Preclinical models of pancreatic ductal adenocarcinoma

Advancing pancreatic cancer research and therapeutics: the transformative role of organoid technology

Research on pancreatic cancer has transformed with the advent of organoid technology, providing a better platform that closely mimics cancer biology in vivo. This review highlights the critical advancements facilitated by pancreatic organoid models in understanding disease progression, evaluating therapeutic responses, and identifying biomarkers. These three-dimensional cultures enable the proper recapitulation of the cellular architecture and genetic makeup of the original tumors, providing insights into the complex molecular and cellular dynamics at various stages of pancreatic ductal adenocarcinoma (PDAC). We explore the applications of pancreatic organoids in dissecting the tumor microenvironment (TME); elucidating cancer progression, metastasis, and drug resistance mechanisms; and personalizing therapeutic strategies. By overcoming the limitations of traditional 2D cultures and animal models, the use of pancreatic organoids has significantly accelerated translational research, which is promising for improving diagnostic and therapeutic approaches in clinical settings, ultimately aiming to improve the outcomes of patients with pancreatic cancer.

Epigenetic Landscape of DNA Methylation in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal malignancies, characterized by its aggressive progression and dismal prognosis. Advances in epigenetic profiling, specifically DNA methylation analysis, have significantly deepened our understanding of PDAC pathogenesis. This review synthesizes findings from recent genome-wide DNA methylation studies, which have delineated a complex DNA methylation landscape differentiating between normal and cancerous pancreatic tissues, as well as across various stages and molecular subtypes of PDAC. These studies identified specific differentially methylated regions (DMRs) that not only enhance our grasp of the epigenetic drivers of PDAC but also offer potential biomarkers for early diagnosis and prognosis, enabling the customization of therapeutic approaches. The review further explores how DNA methylation profiling could facilitate the development of subtype-tailored therapies, potentially improving treatment outcomes based on precise molecular characterizations. Overall, leveraging DNA methylation alterations as functional biomarkers holds promise for advancing our understanding of disease progression and refining PDAC management strategies, which could lead to improved patient outcomes and a deeper comprehension of the disease's underlying biological mechanisms.

Unravelling the complexities of resistance mechanism in pancreatic cancer: Insights from in vitro and ex-vivo model systems

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with poor prognosis and rising global deaths. Late diagnosis, due to absent early symptoms and biomarkers, limits treatment mainly to chemotherapy, which soon encounters resistance. PDAC treatment innovation is hampered by its complex and heterogeneous resistant nature, including mutations in key genes and a stromal-rich, immunosuppressive tumour microenvironment. Recent studies on PDAC resistance stress the need for suitable in vitro and ex vivo models to replicate its complex molecular and microenvironmental landscape. This review summarises advances in these models, which can aid in combating chemoresistance and serve as platforms for discovering new therapeutics. Immortalised cell lines offer homogeneity, unlimited proliferation, and reproducibility, but while many gemcitabine-resistant PDAC cell lines exist, fewer models are available for resistance to other drugs. Organoids from PDAC patients show promise in mimicking tumour heterogeneity and chemosensitivity. Bioreactors, co-culture systems and organotypic slices, incorporating stromal and immune cells, are being developed to understand tumour-stroma interactions and the tumour microenvironment's role in drug resistance. Lastly, another innovative approach is three-dimensional bioprinting, which creates tissue-like structures resembling PDAC architecture, allowing for drug screening. These advanced models can guide researchers in selecting optimal in vitro tests, potentially improving therapeutic strategies and patient outcomes.

Familial Pancreatic Cancer Research: Bridging Gaps in Basic Research and Clinical Application

Familial pancreatic cancer (FPC) represents a significant yet underexplored area in pancreatic cancer research. Basic research efforts are notably limited, and when present, they are predominantly centered on the BRCA1 and BRCA2 mutations due to the scarcity of other genetic variants associated with FPC, leading to a limited understanding of the broader genetic landscape of FPC. This review examines the current state of FPC research, focusing on the molecular mechanisms driving pancreatic ductal adenocarcinoma (PDAC) progression. It highlights the role of homologous recombination (HR) and its therapeutic exploitation via synthetic lethality with PARP inhibitors in BRCA1/2-deficient tumors. The review discusses various pre-clinical models of FPC, including conventional two-dimensional (2D) cell lines, patient-derived organoids (PDOs), patient-derived xenografts (PDXs), and genetically engineered mouse models (GEMMs), as well as new advancements in FPC research.

Evaluation of Targeted Alpha Therapy Using [211At]FAPI1 in Triple-Negative Breast Cancer Xenograft Models

Triple-negative breast cancer (TNBC) presents limited therapeutic options and is associated with poor prognosis. Early detection and the development of novel therapeutic agents are therefore imperative. Fibroblast activation protein (FAP) is a membrane protein expressed on cancer-associated fibroblasts (CAFs) that plays an essential role in TNBC proliferation, migration, and invasion. Consequently, it is hypothesized that the Astatine (211At)-labeled FAP inhibitor (FAPI) selectively exerts anti-tumor effects through alpha-particle emission. In this study, we aimed to assess its theranostic capabilities by integrating [18F]FAPI-74 PET imaging with targeted alpha therapy using [211At]FAPI1 in TNBC models. Mice xenografts were established by transplanting MDA-MB-231 and HT1080 cells (control). As a parallel diagnostic method, [18F]FAPI-74 was administered for PET imaging to validate FAP expression. A single dose of [211At]FAPI1 (1.04 ± 0.10 MBq) was administered to evaluate the therapeutic efficacy. [18F]FAPI-74 exhibited high accumulation in MDA-MB-231 xenografts, and FAP expression was pathologically confirmed via immunostaining. The group that received [211At]FAPI1 (n = 11) demonstrated a significantly enhanced anti-tumor effect compared with the control group (n = 7) (p = 0.002). In conclusion, [18F]FAPI-74 PET imaging was successfully used to diagnose FAP expression, and as [211At]FAPI1 showed promising therapeutic efficacy in TNBC models, it is expected to be a viable therapeutic option.

Establishment and characterization of the PDAC-X3 cell line: a novel Chinese-origin pancreatic ductal adenocarcinoma cell line

In this study, a novel pancreatic cancer cell line, termed pancreatic ductal adenocarcinoma (PDAC)-X3 cell line, was successfully derived from the primary tumor. Comprehensive analyses of its malignant phenotype, molecular properties, specific biomarkers, and histological features confirmed that PDAC-X3 cells serve as a valuable model for investigating the underlying mechanisms driving pancreatic carcinogenesis and advancing potential therapeutic strategies. The newly established cell line was continuously cultured for over 12 months and was stably passaged through more than 50 generations. Morphologically, PDAC-X3 cells displayed characteristics typical of epithelial tumors. The population doubling time for PDAC-X3 cells was determined to be 50 h. Karyotype analysis revealed that 75% of PDAC-X3 cells presented as hypotriploid, while 25% were sub-tetraploid, with representative karyotypes being 53 and XY der (1) inv (9) der (22). In suspension culture, PDAC-X3 cells efficiently formed organoids. Upon inoculation into BALB/C nude mice, these cells initiated the development of xenograft tumors, achieving a tumor formation rate of 33%. Morphologically, these xenografted tumors closely resembled the primary tumor. Drug sensitivity assays indicated that PDAC-X3 cells exhibited resistance to oxaliplatin but demonstrated sensitivity to 5-Fluorouracil (5-FU), gemcitabine, and paclitaxel. Immunohistochemical analysis revealed that CK7, CK19, E-cadherin, Vimentin, CA19-9 were positively expressed in PDAC-X3 cells. Meanwhile, the expression rate for Ki-67 was 30%, and that for CEA was not detected. Our findings underscore that PDAC-X3 represents a novel pancreatic cancer cell line, positioning it as a valuable model for basic research and the advancement of therapeutic strategies against pancreatic cancer.

