Resistance to Gemcitabine in Pancreatic Ductal Adenocarcinoma: A Physiopathologic and Pharmacologic Review

Decoding YOD1: Insights into tumour regulation and translational opportunities

YOD1 deubiquitinase is a 38 kDa protein that belongs to the ovarian tumour protease (OTU) family, and its dysregulation can precipitate cancer development. Still, an up-to-date review article that can summarize its detailed tumour-regulatory function and translational potentials in different cancer types is lacking. To fill this literature gap, this review aims to discuss the tumour-modulatory role of YOD1 based on findings from different pre-clinical and clinical studies, followed by exploring the potential translational values of YOD1 as a tumour biomarker or therapeutic target. Overall, YOD1 could control the development of at least 15 tumour types by deubiquitinating or targeting different cellular proteins to modulate the activities of the cell cycle, p53, β-catenin, extracellular-regulated signal kinase (ERK), and YES-associated pathway (YAP) activities. Additionally, four long non-coding RNAs (lncRNAs), 12 microRNAs (miRNAs), and a few compounds can also directly or indirectly alter the expression and activity of YOD1, mediating tumourigenesis across different cancer types. Cellular expression data showed that YOD1 expression is dysregulated in eight cancer types, giving YOD1 the potential to be used as a diagnostic biomarker. Besides, YOD1 dysregulation can affect the clinical outcomes of various cancers. Hence, targeting YOD1 could potentially help slow tumourigenesis. The major drawback of considering YOD1 as a biomarker or therapeutic target is that its tumour-regulatory role is mainly based on the findings from single-center studies with relatively small sample sizes. Hence, future large-scale and in-depth clinical trials should be conducted to further verify the translational values of YOD1 as a biomarker or therapeutic target.

Cross-Talk Between Cancer and Its Cellular Environment-A Role in Cancer Progression

The tumor microenvironment is a dynamic and complex three-dimensional network comprising the extracellular matrix and diverse non-cancerous cells, including fibroblasts, adipocytes, endothelial cells and various immune cells (lymphocytes T and B, NK cells, dendritic cells, monocytes/macrophages, myeloid-derived suppressor cells, and innate lymphoid cells). A constantly and rapidly growing number of studies highlight the critical role of these cells in shaping cancer survival, metastatic potential and therapy resistance. This review provides a synthesis of current knowledge on the modulating role of the cellular microenvironment in cancer progression and response to treatment.

ECM Stiffness-Induced Redox Signaling Enhances Stearoyl Gemcitabine Efficacy in Pancreatic Cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal malignancies, largely due to its dense fibrotic stroma that promotes drug resistance and tumor progression. While patient-derived organoids (PDOs) have emerged as promising tools for modeling PDAC and evaluating therapeutic responses, the current PDO models grown in soft matrices fail to replicate the tumor's stiff extracellular matrix (ECM), limiting their predictive value for advanced disease.

METHODS

We developed a biomimetic model using gelatin-based matrices of varying stiffness, achieved through modulated transglutaminase crosslinking rates, to better simulate the desmoplastic PDAC microenvironment. Using this platform, we investigated organoid morphology, proliferation, and chemoresistance to gemcitabine (Gem) and its lipophilic derivative, 4-N-stearoyl gemcitabine (Gem-S). Mechanistic studies focused on the interplay between ECM stiffness, hypoxia-inducible factor (HIF) expression, and the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in drug resistance.

RESULTS

PDAC organoids in stiffer matrices demonstrated enhanced stemness features, including rounded morphology and elevated cancer stem cell (CSC) marker expression. Matrix stiffness-induced gemcitabine resistance correlated with the upregulation of ABC transporters and oxidative stress adaptive responses. While gemcitabine activated Nrf2 expression, promoting oxidative stress mitigation, Gem-S suppressed Nrf2 levels and induced oxidative stress, leading to increased reactive oxygen species (ROS) and enhanced cell death. Both compounds reduced HIF expression, with gemcitabine showing greater efficacy.

