Interactions between human colon carcinoma cells, fibroblasts and monocytic cells in coculture--regulation of cathepsin B expression and invasiveness

Gas-Phase Fractionation Data-Independent Acquisition Analysis of 3D Cocultured Spheroid Tumor Model Reveals Altered Translational Processes and Signaling Using Proteomics

Colorectal cancer (CRC) contains considerable heterogeneity; therefore, models of the disease must also reflect the multifarious components. Compared to traditional 2D models, 3D cellular models, such as tumor spheroids, have the utility to determine the drug efficacy of potential therapeutics. Monoculture spheroids are well-known to recapitulate gene expression, cell signaling, and pathophysiological gradients of avascularized tumors. However, they fail to mimic the stromal cell influence present in CRC, which is known to perturb drug efficacy and is associated with metastatic, late-stage colorectal cancer. This study seeks to develop a cocultured spheroid model using carcinoma and noncancerous fibroblast cells. We characterized the proteomic profile of cocultured spheroids in comparison to monocultured spheroids using data-independent acquisition with gas-phase fractionation. Specifically, we determined that proteomic differences related to translation and mTOR signaling are significantly increased in cocultured spheroids compared to monocultured spheroids. Proteins related to fibroblast function, such as exocytosis of coated vesicles and secretion of growth factors, were significantly differentially expressed in the cocultured spheroids. Finally, we compared the proteomic profiles of both the monocultured and cocultured spheroids against a publicly available data set derived from solid CRC tumors. We found that the proteome of the cocultured spheroids more closely resembles that of the patient samples, indicating their potential as tumor mimics.

Lysosomal peptidases – Intriguing roles in cancer progression and neurodegeneration

Lysosomal peptidases are hydrolytic enzymes capable of digesting waste proteins that are targeted to lysosomes via endocytosis and autophagy. Besides intracellular protein catabolism, they play more specific roles in several other cellular processes and pathologies, either within lysosomes, upon secretion into the cell cytoplasm or extracellular space, or bound to the plasma membrane. In cancer, lysosomal peptidases are generally associated with disease progression, as they participate in crucial processes leading to changes in cell morphology, signaling, migration, and invasion, and finally metastasis. However, they can also enhance the mechanisms resulting in cancer regression, such as apoptosis of tumor cells or antitumor immune responses. Lysosomal peptidases have also been identified as hallmarks of aging and neurodegeneration, playing roles in oxidative stress, mitochondrial dysfunction, abnormal intercellular communication, dysregulated trafficking, and the deposition of protein aggregates in neuronal cells. Furthermore, deficiencies in lysosomal peptidases may result in other pathological states, such as lysosomal storage disease. The aim of this review was to highlight the role of lysosomal peptidases in particular pathological processes of cancer and neurodegeneration and to address the potential of lysosomal peptidases in diagnosing and treating patients.

Understanding and improving cellular immunotherapies against cancer: From cell-manufacturing to tumor-immune models

The tumor microenvironment (TME) is shaped by dynamic metabolic and immune interactions between precancerous and cancerous tumor cells and stromal cells like epithelial cells, fibroblasts, endothelial cells, and hematopoietically-derived immune cells. The metabolic states of the TME, including the hypoxic and acidic niches, influence the immunosuppressive phenotypes of the stromal and immune cells, which confers resistance to both host-mediated tumor killing and therapeutics. Numerous in vitro TME platforms for studying immunotherapies, including cell therapies, are being developed. However, we do not yet understand which immune and stromal components are most critical and how much model complexity is needed to answer specific questions. In addition, scalable sourcing and quality-control of appropriate TME cells for reproducibly manufacturing these platforms remain challenging. In this regard, lessons from the manufacturing of immunomodulatory cell therapies could provide helpful guidance. Although immune cell therapies have shown unprecedented results in hematological cancers and hold promise in solid tumors, their manufacture poses significant scale, cost, and quality control challenges. This review first provides an overview of the in vivo TME, discussing the most influential cell populations in the tumor-immune landscape. Next, we summarize current approaches for cell therapies against cancers and the relevant manufacturing platforms. We then evaluate current immune-tumor models of the TME and immunotherapies, highlighting the complexity, architecture, function, and cell sources. Finally, we present the technical and fundamental knowledge gaps in both cell manufacturing systems and immune-TME models that must be addressed to elucidate the interactions between endogenous tumor immunity and exogenous engineered immunity.

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

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

Three-Dimensional Culture Systems in Gastric Cancer Research

Gastric cancer (GC), which includes cancer of the esophagus, the oesophagogastric junction, and the stomach fundus, is highly deadly with strong regional influence, Asia being the most affected. GC is often detected at late stages, with 30% of metastatic cases at diagnosis. Many authors have devised models to both unravel the mechanisms of GC development and to evaluate candidate therapeutics. Among these models, 2D-cell cultures are progressively replaced by 3D-cell cultures that recapitulate, much more comprehensively, tumor cellular and genetic heterogeneity, as well as responsiveness to environmental changes, such as exposure to drugs or irradiation. With respect to the specifics of GC, there are high hopes from such model systems, especially with the aim of identifying prognostic markers and novel drug targets.