CYRI-B-mediated macropinocytosis drives metastasis via lysophosphatidic acid receptor uptake

Pancreatic ductal adenocarcinoma carries a dismal prognosis, with high rates of metastasis and few treatment options. Hyperactivation of KRAS in almost all tumours drives RAC1 activation, conferring enhanced migratory and proliferative capacity as well as macropinocytosis. Macropinocytosis is well understood as a nutrient scavenging mechanism, but little is known about its functions in trafficking of signalling receptors. We find that CYRI-B is highly expressed in pancreatic tumours in a mouse model of KRAS and p53-driven pancreatic cancer. Deletion of Cyrib (the gene encoding CYRI-B protein) accelerates tumourigenesis, leading to enhanced ERK and JNK-induced proliferation in precancerous lesions, indicating a potential role as a buffer of RAC1 hyperactivation in early stages. However, as disease progresses, loss of CYRI-B inhibits metastasis. CYRI-B depleted tumour cells show reduced chemotactic responses to lysophosphatidic acid, a major driver of tumour spread, due to impaired macropinocytic uptake of the lysophosphatidic acid receptor 1. Overall, we implicate CYRI-B as a mediator of growth and signalling in pancreatic cancer, providing new insights into pathways controlling metastasis.

Targeting ROCK2 improves macromolecular permeability in a 3D fibrotic pancreatic cancer microenvironment model

Pancreatic cancer is characterized by a densely fibrotic stroma. The fibrotic stroma hinders the intratumoral penetration of nanomedicine and diminishes therapeutic efficacy. Fibrosis is characterized by an abnormal organization of extracellular matrix (ECM) components, namely the abnormal deposition and/or orientation of collagen and fibronectin. Abnormal ECM organization is chiefly driven by pathological signaling in pancreatic stellate cells (PSCs), the main cell type involved in fibrogenesis. However, whether targeting signaling pathways involved in abnormal ECM organization improves the intratumoral penetration of nanomedicines is unknown. Here, we show that targeting transforming growth factor-β (TGFβ)/Rho-associated kinase (ROCK) 1/2 signaling in PSCs normalizes ECM organization and concomitantly improves macromolecular permeability of the fibrotic stroma. Using a 3-dimensional cell culture model of the fibrotic pancreatic cancer microenvironment, we found that pharmacological inhibition of TGFβ or ROCK1/2 improves the permeation of various macromolecules. By using an isoform-specific pharmacological inhibitor and siRNAs, we show that targeting ROCK2, but not ROCK1, alone is sufficient to normalize ECM organization and improve macromolecular permeability. Moreover, we found that ROCK2 inhibition/knockdown attenuates Yes-associated protein (YAP) nuclear localization in fibroblasts co-cultured with pancreatic cancer cells in 3D. Finally, pharmacological inhibition or siRNA-mediated knockdown of YAP normalized ECM organization and improved macromolecular permeability. Our results together suggest that the TGFβ/ROCK2/YAP signaling axis may be therapeutically targeted to normalize ECM organization and improve macromolecular permeability to augment therapeutic efficacy of nanomedicines in pancreatic cancer.

A novel method for detection of pancreatic Ductal Adenocarcinoma using explainable machine learning

BACKGROUND AND OBJECTIVE

Pancreatic Ductal Adenocarcinoma (PDAC) is a form of pancreatic cancer that is one of the primary causes of cancer-related deaths globally, with less than 10 % of the five years survival rate. The prognosis of pancreatic cancer has remained poor in the last four decades, mainly due to the lack of early diagnostic mechanisms. This study proposes a novel method for detecting PDAC using explainable and supervised machine learning from Raman spectroscopic signals.

METHODS

An insightful feature set consisting of statistical, peak, and extended empirical mode decomposition features is selected using the support vector machine recursive feature elimination method integrated with a correlation bias reduction. Explicable features successfully identified mutations in Kirsten rat sarcoma viral oncogene homolog (KRAS) and tumor suppressor protein53 (TP53) in the fingerprint region for the first time in the literature. PDAC and normal pancreas are classified using K-nearest neighbor, linear discriminant analysis, and support vector machine classifiers.

RESULTS

This study achieved a classification accuracy of 98.5% using a nonlinear support vector machine. Our proposed method reduced test time by 28.5 % and saved 85.6 % memory utilization, which reduces complexity significantly and is more accurate than the state-of-the-art method. The generalization of the proposed method is assessed by fifteen-fold cross-validation, and its performance is evaluated using accuracy, specificity, sensitivity, and receiver operating characteristic curves.

CONCLUSIONS

In this study, we proposed a method to detect and define the fingerprint region for PDAC using explainable machine learning. This simple, accurate, and efficient method for PDAC detection in mice could be generalized to examine human pancreatic cancer and provide a basis for precise chemotherapy for early cancer treatment.

Engrailed-1 Promotes Pancreatic Cancer Metastasis

Engrailed-1 (EN1) is a critical homeodomain transcription factor (TF) required for neuronal survival, and EN1 expression has been shown to promote aggressive forms of triple negative breast cancer. Here, it is reported that EN1 is aberrantly expressed in a subset of pancreatic ductal adenocarcinoma (PDA) patients with poor outcomes. EN1 predominantly repressed its target genes through direct binding to gene enhancers and promoters, implicating roles in the activation of MAPK pathways and the acquisition of mesenchymal cell properties. Gain- and loss-of-function experiments demonstrated that EN1 promoted PDA transformation and metastasis in vitro and in vivo. The findings nominate the targeting of EN1 and downstream pathways in aggressive PDA.

Functional and Clinical Proteomic Exploration of Pancreatic Cancer

Pancreatic cancer, most cases being pancreatic ductal adenocarcinoma (PDAC), is one of the most lethal cancers with a median survival time of less than 6 months. Therapeutic options are very limited for PDAC patients, and surgery is still the most effective treatment, making improvements in early diagnosis critical. One typical characteristic of PDAC is the desmoplastic reaction of its stroma microenvironment, which actively interacts with cancer cells to orchestrate key components in tumorigenesis, metastasis, and chemoresistance. Global exploration of cancer-stroma crosstalk is essential to decipher PDAC biology and design intervention strategies. Over the past decade, the dramatic improvement of proteomics technologies has enabled profiling of proteins, post-translational modifications (PTMs), and their protein complexes at unprecedented sensitivity and dimensionality. Here, starting with our current understanding of PDAC characteristics, including precursor lesions, progression models, tumor microenvironment, and therapeutic advancements, we describe how proteomics contributes to the functional and clinical exploration of PDAC, providing insights into PDAC carcinogenesis, progression, and chemoresistance. We summarize recent achievements enabled by proteomics to systematically investigate PTMs-mediated intracellular signaling in PDAC, cancer-stroma interactions, and potential therapeutic targets revealed by these functional studies. We also highlight proteomic profiling of clinical tissue and plasma samples to discover and verify useful biomarkers that can aid early detection and molecular classification of patients. In addition, we introduce spatial proteomic technology and its applications in PDAC for deconvolving tumor heterogeneity. Finally, we discuss future prospects of applying new proteomic technologies in comprehensively understanding PDAC heterogeneity and intercellular signaling networks. Importantly, we expect advances in clinical functional proteomics for exploring mechanisms of cancer biology directly by high-sensitivity functional proteomic approaches starting from clinical samples.

