Tumor Microenvironment Features and Chemoresistance in Pancreatic Ductal Adenocarcinoma: Insights into Targeting Physicochemical Barriers and Metabolism as Therapeutic Approaches

Analytical approach to distinguishing lactate dehydrogenase fractions for oncological diagnostics

BACKGROUND

One of the crucial enzymes for cancer cell growth is lactate dehydrogenase (LDH, E.C. 1.1.1.27), an oxidoreductase that catalyzes the conversion between pyruvate and lactate. It has been found that in cancer cells metabolism, the LDH isoenzyme profile changes, with forms rich in the muscle-type subunit beginning to dominate over those in which the heart-type predominates. This suggests that by examining changes in the enzymatic activity of isoforms with a specific subunit content, it may be possible to quickly distinguish a physiological sample from a pathological one.

RESULTS

This article focuses on the development of an analytical strategy that enables the estimation of the ratio of LDH fraction activities as a basis for a simple and quick screening test. Spectrophotometric detection of LDH activity is based on the ferrozine photometric reaction with ferrous ions generated during the biocatalytic reduction of ferric ions by NADH. The developed Multicommutated Flow Analysis (MCFA) system, coupled with an optoelectronic flow-through detector, enables the use of a kinetic method based on the inhibition of LDH subunits to monitor the enzyme reaction kinetics. The distinctly different responses of the muscle-type and heart-type subunits to the selected inhibitors revealed a linear relationship between the obtained analytical signal and the percentage content of each subunit. The calibration curves for selected inhibitors are linear within the tested range of standards with coefficients of determination equal to 0.99 each.

SIGNIFICANCE

The developed MCFA system was utilized in the analysis of human serum samples obtained from both healthy patients and patients with cancer. The analysis demonstrates that the proposed approach can differentiate oncological serum samples from reference ones based on the LDH fractions activity ratio, even when their total LDH activity level is low.

Novel Amanitin-Based Antibody-Drug Conjugates Targeting TROP2 for the Treatment of Pancreatic Cancer

Trophoblast cell surface antigen 2 (TROP2) exhibits aberrant expression in pancreatic cancer, correlating with metastasis, advanced tumor stage, and poor prognosis in patients with pancreatic ductal adenocarcinoma. TROP2 has been recognized as a promising therapeutic target for antibody-drug conjugates (ADC), as evidenced by the approval of the anti-TROP2 ADC Trodelvy for the treatment of triple-negative breast cancer (TNBC). In this study, we report the generation of novel second-generation amanitin-based ADCs (ATAC) targeting TROP2, comprising the humanized RS7 antibody of Trodelvy (hRS7) and the highly potent payload amanitin. The specific in vitro binding, efficient antigen internalization, and high cytotoxicity of hRS7 ATACs with EC50 values in the picomolar range in TROP2-expressing cells constituted the foundation for preclinical in vivo evaluation. The hRS7 ATACs demonstrated a significant reduction in tumor growth in vivo in subcutaneous xenograft mouse models of pancreatic cancer and TNBC at well-tolerated doses. The antitumor efficacy correlated with the level of TROP2 expression on the tumors and the in vivo tumor uptake of the ATACs. The long half-life of 9.7 to 10.7 days of hRS7 ATACs without premature payload release in serum supported a high therapeutic index. Notably, the efficacy of the hRS7 ATACs was superior to that of Trodelvy with complete tumor eradication in both refractory pancreatic cancer and TNBC xenograft models. In summary, hRS7 ATACs represent a highly effective and well-tolerated targeted therapy, and our data support their development for pancreatic cancer and other TROP2-expressing tumors.

Breakthroughs in nanoparticle-based strategies for pancreatic cancer therapy

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers worldwide, mainly due to its high heterogeneity, resistance to therapy and late diagnosis, with a 5-year survival rate of less than 10%. This dismal prognosis has promoted strategies to develop more effective treatments. Nanoparticle-based strategies have emerged, in the last decades, as a great opportunity because they can enhance drug delivery and promote controlled release, presenting lower side effects than conventional therapeutic regimens. Moreover, nanoparticles can often be modified to target specific cells or to achieve a sustained release of the drugs into the tumor. However, very few nanoparticle-based therapies are clinically approved. Concretely for pancreatic cancer treatment only two nanoformulations have been approved by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) so far. Clinical translation of nanoparticles remains a challenge for modern medicine, and in particular for pancreatic cancer therapy, because of the complexity of the disease, and a lack of studies been performed in clinically relevant in vitro and in vivo models. In this review, we have summarized the most recent clinical trials using nanoparticle-based formulations in PDAC, giving a small context of the diverse types of nanoparticles employed and the most recent advancements in the field.

Melanophilin-induced primary cilia promote pancreatic cancer metastasis

Pancreatic ductal adenocarcinoma (PDAC) is one of the most malignant tumors because of its high metastatic ability. The glutamine (Gln)-deficient microenvironment contributes to PDAC metastasis; however, the underlying molecular mechanisms remain unclear. Here, we demonstrated that melanophilin (MLPH) promotes PDAC metastasis by inducing the regrowth of primary cilia. Using RNA sequencing, we found that MLPH was upregulated in Gln-deficient conditions. MLPH facilitated PDAC metastasis in vitro and in vivo. Clinically, high MLPH expression is positively correlated with metastasis and poor PDAC prognosis. MLPH localized to the centrosome and facilitated the regrowth of primary cilia. The primary ciliogenesis upregulated phospholipase C γ-1 (PLCG1) to promote PDAC metastasis. Interestingly, PLCG1 was localized to the primary cilia, and depletion of PLCG1 alleviated primary ciliogenesis, suggesting a feedforward role for PLCG1 in mediating primary ciliogenesis. Thus, our study revealed a novel function of the MLPH-primary cilia-PLCG1 axis in facilitating PDAC metastasis under Gln deficiency both in vitro and in vivo.

Synthetic CB1 Cannabinoids Promote Tunneling Nanotube Communication, Cellular Migration, and Epithelial-Mesenchymal Transition in Pancreatic PANC-1 and Colorectal SW-620 Cancer Cell Lines

Metastasizing cancer cells surreptitiously can adapt to metabolic activity during their invasion. By initiating their communications for invasion, cancer cells can reprogram their cellular activities to initiate their proliferation and migration and uniquely counteract metabolic stress during their progression. During this reprogramming process, cancer cells' metabolism and other cellular activities are integrated and mutually regulated by tunneling nanotube communications to alter their specific metabolic functional drivers of tumor growth and progression. Here, we investigated the in vitro effects of the synthetic CB1 cannabinoids AM-404, arvanil, and olvanil on human pancreatic PANC-1 and colorectal SW-620 cancer cell lines to understand further cellular behaviors and the potential risks of their use in cancer therapy. For the first time, the synthetic CB1 cannabinoids AM-404, arvanil, and olvanil significantly altered cancer cells in forming missile-like shapes to induce tunneling nanotube (TNT) communications in PANC-1 cells. Oseltamivir phosphate (OP) significantly prevented TNT formation. To assess the key survival pathways critical for pancreatic cancer progression, we used the AlamarBlue assay to determine synthetic CB1 cannabinoids to induce the cell's metabolic viability drivers to stage migratory intercellular communication. The synthetic CB1 cannabinoids significantly increased cell viability compared to the untreated control for PANC-1 and SW-620 cells, and this response was significantly reduced with the NMBR inhibitor BIM-23127, neuraminidase-1 inhibitor OP, and MMP-9 inhibitor (MMP-9i). CB1 cannabinoids also significantly increased N-cadherin and decreased E-cadherin EMT markers compared to the untreated controls, inducing the process of metastatic phenotype for invasion. BIM-23127, MMP9i, and OP significantly inhibited CB1 agonist-induced NFκB-dependent secretory alkaline phosphatase (SEAP) activity. To confirm this concept, we investigated the migratory invasiveness of PANC-1 and SW-620 cancer cells treated with the synthetic CB1 cannabinoids AM-404, arvanil, and olvanil in a scratch wound assay. CB1 cannabinoids significantly induced the rate of migration and invasiveness of PANC-1 cancer cells, whereas they had minimal effect on the rate of migration of already metastatic SW-620 cancer cells. Interestingly, olvanil-treated SW-620 cells significantly enhanced the migration rate and invasiveness of these cells. The data support the cellular and molecular mechanisms of the synthetic CB1 cannabinoids, orchestrating intercellular conduits to enhance metabolic drivers to stage migratory intercellular communication in pancreatic cancer cells.