A novel dual sensitive polymer-gambogic acid conjugate: synthesis, characterization, and in vitro evaluation

Currently, bio-simulate drug delivery systems are highly considered for efficient targeting of tumors. Nevertheless, there are some potential problems such as intelligent release efficiency, subsequently, influence cell toxicity and blood circulation stability. A novel type of stimuli-responsive nanoparticle was developed in accordance with the specific tumor microenvironment to deliver gambogic acid (GA). Herein, we successfully connected GA with mPEG via two different sensitive linkages, valine-citrulline (VC) and cystamine. The structure was characterized by ESI-MS, ¹H NMR, FT-IR or MALDI-TOF-MS. The mPEG-VC-SS-GA-NPs (PVSG-NPs) were rapidly prepared. The properties of nanoparticles, including solubility, particle size, morphology, and sensitive drug release performance, were investigated. Compared to single sensitive conjugate (mPEG-SS-GA-NPs, PSG-NPs), PVSG-NPs demonstrated greater solubility and higher sensitive release profile. Cytotoxicity test indicated that PVSG-NPs had apparent cytotoxicity on HepG2 cells and reduced cytotoxicity on normal cells. Additionally, PVSG-NPs mainly kill HepG2 cells by inducing early and late apoptosis and restraining the G0/G1 phase proliferation. Albumin adsorption test revealed that the PVSG-NPs had little albumin combination, consequently, enhancing their circulation constancy. In summary, our findings suggested the novel PVSG-NPs capable of being used for tumor targeting and further practical applications.

Cysteine Cathepsins in Tumor-Associated Immune Cells

Cysteine cathepsins are key regulators of the innate and adaptive arms of the immune system. Their expression, activity, and subcellular localization are associated with the distinct development and differentiation stages of immune cells. They promote the activation of innate myeloid immune cells since they contribute to toll-like receptor signaling and to cytokine secretion. Furthermore, they control lysosomal biogenesis and autophagic flux, thus affecting innate immune cell survival and polarization. They also regulate bidirectional communication between the cell exterior and the cytoskeleton, thus influencing cell interactions, morphology, and motility. Importantly, cysteine cathepsins contribute to the priming of adaptive immune cells by controlling antigen presentation and are involved in cytotoxic granule mediated killing in cytotoxic T lymphocytes and natural killer cells. Cathepins'aberrant activity can be prevented by their endogenous inhibitors, cystatins. However, dysregulated proteolysis contributes significantly to tumor progression also by modulation of the antitumor immune response. Especially tumor-associated myeloid cells, such as tumor-associated macrophages and myeloid-derived suppressor cells, which are known for their tumor promoting and immunosuppressive functions, constitute the major source of excessive cysteine cathepsin activity in cancer. Since they are enriched in the tumor microenvironment, cysteine cathepsins represent exciting targets for development of new diagnostic and therapeutic moieties.

'Patchiness' and basic cancer research: unravelling the proteases

The recent developments in Cathepsin protease research have unveiled a number of key observations which are fundamental to further our understanding of normal cellular homeostasis and disease. By far, the most interesting and promising area of Cathepsin biology stems from how these proteins are linked to the fate of living cells through the phenomenon of Lysosomal Leakage and Lysosomal Membrane Permeabilisation. While extracellular Cathepsins are generally believed to be of central importance in tumour progression, through their ability to modulate the architecture of the Extracellular Matrix, intracellular Cathepsins have been established as being of extreme significance in mediating cell death through Apoptosis. With these two juxtaposed key research areas in mind, the focus of this review highlights recent advancements in how this fast-paced area of Cathepsin research has recently evolved in the context of their mechanistic regulation in cancer research. Abbreviations : ECM, Extracellular Matrix; MMP, Matrix Metalloproteases; LL, Lysosomal Leakage; LMP, Lysosomal Membrane Permeabilisation; LMA, Lysosomorphic Agents; BC, Breast Cancer; ASM, Acid Sphingomyelinase; TNF-α, Tumor Necrosis Factor-alpha; LAMP, Lysosomal Associated membrane Protein; PCD, Programmed Cell Death; PDAC, Pancreatic Ductal Adenocarcinoma; ROS, Reactive Oxygen Species; aa, amino acids.