Therapeutic Strategies to Overcome Fibrotic Barriers to Nanomedicine in the Pancreatic Tumor Microenvironment

Pancreatic cancer is notorious for its dismal prognosis. The enhanced permeability and retention (EPR) effect theory posits that nanomedicines (therapeutics in the size range of approximately 10-200 nm) selectively accumulate in tumors. Nanomedicine has thus been suggested to be the "magic bullet"-both effective and safe-to treat pancreatic cancer. However, the densely fibrotic tumor microenvironment of pancreatic cancer impedes nanomedicine delivery. The EPR effect is thus insufficient to achieve a significant therapeutic effect. Intratumoral fibrosis is chiefly driven by aberrantly activated fibroblasts and the extracellular matrix (ECM) components secreted. Fibroblast and ECM abnormalities offer various potential targets for therapeutic intervention. In this review, we detail the diverse strategies being tested to overcome the fibrotic barriers to nanomedicine in pancreatic cancer. Strategies that target the fibrotic tissue/process are discussed first, which are followed by strategies to optimize nanomedicine design. We provide an overview of how a deeper understanding, increasingly at single-cell resolution, of fibroblast biology is revealing the complex role of the fibrotic stroma in pancreatic cancer pathogenesis and consider the therapeutic implications. Finally, we discuss critical gaps in our understanding and how we might better formulate strategies to successfully overcome the fibrotic barriers in pancreatic cancer.

Preclinical models derived from endoscopic ultrasound-guided tissue acquisition for individualized treatment of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with poor outcomes. Although the management strategies have evolved in recent years, the PDAC 5-year survival rate remains at only 9%; it may become the second leading cause of cancer death in the USA by 2030. Only 15-20% of PDAC patients are eligible to undergo surgery; diagnostic biopsies and individualized treatment present a more significant challenge for the remaining group. Endoscopic ultrasound-guided tissue acquisition (EUS-TA) has been widely used in the diagnosis of pancreatic masses. With the advancement of this sampling technique, adequate specimens can be obtained from all patients with PDAC in both early and late clinical stages. Recent data suggest that the specimens obtained from EUS-TA might be used to establish viable preclinical models, which conserve the genetic mutation and preserve the heterogeneity of the original tumors. Additionally, any drug sensitivity evident in the EUS-TA-derived preclinical models might predict the clinical response, thus guiding the prospective therapeutic selection. As we move toward the era of precision medicine, this review provides an update on the role of EUS-TA as a method for obtaining genetic material used in preclinical models that can assess and stratify individuals according to their individual cancer biology.

Tumor extracellular matrix modulating strategies for enhanced antitumor therapy of nanomedicines

Nanomedicines have shown a promising strategy for cancer therapy because of their higher safety and efficiency relative to small-molecule drugs, while the dense extracellular matrix (ECM) in tumors often acts as a physical barrier to hamper the accumulation and diffusion of nanoparticles, thus compromising the anticancer efficacy. To address this issue, two major strategies including degrading ECM components and inhibiting ECM formation have been adopted to enhance the therapeutic efficacies of nanomedicines. In this review, we summarize the recent progresses of tumor ECM modulating strategies for enhanced antitumor therapy of nanomedicines. Through degrading ECM components or inhibiting ECM formation, the accumulation and diffusion of nanoparticles in tumors can be facilitated, leading to enhanced efficacies of chemotherapy and phototherapy. Moreover, the ECM degradation can improve the infiltration of immune cells into tumor tissues, thus achieving strong immune response to reject tumors. The adoptions of these two ECM modulating strategies to improve the efficacies of chemotherapy, phototherapy, and immunotherapy are discussed in detail. A conclusion, current challenges and outlook are then given.

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Extracellular matrix modulating strategies have been adopted to enhance the therapeutic efficacies of nanomedicines.

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Degrading extracellular matrix components or inhibiting extracellular matrix formation can improve the accumulation and diffusion of nanoparticles in tumors and the infiltration of immune cells into tumor tissues.

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The adoptions of two extracellular matrix modulating strategies to improve the efficacies of chemotherapy, phototherapy, and immunotherapy are summarized.

Individualized therapy based on the combination of mini-PDX and NGS for a patient with metastatic AFP-producing and HER-2 amplified gastric cancer

Mini-patient-derived xenograft (mini-PDX) is a novel, rapid and accurate method used to assess in vivo drug susceptibility. In the present study, a mini-PDX combined with next-generation sequencing (NGS) was used to guide the individualized treatment of a patient with metastatic a-fetoprotein-producing and human epidermal growth factor receptor 2 (HER-2) amplified gastric cancer (GC). Tumor cells were isolated from the tumor tissue obtained from gastroscopic biopsy, transferred into capsules and implanted into severe combined immunodeficiency mice to determine their sensitivity to various drug regimens. NGS was also performed to assess the mutation spectrum of the cells. The results were analyzed to select the most appropriate treatment regimen for the patient. The mini-PDX model confirmed that the patient's tumor was sensitive to a combination regimen of irinotecan and tegafur-gimeracil-oteracil (S-1). Fluorescence in situ hybridization assay of the tumor tissue confirmed HER-2 amplification. The NGS results indicated ERBB2 amplification, and tumor protein P53 [c.659A>G (p.Y220C)], ataxia-telengiectasia mutated [c.125A>G (p.H42R)] and MutS homolog 6 [c.3254C(8>7) (p.F1088Sfs*2)] mutation, in which UGT1A1*28, TA6/7 (rs8175347) was a mutant heterozygote. After six courses of treatment with a regimen comprising 300 mg irinotecan on day 1 + 40 mg S-1 twice daily on days 2-15 + 350 mg trastuzumab once-every 3 weeks, the patient continued with S-1 treatment for 4 courses and trastuzumab for 1 year. The patient retained progression-free survival status at the 32-month follow-up. Thus, the mini-PDX model combined with the NGS rapidly assessed drug sensitivity in a patient with GC and revealed key genetic mutations. However, the proposed technique requires further research to confirm its potential in the individualized treatment of patients with refractory malignancies.

Research progress in the establishment of pancreatic cancer models and preclinical applications

Pancreatic cancer (PC) is a highly malignant tumor in the digestive system. The transformation of tissue from normal to pancreatic intraepithelial neoplasm is driven by certain oncogenes, among which the mutation rate of the KRAS gene is as high as 90%. Currently, PC has limited treatment options, low therapeutic effects, and poor prognosis. Thus, more effective methods to combat PC are urgently needed. Some models that can more accurately reflect the biological behaviors and genomic characteristics of PC, such as its morphology, pathology, proliferation, and invasion, are being continuously developed. These include genetic engineering models, orthotopic xenograft models, and heterotopic xenograft models. Using these PC models, scientists have further verified promising drugs and potential therapeutic targets for PC treatment. This is of great significance for limiting the progression of PC with clinical intervention, improving patient outcomes, and improving survival rates.

Programmable Living Units for Emulating Pancreatic Tumor-Stroma Interplay

Bioengineering close-to-native in vitro models that emulate tumors bioarchitecture and microenvironment is highly appreciable for improving disease modeling toolboxes. Herein, pancreatic cancer living units-so termed cancer-on-a-bead models-are generated. Such user-programmable in vitro platforms exhibit biomimetic multicompartmentalization and tunable integration of cancer associated stromal elements. These stratified units can be rapidly assembled in-air, exhibit reproducible morphological features, tunable size, and recapitulate spatially resolved tumor-stroma extracellular matrix (ECM) niches. Compartmentalization of pancreatic cancer and stromal cells in well-defined ECM microenvironments stimulates the secretion of key biomolecular effectors including transforming growth factor β and Interleukin 1-β, closely emulating the signatures of human pancreatic tumors. Cancer-on-a-bead models also display increased drug resistance to chemotherapeutics when compared to their reductionistic counterparts, reinforcing the importance to differentially model ECM components inclusion and their spatial stratification as observed in vivo. Beyond providing a universal technology that enables spatial modularity in tumor-stroma elements bioengineering, a scalable, in-air fabrication of ECM-tunable 3D platforms that can be leveraged for recapitulating differential matrix composition occurring in other human neoplasias is provided here.