CONCLUSIONS

Our study reveals ECM stiffness as a critical mediator of PDAC chemoresistance through the promotion of stemness and modulation of Nrf2 and HIF pathways. Gem-S demonstrates promise in overcoming gemcitabine resistance by disrupting Nrf2-mediated adaptive responses and inducing oxidative stress. These findings underscore the importance of biomechanically accurate tumor models and suggest that dual targeting of mechanical and oxidative stress pathways may improve PDAC treatment outcomes.

Acyl-CoA thioesterase 8 induces gemcitabine resistance via regulation of lipid metabolism and antiferroptotic activity in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) comprises a group of highly malignant tumors of the pancreas. Metabolic reprogramming in tumors plays a pivotal role in promoting cancer progression. However, little is known about the metabolic alterations in tumors that drive cancer drug resistance in patients with PDAC. Here, we identified acyl-CoA thioesterase 8 (ACOT8) as a key player in driving PDAC gemcitabine (GEM) resistance. The expression of ACOT8 is significantly upregulated in GEM-resistant PDAC tissues and is closely associated with poor survival in patients with PDAC. Gain- and loss-of-function studies have shown that ACOT8 drives PDAC GEM resistance both in vitro and in vivo. Mechanistically, ACOT8 regulates cellular cholesterol ester (CE) levels, decreases the levels of phosphatidylethanolamines (PEs) that bind to polyunsaturated fatty acids and promote peroxisome activation. The knockdown of ACOT8 promotes ferroptosis and increases the chemosensitivity of tumors to GEM by inducing ferroptosis-associated pathway activation in PDAC cell lines. The combination of orlistat, an ACOT8 inhibitor, and GEM significantly inhibited tumor growth in PDAC organoid and mouse models. This study reveals the biological importance of ACOT8 and provides a potential combination therapy for treating patients with advanced GEM-resistant PDAC.

Metabolic crossroads: unravelling immune cell dynamics in gastrointestinal cancer drug resistance

Metabolic reprogramming within the tumor microenvironment (TME) plays a critical role in driving drug resistance in gastrointestinal cancers (GI), particularly through the pathways of fatty acid oxidation and glycolysis. Cancer cells often rewire their metabolism to sustain growth and reshape the TME, creating conditions such as nutrient depletion, hypoxia, and acidity that impair antitumor immune responses. Immune cells within the TME also undergo metabolic alterations, frequently adopting immunosuppressive phenotypes that promote tumor progression and reduce the efficacy of therapies. The competition for essential nutrients, particularly glucose, between cancer and immune cells compromises the antitumor functions of effector immune cells, such as T cells. Additionally, metabolic by-products like lactate and kynurenine further suppress immune activity and promote immunosuppressive populations, including regulatory T cells and M2 macrophages. Targeting metabolic pathways such as fatty acid oxidation and glycolysis presents new opportunities to overcome drug resistance and improve therapeutic outcomes in GI cancers. Modulating these key pathways has the potential to reinvigorate exhausted immune cells, shift immunosuppressive cells toward antitumor phenotypes, and enhance the effectiveness of immunotherapies and other treatments. Future strategies will require continued research into TME metabolism, the development of novel metabolic inhibitors, and clinical trials evaluating combination therapies. Identifying and validating metabolic biomarkers will also be crucial for patient stratification and treatment monitoring. Insights into metabolic reprogramming in GI cancers may have broader implications across multiple cancer types, offering new avenues for improving cancer treatment.