3D breast cancer microtissue reveals the role of tumor microenvironment on the transport and efficacy of free-doxorubicin in vitro

The use of 3D cancer models will have both ethical and economic impact in drug screening and development, to promote the reduction of the animals employed in preclinical studies. Nevertheless, to be effective, such cancer surrogates must preserve the physiological relevance of the in vivo models in order to provide realistic information on drugs' efficacy. To figure out the role of the architecture and composition of 3D cancer models on their tumor-mimicking capability, here we studied the efficacy of doxorubicin (DOX), a well-known anticancer molecule in two different 3D cancer models: our 3D breast cancer microtissue (3D-μTP) versus the golden standard represented by spheroid model (sph). Both models were obtained by using cancer associated fibroblast (CAF) and breast cancer cells (MCF-7) as cellular component. Unlike spheroid model, 3D-μTP was engineered in order to induce the production of endogenous extracellular matrix by CAF. 3D-μTP have been compared to spheroid in mono- (MCF-7 alone) and co-culture (MCF-7/CAF), after the treatment with DOX in order to study cytotoxicity effect, diffusional transport and expression of proteins related to cancer progression. Compared to the spheroid model, 3D-μTP showed higher diffusion coefficient of DOX and lower cell viability. Also, the expression of some tumoral biomarkers related to cell junctions were different in the two models.

STATEMENTS OF SIGNIFICANCE

Cancer biology has made progress in unraveling the mechanism of cancer progression, anyway the most of the results are still obtained by 2D cell cultures or animal models, that do not faithfully copycat the tumor microenvironment. The lack of correlation between preclinical models and in vivo organisms negatively influences the clinical efficacy of chemotherapeutic drugs. Consequently, even if a huge amount of new drugs has been developed in the last decades, still people are dying because of cancer. Pharmaceutical companies are interested in 3D tumor model as valid alternative in drug screening in preclinical studies. However, a 3D tumor model that completely mimics tumor heterogeneity is still far to achieve. In our work we compare 3D human breast cancer microtissues and spheroids in terms of response to doxorubicin and drug diffusion. We believe that our results are interesting because they highlight the potential role of the proposed tumor model in the attempts to improve efficacy tests.

Liquid-based three-dimensional tumor models for cancer research and drug discovery

Tumors are three-dimensional tissues where close contacts between cancer cells, intercellular interactions between cancer and stromal cells, adhesion of cancer cells to the extracellular matrix, and signaling of soluble factors modulate functions of cancer cells and their response to therapeutics. Three-dimensional cultures of cancer cells overcome limitations of traditionally used monolayer cultures and recreate essential characteristics of tumors such as spatial gradients of oxygen, growth factors, and metabolites and presence of necrotic, hypoxic, quiescent, and proliferative cells. As such, three-dimensional tumor models provide a valuable tool for cancer research and oncology drug discovery. Here, we describe different tumor models and primarily focus on a model known as tumor spheroid. We summarize different technologies of spheroid formation, and discuss the use of spheroids to address the influence of stromal fibroblasts and immune cells on cancer cells in tumor microenvironment, study cancer stem cells, and facilitate compound screening in the drug discovery process. We review major techniques for quantification of cellular responses to drugs and discuss challenges ahead to enable broad utility of tumor spheroids in research laboratories, integrate spheroid models into drug development and discovery pipeline, and use primary tumor cells for drug screening studies to realize personalized cancer treatment.

Toward the Broad Adoption of 3D Tumor Models in the Cancer Drug Pipeline

Despite a cost of approximately $1 billion to develop a new cancer drug, about 90% of drugs that enter clinical trials fail. A tremendous opportunity exists to streamline the drug selection and testing process, and innovative approaches promise to reduce the burdensome cost of health care for those suffering from cancer. There is great potential for 3D models of human tumors to complement more traditional testing methods; however, the shift from 2D to 3D assays at early stages of the drug discovery and development process is far from widely accepted. 3D platforms range from simple tumor spheroids to more complex microfluidic hydrogels that better mimic the tumor microenvironment. While several companies have developed and patented advanced high-throughput 3D platforms for drug screening, their cost and complexity have limited their adoption as an industry standard. In this review, we will highlight the various tumor platforms that have been developed, emphasizing the approaches that have successfully led to commercial products. We will then consider potential directions toward more relevant tumor models, advantages of the adoption of such platforms within the drug development and screening process, and new opportunities in personalized medicine that such platforms will uniquely enable.

Matrigel: from discovery and ECM mimicry to assays and models for cancer research

The basement membrane is an important extracellular matrix that is found in all epithelial and endothelial tissues. It maintains tissue integrity, serves as a barrier to cells and to molecules, separates different tissue types, transduces mechanical signals, and has many biological functions that help to maintain tissue specificity. A well-defined soluble basement membrane extract, termed BME/Matrigel, prepared from an epithelial tumor is similar in content to authentic basement membrane, and forms a hydrogel at 24-37°C. It is used in vitro as a substrate for 3D cell culture, in suspension for spheroid culture, and for various assays, such as angiogenesis, invasion, and dormancy. In vivo, BME/Matrigel is used for angiogenesis assays and to promote xenograft and patient-derived biopsy take and growth. Studies have shown that both the stiffness of the BME/Matrigel and its components (i.e. chemical signals) are responsible for its activity with so many different cell types. BME/Matrigel has widespread use in assays and in models that improve our understanding of tumor biology and help define therapeutic approaches.