Germline Aberrations in Pancreatic Cancer: Implications for Clinical Care

Pancreatic ductal adenocarcinoma (PDAC) has an extremely poor prognosis and represents a major public health issue, as both its incidence and mortality are expecting to increase steeply over the next years. Effective screening strategies are lacking, and most patients are diagnosed with unresectable disease precluding the only chance of cure. Therapeutic options for advanced disease are limited, and the treatment paradigm is still based on chemotherapy, with a few rare exceptions to targeted therapies. Germline variants in cancer susceptibility genes-particularly those involved in mechanisms of DNA repair-are emerging as promising targets for PDAC treatment and prevention. Hereditary PDAC is part of the spectrum of several syndromic disorders, and germline testing of PDAC patients has relevant implications for broad cancer prevention. Germline aberrations in BRCA1 and BRCA2 genes are predictive biomarkers of response to poly(adenosine diphosphate-ribose) polymerase (PARP) inhibitor olaparib and platinum-based chemotherapy in PDAC, while mutations in mismatch repair genes identify patients suitable for immune checkpoint inhibitors. This review provides a timely and comprehensive overview of germline aberrations in PDAC and their implications for clinical care. It also discusses the need for optimal approaches to better select patients for PARP inhibitor therapy, novel therapeutic opportunities under clinical investigation, and preclinical models for cancer susceptibility and drug discovery.

State-matched organoid models to fight pancreatic cancer

As one of the deadliest cancers, pancreatic ductal adenocarcinoma (PDAC) requires sophisticated model systems to dissect disease onset, progression, and therapy resistance, as well as to personalize therapy. In recent years, patient- and pluripotent stem cell-derived organoids have become state-of-the-art systems to refine existing therapeutic strategies and deepen our knowledge of disease pathophysiology.

Establishment of a mouse model of pancreatic cancer using human pancreatic cancer cell line S2-013-derived organoid

A well-established preclinical model of pancreatic cancer needs to be established to facilitate research on new therapeutic targets. Recently established animal models of pancreatic cancer, including patient-derived tumor models and organoid models, are used for pre-clinical drug testing and biomarker discovery. These models have useful characteristics over conventional xenograft mouse models based on cell lines in preclinical studies, but still cannot accurately predict the clinical outcomes of new treatments and have not yet been broadly implemented in research. We employed pancreatic cancer organoid culture methods using the pancreatic cancer cell line S2-013, and performed pathological and immunohistochemical analyses to characterize tumor xenografts obtained from a mouse model implanted with S2-013 cell line-derived organoids. Serum levels of the pancreatic cancer tumor marker CA19-9 were measured by ELISA. We generated human pancreatic cancer organoids using a co-culture of S2-013 cells, human endothelial cells derived from human umbilical vein endothelial cells, and human mesenchymal stem cells, and established a mouse model with subcutaneously transplanted human pancreatic cancer organoids (S2-013-organoid model). Although blood clotting crater-like formation developed in the middle of subcutaneous xenografts in the S2-013-conventional model, created by subcutaneously injecting S2-013 cells into the right flank of nude mice, the size of xenografts in the S2-013-organoid model gradually increased without crater-like formation. Importantly, tumor xenografts obtained from the S2-013-organoid model exhibited a clinical human pancreatic cancer tissue-like cellular morphology, tissue architecture, and polarity, and actively formed cancer stroma containing mature blood vessels with the high expression of the vascular tight junction marker CD31. In subcutaneous xenografts of S2-013-conventional mice, no blood vessel density or widely expanding areas of necrotic regions were present. Consequently, serum levels of CA19-9 in the S2-013-organoid model correlated with tumor volumes. In addition, epithelial–mesenchymal transition, the conversion of epithelial cells to the mesenchymal phenotype, was observed in tumor xenografts of the S2-013-organoid model. The S2-013-organoid model provides tumor xenografts consisting of clinical human pancreatic cancer-like tissue formation with the effective development of vascularized stroma, and may be valuable for facilitating studies on pre-clinical drug testing and biomarker discovery.

Decellularized In Vitro Capillaries for Studies of Metastatic Tendency and Selection of Treatment

Vascularization plays an important role in the microenvironment of the tumor. Therefore, it should be a key element to be considered in the development of in vitro cancer assays. In this study, we decellularized in vitro capillaries to remove genetic material and optimized the medium used to increase the robustness and versatility of applications. The growth pattern and drug responses of cancer cell lines and patient-derived primary cells were studied on decellularized capillaries. Interestingly, two distinct growth patterns were seen when cancer cells were grown on decellularized capillaries: “network” and “cluster”. Network formation correlated with the metastatic properties of the cells and cluster formation was observed in non-metastatic cells. Drug responses of patient-derived cells correlated better with clinical findings when cells were cultured on decellularized capillaries compared with those cultured on plastic. Decellularized capillaries provide a novel method for cancer cell culture applications. It bridges the gap between complex 3D culture methods and traditional 2D culture methods by providing the ease and robustness of 2D culture as well as an in vivo-like microenvironment and scaffolding for 3D cultures.

Smart Nanoparticles as Advanced Anti-Akt Kinase Delivery Systems for Pancreatic Cancer Therapy

Pancreatic cancer is one of the deadliest cancers partly due to late diagnosis, poor drug delivery to the target site, and acquired resistance to therapy. Therefore, more effective therapies are urgently needed to improve the outcome of patients. In this work, we have tested self-assembling genetically engineered polymeric nanoparticles formed by elastin-like recombinamers (ELRs), carrying a small peptide inhibitor of the protein kinase Akt, in both PANC-1 and patient-derived pancreatic cancer cells (PDX models). Nanoparticle cell uptake was measured by flow cytometry, and subcellular localization was determined by confocal microscopy, which showed a lysosomal localization of these nanoparticles. Furthermore, metabolic activity and cell viability were significantly reduced after incubation with nanoparticles carrying the Akt inhibitor in a time- and dose-dependent fashion. Self-assembling 73 ± 3.2 nm size nanoparticles inhibited phosphorylation and consequent activation of Akt protein, blocked the NF-κB signaling pathway, and triggered caspase 3-mediated apoptosis. Furthermore, in vivo assays showed that ELR-based nanoparticles were suitable devices for drug delivery purposes with long circulating time and minimum toxicity. Hence, the use of these smart nanoparticles could lead to the development of more effective treatment options for pancreatic cancer based on the inhibition of Akt.

Pre-clinical Models of Metastasis in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is a hostile solid malignancy coupled with an extremely high mortality rate. Metastatic disease is already found in most patients at the time of diagnosis, resulting in a 5-year survival rate below 5%. Improved comprehension of the mechanisms leading to metastasis is pivotal for the development of new targeted therapies. A key field to be improved are modeling strategies applied in assessing cancer progression, since traditional platforms fail in recapitulating the complexity of PDAC. Consequently, there is a compelling demand for new preclinical models that mirror tumor progression incorporating the pressure of the immune system, tumor microenvironment, as well as molecular aspects of PDAC. We suggest the incorporation of 3D organoids derived from genetically engineered mouse models or patients as promising new tools capable to transform PDAC pre-clinical modeling and access new frontiers in personalized medicine.

The Diverse Applications of Pancreatic Ductal Adenocarcinoma Organoids

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal solid malignancies. While immortalized cancer cell lines and genetically engineered murine models have increased our understanding of PDAC tumorigenesis, they do not recapitulate inter- and intra-patient heterogeneity. PDAC patient derived organoid (PDO) biobanks have overcome this hurdle, and provide an opportunity for the high throughput screening of potential new therapies. This review provides a summary of the PDAC PDO biobanks established to date, and discusses how they have advanced our understanding of PDAC biology. Looking forward, the development of coculturing techniques for specific immune or stromal cell populations will enable a better understanding of the crosstalk that occurs within the tumor microenvironment, and the impact of this crosstalk on treatment response.