Stroma gene signature predicts responsiveness to chemotherapy in pancreatic ductal adenocarcinoma patient-derived xenograft models

Despite many efforts to understand the molecular mechanisms of pancreatic ductal adenocarcinoma (PDAC) treatment resistance, there is still no reliable method for selecting patients who could benefit from standard pharmacological treatment. Here, four PDAC patient-derived xenografts (PDAC-PDXs) with different responses to gemcitabine plus nab-paclitaxel (nanoparticle albumin-bound paclitaxel) were studied to dissect the contribution of both tumor and host microenvironment to treatment response. PDAC-PDXs transplanted into the pancreas of immunodeficient mice retained the main genetic and histopathological characteristics of the original human tumors, including invasiveness and desmoplastic reaction. Response to chemotherapy was associated with a specific 294 stroma gene signature and was not due to the intrinsic responsiveness of tumor cells or differences in drug delivery. Human dataset analysis validated the expression of the 294 stroma gene signature in PDAC clinical samples, confirming PDAC-PDXs as a useful tool to study the biology of tumor-host interactions and to test drug efficacy. In summary, we identified a stroma gene signature that differentiates PDAC-PDXs that are responsive to gemcitabine plus Nab-paclitaxel treatment from those that are not, confirming the active role of the tumor microenvironment in the drug response.

New insights into Notch signaling as a crucial pathway of pancreatic cancer stem cell behavior by chrysin-polylactic acid-based nanocomposite

Pancreatic cancer is an extremely deadly illness for which there are few reliable treatments. Recent research indicates that malignant tumors are highly variable and consist of a tiny subset of unique cancer cells, known as cancer stem cells (CSCs), which are responsible for the beginning and spread of tumors. These cells are typically identified by the expression of specific cell surface markers. A population of pancreatic cancer stem cells with aberrantly active developmental signaling pathways has been identified in recent studies of human pancreatic tumors. Among these Notch signaling pathway has been identified as a key regulator of CSCs self-renewal, making it an attractive target for therapeutic intervention. Chrysin-loaded polylactic acid (PLA) as polymeric nanoparticles systems have been growing interest in using as platforms for improved drug delivery. This review aims to explore innovative strategies for targeted therapy and optimized drug delivery in pancreatic CSCs by manipulating the Notch pathway and leveraging PLA-based drug delivery systems. Furthermore, we will assess the capability of PLA nanoparticles to enhance the bioavailability and effectiveness of gemcitabine in pancreatic cancer cells. The insights gained from this review have the potential to contribute to the development of novel treatment approaches that combine targeted therapy with advanced drug delivery utilizing biodegradable polymeric nanoparticles.

Pioneering first-in-class HDAC-ROCK inhibitors as potential multitarget anticancer agents

AIM

With the aim of simultaneously modulating the epigenetic system and the protein kinase pathway, we selected the enzyme histone deacetylase (HDAC) and the Rho-associated protein kinases (ROCK) as desired targets to develop potential multitarget anticancer agents with additional antimetastatic properties. We report here the rational design, synthesis, and biological evaluation of the first-in-class HDAC/ROCK multitarget inhibitors in pancreatic ductal adenocarcinoma (PDAC) and triple-negative breast cancer (TNBC).

MATERIALS AND METHODS

A molecular docking study performed with the Gold software was used to develop HDAC/ROCK multitarget inhibitors. IC50 values were determined by enzyme assays. The cytotoxicity, anti-migratory and anti-invasive properties of the inhibitors were evaluated using triple-negative breast cancer cells (MDA-MB-231 and HCC 1973) and pancreatic ductal adenocarcinoma cells (Panc-1 and MiaPaCa-2).

RESULTS

C-9 showed significant inhibition of HDAC6, ROCK1 and ROCK2. At the same time, this compound showed strong antiproliferative effects on MDA-MB-231, MiaPaCa-2 and Panc-1 cell lines with IC50 values of 5.81 μM, 3.87 μM and 19.57 μM. In addition, it demonstrated great anti-invasive and anti-migratory effects.

CONCLUSION

The findings of this study strongly suggest that the simultaneous inhibition of ROCK and HDACs holds significant potential as a promising therapeutic strategy in the advancement of cancer treatment.