Comparative genomic of the teleost cathepsin B and H and involvement in bacterial induced immunity of miiuy croaker

Cathepsins are a family of lysosomal proteases play different roles at physiological and pathological states and present in almost all animals as well as other organisms. Cathepsins B and H are both cysteine proteases of cathepsins. Cathepsin B and H have been studied playing parts in protein degradation/turnover, antigen presentation/processing and hormone maturation in mammals. However, little is known about the structures and functions of cathepsin B and H in teleosts. In the present study, we identified and characterized the full-length miiuy croaker (Miichthys miiuy) cathepsin B and H genes. The sequence analysis results showed that both cathepsin B and H contain the characteristics of papain family with a signal peptide, propeptide and mature peptide regions. The comparison of the genomic organizations and locations indicated the conserved synteny and mild evolution in the cathepsin B and H genes adjacent regions. In addition, the gene synteny analysis showed that miiuy croaker cathepsin B has a closer relationship to stickleback and fugu than to cave fish and zebrafish, and cathepsin H was most similar with the 2 subtype in tilapia and fugu. By phylogenetic analysis, miiuy croaker cathepsin B and H were all assigned to cysteine proteases, and with a close relationship to Salmo salar cathepsin B and Oplegnathus fasciatus cathepsin H, respectively. Quantitative real-time RT-PCR analysis results confirmed that cathepsin B and H genes expressed ubiquitously in all tested healthy tissues from miiuy croaker. Furthermore, up-regulated expression of the cathepsin B and H transcripts in liver, spleen and kidney after exposure upon Vibrio anguillarum suggested that they may play important roles in innate immune response and antigen processing of miiuy croaker.

Impact of proteolytic enzymes in colorectal cancer development and progression

Tumor invasion and metastasis is a highly complicated, multi-step phenomenon. In the complex event of tumor progression, tumor cells interact with basement membrane and extracellular matrix components. Proteolytic enzymes (proteinases) are involved in the degradation of extracellular matrix, but also in cancer invasion and metastasis. The four categories of proteinases (cysteine-, serine-, aspartic-, and metalloproteinases) are named and classified according to the essential catalytic component in their active site. We and others have shown that proteolytic enzymes play a major role not only in colorectal cancer (CRC) invasion and metastasis, but also in malignant transformation of precancerous lesions into cancer. Tissue and serum-plasma antigen concentrations of proteinases might be of great value in identifying patients with poor prognosis in CRC. Our results, in concordance with others indicate the potential tumor marker impact of proteinases for the early diagnosis of CRC. In addition, proteinases may also serve as potential target molecules for therapeutic agents.

Characterization of cathepsin X in colorectal cancer development and progression

The lysosomal cysteine carboxypeptidase cathepsin X (CTSX), localized predominantly in immune cells, has been associated with the development and progression of cancer. To determine its specific role in colorectal carcinoma (CRC), we analyzed CTSX expression in non-malignant mucosa and carcinoma of 177 patients as well as in 111 adenomas and related it with clinicopathological parameters. Further, the role of CTSX in the adhesion and invasion of the colon carcinoma cell lines HT-29 and HCT116 was investigated in an in vitro culture cell system with fibroblasts and monocytes, reflecting the situation at the tumor invasion front. Epithelial CTSX expression significantly increased from normal mucosa to adenoma and carcinoma, with highest expression levels in high grade intraepithelial neoplasia and in early tumor stages. Loss of CTSX occurred with tumor progression, and correlated with advanced local invasion, lymph node and distal metastasis, lymphatic vessel and vein invasion, tumor cell budding and poorer overall survival of patients with CRC. The subcellular distribution of CTSX changed from vesicular paranuclear expression in the tumor center to submembranous expression in cells of the invasion front. Peritumoral macrophages showed highest expression of CTSX. In vitro assays identified CTSX as relevant factor for cell-cell adhesion and tumor cell anchorage to fibroblasts and basal membrane components, whereas inhibition of CTSX caused increased invasiveness of colon carcinoma cells in mono- and co-culture. In conclusion, CTSX is involved in early tumorigenesis and in the stabilization of tumor cell formation in CRC. The results suggest that loss of CTSX may be needed for tumor cell detachment, local invasion and tumor progression. In addition, CTSX in tumor-associated macrophages indicates a role for CTSX in the anti-tumor immune response.