Models of pancreatic ductal adenocarcinoma

Although pancreatic cancer remains to be a leading cause of cancer-related deaths in many industrialized countries, there have been major advances in research over the past two decades that provided a detailed insight into the molecular and developmental processes that govern the genesis of this highly malignant tumor type. There is a continuous need for the development and analysis of preclinical and genetically engineered pancreatic cancer models to study the biological significance of new molecular targets that are identified using various genome-wide approaches and to better understand the mechanisms by which they contribute to pancreatic cancer onset and progression. Following an introduction into the etiology of pancreatic cancer, the molecular subtypes, and key signaling pathways, this review provides an overview of the broad spectrum of models for pancreatic cancer research. In addition to conventional and patient-derived xenografting, this review highlights major milestones in the development of chemical carcinogen-induced and genetically engineered animal models to study pancreatic cancer. Particular emphasis was placed on selected research findings of ligand-controlled tumor models and current efforts to develop genetically engineered strains to gain insight into the biological functions of genes at defined developmental stages during cancer initiation and metastatic progression.

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.

Tissue-Engineering the Fibrous Pancreatic Tumour Stroma Capsule in 3D Tumouroids to Demonstrate Paclitaxel Response

Pancreatic cancer is a unique cancer in that up to 90% of its tumour mass is composed of a hypovascular and fibrotic stroma. This makes it extremely difficult for chemotherapies to be delivered into the core of the cancer mass. We tissue-engineered a biomimetic 3D pancreatic cancer ("tumouroid") model comprised of a central artificial cancer mass (ACM), containing MIA Paca-2 cells, surrounded by a fibrotic stromal compartment. This stromal compartment had a higher concentration of collagen type I, fibronectin, laminin, and hyaluronic acid (HA) than the ACM. The incorporation of HA was validated with alcian blue staining. Response to paclitaxel was determined in 2D MIA Paca-2 cell cultures, the ACMs alone, and in simple and complex tumouroids, in order to demonstrate drug sensitivity within pancreatic tumouroids of increasing complexity. The results showed that MIA Paca-2 cells grew into the complex stroma and invaded as cell clusters with a maximum distance of 363.7 µm by day 21. In terms of drug response, the IC50 for paclitaxel for MIA Paca-2 cells increased from 0.819 nM in 2D to 3.02 nM in ACMs and to 5.87 nM and 3.803 nM in simple and complex tumouroids respectively, indicating that drug penetration may be significantly reduced in the latter. The results demonstrate the need for biomimetic models during initial drug testing and evaluation.

The Revolutionary Roads to Study Cell-Cell Interactions in 3D In Vitro Pancreatic Cancer Models

Pancreatic cancer, the fourth most common cancer worldwide, shows a highly unsuccessful therapeutic response. In the last 10 years, neither important advancements nor new therapeutic strategies have significantly impacted patient survival, highlighting the need to pursue new avenues for drug development discovery and design. Advanced cellular models, resembling as much as possible the original in vivo tumor environment, may be more successful in predicting the efficacy of future anti-cancer candidates in clinical trials. In this review, we discuss novel bioengineered platforms for anticancer drug discovery in pancreatic cancer, from traditional two-dimensional models to innovative three-dimensional ones.

Preclinical Models of Pancreatic Ductal Adenocarcinoma and Their Utility in Immunotherapy Studies

Simple Summary

Immune checkpoint blockade has provided durable clinical responses in a number of human malignancies, but not in patients with pancreatic cancer. Efforts to understand mechanisms of resistance and increase efficacy of immune checkpoint blockade in pancreatic cancer require the use of appropriate preclinical models in the laboratory. Here, we discuss the benefits, caveats, and potentials for improvement of the most commonly used models, including murine-based and patient-derived models.

Abstract

The advent of immunotherapy has transformed the treatment landscape for several human malignancies. Antibodies against immune checkpoints, such as anti-PD-1/PD-L1 and anti-CTLA-4, demonstrate durable clinical benefits in several cancer types. However, checkpoint blockade has failed to elicit effective anti-tumor responses in pancreatic ductal adenocarcinoma (PDAC), which remains one of the most lethal malignancies with a dismal prognosis. As a result, there are significant efforts to identify novel immune-based combination regimens for PDAC, which are typically first tested in preclinical models. Here, we discuss the utility and limitations of syngeneic and genetically-engineered mouse models that are currently available for testing immunotherapy regimens. We also discuss patient-derived xenograft mouse models, human PDAC organoids, and ex vivo slice cultures of human PDAC tumors that can complement murine models for a more comprehensive approach to predict response and resistance to immunotherapy regimens.

Microenvironmental Determinants of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) belongs to the most lethal solid tumors in humans. A histological hallmark feature of PDAC is the pronounced tumor microenvironment (TME) that dynamically evolves during tumor progression. The TME consists of different non-neoplastic cells such as cancer-associated fibroblasts, immune cells, endothelial cells, and neurons. Furthermore, abundant extracellular matrix components such as collagen and hyaluronic acid as well as matricellular proteins create a highly dynamic and hypovascular TME with multiple biochemical and physical interactions among the various cellular and acellular components that promote tumor progression and therapeutic resistance. In recent years, intensive research efforts have resulted in a significantly improved understanding of the biology and pathophysiology of the TME in PDAC, and novel stroma-targeted approaches are emerging that may help to improve the devastating prognosis of PDAC patients. However, none of anti-stromal therapies has been approved in patients so far, and there is still a large discrepancy between multiple successful preclinical results and subsequent failure in clinical trials. Furthermore, recent findings suggest that parts of the TME may also possess tumor-restraining properties rendering tailored therapies even more challenging.

Three-Dimensional Cell Culture Systems in Radiopharmaceutical Cancer Research

In preclinical cancer research, three-dimensional (3D) cell culture systems such as multicellular spheroids and organoids are becoming increasingly important. They provide valuable information before studies on animal models begin and, in some cases, are even suitable for reducing or replacing animal experiments. Furthermore, they recapitulate microtumors, metastases, and the tumor microenvironment much better than monolayer culture systems could. Three-dimensional models show higher structural complexity and diverse cell interactions while reflecting (patho)physiological phenomena such as oxygen and nutrient gradients in the course of their growth or development. These interactions and properties are of great importance for understanding the pathophysiological importance of stromal cells and the extracellular matrix for tumor progression, treatment response, or resistance mechanisms of solid tumors. Special emphasis is placed on co-cultivation with tumor-associated cells, which further increases the predictive value of 3D models, e.g., for drug development. The aim of this overview is to shed light on selected 3D models and their advantages and disadvantages, especially from the radiopharmacist's point of view with focus on the suitability of 3D models for the radiopharmacological characterization of novel radiotracers and radiotherapeutics. Special attention is paid to pancreatic ductal adenocarcinoma (PDAC) as a predestined target for the development of new radionuclide-based theranostics.

Proteomic Analysis of Cell Lines and Primary Tumors in Pancreatic Cancer Identifies Proteins Expressed Only In Vitro and Only In Vivo

OBJECTIVES

A limited repertoire of good pancreatic ductal adenocarcinoma (PDAC) models is one of the main barriers in developing effective new PDAC treatments. We aimed to characterize 6 commonly used PDAC cell lines and compare them with PDAC patient tumor samples using proteomics.

METHODS

Proteomic methods were used to generate an extensive catalog of proteins from 10 PDAC surgical specimens, 9 biopsies of adjacent normal tissue, and 6 PDAC cell lines. Protein lists were interrogated to determine what extent the proteome of the cell lines reflects the proteome of primary pancreatic tumors.