Wnt Pathway-Targeted Therapy in Gastrointestinal Cancers: Integrating Benchside Insights with Bedside Applications

The Wnt signaling pathway is critical in the onset and progression of gastrointestinal (GI) cancers. Anomalies in this pathway, often stemming from mutations in critical components such as adenomatous polyposis coli (APC) or β-catenin, lead to uncontrolled cell proliferation and survival. In the case of colorectal cancer, dysregulation of the Wnt pathway drives tumor initiation and growth. Similarly, aberrant Wnt signaling contributes to tumor development, metastasis, and resistance to therapy in other GI cancers, such as gastric, pancreatic, and hepatocellular carcinomas. Targeting the Wnt pathway or its downstream effectors has emerged as a promising therapeutic strategy for combating these highly aggressive GI malignancies. Here, we review the dysregulation of the Wnt signaling pathway in the pathogenesis of GI cancers and further explore the therapeutic potential of targeting the various components of the Wnt pathway. Furthermore, we summarize and integrate the preclinical evidence supporting the therapeutic efficacy of potent Wnt pathway inhibitors with completed and ongoing clinical trials in GI cancers. Additionally, we discuss the challenges of Wnt pathway-targeted therapies in GI cancers to overcome these concerns for effective clinical translation.

Longitudinal Circulating Tumor Cell Collection, Culture, and Characterization in Pancreatic Adenocarcinomas

BACKGROUND/OBJECTIVES

Pancreatic adenocarcinoma (PDAC) remains one of the most lethal cancers, with limited advancements in treatment efficacy due to high rates of chemoresistance. Circulating tumor cells (CTCs) derived from liquid biopsies offer a non-invasive approach to monitoring tumor evolution and identifying molecular mechanisms of resistance. This study aims to longitudinally collect, culture, and characterize CTCs from PDAC patients to elucidate resistance mechanisms and tumor-specific gene expression profiles.

METHODS

Blood samples from 10 PDAC patients were collected across different treatment stages, yielding 16 CTC cultures. Differential gene expression, pathway dysregulation, and protein-protein interaction studies were utilized, highlighting patient-specific and disease progression-associated changes. Longitudinal comparisons within five patients provided further insights into dynamic molecular changes associated with therapeutic resistance.

RESULTS

CTC cultures exhibited the activation of key pathways implicated in PDAC progression and resistance, including TNFα/NF-kB, hedgehog signaling, and the epithelial-to-mesenchymal transition. Longitudinal samples revealed dynamic changes in signaling pathways, highlighting upregulated mechanisms of chemoresistance, including PI3K/Akt/mTOR and TGF-β pathways. Additionally, protein-protein interaction analysis emphasized the role of the immune system in PDAC progression and therapy response. Patient-specific gene expression patterns therefore suggest potential applications for precision medicine.

CONCLUSIONS

This proof-of-concept study demonstrates the feasibility of longitudinally capturing and analyzing CTCs from PDAC patients. The findings provide critical insights into molecular drivers of chemoresistance and highlight the potential of CTC profiling to inform personalized therapeutic strategies. Future large-scale studies are warranted to validate these findings and further explore CTC-based approaches in PDAC management.

The role of AMPK in pancreatic cancer: from carcinogenesis to treatment

Pancreatic cancer has doubled over the previous two decades. Routine therapies are becoming incredibly resistant and failing to compensate for the burden caused by this aggressive neoplasm. As genetic susceptibility has always been a highlighted concern for this disease, identifying the molecular pathways involved in the survival and function of pancreatic cancer cells provides insight into its variant etiologies, one of which is the role of AMPK. This regulating factor of cell metabolism is crucial in the homeostasis and growth of the cell. Herein, we review the possible role of AMPK in pancreatic cancer while considering its leading effects on glycolysis and autophagy. Then, we assess the probable therapeutic agents that have resulted from the suggested pathways. Studying the underlying genetic changes in pancreatic cancer provides a chance to detect and treat patients suffering from advanced stages of the disease, and those who have given up their hope on conventional therapies can gain an opportunity to combat this cancer.

