroma surrounding tumor cells, which supports tumor progression as well as increases the resistance against the treatment. In particular, the growing understanding of the PDAC TME points out a different challenge in the development of efficient therapeutics - a lack of biologically relevant in vitro and in vivo models that resemble the complexity and heterogeneity of PDAC observed in patients. The purpose and scope of this review is to provide an overview of the recent developments in different in vitro and in vivo models, which aim to recapitulate the complexity of PDAC in a laboratory environment, as well to describe how 3D in vitro models can be integrated into drug development pipelines that are already including sophisticated in vivo models. Hereby a special focus will be given on the complexity of in vivo models and the challenges in vitro models face to reach the same levels of complexity in a controllable manner. First, a brief introduction of novel developments in two dimensional (2D) models and ex vivo models is provided. Next, recent developments in three dimensional (3D) in vitro models are described ranging from spheroids, organoids, scaffold models, bioprinted models to organ-on-chip models including a discussion on advantages and limitations for each model. Furthermore, we will provide a detailed overview on the current PDAC in vivo models including chemically-induced models, syngeneic and xenogeneic models, highlighting hetero- and orthotopic, patient-derived tissues (PDX) models, and genetically engineered mouse models. Finally, we will provide a discussion on overall limitations of both, in vitro and in vivo models, and discuss necessary steps to overcome these limitations to reach an efficient drug development pipeline, as well as discuss possibilities to include novel in silico models in the process.

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).

Tumor Microenvironment Alters Chemoresistance of Hepatocellular Carcinoma Through CYP3A4 Metabolic Activity

Variations in tumor biology from patient to patient combined with the low overall survival rate of hepatocellular carcinoma (HCC) present significant clinical challenges. During the progression of chronic liver diseases from inflammation to the development of HCC, microenvironmental properties, including tissue stiffness and oxygen concentration, change over time. This can potentially impact drug metabolism and subsequent therapy response to commonly utilized therapeutics, such as doxorubicin, multi-kinase inhibitors (e.g., sorafenib), and other drugs, including immunotherapies. In this study, we utilized four common HCC cell lines embedded in 3D collagen type-I gels of varying stiffnesses to mimic normal and cirrhotic livers with environmental oxygen regulation to quantify the impact of these microenvironmental factors on HCC chemoresistance. In general, we found that HCC cells with higher baseline levels of cytochrome p450-3A4 (CYP3A4) enzyme expression, HepG2 and C3Asub28, exhibited a cirrhosis-dependent increase in doxorubicin chemoresistance. Under the same conditions, HCC cell lines with lower CYP3A4 expression, HuH-7 and Hep3B2, showed a decrease in doxorubicin chemoresistance in response to an increase in microenvironmental stiffness. This differential therapeutic response was correlated with the regulation of CYP3A4 expression levels under the influence of stiffness and oxygen variation. In all tested HCC cell lines, the addition of sorafenib lowered the required doxorubicin dose to induce significant levels of cell death, demonstrating its potential to help reduce systemic doxorubicin toxicity when used in combination. These results suggest that patient-specific tumor microenvironmental factors, including tissue stiffness, hypoxia, and CYP3A4 activity levels, may need to be considered for more effective use of chemotherapeutics in HCC patients.

Improving selective targeting to cancer-associated fibroblasts by modifying liposomes with arginine based materials

A library of arginine-like surface modifiers was tested to improve the targetability of DOPE:DOPC liposomes towards myofibroblasts in a tumour microenvironment. Liposomes were characterised using zeta potential and dynamic light scattering. Cell viability remained unchanged for all liposomes. Liposomes were encapsulated using doxorubicin (DOX) with an encapsulation efficiency >94%. The toxicity of DOX-loaded liposomes was calculated via half-maximal inhibitory concentration (IC₅₀) for fibroblasts and myofibroblasts. These liposomes resulted in significantly lower IC₅₀-values for myofibroblasts compared to fibroblasts, making them more toxic towards the myofibroblasts. Furthermore, a significant increase in cell internalisation was observed for myofibroblasts compared to fibroblasts, using fluorescein-loaded liposomes. Most importantly, a novel regression model was constructed to predict the IC₅₀-values for different modifications using their physicochemical properties. Fourteen modifications (A-N) were used to train and validate this model; subsequently, this regression model predicted IC₅₀-values for three new modifications (O, P and Q) for both fibroblasts and myofibroblasts. Predicted and measured IC₅₀-values showed no significant difference for fibroblasts. For myofibroblasts, modification O showed no significant difference. This study demonstrates that the tested surface modifications can improve targeting to myofibroblasts in the presence of fibroblasts and hence are suitable drug delivery vehicles for myofibroblasts in a tumour microenvironment.

A Covalently Crosslinked Ink for Multimaterials Drop-on-Demand 3D Bioprinting of 3D Cell Cultures

In vitro 3D cell models have been accepted to better recapitulate aspects of in vivo organ environment than 2D cell culture. Currently, the production of these complex in vitro 3D cell models with multiple cell types and microenvironments remains challenging and prone to human error. Here, a versatile ink comprising a 4-arm poly(ethylene glycol) (PEG)-based polymer with distal maleimide derivatives as the main ink component and a bis-thiol species as the activator that crosslinks the polymer to form the hydrogel in less than a second is reported. The rapid gelation makes the polymer system compatible with 3D bioprinting. The ink is combined with a novel drop-on-demand 3D bioprinting platform, designed specifically for producing 3D cell cultures, consisting of eight independently addressable nozzles and high-throughput printing logic for creating complex 3D cell culture models. The combination of multiple nozzles and fast printing logic enables the rapid preparation of many complex 3D cell cultures comprising multiple hydrogel environments in one structure in a standard 96-well plate format. The platform's compatibility for biological applications is validated using pancreatic ductal adenocarcinoma cancer (PDAC) and human dermal fibroblast cells with their phenotypic responses controlled by tuning the hydrogel microenvironment.

Co-evolution of matrisome and adaptive adhesion dynamics drives ovarian cancer chemoresistance

Due to its dynamic nature, the evolution of cancer cell-extracellular matrix (ECM) crosstalk, critically affecting metastasis and treatment resistance, remains elusive. Our results show that platinum-chemotherapy itself enhances resistance by progressively changing the cancer cell-intrinsic adhesion signaling and cell-surrounding ECM. Examining ovarian high-grade serous carcinoma (HGSC) transcriptome and histology, we describe the fibrotic ECM heterogeneity at primary tumors and distinct metastatic sites, prior and after chemotherapy. Using cell models from systematic ECM screen to collagen-based 2D and 3D cultures, we demonstrate that both specific ECM substrates and stiffness increase resistance to platinum-mediated, apoptosis-inducing DNA damage via FAK and β1 integrin-pMLC-YAP signaling. Among such substrates around metastatic HGSCs, COL6 was upregulated by chemotherapy and enhanced the resistance of relapse, but not treatment-naïve, HGSC organoids. These results identify matrix adhesion as an adaptive response, driving HGSC aggressiveness via co-evolving ECM composition and sensing, suggesting stromal and tumor strategies for ECM pathway targeting.