Ex-Vivo 3D Cellular Models of Pancreatic Ductal Adenocarcinoma: From Embryonic Development to Precision Oncology

ABSTRACT

Pancreas is a vital gland of gastrointestinal system with exocrine and endocrine secretory functions, interweaved into essential metabolic circuitries of the human body. Pancreatic ductal adenocarcinoma (PDAC) represents one of the most lethal malignancies, with a 5-year survival rate of 11%. This poor prognosis is primarily attributed to the absence of early symptoms, rapid metastatic dissemination, and the limited efficacy of current therapeutic interventions. Despite recent advancements in understanding the etiopathogenesis and treatment of PDAC, there remains a pressing need for improved individualized models, identification of novel molecular targets, and development of unbiased predictors of disease progression. Here we aim to explore the concept of precision medicine utilizing 3-dimensional, patient-specific cellular models of pancreatic tumors and discuss their potential applications in uncovering novel druggable molecular targets and predicting clinical parameters for individual patients.

A single-cell perspective on immunotherapy for pancreatic cancer: from microenvironment analysis to therapeutic strategy innovation

Pancreatic cancer remains one of the most lethal malignancies, with conventional treatment options providing limited efficacy. Recent advancements in immunotherapy have offered new hope, yet the unique tumor microenvironment (TME) of pancreatic cancer poses significant challenges to its successful application. This review explores the transformative impact of single-cell technology on the understanding and treatment of pancreatic cancer. By enabling high-resolution analysis of cellular heterogeneity within the TME, single-cell approaches have elucidated the complex interplay between various immune and tumor cell populations. These insights have led to the identification of predictive biomarkers and the development of innovative, personalized immunotherapeutic strategies. The review discusses the role of single-cell technology in dissecting the intricate immune landscape of pancreatic cancer, highlighting the discovery of T cell exhaustion profiles and macrophage polarization states that influence treatment response. Moreover, it outlines the potential of single-cell data in guiding the selection of immunotherapy drugs and optimizing treatment plans. The review also addresses the challenges and prospects of translating these single-cell-based innovations into clinical practice, emphasizing the need for interdisciplinary research and the integration of artificial intelligence to overcome current limitations. Ultimately, the review underscores the promise of single-cell technology in driving therapeutic strategy innovation and improving patient outcomes in the battle against pancreatic cancer.

Redefining the tumor microenvironment with emerging therapeutic strategies

The environment surrounding a tumor, known as the tumor microenvironment (TME), plays a role in how cancer progresses and responds to treatment. It poses both challenges and opportunities for improving cancer therapy. Recent progress in understanding the TME complexity and diversity has led to approaches for treating cancer. This perspective discusses the strategies for targeting the TME, such as adjusting networks using extracellular vesicles to deliver drugs and enhancing immune checkpoint inhibitors (ICIS) through combined treatments. Furthermore, it highlights adoptive cell transfer (ACT) therapies as an option for tumors. By studying how components of the TME interact and utilizing technologies like single-cell RNA sequencing and spatial transcriptomics, we can develop more precise and efficient treatments for cancer. This article emphasizes the need to reshape the TME to boost antitumor immunity and overcome resistance to therapy, providing guidance for research and clinical practices in precision oncology.

The Gut Microbiota Impacts Gastrointestinal Cancers through Obesity, Diabetes, and Chronic Inflammation

The gut microbiota's pivotal role in human health is increasingly evident, particularly in chronic conditions like obesity, diabetes, and inflammatory diseases. This intricate symbiotic relationship influences metabolic balance and immune responses. Notably, gut microbial dysbiosis is linked to obesity's metabolic disruption and chronic low-grade inflammation. Similarly, in diabetes, the microbiota's impact on insulin resistance and glucose metabolism is becoming evident. Chronic inflammation, a common denominator in these conditions, is also a recognized precursor to carcinogenesis. This intersection prompts a compelling question: does the gut microbiota's influence extend to gastrointestinal cancers like colorectal and pancreatic cancer? These malignancies are closely intertwined with inflammation and metabolic dysregulation. Exploring whether the microbial signatures associated with chronic conditions overlap with precancerous or cancerous states offers new perspectives. This article reviews emerging evidence on the interplay between the gut microbiota, chronic conditions, and gastrointestinal cancers. By elucidating these connections, we aim to uncover potential avenues for innovative diagnostic, preventative, and therapeutic strategies in colorectal and pancreatic cancer management.

Optimizing Pancreatic Cancer Therapy: The Promise of Immune Stimulatory Oncolytic Viruses

Pancreatic cancer presents formidable challenges due to rapid progression and resistance to conventional treatments. Oncolytic viruses (OVs) selectively infect cancer cells and cause cancer cells to lyse, releasing molecules that can be identified by the host's immune system. Moreover, OV can carry immune-stimulatory payloads such as interleukin-12, which when delivered locally can enhance immune system-mediated tumor killing. OVs are very well tolerated by cancer patients due to their ability to selectively target tumors without affecting surrounding normal tissues. OVs have recently been combined with other therapies, including chemotherapy and immunotherapy, to improve clinical outcomes. Several OVs including adenovirus, herpes simplex viruses (HSVs), vaccinia virus, parvovirus, reovirus, and measles virus have been evaluated in preclinical and clinical settings for the treatment of pancreatic cancer. We evaluated the safety and tolerability of a replication-competent oncolytic adenoviral vector carrying two suicide genes (thymidine kinase, TK; and cytosine deaminase, CD) and human interleukin-12 (hIL12) in metastatic pancreatic cancer patients in a phase 1 trial. This vector was found to be safe and well-tolerated at the highest doses tested without causing any significant adverse events (SAEs). Moreover, long-term follow-up studies indicated an increase in the overall survival (OS) in subjects receiving the highest dose of the OV. Our encouraging long-term survival data provide hope for patients with advanced pancreatic cancer, a disease that has not seen a meaningful increase in OS in the last five decades. In this review article, we highlight several preclinical and clinical studies and discuss future directions for optimizing OV therapy in pancreatic cancer. We envision OV-based gene therapy to be a game changer in the near future with the advent of newer generation OVs that have higher specificity and selectivity combined with personalized treatment plans developed under AI guidance.