AI screening and molecular dynamic simulation-driven identification of novel inhibitors of TGFßR1 for pancreatic cancer therapy

Pancreatic cancer, with a 5-year survival rate below 10 %, is one of the deadliest malignancies. The TGF-ß pathway plays a crucial role in this disease, making it a key target for therapeutic intervention. Clinical trials targeting TGF-β have faced challenges of toxicity and limited efficacy, highlighting the need for more potent small molecule inhibitors. We selected TGFßR1 as the drug target to inhibit TGF-ß signaling in pancreatic cancer. A multi-faceted approach was employed, commencing with AI-driven screening techniques to rapidly identify potential TGFßR1 inhibitors from vast compound libraries, including the ZINC and ChEMBL databases. AI-screened compounds were further validated through structure-based high-throughput virtual screening (HTVS) to evaluate their binding affinity to TGFßR1. In addition to this, a dedicated library of anticancer compounds (65,000 compounds) and protein kinase inhibitors (36,324 compounds) were also used for HTVS. Subsequently, pharmacokinetic profiling narrowed the selection to 40 hit compounds. Five hit compounds were chosen based on binding affinity, non-bonded interactions, stereochemistry, and pharmacokinetic profiles for molecular dynamics (MD) simulations. Trajectory analysis showed that residues HIS283, ASP351, LYS232, SER280, ILE211, and LYS213 within TGFßR1's active site are crucial for ligand binding through hydrogen bonds and hydrophobic interactions. Principal component analysis (PCA) and Dynamic cross-correlation matrix (DCCM) analysis were used to evaluate the receptor's dynamic response to the hit compounds. The simulation data revealed that compounds 1, 2, 3, 4, and 5 formed stable complexes with TGFßR1. Notably, post-MDS MM-GBSA analysis showed that compounds 4 and 5 exhibited exceptionally strong binding energies of -81.0 kcal/mol and -85.5 kcal/mol, respectively. The comprehensive computational analysis confirms compounds 4 and 5 as promising TGFßR1 hits with potential therapeutic applications in development of new treatments for pancreatic cancer.

Unveiling the 4-aminoquinoline derivatives as potent agents against pancreatic ductal adenocarcinoma (PDAC) cell lines

Common antimalarials such as artemisinins, chloroquine and their derivatives also possess potent anti-inflamantory, antiviral and anticancer properties. In the search for new therapeutics to combat difficult-to-treat pancreatic carcinomas, we unveiled that 4-aminoquinoline derivatives, with significant antiplasmodial properties and a great safety profile in vivo, have remarkable anticancer activity against pancreatic ductal adenocarcinoma (PDAC) and considerable efficacy in the xenograft model in vivo. The aim of the present study was to further investigate anticancer properties of these compounds in a drug-repurposing manner. The compounds showed profound cytotoxic effects at nanomolar to low micromolar concentration in 2D cultured cells (in vitro) and in the zebrafish PDAC xenograft model (in vivo). A deeper insight into their mechanisms of cytotoxic action showed these compounds induce apoptosis while increasing reactive oxygen species levels along with autophagy inhibition. Additional investigation of the autophagy modulation proved that tested quinoline derivatives cause P62 and LC3-II accumulation in PDAC cells alongside lysosomal alkalinization. Further, in vivo toxicity studies in the zebrafish model showed low toxicity without developmental side effects of the investigated 4-aminoquinolines, while the applied compounds effectively inhibited tumor growth and prevented the metastasis of xenografted pancreatic cells. Taken together, these results highlight the 4-aminoquinolines as privileged structures that ought to be investigated further for potential application in pancreatic carcinoma treatment.