RESULTS

We identified 7973 proteins from the cell lines, 5680 proteins from the tumor tissues, and 4943 proteins from the adjacent normal tissues. We identified 324 proteins unique to the cell lines, some of which may play a role in survival of cells in culture. Conversely, a list of 63 proteins expressed only in the patient samples, whose expression is lost in culture, may place limitations on the degree to which these model systems reflect tumor biology in vivo.

CONCLUSIONS

Our work offers a catalog of proteins detected in each of the PDAC cell lines, providing a useful guide for researchers seeking model systems for PDAC functional studies.

Promising xenograft animal model recapitulating the features of human pancreatic cancer

BACKGROUND

Multiple sites of metastasis and desmoplastic reactions in the stroma are key features of human pancreatic cancer (PC). There are currently no simple and reliable animal models that can mimic these features for accurate disease modeling.

AIM

To create a new xenograft animal model that can faithfully recapitulate the features of human PC.

METHODS

Interleukin 2 receptor subunit gamma (IL2RG) gene knockout Syrian hamster was created and characterized. A panel of human PC cell lines were transplanted into IL2RG knockout Syrian hamsters and severe immune-deficient mice subcutaneously or orthotopically. Tumor growth, local invasion, remote organ metastasis, histopathology, and molecular alterations of tumor cells and stroma were compared over time.

RESULTS

The Syrian hamster with IL2RG gene knockout (named ZZU001) demonstrated an immune-deficient phenotype and function. ZZU001 hamsters faithfully recapitulated most features of human PC, in particular, they developed metastasis at multiple sites. PC tissues derived from ZZU001 hamsters displayed desmoplastic reactions in the stroma and epithelial to mesenchymal transition phenotypes, whereas PC tissues derived from immune-deficient mice did not present such features.

CONCLUSION

ZZU001 hamsters engrafted with human PC cells are a superior animal model compared to immune-deficient mice. ZZU001 hamsters can be a valuable animal model for better understanding the molecular mechanism of tumorigenesis and metastasis and the evaluation of new drugs targeting human PC.

The physiological characteristics of the basal microvilli microvessels in pancreatic cancers

Pancreatic cancer (PC) is a highly lethal tumor with controversial high glucose uptake and hypomicrovascularity, and the hypomicrovasculature, which is considered to have poor perfusion, blocks the delivery of drugs to tumors. The preferential existence of a novel endothelial projection with trafficking vesicles in PCs, referring to basal microvilli, was described previously. However, the perfusion and nutrients delivering status of the basal microvilli microvessels are unknown. Here, we used the perfusion of fluorescently labeled CD31 antibody, lectin, and 2‐NBDG to autochthonous PC‐bearing mice, immunostaining, probe‐based confocal laser endoscopy and three‐dimensional (3D) reconstruction to study the nutrient trafficking, and perfusion status of the basal microvilli microvasculature in PC. Our data showed that the coperfusion of lectin and CD31 is an efficient way to show the microcirculation in most healthy organs. However, coperfusion with lectin and CD31 is inefficient for showing the microcirculation in PCs compared with that in healthy organs and immunostaining. This method does not reflect the nutrient trafficking status in the microvessels, especially in basal microvilli microvessels of PCs. In basal microvilli microvessels that were poorly labeled by lectin, we observed large vesicle‐like structures with 2‐NBDG preferentially located at the base of the basal microvilli or in basal microvilli, and there were long filopodia on the luminal surface of the human PC microvasculature. Our observations suggest that the PC microvasculature, especially basal microvilli microvessels, is well perfused and might be highly efficient in the trafficking of glucose or other nutrients, indicating that macropinocytosis might participate in the nutrient trafficking.

Long non-coding RNA MVIH promotes cell proliferation, migration, invasion through regulating multiple cancer-related pathways, and correlates with worse prognosis in pancreatic ductal adenocarcinomas

We aimed to explore the effect of long non-coding RNA MVIH (lnc-MVIH) on cell proliferation, migration as well as invasion, and investigate the landscape of its molecular mechanism in pancreatic ductal adenocarcinomas (PDAC). Control overexpression (OE-NC group) and lnc-MVIH overexpression (OE-MVIH group) plasmids were transfected in BxPC-3 cells; control knock-down (KD-NC group) and lnc-MVIH knock-down (KD-MVIH group) plasmids were transfected in PANC-1 cells. Cellular functions were measured and mRNA sequencing was conducted. In 70 PDAC patients, lnc-MVIH expression in tumor and adjacent tissues was detected. Lnc-MVIH expression was higher in human PDAC cell lines than human normal pancreatic ductal epithelial cell line. Cell proliferation, migration and invasion were increased in OE-MVIH group compared to OE-NC group, but decreased in KD-MVIH group compared to KD-NC group. mRNA sequencing showed 145 differentially expressing genes (DEGs) upregulated in OE-MVIH group vs. OE-NC group and downregulated in KD-MVIH group vs. KD-NC group, and 51 DEGs downregulated in OE-MVIH group vs. OE-NC group and upregulated in KD-MVIH group vs. KD-NC group. These DEGs were enriched in several cancer-related pathways (including Hippo signaling pathway, cell cycle, Forkhead box O signaling pathway, apoptosis and advanced glycation end products-RAGE signaling pathway), and the effect of lnc-MVIH on regulating these DEGs was further validated by RT-qPCR. In PDAC patients, lnc-MVIH expression was increased in tumor tissue and correlated with advanced tumor size, lymph node metastasis, TNM stage and poor OS. In conclusion, lnc-MVIH might be a potential therapeutic target which regulated multiple cancer-related pathways in PDAC.

Polymer nanoparticle-assisted chemotherapy of pancreatic cancer

Pancreatic cancer is a lethal disease characterized by highly dense stroma fibrosis. Only 15-20% of patients with pancreatic cancer have resectable tumors, and only around 20% of them survive to 5 years. Traditional cancer treatments have little effect on their prognosis, and successful surgical resection combined with effective perioperative therapy is the main method for maximizing long-term survival. For this reason, chemotherapy is an adjunct treatment for resectable cancer and is the main therapy for incurable pancreatic cancer, including metastatic pancreatic adenocarcinoma. However, there are various side effects of chemotherapeutic medicine and low drug penetration because the complex tumor microenvironment limits the application of chemotherapy. As a novel strategy, polymer nanoparticles make it possible to target the tumor microenvironment, release cytotoxic agents through various responsive reactions, and thus overcome the treatment barrier. As drug carriers, polymer nanoparticles show marked advantages, such as increased drug delivery and efficiency, controlled drug release, decreased side effects, prolonged half-life, and evasion of immunogenic blockade. In this review, we discuss the factors that cause chemotherapy obstacles in pancreatic cancer, and introduce the application of polymer nanoparticles to treat pancreatic cancer.

Zebrafish Xenografts for Drug Discovery and Personalized Medicine

Cancer is the second leading cause of death in the world. Given that cancer is a highly individualized disease, predicting the best chemotherapeutic treatment for individual patients can be difficult. Ex vivo models such as mouse patient-derived xenografts (PDX) and organoids are being developed to predict patient-specific chemosensitivity profiles before treatment in the clinic. Although promising, these models have significant disadvantages including long growth times that introduce genetic and epigenetic changes to the tumor. The zebrafish xenograft assay is ideal for personalized medicine. Imaging of the small, transparent fry is unparalleled among vertebrate organisms. In addition, the speed (5-7 days) and small patient tissue requirements (100-200 cells per animal) are unique features of the zebrafish xenograft model that enable patient-specific chemosensitivity analyses.