Decoding the Intricate Landscape of Pancreatic Cancer: Insights into Tumor Biology, Microenvironment, and Therapeutic Interventions

Pancreatic ductal adenocarcinoma (PDAC) presents significant oncological challenges due to its aggressive nature and poor prognosis. The tumor microenvironment (TME) plays a critical role in progression and treatment resistance. Non-neoplastic cells, such as cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs), contribute to tumor growth, angiogenesis, and immune evasion. Although immune cells infiltrate TME, tumor cells evade immune responses by secreting chemokines and expressing immune checkpoint inhibitors (ICIs). Vascular components, like endothelial cells and pericytes, stimulate angiogenesis to support tumor growth, while adipocytes secrete factors that promote cell growth, invasion, and treatment resistance. Additionally, perineural invasion, a characteristic feature of PDAC, contributes to local recurrence and poor prognosis. Moreover, key signaling pathways including Kirsten rat sarcoma viral oncogene (KRAS), transforming growth factor beta (TGF-β), Notch, hypoxia-inducible factor (HIF), and Wnt/β-catenin drive tumor progression and resistance. Targeting the TME is crucial for developing effective therapies, including strategies like inhibiting CAFs, modulating immune response, disrupting angiogenesis, and blocking neural cell interactions. A recent multi-omic approach has identified signature genes associated with anoikis resistance, which could serve as prognostic biomarkers and targets for personalized therapy.

Extracellular volume-based scoring system for tracking tumor progression in pancreatic cancer patients receiving intraoperative radiotherapy

OBJECTIVES

To investigate the value of extracellular volume (ECV) derived from portal-venous phase (PVP) in predicting prognosis in locally advanced pancreatic cancer (LAPC) patients receiving intraoperative radiotherapy (IORT) with initial stable disease (SD) and to construct a risk-scoring system based on ECV and clinical-radiological features.

MATERIALS AND METHODS

One hundred and three patients with LAPC who received IORT demonstrating SD were enrolled and underwent multiphasic contrast-enhanced CT (CECT) before and after IORT. ECV maps were generated from unenhanced and PVP CT images. Clinical and CT imaging features were analyzed. The independent predictors of progression-free survival (PFS) determined by multivariate Cox regression model were used to construct the risk-scoring system. Time-dependent receiver operating characteristic (ROC) curve analysis and the Kaplan-Meier method were used to evaluate the predictive performance of the scoring system.

RESULTS

Multivariable analysis revealed that ECV, rim-enhancement, peripancreatic fat infiltration, and carbohydrate antigen 19-9 (CA19-9) response were significant predictors of PFS (all p < 0.05). Time-dependent ROC of the risk-scoring system showed a satisfactory predictive performance for disease progression with area under the curve (AUC) all above 0.70. High-risk patients (risk score ≥ 2) progress significantly faster than low-risk patients (risk score < 2) (p < 0.001).

CONCLUSION

ECV derived from PVP of conventional CECT was an independent predictor for progression in LAPC patients assessed as SD after IORT. The scoring system integrating ECV, radiological features, and CA19-9 response can be used as a practical tool for stratifying prognosis in these patients, assisting clinicians in developing an appropriate treatment approach.

CRITICAL RELEVANCE STATEMENT

The scoring system integrating ECV fraction, radiological features, and CA19-9 response can track tumor progression in patients with LAPC receiving IORT, aiding clinicians in choosing individual treatment strategies and improving their prognosis.

KEY POINTS

Predicting the progression of LAPC in patients receiving IORT is important. Our ECV-based scoring system can risk stratifying patients with initial SD. Appropriate prognostication can assist clinicians in developing appropriate treatment approaches.

Tumor Microenvironment Modulates Invadopodia Activity of Non-Selected and Acid-Selected Pancreatic Cancer Cells and Its Sensitivity to Gemcitabine and C18-Gemcitabine

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease with high mortality due to early metastatic dissemination and high chemoresistance. All these factors are favored by its extracellular matrix (ECM)-rich microenvironment, which is also highly hypoxic and acidic. Gemcitabine (GEM) is still the first-line therapy in PDAC. However, it is quickly deaminated to its inactive metabolite. Several GEM prodrugs have emerged to improve its cytotoxicity. Here, we analyzed how the acidic/hypoxic tumor microenvironment (TME) affects the response of PDAC cell death and invadopodia-mediated ECM proteolysis to both GEM and its C18 prodrug.

METHODS

For this, two PDAC cell lines, PANC-1 and Mia PaCa-2 were adapted to pHe 6.6 or not for 1 month, grown as 3D organotypic cultures and exposed to either GEM or C18 in the presence and absence of acidosis and the hypoxia inducer, deferoxamine.

RESULTS

We found that C18 has higher cytotoxic and anti-invadopodia activity than GEM in all culture conditions and especially in acid and hypoxic environments.

CONCLUSIONS

We propose C18 as a more effective approach to conventional GEM in developing new therapeutic strategies overcoming PDAC chemoresistance.

Circulating nucleosomes as potential biomarkers for cancer diagnosis and treatment monitoring

Nucleosomes play a crucial role in regulating gene expression through their composition and post-translational modifications. When cells die, intracellular endonucleases are activated and cleave chromatin into oligo- and mono-nucleosomes, which are then released into the body fluids. Studies have shown that the levels of nucleosomes are increased in serum and plasma in various cancer types, suggesting that analysis of circulating nucleosomes can provide an initial assessment of carcinogenesis. However, it should be noted that elevated serum nucleosome levels may not accurately diagnose certain tumor types, as increased cell death may occur in different pathological conditions. Nevertheless, detection of circulating nucleosomes and their histone modifications, along with specific tumor markers, can help diagnose certain types of cancer. Furthermore, monitoring changes in circulating nucleosome levels during chemotherapy or radiotherapy in patients with malignancies can provide valuable insights into clinical outcomes and therapeutic efficacy. The utilization of circulating nucleosomes as biomarkers is an exciting and emerging area of research, with the potential for early detection of various diseases and monitoring of treatment response. Integrating nucleosome-based biomarkers with existing ones may improve the specificity and sensitivity of current assays, offering the possibility of personalized precision medical treatment for patients.

Advancements in Preclinical Models of Pancreatic Cancer

ABSTRACT

Pancreatic cancer remains one of the deadliest of all cancer types with a 5-year overall survival rate of just 12%. Preclinical models available for understanding the disease pathophysiology have evolved significantly in recent years. Traditionally, commercially available 2-dimensional cell lines were developed to investigate mechanisms underlying tumorigenesis, metastasis, and drug resistance. However, these cells grow as monolayer cultures that lack heterogeneity and do not effectively represent tumor biology. Developing patient-derived xenografts and genetically engineered mouse models led to increased cellular heterogeneity, molecular diversity, and tissues that histologically represent the original patient tumors. However, these models are relatively expensive and very timing consuming. More recently, the advancement of fast and inexpensive in vitro models that better mimic disease conditions in vivo are on the rise. Three-dimensional cultures like organoids and spheroids have gained popularity and are considered to recapitulate complex disease characteristics. In addition, computational genomics, transcriptomics, and metabolomic models are being developed to simulate pancreatic cancer progression and predict better treatment strategies. Herein, we review the challenges associated with pancreatic cancer research and available analytical models. We suggest that an integrated approach toward using these models may allow for developing new strategies for pancreatic cancer precision medicine.

Macrophages reprogramming driven by cancer-associated fibroblasts under FOLFIRINOX treatment correlates with shorter survival in pancreatic cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) remains a clinically challenging cancer, mainly due to limited therapeutic options and the presence of a highly prominent tumor microenvironment (TME), facilitating tumor progression. The TME is predominated by heterogeneous populations of cancer-associated fibroblasts (CAFs) and tumor associated macrophages (TAMs), in constant communication with each other and with tumor cells, influencing many tumoral abilities such as therapeutic resistance. However how the crosstalk between CAFs and macrophages evolves following chemotherapeutic treatment remains poorly understood, limiting our capacity to halt therapeutic resistance.