Unveiling the resistance to therapies in pancreatic ductal adenocarcinoma

Despite the ongoing advances in interventional strategies (surgery, chemotherapy, radiotherapy, and immunotherapy) for managing pancreatic ductal adenocarcinoma (PDAC), the development of therapy refractory phenotypes remains a significant challenge. Resistance to various therapeutic modalities in PDAC emanates from a combination of inherent and acquired factors and is attributable to cancer cell-intrinsic and -extrinsic mechanisms. The critical determinants of therapy resistance include oncogenic signaling and epigenetic modifications that drive cancer cell stemness and metabolic adaptations, CAF-mediated stromagenesis that results in ECM deposition altered mechanotransduction, and secretome and immune evasion. We reviewed the current understanding of these multifaceted mechanisms operating in the PDAC microenvironment, influencing the response to chemotherapy, radiotherapy, and immunotherapy regimens. We then describe how the lessons learned from these studies can guide us to discover novel therapeutic regimens to prevent, delay, or revert resistance and achieve durable clinical responses.

A 3D Pancreatic Cancer Model with Integrated Optical Sensors for Noninvasive Metabolism Monitoring and Drug Screening

A distinct feature of pancreatic ductal adenocarcinoma (PDAC) is a prominent tumor microenvironment (TME) with remarkable cellular and spatial heterogeneity that meaningfully impacts disease biology and treatment resistance. The dynamic crosstalk between cancer cells and the dense stromal compartment leads to spatially and temporally heterogeneous metabolic alterations, such as acidic pH that contributes to drug resistance in PDAC. Thus, monitoring the extracellular pH metabolic fluctuations within the TME is crucial to predict and to quantify anticancer drug efficacy. Here, a simple and reliable alginate-based 3D PDAC model embedding ratiometric optical pH sensors and cocultures of tumor (AsPC-1) and stromal cells for simultaneously monitoring metabolic pH variations and quantify drug response is presented. By means of time-lapse confocal laser scanning microscopy (CLSM) coupled with a fully automated computational analysis, the extracellular pH metabolic variations are monitored and quantified over time during drug testing with gemcitabine, folfirinox, and paclitaxel, commonly used in PDAC therapy. In particular, the extracellular acidification is more pronounced after drugs treatment, resulting in increased antitumor effect correlated with apoptotic cell death. These findings highlight the importance of studying the influence of cellular metabolic mechanisms on tumor response to therapy in 3D tumor models, this being crucial for the development of personalized medicine approaches.

YBX1 as a therapeutic target to suppress the LRP1-β-catenin-RRM1 axis and overcome gemcitabine resistance in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is highly malignant and has a poor prognosis, without effective therapeutic targets in common gene mutations. Gemcitabine, a first-line chemotherapeutic for PDAC, confers <10 % 5-year survival rate because of drug resistance. Y-box binding protein 1 (YBX1), associated with multidrug-resistance gene activation, remains unelucidated in PDAC gemcitabine resistance. In vivo and in vitro, we verified YBX1's promotional effects, especially gemcitabine resistance, in pancreatic cancer cells. YBX1-induced LRP1 transcription by binding to the LRP1 promoter region significantly altered the concentration and distribution of β-catenin in pancreatic cancer cells. Through TCF3, β-catenin bound to the promoter region of RRM1, a key gene for gemcitabine resistance, that promotes RRM1 expression. Combination therapy with the YBX1 inhibitor SU056 and gemcitabine effectively reduced gemcitabine resistance in in vivo and in vitro experiments. High YBX1 expression promoted pathogenesis and gemcitabine resistance in pancreatic cancer through the YBX1-LRP1-β-catenin-RRM1 axis. Combining YBX1 inhibitors with gemcitabine may provide a new direction for combination chemotherapy to overcome gemcitabine resistance, which frequently occurs during chemotherapy for pancreatic cancer.