Non-invasive optical imaging of cathepsin B with activatable fluorogenic nanoprobes in various metastatic models

An increasing number of treatments of metastases rely on diagnostics and imaging these days. The facts that the activity of cathepsin B (CB) is markedly linked to the metastatic process and that CB is found highly expressed in the pericellular regions in this process make CB an attractive target for diagnosing metastases. We have developed a CB-sensitive nanoprobe (CB-CNP) consisting of self-quenched CB-sensitive fluorogenic peptide probes conjugated onto the surface of tumor-targeting glycol chitosan nanoparticles (CNPs). The freshly prepared CB-CNP formed a spherical nanoparticle structure (280 nm in diameter) and the fluorescence intensity of CB-CNP was strongly quenched in physiological condition. However, self-quenched CB-CNP boosted strong fluorescence signals in the presence of CB, not of cathepsin l or cathepsin d, due to the CB-specific cleavage of self-quenched peptide probes. Importantly, the intravenously injected CB-CNP demonstrated the potential to discriminate metastases in vivo in three metastatic mouse models, including 4T1-luc2 liver metastases, RFP-B16F10 lung metastases and HT1080 peritoneal metastases. Indeed, Western blot analysis confirmed that the CB expression of metastases had increased compared to normal organ in these metastatic mouse models. CB-CNPs may be useful for depicting metastases through non-invasive CB molecular imaging.

In vitro cell migration and invasion assays

Determining the migratory and invasive capacity of tumor and stromal cells and clarifying the underlying mechanisms is most relevant for novel strategies in cancer diagnosis, prognosis, drug development and treatment. Here we shortly summarize the different modes of cell travelling and review in vitro methods, which can be used to evaluate migration and invasion. We provide a concise summary of established migration/invasion assays described in the literature, list advantages, limitations and drawbacks, give a tabular overview for convenience and depict the basic principles of the assays graphically. In many cases particular research problems and specific cell types do not leave a choice for a broad variety of usable assays. However, for most standard applications using adherent cells, based on our experience we suggest to use exclusion zone assays to evaluate migration/invasion. We substantiate our choice by demonstrating that the advantages outbalance the drawbacks e.g. the simple setup, the easy readout, the kinetic analysis, the evaluation of cell morphology and the feasibility to perform the assay with standard laboratory equipment. Finally, innovative 3D migration and invasion models including heterotypic cell interactions are discussed. These methods recapitulate the in vivo situation most closely. Results obtained with these assays have already shed new light on cancer cell spreading and potentially will uncover unknown mechanisms.

Optical Imaging with a Cathepsin B Activated Probe for the Enhanced Detection of Esophageal Adenocarcinoma by Dual Channel Fluorescent Upper GI Endoscopy

Despite significant advances in diagnosis and treatment, the prognosis of esophageal adenocarcinoma remains poor highlighting the importance of early detection. Although white light (WL) upper endoscopy can be used for screening of the esophagus, it has limited sensitivity for early stage disease. Thus, development of new imaging technology to improve the diagnostic capabilities of upper GI endoscopy for early detection of esophageal adenocarcinoma is an important unmet need. The goal of this study was to develop a method for the detection of malignant lesions in the esophagus using WL upper endoscopy combined with near infrared (NIR) imaging with a protease activatable probe (Prosense750) selective for cathepsin B (CTSB). An orthotopic murine model for distal esophageal adenocarcinoma was generated through the implantation of OE-33 and OE-19 human esophageal adenocarcinoma lines in immunocompromised mice. The mice were imaged simultaneously for WL and NIR signal using a custom-built dual channel upper GI endoscope. The presence of tumor was confirmed by histology and target to background ratios (TBR) were compared for both WL and NIR imaging. NIR imaging with ProSense750 significantly improved upon the TBRs of esophageal tumor foci, with a TBR of 3.64±0.14 and 4.50±0.11 for the OE-33 and OE-19 tumors respectively, compared to 0.88±0.04 and 0.81±0.02 TBR for WL imaging. The combination of protease probes with novel imaging devices has the potential to improve esophageal tumor detection by fluorescently highlighting neoplastic regions.

Molecular cloning, characterization and expression analysis of cathepsin C gene involved in the antibacterial response in Chinese mitten crab, Eriocheir sinensis

Cathepsins, a superfamily of hydrolytic enzymes produced and enclosed within lysosomes, function in immune response in vertebrates; however, their function within the innate immune system of invertebrates remains largely unknown. Therefore, we investigated the immune functionality of cathepsin C (catC) in Chinese mitten crab (Eriocheir sinensis), a commercially important and disease vulnerable aquaculture species. The full-length catC cDNA (1481 bp) was cloned via PCR based upon an initial expressed sequence tag (EST) isolated from a hepatopancreatic cDNA library. The catC cDNA contained a 1284 bp open reading frame (ORF) that encoded a putative 427 amino acid (aa) protein. Comparisons with other reported invertebrate and vertebrate cathepsins sequences revealed high percent identity. CatC mRNA expression in E. sinensis was responsive in hemocytes to a Vibrio anguillarum challenge, with peak exposure observed 6 h post-injection. Collectively, data demonstrate the successful isolation of catC from the Chinese mitten crab, and its involvement in the innate immune system of an invertebrate.