METHODS

We combined biological characterization of macrophages indirectly cocultured with human PDAC CAFs, under FOLFIRINOX treatment, with mRNAseq analyses of such macrophages and evaluated the relevance of the specific gene expression signature in a large series of primary PDAC patients to search for correlation with overall survival (OS) after FOLFIRINOX chemotherapy.

RESULTS

Firstly, we demonstrated that CAFs polarize naïve and M1 macrophages towards an M2-like phenotype with a specific increase of CD200R and CD209 M2 markers. Then, we demonstrated that CAFs counteract the pro-inflammatory phenotype induced by the FOLFIRINOX on Macrophages. Indeed, we highlighted that, under FOLFIRINOX, CAFs limit the FOLFIRINOX-induced cell death of macrophages and further reinforce their M2 phenotype as well as their immunosuppressive impact through specific chemokines production. Finally, we revealed that under FOLFIRINOX CAFs drive a specific macrophage gene expression signature involving SELENOP and GOS2 that correlates with shortened OS in FOLFIRINOX-treated PDAC patients.

CONCLUSION

Our study provides insight into the complex interactions between TME cells under FOLFIRINOX treatment. It suggests potential novel candidates that could be used as therapeutic targets in combination with FOLFIRINOX to prevent and alleviate TME influx on therapeutic resistance as well as biomarkers to predict FOLFIRINOX response in PDAC patients. Video Abstract.

Galectin-1 in Pancreatic Ductal Adenocarcinoma: Bridging Tumor Biology, Immune Evasion, and Therapeutic Opportunities

Pancreatic Ductal Adenocarcinoma (PDAC) remains one of the most challenging malignancies to treat, with a complex interplay of molecular pathways contributing to its aggressive nature. Galectin-1 (Gal-1), a member of the galectin family, has emerged as a pivotal player in the PDAC microenvironment, influencing various aspects from tumor growth and angiogenesis to immune modulation. This review provides a comprehensive overview of the multifaceted role of Galectin-1 in PDAC. We delve into its contributions to tumor stroma remodeling, angiogenesis, metabolic reprogramming, and potential implications for therapeutic interventions. The challenges associated with targeting Gal-1 are discussed, given its pleiotropic functions and complexities in different cellular conditions. Additionally, the promising prospects of Gal-1 inhibition, including the utilization of nanotechnology and theranostics, are highlighted. By integrating recent findings and shedding light on the intricacies of Gal-1's involvement in PDAC, this review aims to provide insights that could guide future research and therapeutic strategies.

Role of exosomes in transferring chemoresistance through modulation of cancer glycolytic cell metabolism

Chemoresistance constitute a major obstacle in cancer treatment, leading to limited options and decreased patient survival. Recent studies have revealed a novel mechanism of chemoresistance acquisition: the transfer of information via exosomes, small vesicles secreted by various cells. Exosomes play a crucial role in intercellular communication by carrying proteins, nucleic acids, and metabolites, influencing cancer cell behavior and response to treatment. One crucial mechanism of resistance is cancer metabolic reprogramming, which involves alterations in the cellular metabolic pathways to support the survival and proliferation of drug-resistant cancer cells. This metabolic reprogramming often includes increased glycolysis, providing cancer cells with the necessary energy and building blocks to evade the effects of chemotherapy. Notably, exosomes have been found to transport glycolytic enzymes, as identified in proteomic profiling, leading to the reprogramming of metabolic pathways, facilitating altered glucose metabolism and increased lactate production. As a result, they profoundly impact the tumor microenvironment, promoting tumor progression, survival, immune evasion, and drug resistance.Understanding the complexities of such exosome-mediated cell-to-cell communication might open new therapeutic avenues and facilitate biomarker development in managing cancers characterized by aggressive glycolytic features. Moreover, given the intricate nature of metabolic abnormalities combining future exosome-based-targeted therapies with existing treatments like chemotherapy, immunotherapy, and targeted therapies holds promise for achieving synergistic effects to overcome resistance and improve cancer treatment outcomes.

Extracellular Matrix Collagen I Differentially Regulates the Metabolic Plasticity of Pancreatic Ductal Adenocarcinoma Parenchymal Cell and Cancer Stem Cell

Pancreatic ductal adenocarcinoma (PDAC) has a 5-year survival rate of less than 10 percent largely due to the intense fibrotic desmoplastic reaction, characterized by high levels of extracellular matrix (ECM) collagen I that constitutes a niche for a subset of cancer cells, the cancer stem cells (CSCs). Cancer cells undergo a complex metabolic adaptation characterized by changes in metabolic pathways and biosynthetic processes. The use of the 3D organotypic model in this study allowed us to manipulate the ECM constituents and mimic the progression of PDAC from an early tumor to an ever more advanced tumor stage. To understand the role of desmoplasia on the metabolism of PDAC parenchymal (CPC) and CSC populations, we studied their basic metabolic parameters in organotypic cultures of increasing collagen content to mimic in vivo conditions. We further measured the ability of the bioenergetic modulators (BMs), 2-deoxyglucose, dichloroacetate and phenformin, to modify their metabolic dependence and the therapeutic activity of paclitaxel albumin nanoparticles (NAB-PTX). While all the BMs decreased cell viability and increased cell death in all ECM types, a distinct, collagen I-dependent profile was observed in CSCs. As ECM collagen I content increased (e.g., more aggressive conditions), the CSCs switched from glucose to mostly glutamine metabolism. All three BMs synergistically potentiated the cytotoxicity of NAB-PTX in both cell lines, which, in CSCs, was collagen I-dependent and the strongest when treated with phenformin + NAB-PTX. Metabolic disruption in PDAC can be useful both as monotherapy or combined with conventional drugs to more efficiently block tumor growth.

Tunable hybrid hydrogels with multicellular spheroids for modeling desmoplastic pancreatic cancer

The tumor microenvironment consists of diverse, complex etiological factors. The matrix component of pancreatic ductal adenocarcinoma (PDAC) plays an important role not only in physical properties such as tissue rigidity but also in cancer progression and therapeutic responsiveness. Although significant efforts have been made to model desmoplastic PDAC, existing models could not fully recapitulate the etiology to mimic and understand the progression of PDAC. Here, two major components in desmoplastic pancreatic matrices, hyaluronic acid- and gelatin-based hydrogels, are engineered to provide matrices for tumor spheroids composed of PDAC and cancer-associated fibroblasts (CAF). Shape analysis profiles reveals that incorporating CAF contributes to a more compact tissue formation. Higher expression levels of markers associated with proliferation, epithelial to mesenchymal transition, mechanotransduction, and progression are observed for cancer-CAF spheroids cultured in hyper desmoplastic matrix-mimicking hydrogels, while the trend can be observed when those are cultured in desmoplastic matrix-mimicking hydrogels with the presence of transforming growth factor-β1 (TGF-β1). The proposed multicellular pancreatic tumor model, in combination with proper mechanical properties and TGF-β1 supplement, makes strides in developing advanced pancreatic models for resembling and monitoring the progression of pancreatic tumors, which could be potentially applicable for realizing personalized medicine and drug testing applications.