A 3D Bio-Printed-Based Model for Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a disease with a very poor prognosis, characterized by incidence rates very close to death rates. Despite the efforts of the scientific community, preclinical models that faithfully recreate the PDAC tumor microenvironment remain limited. Currently, the use of 3D bio-printing is an emerging and promising method for the development of cancer tumor models with reproducible heterogeneity and a precisely controlled structure. This study presents the development of a model using the extrusion 3D bio-printing technique. Initially, a model combining pancreatic cancer cells (Panc-1) and cancer-associated fibroblasts (CAFs) encapsulated in a sodium alginate and gelatin-based hydrogel to mimic the metastatic stage of PDAC was developed and comprehensively characterized. Subsequently, efforts were made to vascularize this model. This study demonstrates that the resulting tumors can maintain viability and proliferate, with cells self-organizing into aggregates with a heterogeneous composition. The utilization of 3D bio-printing in creating this tumor model opens avenues for reproducing tumor complexity in the future, offering a versatile platform for improving anti-cancer therapy models.

MicroRNAs: emerging biomarkers and therapeutic targets in pancreatic cancer

Pancreatic cancer (PC) is a highly malignant disease with high aggressiveness and a dismal prognosis, which is challenging to diagnose clinically early and gains low benefit from standard therapies. MicroRNAs (miRNAs) have become a hot topic in oncology research. Current evidence indicates that miRNAs are regulators involved in the entire process of PC, providing new diagnostic and therapeutic strategies for this fatal disease. Related research has been rapidly updated, making it necessary to review it to propose new directions and ideas and provide guidance for the development of precision medicine for PC. We reviewed the relevant literature through Pubmed, Embase, Web of Science and Medline, showing that abnormally expressed miRNAs in PC patients have the potential to be used as biomarkers for diagnosis and prognosis, highlighting the excellent prospect of combining miRNAs with traditional therapies, and the effective application of these factors for PC, especially miRNA mimics and inhibitors. MiRNAs participate in the entire process of PC and play important roles in diagnosis, treatment and prognosis. They are potential factors in conquering PC in the future.

Overcoming Cancer Resistance: Strategies and Modalities for Effective Treatment

Resistance to cancer drugs is a complex phenomenon that poses a significant challenge in the treatment of various malignancies. This review comprehensively explores cancer resistance mechanisms and discusses emerging strategies and modalities to overcome this obstacle. Many factors contribute to cancer resistance, including genetic mutations, activation of alternative signaling pathways, and alterations in the tumor microenvironment. Innovative approaches, such as targeted protein degradation, immunotherapy combinations, precision medicine, and novel drug delivery systems, hold promise for improving treatment outcomes. Understanding the intricacies of cancer resistance and leveraging innovative modalities are essential for advancing cancer therapy.

Exosomes regulate doxorubicin resistance in breast cancer via miR-34a-5p/NOTCH1

Breast cancer (BRCA) is the most common cancer among women. Adriamycin (ADR), also known as doxorubicin (Dox), is a commonly used chemotherapeutic agent for BRCA patients, however, the susceptibility of tumor cells to develop resistance to Dox has severely limited its clinical use. One new promising therapeutic target for breast cancer patients is exosomes. The objective of this study was to investigate the role of exosomes in regulating Dox resistance in BRCA. In this study, the exosomes from both types of cells were extracted by differential centrifugation. The effect of exosomes on drug resistance was assessed by laser confocal microscopy, MTT assay, and qRT-PCR. The miRNA was transfected into cells using Lipofectamine 2000, which was then evaluated for downstream genes and changes in drug resistance. Exosomes from MCF-7 cells (MCF-7/exo) and MCF-7/ADR cells (ADR/exo) were effectively extracted in this study. The ADR/exo was able to endocytose MCF-7 cells and make them considerably more resistant to Dox. Moreover, we observed a significant difference in miR-34a-5p expression in MCF-7/ADR and ADR/exo compared to MCF-7 and MCF-7/exo. Among the miR-34a-5p target genes, NOTCH1 displayed a clear change with a negative correlation. In addition, when miR-34a-5p expression was elevated in MCF-7/ADR cells, the expression of miR-34a-5p in ADR/exo was also enhanced alongside NOTCH1, implying that exosomes may carry miRNA into and out of cells and perform their function. In conclusion, exosomes can influence Dox resistance in breast cancer cells by regulating miR-34a-5p/NOTCH1. These findings provide novel insights for research into the causes of tumor resistance and the enhancement of chemotherapy efficacy in breast cancer.