Cathepsin B is the driving force of esophageal cell invasion in a fibroblast-dependent manner

Esophageal cancer, which frequently exhibits coordinated loss of E-cadherin (Ecad) and transforming growth factor beta (TGFbeta) receptor II (TbetaRII), has a high mortality rate. In a three-dimensional organotypic culture model system, esophageal keratinocytes expressing dominant-negative mutant versions of both Ecad and TbetaRII (ECdnT) invade into the underlying matrix embedded with fibroblasts. We also find that cathepsin B induction is necessary for fibroblast-mediated invasion. Furthermore, the ECdnT cells in this physiological context activate fibroblasts through the secretion of TGFbeta1, which, in turn, is activated by cathepsin B. These results suggest that the interplay between the epithelial compartment and the surrounding microenvironment is crucial to invasion into the extracellular matrix.

Multicellular tumor spheroids: an underestimated tool is catching up again

The present article highlights the rationale, potential and flexibility of tumor spheroid mono- and cocultures for implementation into state of the art anti-cancer therapy test platforms. Unlike classical monolayer-based models, spheroids strikingly mirror the 3D cellular context and therapeutically relevant pathophysiological gradients of in vivo tumors. Some concepts for standardization and automation of spheroid culturing, monitoring and analysis are discussed, and the challenges to define the most convenient analytical endpoints for therapy testing are outlined. The potential of spheroids to contribute to either the elimination of poor drug candidates at the pre-animal and pre-clinical state or the identification of promising drugs that would fail in classical 2D cell assays is emphasised. Microtechnologies, in the form of micropatterning and microfluidics, are also discussed and offer the exciting prospect of standardized spheroid mass production to tackle high-throughput screening applications within the context of traditional laboratory settings. The extension towards more sophisticated spheroid coculture models which more closely reflect heterologous tumor tissues composed of tumor and various stromal cell types is also covered. Examples are given with particular emphasis on tumor-immune cell cocultures and their usefulness for testing novel immunotherapeutic treatment strategies. Finally, tumor cell heterogeneity and the extraordinary possibilities of putative cancer stem/tumor-initiating cell populations that can be maintained and expanded in sphere-forming assays are introduced. The relevance of the cancer stem cell hypothesis for cancer cure is highlighted, with the respective sphere cultures being envisioned as an integral tool for next generation drug development offensives.

Compensation of optical heterogeneity-induced artifacts in fluorescence molecular tomography: theory and in vivo validation

We present a method for reduction of image artifacts induced by the optical heterogeneities of tissue in fluorescence molecular tomography (FMT) through identification and compensation of image regions that evidence propagation of emission light through thin or low-absorption tunnels in tissue. The light tunneled as such contributes to the emission image as spurious components that might substantially overwhelm the desirable fluorescence emanating from the targeted lesions. The proposed method makes use of the strong spatial correlation between the emission and excitation images to estimate the tunneled components and yield a residual image that mainly consists of the signal due to the desirable fluorescence. This residual image is further refined using a coincidence mask constructed for each excitation-emission image pair. The coincidence mask is essentially a map of the "hot spots" that occur in both excitation and emission images, as such areas are often associated with tunneled emission. In vivo studies are performed on a human colon adenocarcinoma xenograft tumor model with subcutaneous tumors and a murine breast adenocarcinoma model with aggressive tumor cell metastasis and growth in the lungs. Results demonstrate significant improvements in the reconstructions achieved by the proposed method.

Regulation of cathepsin X overexpression in H. pylori-infected gastric epithelial cells and macrophages

Cathepsin X (CTSX) is strongly up-regulated in Helicobacter pylori-infected gastric mucosa and intestinal-type gastric cancer. The overexpression of CTSX is mediated predominantly by associated macrophages; depends on a functional type IV-secretion system; and leads to increased migration of gastric epithelial cells. In the present study, we analysed the role of CagA in CTSX overexpression and identified H. pylori-induced inflammatory factors and signalling pathways required for stimulating CTSX expression by H. pylori. Gastric epithelial cells were co-cultured with macrophages in Transwell chambers of 0.4 microm pore size, enabling exchange of fluids but retracting H. pylori. N87 gastric epithelial cells were infected with H. pylori P1 wild-type strain in the presence of inhibitors for p38, JNK, and ERK1/2 signal transduction pathways. Furthermore, cytokines and growth factors were tested for their regulatory function using inhibitory antibodies, and their gene expression was studied by quantitative RT-PCRs and western blots. CTSX is strongly up-regulated at both the mRNA and the protein levels by TNF-alpha, IL-1beta, IL-6, and IL-8, depending on cell type. All these cytokines were found to be increased by five- to ten-fold in macrophages by H. pylori infection of co-cultured N87 gastric epithelial cells. In macrophages, H. pylori up-regulated CTSX via ERK1/2 signalling pathways, and in N87 cells via JNK irrespective of p38 signalling. Our results suggest that H. pylori induced overexpression of CTSX in macrophages and epithelium through specific cytokines that are initiated by CagA-dependent pathways in a cell type-dependent manner.