ECM Composition Differentially Regulates Intracellular and Extracellular pH in Normal and Cancer Pancreatic Duct Epithelial Cells

Intracellular pH (pHi) regulation is a challenge for the exocrine pancreas, where the luminal secretion of bicarbonate-rich fluid is accompanied by interstitial flows of acid. This acid-base transport requires a plethora of ion transporters, including bicarbonate transporters and the Na⁺/H⁺ exchanger isoform 1 (NHE1), which are dysregulated in Pancreatic Ductal Adenocarcinoma (PDAC). PDAC progression is favored by a Collagen-I rich extracellular matrix (ECM) which exacerbates the physiological interstitial acidosis. In organotypic cultures of normal human pancreatic cells (HPDE), parenchymal cancer cells (CPCs) and cancer stem cells (CSCs) growing on matrices reproducing ECM changes during progression, we studied resting pHi, the pHi response to fluxes of NaHCO₃ and acidosis and the role of NHE1 in pHi regulation. Our findings show that: (i) on the physiological ECM, HPDE cells have the most alkaline pHi, followed by CSCs and CPCs, while a Collagen I-rich ECM reverses the acid-base balance in cancer cells compared to normal cells; (ii) both resting pHi and pHi recovery from an acid load are reduced by extracellular NaHCO₃, especially in HPDE cells on a normal ECM; (iii) cancer cell NHE1 activity is less affected by NaHCO₃. We conclude that ECM composition and the fluctuations of pHe cooperate to predispose pHi homeostasis towards the presence of NaHCO₃ gradients similar to that expected in the tumor.

Quantitative intravital imaging for real-time monitoring of pancreatic tumor cell hypoxia and stroma in an orthotopic mouse model

Pancreatic cancer is a lethal disease with few successful treatment options. Recent evidence demonstrates that tumor hypoxia promotes pancreatic tumor invasion, metastasis, and therapy resistance. However, little is known about the complex relationship between hypoxia and the pancreatic tumor microenvironment (TME). In this study, we developed a novel intravital fluorescence microscopy platform with an orthotopic mouse model of pancreatic cancer to study tumor cell hypoxia within the TME in vivo, at cellular resolution, over time. Using a fluorescent BxPC3-DsRed tumor cell line with a hypoxia-response element (HRE)/green fluorescent protein (GFP) reporter, we showed that HRE/GFP is a reliable biomarker of pancreatic tumor hypoxia, responding dynamically and reversibly to changing oxygen concentrations within the TME. We also characterized the spatial relationships between tumor hypoxia, microvasculature, and tumor-associated collagen structures using in vivo second harmonic generation microscopy. This quantitative multimodal imaging platform enables the unprecedented study of hypoxia within the pancreatic TME in vivo.

Acidic Growth Conditions Promote Epithelial-to-Mesenchymal Transition to Select More Aggressive PDAC Cell Phenotypes In Vitro

Pancreatic Ductal Adenocarcinoma (PDAC) is characterized by an acidic microenvironment, which contributes to therapeutic failure. So far there is a lack of knowledge with respect to the role of the acidic microenvironment in the invasive process. This work aimed to study the phenotypic and genetic response of PDAC cells to acidic stress along the different stages of selection. To this end, we subjected the cells to short- and long-term acidic pressure and recovery to pH_e 7.4. This treatment aimed at mimicking PDAC edges and consequent cancer cell escape from the tumor. The impact of acidosis was assessed for cell morphology, proliferation, adhesion, migration, invasion, and epithelial-mesenchymal transition (EMT) via functional in vitro assays and RNA sequencing. Our results indicate that short acidic treatment limits growth, adhesion, invasion, and viability of PDAC cells. As the acid treatment progresses, it selects cancer cells with enhanced migration and invasion abilities induced by EMT, potentiating their metastatic potential when re-exposed to pH_e 7.4. The RNA-seq analysis of PANC-1 cells exposed to short-term acidosis and pH_e-selected recovered to pH_e 7.4 revealed distinct transcriptome rewiring. We describe an enrichment of genes relevant to proliferation, migration, EMT, and invasion in acid-selected cells. Our work clearly demonstrates that upon acidosis stress, PDAC cells acquire more invasive cell phenotypes by promoting EMT and thus paving the way for more aggressive cell phenotypes.

Drug Delivery Strategies for the Treatment of Pancreatic Cancer

Pancreatic cancer is fast becoming a global menace and it is projected to be the second leading cause of cancer-related death by 2030. Pancreatic adenocarcinomas, which develop in the pancreas' exocrine region, are the predominant type of pancreatic cancer, representing about 95% of total pancreatic tumors. The malignancy progresses asymptomatically, making early diagnosis difficult. It is characterized by excessive production of fibrotic stroma known as desmoplasia, which aids tumor growth and metastatic spread by remodeling the extracellular matrix and releasing tumor growth factors. For decades, immense efforts have been harnessed toward developing more effective drug delivery systems for pancreatic cancer treatment leveraging nanotechnology, immunotherapy, drug conjugates, and combinations of these approaches. However, despite the reported preclinical success of these approaches, no substantial progress has been made clinically and the prognosis for pancreatic cancer is worsening. This review provides insights into challenges associated with the delivery of therapeutics for pancreatic cancer treatment and discusses drug delivery strategies to minimize adverse effects associated with current chemotherapy options and to improve the efficiency of drug treatment.

Chemoresistance in pancreatic ductal adenocarcinoma: Overcoming resistance to therapy

Pancreatic ductal adenocarcinoma (PDAC), a prominent cause of cancer deaths worldwide, is a highly aggressive cancer most frequently detected at an advanced stage that limits treatment options to systemic chemotherapy, which has provided only marginal positive clinical outcomes. More than 90% of patients with PDAC die within a year of being diagnosed. PDAC is increasing at a rate of 0.5-1.0% per year, and it is expected to be the second leading cause of cancer-related mortality by 2030. The resistance of tumor cells to chemotherapeutic drugs, which can be innate or acquired, is the primary factor contributing to the ineffectiveness of cancer treatments. Although many PDAC patients initially responds to standard of care (SOC) drugs they soon develop resistance caused partly by the substantial cellular heterogeneity seen in PDAC tissue and the tumor microenvironment (TME), which are considered key factors contributing to resistance to therapy. A deeper understanding of molecular mechanisms involved in PDAC progression and metastasis development, and the interplay of the TME in all these processes is essential to better comprehend the etiology and pathobiology of chemoresistance observed in PDAC. Recent research has recognized new therapeutic targets ushering in the development of innovative combinatorial therapies as well as enhancing our comprehension of several different cell death pathways. These approaches facilitate the lowering of the therapeutic threshold; however, the possibility of subsequent resistance development still remains a key issue and concern. Discoveries, that can target PDAC resistance, either alone or in combination, have the potential to serve as the foundation for future treatments that are effective without posing undue health risks. In this chapter, we discuss potential causes of PDAC chemoresistance and approaches for combating chemoresistance by targeting different pathways and different cellular functions associated with and mediating resistance.

Anticancer Activity of Novel Difluorinated Curcumin Analog and Its Inclusion Complex with 2-Hydroxypropyl-β-Cyclodextrin against Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is the primary reason for cancer-related deaths in the US. Genetic mutations, drug resistance, the involvement of multiple signaling pathways, cancer stem cells (CSCs), and desmoplastic stroma, which hinders drug penetrance, contribute to poor chemotherapeutic efficacy. Hence, there is a need to identify novel drugs with improved delivery to improve treatment outcomes. Curcumin is one such compound that can inhibit multiple signaling pathways and CSCs. However, curcumin’s clinical applicability for treating PDAC is limited because of its poor solubility in water and metabolic instability. Hence, we developed a difluorinated curcumin (CDF) analog that accumulates selectively in the pancreas and inhibits PDAC growth in vitro and in vivo. In the present work, we developed its 2-hydroxy-propyl-β-cyclodextrin (HCD) inclusion complex to increase its water solubility and hydrolytic stability. The CDFHCD inclusion complex was characterized by spectroscopic, thermal, and microscopic techniques. The inclusion complex exhibited increased aqueous solubility, hydrolytic stability, and antiproliferative activity compared to parent CDF. Moreover, CDF and CDFHCD inhibited colony and spheroid formation, and induced cell cycle and apoptosis in PDAC cell lines. Hence, CDFHCD self-assembly is an efficient approach to increase water solubility and anticancer therapeutic efficacy, which now warrants advancement towards a clinical proof of concept in PDAC patients.