Pancreatic Ductal Adenocarcinoma: MicroRNAs Affecting Tumor Growth and Metastasis in Preclinical In Vivo Models

Patients with pancreatic ductal adenocarcinoma have a dismall prognosis because at the time of diagnosis, in the vast majority of patients the tumor has already disseminated to distant organs and the therapeutic benefit of approved agents such as gemcitabine is limited. Therefore, the identification and preclinical and clinical validation of therapeutic agents covering new targets is of paramount importance. In this review we have summarized microRNAs and corresponding targets which affect growth and metastasis of pancreatic tumors in preclinical mouse in vivo models. We identified four up-regulated and 16 down-regulated miRs in PDAC in comparison to corresponding normal tissues. Three sub-categories of miRs have emerged: miRs affecting tumor growth and miRs with an impact on both, tumor growth and metastasis or metastasis only. Finally, we discuss technical and therapeutic aspects of miR-related therapeutic agents for the treatment of pancreatic ductal adenocarcinoma.

Synergistic cytotoxicity and co-autophagy inhibition in pancreatic tumor cells and cancer-associated fibroblasts by dual functional peptide-modified liposomes

Pancreatic ductal adenocarcinoma (PDA) is a highly fatal disease with 5-year survival of ∼8.5%. Nanoplatforms such as nab-paclitaxel and nanoliposomal irinotecan demonstrate superiority and utility in treating different progressions of PDA by prolonging the median overall survival by only a few months. Due to the dense surrounding stroma and the high autophagy in pancreatic cancer, integrin ɑ_vβ₃ targeting, acid environmental sensitive, TR peptide-modified liposomal platforms loaded with combined autophagy inhibiting hydroxychloroquine (HCQ), and cytotoxic paclitaxel (PTX) were designed (TR-PTX/HCQ-Lip) to accomplish the aim of synergistically killing tumor cells while inhibiting stroma fibrosis. The results showed that TR peptide-modified liposomes (TR-Lip) have superior targeting and penetrating effects both in vitro and in vivo. TR-PTX/HCQ-Lip efficiently inhibited autophagy in pancreatic cells and surrounding cancer-associated fibroblasts. The synergistic anti-fibrosis roles were also confirmed both in vitro and in vivo, all of which contributes to the enhanced curative effects of TR-PTX/HCQ-Lip in both heterogenetic and orthotopic pancreatic cancer models. STATEMENT OF SIGNIFICANCE: Autophagy plays a significant role in pancreatic ductal adenocarcinoma, especially in activating cancer associated fibroblasts which is also related to collagen generation that promotes the formation of dense stroma, which hinder the cytotoxic drugs to target and kill cancer cells. In this study, we designed integrin ɑvβ3 targeting, acid environmental sensitive liposomal platforms to co-loaded paclitaxel and the autophagy inhibitor hydroxychloroquine. The results showed that the muti-functional liposomes can target to the pancreatic tumor and efficiently kill tumor cells and inhibit stroma fibrosis, thus improve the therapeutic effect in orthotopic pancreatic cancer models.

Towards manufacturing of human organoids

Organoids are 3D miniature versions of organs produced from stem cells derived from either patient or healthy individuals in vitro that recapitulate the actual organ. Organoid technology has ensured an alternative to pre-clinical drug testing as well as being currently used for "personalized medicine" to modulate the treatment as they are uniquely identical to each patient's genetic makeup. Researchers have succeeded in producing different types of organoids and have demonstrated their efficient application in various fields such as disease modeling, pathogenesis, drug screening and regenerative medicine. There are several protocols for fabricating organoids in vitro. In this comprehensive review, we focus on key methods of producing organoids and manufacturing considerations for each of them while providing insights on the advantages, applications and challenges of these methods. We also discuss pertinent challenges faced during organoid manufacturing and various bioengineering approaches that can improve the organoid manufacturing process. Organoids size, number and the reproducibility of the fabrication processes are touched upon. The major factors which are involved in organoids manufacturing such as spatio-temporal controls, scaffold designs/types, cell culture parameters and vascularization have been highlighted.

Downregulation of thymopoietin by miR-139-5p suppresses cell proliferation and induces cell cycle arrest/apoptosis in pancreatic ductal adenocarcinoma

MicroRNAs (miRNAs) serve a pivotal role in tumor development and progression, in which miRNA (miR)-139-5p functions as a tumor suppressor. However, the functions and mechanisms of miR-139-5p in pancreatic ductal adenocarcinoma (PDAC) remain unclear. In the present study, it was found that miR-139-5p was markedly decreased in PDAC tissues and cell lines. Noticeably, thymopoietin (TMPO) was predicted and confirmed as a direct target of miR-139-5p using a luciferase reporter system. The expression level of miR-139-5p was inversely associated with the expression of TMPO in PDAC specimens. A series of gain-of-function assays elucidated that the overexpression of miR-139-5p suppressed cell proliferation, and induced cell cycle arrest and cell apoptosis, determined with a Cell Counting Kit-8, colony formation assays and flow cytometry, respectively. Furthermore, the re-expression of TMPO eliminated the effects of miR-139-5p on cell proliferation, cell cycle progression and apoptosis. In summary, these findings demonstrated that miR-139-5p may be a tumor suppressor in PDAC, which may be useful in developing promising therapies for PDAC.

Development of Patient-Derived Preclinical Platform for Metastatic Pancreatic Cancer: PDOX and a Subsequent Organoid Model System Using Percutaneous Biopsy Samples

Pancreatic ductal adenocarcinoma (PDAC) is the most lethal malignant tumor and more than 50% patients are diagnosed at metastatic stage. The preclinical model systems that reflect the genetic heterogeneity of metastatic tumors are urgently needed to guide optimal treatment. This study describes the development of patient-derived preclinical platform using very small sized-percutaneous liver gun biopsy (PLB) of metastatic pancreatic cancer, based on patient-derived xenograft (PDX)-mediated tissue amplification and subsequent organoid generation. To increase the success rate and shorten the tumor growth period, patient-derived orthotopic xenograft (PDOX) model was developed to directly implant threadlike PLB samples into the pancreas. The engraftment success rate of PDOX samples from 35 patients with metastatic PDAC was 47%, with these samples showing the potential to metastasize to distant organs, as in patients. The PDOX models retained the genetic alterations and histopathological features of the primary tumors. Tumor organoids were subsequently generated from first passage cancer cells isolated from F1 tumor tissue of PDOX that preserve the epithelial cancer characteristics and KRAS mutations of primary tumors. The response to gemcitabine of PDOX-derived organoids correlated with clinical outcomes in corresponding patients as well as PDOX models in vivo, suggesting that this PDOX-organoid system reflects clinical conditions. Collectively, these findings indicate that the proposed PDOX-organoid platform using PLB samples assessed both in vitro and in vivo could predict drug response under conditions closer to those found in actual patients, as well as enhancing understanding of the complexity of metastatic PDAC.

Establishment and Analysis of a 3D Co-Culture Spheroid Model of Pancreatic Adenocarcinoma for Application in Drug Discovery

The high attrition rate of oncology drug candidates can be in part explained by the disconnect between the standard preclinical models (e.g., 2D culture, xenograft tumors) commonly employed for drug discovery and the complex multicellular microenvironment of human cancers. As such, significant focus has recently shifted to the establishment of preclinical models that more closely recapitulate human tumors, such as patient-derived xenografts, 3D spheroids, humanized mice, and mixed-culture models. For these models to be suited to drug discovery, they should optimally exhibit reproducibility, high-throughput, and robust and simple assay readouts. In this article, we describe a protocol for the generation of an in vitro 3D co-culture spheroid model that recapitulates the interaction of tumor cells with stromal fibroblasts in pancreatic adenocarcinoma. We additionally describe protocols relevant to the analysis of these spheroids in high-throughput drug discovery campaigns such as the assessment of spheroid proliferation, immunofluorescence and immunohistochemistry staining of spheroids, live-cell and confocal imaging and analysis of cell surface markers.