Serum cathepsin B and plasma urokinase-type plasminogen activator levels in gastrointestinal tract cancers

Cathepsin B (CATB) and urokinase-type plasminogen activator (UPA) play an important part in cancer invasion and metastasis. The behavior of CATB and UPA has not been evaluated in the same experimental setting in different gastrointestinal tumors and in precancerous lesions. Serum CATB and plasma UPA levels were determined by enzyme-linked immunoadsorbent assay and their sensitivity, specificity, and diagnostic accuracy have been calculated in patients with colorectal (n=72), gastric (n=30), hepatocellular (n=28), and pancreatic cancer (n=15) as well as in gastric epithelial dysplasia (n=25), colorectal adenomas (n=30), and tumor-free control patients (n=44). Serum CATB and plasma UPA antigen concentrations were significantly higher in patients with cancer than in controls. When all tumors were considered, the sensitivity, specificity, and diagnostic accuracy of CATB (89, 86, and 89%) were higher than that of UPA (76, 70, and 74%). CATB demonstrated in all types of tumors a better diagnostic accuracy than UPA. The positive predictive values of CATB (95%) and UPA (89%) may suggest their use in the evaluation of patients with a suspicion of malignancy. CATB and UPA were significantly higher in patients with gastric epithelial dysplasia and colorectal adenomas than in controls. Antigen levels of CATB and UPA were significantly correlated in both cancers and precancerous lesions. At the time of clinical presentation, serum CATB and plasma UPA antigen levels are sensitive indicators of gastrointestinal malignancies. Determination of serum CATB and plasma UPA levels may be useful to identify patients at a higher risk for progression to cancer, who could be subjected to a more strict follow-up protocol.

Origin and pathogenesis of nodular lymphocyte-predominant Hodgkin lymphoma as revealed by global gene expression analysis

The pathogenesis of nodular lymphocyte–predominant Hodgkin lymphoma (NLPHL) and its relationship to other lymphomas are largely unknown. This is partly because of the technical challenge of analyzing its rare neoplastic lymphocytic and histiocytic (L&H) cells, which are dispersed in an abundant nonneoplastic cellular microenvironment. We performed a genome-wide expression study of microdissected L&H lymphoma cells in comparison to normal and other malignant B cells that indicated a relationship of L&H cells to and/or that they originate from germinal center B cells at the transition to memory B cells. L&H cells show a surprisingly high similarity to the tumor cells of T cell–rich B cell lymphoma and classical Hodgkin lymphoma, a partial loss of their B cell phenotype, and deregulation of many apoptosis regulators and putative oncogenes. Importantly, L&H cells are characterized by constitutive nuclear factor κB activity and aberrant extracellular signal-regulated kinase signaling. Thus, these findings shed new light on the nature of L&H cells, reveal several novel pathogenetic mechanisms in NLPHL, and may help in differential diagnosis and lead to novel therapeutic strategies.

Thymoquinone reduces mouse colon tumor cell invasion and inhibits tumor growth in murine colon cancer models

We have shown that thymoquinone (TQ) is a potent antitumor agent in human colorectal cancer cells. In this study, we evaluated TQ's therapeutic potential in two different mice colon cancer models [1,2-dimethyl hydrazine (DMH) and xenografts]. We also examined TQ effects on the growth of C26 mouse colorectal carcinoma spheroids and assessed tumor invasion in vitro. Mice were treated with saline, TQ, DMH, or combinations once per week for 30 weeks and the multiplicity, size and distribution of aberrant crypt foci (ACF) and tumors were determined at weeks 10, 20 and 30. TQ injected intraperitoneally (i.p.) significantly reduced the numbers and sizes of ACF at week 10; ACF numbers were reduced by 86%. Tumor multiplicity was reduced at week 20 from 17.8 in the DMH group to 4.2 in mice injected with TQ. This suppression was observed at week 30 and was long-term; tumors did not re-grow even when TQ injection was discontinued for 10 weeks. In a xenograft model of HCT116 colon cancer cells, TQ significantly (P < 0.05) delayed the growth of the tumor cells. Using a matrigel artificial basement membrane invasion assay, we demonstrated that sub-cyto-toxic doses of TQ (40μM) decreased C26 cell invasion by 50% and suppressed growth in three-dimensional spheroids. Apoptotic signs seen morphologically were increased significantly in TQ-treated spheroids. TUNEL staining of xenografts and immunostaining for caspase 3 cleavage in DMH tumors confirmed increased apoptosis in mouse tumors in response to TQ. These data should encourage further in vivo testing and support the potential use of TQ as a therapeutic agent in human colorectal cancer.