Extracellular volume fraction determined by dual-layer spectral detector CT: Possible role in predicting the efficacy of preoperative neoadjuvant chemotherapy in pancreatic ductal adenocarcinoma

PURPOSE

To clarify the relationship between extracellular volume (ECV) measured by dual-energy CT (DECT) and efficacy of preoperative neoadjuvant chemotherapy (NAC) in patients with pancreatic ductal adenocarcinoma (PDAC), as compared with single-energy CT (SECT).

METHODS

We enrolled 67 patients with PDAC who underwent dynamic contrast-enhanced CT with a dual-energy CT system prior to NAC. Attenuation values were measured on unenhanced and the equilibrium-phase 120-kVp equivalent CT images for PDAC and the aorta. ΔHU-tumor, ΔHU-tumor/ΔHU-aorta, and SECT-ECV were calculated. Iodine densities of the tumor and aorta were measured in the equilibrium phase, and DECT-ECV of the tumor was calculated. Response to NAC was evaluated and the correlation between imaging parameters and response to NAC was statistically assessed.

RESULTS

Tumor DECT-ECVs were significantly lower in the response group (n = 7) than in the non-response group (n = 60), with most significant difference (p = 0.0104). DECT-ECV showed highest diagnostic value with an Az value of 0.798. When using the optimal cut off value of DECT-ECV (<26.0 %), sensitivity, specificity, accuracy, positive predictive value, and negative value for predicting response group were 71.4 %, 85.0 %, 83.6 %, 35.7 % and 96.2 %, respectively.

CONCLUSION

PDAC with lower DECT-ECV can potentially show better response to NAC. DECT-ECV might be a useful biomarker for predicting response to NAC in patients with PDAC.

Hepatic myofibroblasts exert immunosuppressive effects independent of the immune checkpoint regulator PD-L1 in liver metastasis of pancreatic ductal adenocarcinoma

Introduction

Pancreatic ductal adenocarcinoma (PDAC) represents the 4^th most common cause of cancer-related deaths in Western countries. Most patients are diagnosed at advanced stages, often already with metastases. The main site of metastasis is the liver and hepatic myofibroblasts (HMF) play a pivotal role in metastatic outgrowth. Immune checkpoint inhibitors (ICI) targeting programmed death ligand 1 (PD-L1) or programmed cell death protein 1 (PD-1) improved treatment of several cancers but not of PDAC. Therefore, this study aimed to better understand the impact of HMF on PD-L1 expression and immune evasion of PDAC cells during liver metastasis.

Methods

Formalin-fixed and paraffin embedded biopsy samples or diagnostic resection specimens from liver metastases of 15 PDAC patients were used for immunohistochemical analyses. Serial sections were stained with antibodies directed against Pan-Cytokeratin, αSMA, CD8, and PD-L1. To investigate whether the PD-1/PD-L1 axis and HMF contribute to immune escape of PDAC liver metastases, a stroma enriched 3D spheroid coculture model was established in vitro, using two different PDAC cell lines, HMF, and CD8⁺ T cells. Here, functional and flow cytometry analyses were conducted.

Results

Immunohistochemical analysis of liver tissue sections of PDAC patients revealed that HMF represent an abundant stroma population in liver metastases, with clear differences in the spatial distribution in small (1500 µm) and large (> 1500 μm) metastases. In the latter, PD-L1 expression was mainly located at the invasion front or evenly distributed, while small metastases either lacked PD-L1 expression or showed mostly weak expression in the center. Double stainings revealed that PD-L1 is predominantly expressed by stromal cells, especially HMF. Small liver metastases with no or low PD-L1 expression comprised more CD8⁺ T cells in the tumor center, while large metastases exhibiting stronger PD-L1 expression comprised less CD8⁺ T cells being mostly located at the invasion front. HMF-enriched spheroid cocultures with different ratios of PDAC cells and HMF well mimicking conditions of hepatic metastases in situ. Here, HMF impaired the release of effector molecules by CD8⁺ T cells and the induction of PDAC cell death, an effect that was dependent on the amount of HMF but also of PDAC cells. ICI treatment led to elevated secretion of distinct CD8⁺ T cell effector molecules but did not increase PDAC cell death under either spheroid condition.

Conclusion

Our findings indicate a spatial reorganization of HMF, CD8⁺ T cells, and PD-L1 expression during progression of PDAC liver metastases. Furthermore, HMF potently impair the effector phenotype of CD8⁺ T cells but the PD-L1/PD-1 axis apparently plays a minor role in this scenario suggesting that immune evasion of PDAC liver metastases relies on other immunosuppressive mechanisms.

Interplay between MAP kinases and tumor microenvironment: Opportunity for immunotherapy in pancreatic cancer

Pancreatic Ductal Adenocarcinoma (PDAC), commonly called pancreatic cancer, is aggressive cancer usually detected at a late stage, limiting treatment options with modest clinical responses. It is projected that by 2030, PDAC will be the second most common cause of cancer-related mortality in the United States. Drug resistance in PDAC is common and significantly affects patients' overall survival (OS). Oncogenic KRAS mutations are nearly uniform in PDAC, affecting over 90% of patients. However, effective drugs directed to target prevalent KRAS mutants in pancreatic cancer are not in clinical practice. Accordingly, efforts are continued on identifying alternative druggable target(s) or approaches to improve patient outcomes with PDAC. In most PDAC cases, the KRAS mutations turn-on the RAF-MEK-MAPK pathways, leading to pancreatic tumorigenesis. The MAPK signaling cascade (MAP4K→MAP3K→MAP2K→MAPK) plays a central role in the pancreatic cancer tumor microenvironment (TME) and chemotherapy resistance. The immunosuppressive pancreatic cancer TME is another unfavorable factor affecting the therapeutic efficacy of chemotherapy and immunotherapy. The immune checkpoint proteins (ICPs), including CTLA-4, PD-1, PD-L1, and PD-L2, are critical players in T cell dysfunction and pancreatic tumor cell growth. Here, we review the activation of MAPKs, a molecular trait of KRAS mutations and their impact on pancreatic cancer TME, chemoresistance, and expression of ICPs that could influence the clinical outcomes in PDAC patients. Therefore, understanding the interplay between MAPK pathways and TME could help to design rational therapy combining immunotherapy and MAPK inhibitors for pancreatic cancer treatment.

Role of noncoding RNAs in pancreatic ductal adenocarcinoma associated cachexia

Cachexia is an acute syndrome that is very commonly observed in patients with cancer. Cachexia is the number one cause of death in patients with metastatic disease and is also the major factor for physical toxicity and financial burden. More importantly, the majority of patients with advanced-stage pancreatic ductal adenocarcinoma (PDAC) cancer undergo cachexia. Pancreatic cancer causes deaths of ∼50,000 Americans and about 400,000 people worldwide every year. The high mortality rates in metastatic PDAC are due to systemic pathologies and cachexia, which quickens death in these patients. About 90% of all patients with PDAC undergo wasting of muscle causing mobility loss and leading to a number of additional pathological conditions. PDAC-associated cancer cachexia emanates from complex signaling cues involving both mechanical and biological signals. Tumor invasion is associated with the loss of pancreatic function-induced digestive disorders and malabsorption, which causes subsequent weight loss and eventually promotes cachexia. Besides, systemic inflammation of patients with PDAC could release chemical cues (e.g., cytokine-mediated Atrogin-1/MAFbx expression) that participate in muscle wasting. Our understanding of genes, proteins, and cytokines involved in promoting cancer cachexia has evolved considerably. However, the role of epigenetic factors, particularly the role of noncoding RNAs (ncRNAs) in regulating PDAC-associated cachexia is less studied. In this review article, the most updated knowledge on the various ncRNAs including microRNAs (miRs), long noncoding RNA (lncRNAs), piwi interacting RNAs (PiwiRNAs), small nucleolar RNA (snoRNAs), and circular RNAs (circRNA) and their roles in cancer cachexia are described.