Establishment of pancreatic cancer cell lines with endoscopic ultrasound-guided biopsy via conditionally reprogrammed cell culture

Recent studies have identified the mutational landscape of pancreatic cancer and suggested tumor-specific subtypes. However, the major hurdle against personalized treatment is the difficulty to obtain sufficient cancer tissues from most inoperable cases. We investigated whether patient-derived conditionally reprogrammed cells (CRCs) can be constructed using a small piece of tumor tissue using endoscopic ultrasound (EUS)-guided fine needle biopsy (FNB). Thirty patients with pancreatic solid mass (mean size, 34.6 mm) were enrolled prospectively. Among 22 patients who were diagnosed with pancreatic ductal adenocarcinoma, we established patient-derived pancreatic cancer cell lines from eight patients (36.4%). Immunofluorescence colony staining for CRCs showed that the cytoplasm of cancer cells was clearly stained with anti-cytokeratin 19 monoclonal antibody. In the soft agar colony formation assay, CRCs formed colonies compared with the negative control by day 15. In vivo, implanted CRCs showed tumor engraftment and hematoxylin and eosin staining showed pancreatic cancer ductal structure. All established CRCs showed a KRAS mutation. In conclusion, we established patient-derived pancreatic cancer cell lines with a small tumor tissue obtained by EUS-FNB. With in vitro drug sensitivity and genomic studies, established patient-derived cell lines can be used in identification of new targets for diagnosis and treatment of pancreatic cancer.

Characterization of Novel Murine and Human PDAC Cell Models: Identifying the Role of Intestine Specific Homeobox Gene ISX in Hypoxia and Disease Progression

Therapy failure and metastasis-associated mortality are stumbling blocks in the management of PDAC in patients. Failure of therapy is associated to intense hypoxic conditions of tumors. To develop effective therapies, a complete understanding of hypoxia-associated changes in genetic landscape of tumors during disease progression is needed. Because artificially immortalized cell lines do not rightly represent the disease progression, studying genetics of tumors in spontaneous models is warranted. In the current study, we generated a spectrum of spontaneous human (UM-PDC1; UM-PDC2) and murine (HI-PanL, HI-PancI, HI-PanM) models representing localized, invasive, and metastatic PDAC from a patient and transgenic mice (K-ras^G12D/Pdx^cre/Ink4a/p16^-/). These spontaneous models grow vigorously under hypoxia and exhibit activated K-ras signaling, progressive loss of PTEN, and tumorigenicity in vivo. Whereas UM-PDC1 form localized tumors, the UM-PDC2 metastasize to lungs in mice. In an order of progression, these models exhibit genomic instability marked by gross chromosomal rearrangements, centrosome-number variations, Aurora-kinase/H2AX colocalization, loss of primary cilia, and α-tubulin acetylation. The RNA sequencing of hypoxic models followed by qRT-PCR validation and gene-set enrichment identified Intestine-Specific Homeobox factor (ISX)–driven molecular pathway as an indicator PDAC aggressivness. TCGA-PAAD clinical data analysis showed high ISX expression correlation to poor survival of PDAC patients, particularly women. The functional studies showed ISX as a regulator of i) invasiveness and migratory potential and ii) VEGF, MMP2, and NFκB activation in PDAC cells. We suggest that ISX is a potential druggable target and newly developed spontaneous cell models are valuable tools for studying mechanism and testing therapies for PDAC.

Quantification of microenvironmental metabolites in murine cancers reveals determinants of tumor nutrient availability

Cancer cell metabolism is heavily influenced by microenvironmental factors, including nutrient availability. Therefore, knowledge of microenvironmental nutrient levels is essential to understand tumor metabolism. To measure the extracellular nutrient levels available to tumors, we utilized quantitative metabolomics methods to measure the absolute concentrations of >118 metabolites in plasma and tumor interstitial fluid, the extracellular fluid that perfuses tumors. Comparison of nutrient levels in tumor interstitial fluid and plasma revealed that the nutrients available to tumors differ from those present in circulation. Further, by comparing interstitial fluid nutrient levels between autochthonous and transplant models of murine pancreatic and lung adenocarcinoma, we found that tumor type, anatomical location and animal diet affect local nutrient availability. These data provide a comprehensive characterization of the nutrients present in the tumor microenvironment of widely used models of lung and pancreatic cancer and identify factors that influence metabolite levels in tumors.

In the body, cancer cells can rely on different nutrients than normal cells, and they can use these nutrients in a different way. What cancer cells consume also depends on what is available in their immediate environment. In a tumor, cells grab nutrients from the ‘interstitial’ fluid that surrounds them, but what is present in this liquid may vary within tumors arising in different locations. Understanding what nutrients are ‘on the menu’ in specific tumors would help to target diseased cells while sparing healthy ones, but this knowledge has been difficult to obtain.

To investigate this, Sullivan et al. used a technique called mass spectrometry to measure the amounts of 120 nutrients present in the interstitial fluid of mouse pancreas and lung tumors. Different levels of nutrients were found in the two types of tumors, and analyses showed that what was present in the interstitial fluid depended on the type of cancer cells, where the tumor was located, and what the animals ate. This suggests that cancer cells may have different needs because they are limited in what they have access to.

It remains to be seen whether the nutrients levels found in mouse tumors are the same as those in humans. Armed with this knowledge, it may then be possible to feed cancer cells grown in the laboratory with the nutrient menu that they would have access to in the body. This could help identify new cancer treatments.

Systematic Generation of Patient-Derived Tumor Models in Pancreatic Cancer

In highly aggressive malignancies like pancreatic cancer (PC), patient-derived tumor models can serve as disease-relevant models to understand disease-related biology as well as to guide clinical decision-making. In this study, we describe a two-step protocol allowing systematic establishment of patient-derived primary cultures from PC patient tumors. Initial xenotransplantation of surgically resected patient tumors (n = 134) into immunodeficient mice allows for efficient in vivo expansion of vital tumor cells and successful tumor expansion in 38% of patient tumors (51/134). Expansion xenografts closely recapitulate the histoarchitecture of their matching patients' primary tumors. Digestion of xenograft tumors and subsequent in vitro cultivation resulted in the successful generation of semi-adherent PC cultures of pure epithelial cell origin in 43.1% of the cases. The established primary cultures include diverse pathological types of PC: Pancreatic ductal adenocarcinoma (86.3%, 19/22), adenosquamous carcinoma (9.1%, 2/22) and ductal adenocarcinoma with oncocytic IPMN (4.5%, 1/22). We here provide a protocol to establish quality-controlled PC patient-derived primary cell cultures from heterogeneous PC patient tumors. In vitro preclinical models provide the basis for the identification and preclinical assessment of novel therapeutic opportunities targeting pancreatic cancer.

Subcutaneous Inoculation of 3D Pancreatic Cancer Spheroids Results in Development of Reproducible Stroma-Rich Tumors

Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease characterized by high expression of extracellular matrix in tumor tissue, which contributes to chemoresistance and poor prognosis. Here, we developed 3D pancreatic cancer spheroids, based on pancreatic cancer cells and fibroblast co-culture, which demonstrate innate desmoplastic properties and stay poorly permeable for model nanoparticles. Our study revealed that establishment of tumors by transplantation of spheroids significantly improved subcutaneous xenograft model of PDAC, which stays the most widely used animal model for testing of new drugs and drug delivery approaches. Spheroid based tumors abundantly produced different extracellular matrix (ECM) components including collagen I, fibronectin, laminin and hyaluronic acid. These tumors were highly reproducible with excellent uniformity in terms of ECM architecture recapitulating clinical PDAC tumors, whereas in more common cell based xenografts a significant intertumor heterogeneity in extracellular matrix production was found. Moreover, spheroid based xenografts demonstrated higher expression of pro-fibrotic and pro-survival PDAC hallmarks in opposite to cell based counterparts. We believe that future development of this model will provide an effective instrument for testing of anti-cancer drugs with improved predictive value.