Tumor marker utility and prognostic relevance of cathepsin B, cathepsin L, urokinase-type plasminogen activator, plasminogen activator inhibitor type-1, CEA and CA 19-9 in colorectal cancer

BACKGROUND

Cathepsin B and L (CATB, CATL), urokinase-type plasminogen activator (uPA) and its inhibitor PAI-1 play an important role in colorectal cancer invasion. The tumor marker utility and prognostic relevance of these proteases have not been evaluated in the same experimental setting and compared with that of CEA and CA-19-9.

METHODS

Protease, CEA and CA 19-9 serum or plasma levels were determined in 56 patients with colorectal cancer, 25 patients with ulcerative colitis, 26 patients with colorectal adenomas and 35 tumor-free control patients. Protease, CEA, CA 19-9 levels have been determined by ELISA and electrochemiluminescence immunoassay, respectively; their sensitivity, specificity, diagnostic accuracy have been calculated and correlated with clinicopathological staging.

RESULTS

The protease antigen levels were significantly higher in colorectal cancer compared with other groups. Sensitivity of PAI-1 (94%), CATB (82%), uPA (69%), CATL (41%) were higher than those of CEA or CA 19-9 (30% and 18%, respectively). PAI-1, CATB and uPA demonstrated a better accuracy than CEA or CA 19-9. A combination of PAI-1 with CATB or uPA exhibited the highest sensitivity value (98%). High CATB, PAI-1, CEA and CA 19-9 levels correlated with advanced Dukes stages. CATB (P = 0.0004), CATL (P = 0.02), PAI-1 (P = 0.01) and CA 19-9 (P = 0.004) had a significant prognostic impact. PAI-1 (P = 0.001), CATB (P = 0.04) and CA 19-9 (P = 0.02) proved as independent prognostic variables.

CONCLUSION

At the time of clinical detection proteases are more sensitive indicators for colorectal cancer than the commonly used tumor markers. Determinations of CATB, CATL and PAI-1 have a major prognostic impact in patients with colorectal cancer.

The cathepsin family and their role in colorectal cancer

Cathepsins are a class of globular proteases, initially described as intracellular peptide hydrolases, although several cathepsins also have extracellular functions. Cathepsins B, C, F, H, L, K, O, S, V, W, and X are cysteine proteases of the papain family, and represent the largest and best-known class of the cathepsins. Cathepsin G is a serine carboxypeptidases, and cathepsins D and E are aspartic proteases. Cathepsins are synthesized as inactive proenzymes and processed to become mature and active enzymes. Endogenous protein inhibitors, such as cystatins and some serpins, inhibit active enzymes. As primarily lysosomal proteases, cathepsins play important roles in proteolysis during physiological processes, as well as in several diseases. On the basis of their ability to degrade extracellular matrix proteins, cathepsins have been implicated to play a role in invasion and metastasis of colorectal cancer. In the present review, the role of cathepsins in the disease process of colorectal cancers and the correlation of cathepsin expression and activity with clinicopathological features is discussed. Furthermore, we give an overview of the recent developments of cathepsins in animal models and in in vitro experiments of colorectal disease, and provide information on inhibitors of cathepsins as possible therapeutics.

Effect of endothelin-1 in esophageal squamous cell carcinoma invasion and its correlation with cathepsin B

AIM: To investigate the effect of endothelin-1 in the invasion of esophageal cancer and determine whether cathepsin B plays a role in the course.

METHODS: Western blotting was employed to detect the expression of ET-1 protein in 75 samples of esophageal squamous cell cancer and matched normal esophageal mucosa. Bosentan, a dual ET (A/B)-receptor antagonist, was used to inhibit the binding of endothelin-1 and its receptors and cut down its biological role. In vitro matrigel invasion assays were made to show the invasive ability of esophageal cancer cells with and without bosentan. Subsequently, we evaluated cathepsin B activity and expression in EC9706 cell with and without bosentan.

RESULTS: We found 74.7% (56/75) tumors had an overexpression of ET-1 protein by Western blotting. Bosentan significantly inhibited matrigel invasion of cancer cells in vitro. EC9706 cells have a positive expression of cathepsin B protein, and bosentan can down-regulate its expression and activity.

CONCLUSION: Endothelin-1 may enhance the invasive ability of human esophageal cancer cells, and its role is correlated with cathepsin B.