Therapeutic Response of Multifunctional Lipid and Micelle Formulation in Hepatocellular Carcinoma

Hepatic stellate cells (HSCs), as an important part of the tumor microenvironment (TME), could be activated by tumor cells as cancer-associated fibroblasts (CAFs), thereby promoting the production of extracellular matrix (ECM) and favoring the development of tumors. Therefore, blocking the "CAFs-ECM" axis is a promising pathway to improve antitumor efficacy. Based on this, we developed a multifunctional nanosized delivery system composed of hyaluronic acid-modified pH-sensitive liposomes (CTHLs) and glycyrrheic acid-modified nanomicelles (DGNs), which combines the advantages of targeted delivery, pH-sensitivity, and deep drug penetration. To mimic actual TME, a novel HSCs+BEL-7402 cocultured cell model and a m-HSCs+H22 coimplanted mice model were established. As expected, CTHLs and DGNs could target CAFs and tumor cells, respectively, and promote the drug penetration and retention in tumor regions. Notably, CTHLs+DGNs not only exhibited a superior antitumor effect in three-level tumor-bearing mice but also presented excellent antimetastasis efficiency in lung-metastatic mice. The antitumor mechanism revealed that the lipid&micelle mixed formulations effectively inhibited the activation of CAFs, reduced the deposition of ECM, and reversed the epithelial-mesenchymal transition (EMT) of tumor cells. In brief, the nanosized delivery system composed of CTHLs and DGNs could effectively improve the therapeutic effect of liver cancer by blocking the "CAFs-ECM" axis, which has a good clinical application prospect.

Biomimetic nanomaterial-facilitated oxygen generation strategies for enhancing tumour treatment outcomes

Hypoxia, as a typical hallmark of the tumour microenvironment (TME), has been verified to exist in most malignancies and greatly hinders the outcome of tumour treatments, including chemotherapy, photodynamic therapy, radiotherapy, and immunotherapy. Various approaches to alleviate tumour hypoxia have been reported. Among them, biomimetic nanomaterial-facilitated tumour oxygenation strategies, based on the engagement of human endogenous proteins, red blood cells, the cell membrane, and catalase, are the most impressive due to their excellent tumour active-targeting ability and superior tumour-selective capability, which, however, have not yet been systematically reviewed. Herein, we are ready to describe the current progress in biomimetic nanomaterial-facilitated tumour oxygenation strategies and corresponding improvements in tumour treatment outputs. In this review, the underlying mechanism behind the superior effect of these biomimetic nanomaterials, compared with other materials, on alleviating the hypoxic TME is highlighted. Additionally, the ongoing problems and potential solutions are also discussed.

Lactate Dehydrogenase and its clinical significance in pancreatic and thoracic cancers

The energy metabolism of tumor cells is considered one of the hallmarks of cancer because it is different from normal cells and mainly consists of aerobic glycolysis, fatty acid oxidation, and glutaminolysis. It is about one hundred years ago since Warburg observed that cancer cells prefer aerobic glycolysis even in normoxic conditions, favoring their high proliferation rate. A pivotal enzyme driving this phenomenon is lactate dehydrogenase (LDH), and this review describes prognostic and therapeutic opportunities associated with this enzyme, focussing on tumors with limited therapeutic strategies and life expectancy (i.e., pancreatic and thoracic cancers). Expression levels of LDH-A in pancreatic cancer tissues correlate with clinicopathological features: LDH-A is overexpressed during pancreatic carcinogenesis and showed significantly higher expression in more aggressive tumors. Similarly, LDH levels are a marker of negative prognosis in patients with both adenocarcinoma or squamous cell lung carcinoma, as well as in malignant pleural mesothelioma. Additionally, serum LDH levels may play a key role in the clinical management of these diseases because they are associated with tissue damage induced by tumor burden. Lastly, we discuss the promising results of strategies targeting LDH as a treatment strategy, reporting recent preclinical and translational studies supporting the use of LDH-inhibitors in combinations with current/novel chemotherapeutics that can synergistically target the oxygenated cells present in the tumor.

Cancer Associated Fibroblast (CAF) Regulation of PDAC Parenchymal (CPC) and CSC Phenotypes Is Modulated by ECM Composition

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest of all cancers, having one of the lowest five-year survival rates. One of its hallmarks is a dense desmoplastic stroma consisting in the abnormal accumulation of extracellular matrix (ECM) components, especially Collagen I. This highly fibrotic stroma embeds the bulk cancer (parenchymal) cells (CPCs), cancer stem cells (CSCs) and the main producers of the stromal reaction, the Cancer Associated Fibroblasts (CAFs). Little is known about the role of the acellular ECM in the interplay of the CAFs with the different tumor cell types in determining their phenotypic plasticity and eventual cell fate.

METHODS

Here, we analyzed the role of ECM collagen I in modulating the effect of CAF-derived signals by incubating PDAC CPCs and CSCs grown on ECM mimicking early (low collagen I levels) and late (high collagen I levels) stage PDAC stroma with conditioned medium from primary cultured CAFs derived from patients with PDAC in a previously described three-dimensional (3D) organotypic model of PDAC.

RESULTS

We found that CAFs (1) reduced CPC growth while favoring CSC growth independently of the ECM; (2) increased the invasive capacity of only CPCs on the ECM mimicking the early tumor; and (3) favored vasculogenic mimicry (VM) especially of the CSCs on the ECM mimicking an early tumor.

CONCLUSIONS

We conclude that the CAFs and acellular stromal components interact to modulate the tumor behaviors of the PDAC CPC and CSC cell types and drive metastatic progression by stimulating the phenotypic characteristics of each tumor cell type that contribute to metastasis.

Thermomagnetic Resonance Effect of the Extremely Low Frequency Electromagnetic Field on Three-Dimensional Cancer Models

In our recent studies, we have developed a thermodynamic biochemical model able to select the resonant frequency of an extremely low frequency electromagnetic field (ELF-EMF) specifically affecting different types of cancer, and we have demonstrated its effects in vitro. In this work, we investigate the cellular response to the ELF electromagnetic wave in three-dimensional (3D) culture models, which mimic the features of tumors in vivo. Cell membrane was modelled as a resistor–capacitor circuit and the specific thermal resonant frequency was calculated and tested on two-dimensional (2D) and three-dimensional (3D) cell cultures of human pancreatic cancer, glioblastoma and breast cancer. Cell proliferation and the transcription of respiratory chain and adenosine triphosphate synthase subunits, as well as uncoupling proteins, were assessed. For the first time, we demonstrate that an ELF-EMF hampers growth and potentiates both the coupled and uncoupled respiration of all analyzed models. Interestingly, the metabolic shift was evident even in the 3D aggregates, making this approach particularly valuable and promising for future application in vivo, in aggressive cancer tissues characterized by resistance to treatments.

Integrin β1 in Pancreatic Cancer: Expressions, Functions, and Clinical Implications

Simple Summary

Pancreatic cancer (PC) is a highly aggressive malignant tumor with an extremely poor prognosis. Early diagnosis and treatment are key to improving the survival rate of PC patients. Emerging studies show that integrins might contribute to the pathogenesis of PC. This review presents the various signaling pathways that are mediated by integrins in PC and emphasizes the multiple functions of integrin β1 in malignant behaviors of PC. It also discusses the clinical significance of integrin β1 as well as integrin β1-based therapy in PC patients.

Abstract

Pancreatic cancer (PC) is characterized by rapid progression and a high mortality rate. The current treatment is still based on surgical treatment, supplemented by radiotherapy and chemotherapy, and new methods of combining immune and molecular biological treatments are being explored. Despite this, the survival rate of PC patients is still very disappointing. Therefore, clarifying the molecular mechanism of PC pathogenesis and developing precisely targeted drugs are key to improving PC prognosis. As the most common β subunit of the integrin family, integrin β1 has been proved to be closely related to the vascular invasion, distant metastasis, and survival of PC patients, and treatment targeting integrin β1 in PC has gained initial success in animal models. In this review, we summarize the various signaling pathways by which integrins are involved in PC, focusing on the roles of integrin β1 in the malignant behaviors of PC. Additionally, recent studies regarding the feasibility of integrin β1 as a diagnostic and prognostic biomarker in PC are also discussed. Finally, we present the progress of several integrin β1-based clinical trials to highlight the potential of integrin β1 as a target for personalized therapy in PC.

Effects of TP53 Mutations and miRs on Immune Responses in the Tumor Microenvironment Important in Pancreatic Cancer Progression

Approximately 90% of pancreatic cancers are pancreatic ductal adenocarcinomas (PDAC). PDAC is the fourth leading cause of cancer death world-wide. Therapies for PDAC are largely ineffective due to the dense desmoplastic tumor microenvironment which prevents chemotherapeutic drugs and small molecule inhibitors from exerting effective anti-cancer effects. In this review, we will discuss the roles of TP53 and miRs on the PDAC tumor microenvironment and how loss of the normal functions of TP53 promote tumor progression. The TP53 gene is mutated in approximately 50% of pancreatic cancers. Often, these TP53 mutations are point mutations which confer additional functions for the TP53 proteins. These are called gain of function (GOF) mutations (mut). Another class of TP53 mutations are deletions which result in loss of the TP53 protein; these are referred to TP53-null mutations. We have organized this review into various components/properties of the PDAC microenvironment and how they may be altered in the presence of mutant TP53 and loss of certain miR expression.

Role of pH in Regulating Cancer Pyrimidine Synthesis

Replication is a fundamental aspect of cancer, and replication is about reproducing all the elements and structures that form a cell. Among them are DNA, RNA, enzymes, and coenzymes. All the DNA is doubled during each S (synthesis) cell cycle phase. This means that six billion nucleic acids must be synthesized in each cycle. Tumor growth, proliferation, and mutations all depend on this synthesis. Cancer cells require a constant supply of nucleotides and other macromolecules. For this reason, they must stimulate de novo nucleotide synthesis to support nucleic acid provision. When deregulated, de novo nucleic acid synthesis is controlled by oncogenes and tumor suppressor genes that enable increased synthesis and cell proliferation. Furthermore, cell duplication must be achieved swiftly (in a few hours) and in the midst of a nutrient-depleted and hypoxic environment. This also means that the enzymes participating in nucleic acid synthesis must work efficiently. pH is a critical factor in enzymatic efficiency and speed. This review will show that the enzymatic machinery working in nucleic acid synthesis requires a pH on the alkaline side in most cases. This coincides with many other pro-tumoral factors, such as the glycolytic phenotype, benefiting from an increased intracellular pH. An increased intracellular pH is a perfect milieu for high de novo nucleic acid production through optimal enzymatic performance.

Next Generation of Cancer Drug Repurposing: Therapeutic Combination of Aspirin and Oseltamivir Phosphate Potentiates Gemcitabine to Disable Key Survival Pathways Critical for Pancreatic Cancer Progression

Resistance to chemotherapeutics and high metastatic rates contribute to the abysmal survival rate in patients with pancreatic cancer. An alternate approach for treating human pancreatic cancer involves repurposing the anti-inflammatory drug, aspirin (ASA), with oseltamivir phosphate (OP) in combination with the standard chemotherapeutic agent, gemcitabine (GEM). The question is whether treatment with ASA and OP can sensitize cancer cells to the cytotoxicity induced by GEM and limit the development of chemoresistance. To assess the key survival pathways critical for pancreatic cancer progression, we used the AlamarBlue cytotoxicity assay to determine the cell viability and combination index for the drug combinations, flow cytometric analysis of annexin V apoptosis assay to detect apoptotic and necrotic cells, fluorometric QCM™ chemotaxis migration assay to assess cellular migration, fluorometric extracellular matrix (ECM) cell adhesion array kit to assess the expression of the ECM proteins, scratch wound assay using the 96-well WoundMaker™, and the methylcellulose clonogenic assay to assess clonogenic potential. The combination of ASA and OP with GEM significantly upended MiaPaCa-2 and PANC-1 pancreatic cancer cell viability, clonogenic potential, expression of critical extracellular matrix proteins, migration, and promoted apoptosis. ASA in combination with OP significantly improves the effectiveness of GEM in the treatment of pancreatic cancer and disables key survival pathways critical to disease progression.

HIF-1 and NRF2; Key Molecules for Malignant Phenotypes of Pancreatic Cancer

Simple Summary

Pancreatic cancer progression involves interactions between cancer cells and stromal cells in harsh tumor microenvironments, which are characterized by hypoxia, few nutrients, and oxidative stress. Clinically, cancer cells overcome therapeutic interventions, such as chemotherapy and radiotherapy, to continue to survive. Activation of the adaptation mechanism is required for cancer cell survival under these conditions, and it also contributes to the acquisition of the malignant phenotype. Stromal cells, especially pancreatic stellate cells, play a critical role in the formation of a cancer-promoting microenvironment. We here review the roles of key molecules, hypoxia inducible factor-1 and KEAP1-NRF2, in stress response mechanisms for the adaptation to hypoxia and oxidative stress in pancreatic cancer cells and stellate cells. Various cancer-promoting properties associated with these molecules have been identified, and they might serve as novel therapeutic targets in the future.

Abstract

Pancreatic cancer is intractable due to early progression and resistance to conventional therapy. Dense fibrotic stroma, known as desmoplasia, is a characteristic feature of pancreatic cancer, and develops through the interactions between pancreatic cancer cells and stromal cells, including pancreatic stellate cells. Dense stroma forms harsh tumor microenvironments characterized by hypoxia, few nutrients, and oxidative stress. Pancreatic cancer cells as well as pancreatic stellate cells survive in the harsh microenvironments through the altered expression of signaling molecules, transporters, and metabolic enzymes governed by various stress response mechanisms. Hypoxia inducible factor-1 and KEAP1-NRF2, stress response mechanisms for hypoxia and oxidative stress, respectively, contribute to the aggressive behaviors of pancreatic cancer. These key molecules for stress response mechanisms are activated, both in pancreatic cancer cells and in pancreatic stellate cells. Both factors are involved in the mutual activation of cancer cells and stellate cells, by inducing cancer-promoting signals and their mediators. Therapeutic interventions targeting these pathways are promising approaches for novel therapies. In this review, we summarize the roles of stress response mechanisms, focusing on hypoxia inducible factor-1 and KEAP1-NRF2, in pancreatic cancer. In addition, we discuss the potential of targeting these molecules for the treatment of pancreatic cancer.