Investigating underlying molecular mechanisms, signaling pathways, emerging therapeutic approaches in pancreatic cancer

Pancreatic adenocarcinoma, a clinically challenging malignancy constitutes a significant contributor to cancer-related mortality, characterized by an inherently poor prognosis. This review aims to provide a comprehensive understanding of pancreatic adenocarcinoma by examining its multifaceted etiologies, including genetic mutations and environmental factors. The review explains the complex molecular mechanisms underlying its pathogenesis and summarizes current therapeutic strategies, including surgery, chemotherapy, and emerging modalities such as immunotherapy. Critical molecular pathways driving pancreatic cancer development, including KRAS, Notch, and Hedgehog, are discussed. Current therapeutic strategies, including surgery, chemotherapy, and radiation, are discussed, with an emphasis on their limitations, particularly in terms of postoperative relapse. Promising research areas, including liquid biopsies, personalized medicine, and gene editing, are explored, demonstrating the significant potential for enhancing diagnosis and treatment. While immunotherapy presents promising prospects, it faces challenges related to immune evasion mechanisms. Emerging research directions, encompassing liquid biopsies, personalized medicine, CRISPR/Cas9 genome editing, and computational intelligence applications, hold promise for refining diagnostic approaches and therapeutic interventions. By integrating insights from genetic, molecular, and clinical research, innovative strategies that improve patient outcomes can be developed. Ongoing research in these emerging fields holds significant promise for advancing the diagnosis and treatment of this formidable malignancy.

Expression of gemcitabine metabolizing enzymes and stromal components reveal complexities of preclinical pancreatic cancer models for therapeutic testing

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) poorly responds to antineoplastic agents. Discrepancies between preclinical success and clinical failure of compounds has been a continuous challenge and major obstacle in PDAC research.

AIM

To investigate the association of the tumor microenvironment (TME) composition and gemcitabine metabolizing enzyme (GME) expression in vitro and several in vivo models.

METHODS

mRNA expression and protein levels of GME (cytosolic 5'-nucleotidase 1 A; NT5C1A, cytidine deaminase; CDA, deoxycytidine kinase; DCK), gemcitabine transporters (ENT1, ENT2, RRM1, RRM2) and stromal components (hyaluroninc acid, podoplanin, masson trichrome, picrosirius) were assessed by qRT-PCR and immunohistochemistry in murine LSL-KrasG12D/+;LSL-Trp53R172 H/+; Pdx-1-Cre (KPC), orthotopically transplanted mice (OTM), human primary resected PDAC tissue (hPRT), corresponding patient-derived xenograft (PDX) mice, and KPC-SPARC-/- mice. mRNA expression of GME was analyzed in PDAC cell lines (Panc-1, MIA PaCa, BXPC3 and L3.6) upon incubation on collagen or pancreatic stellate cell (PSC) conditioned media by qRT-PCR.

RESULTS

Endogenous KPC tumors exhibited significantly higher levels of GME compared to OTM. However, GME levels did not differ between hPRT and corresponding PDX mice. Using Kendalls Tau correlation coefficient we did not show a significant correlation of GME and components of the TME except for NT5C1A and hyaluronic acid in PDX mice (p=0.029). GME were not significantly altered upon SPARC depletion in vivo, and upon treatment with PSC-conditioned media or incubation on collagen plated dishes in vitro.

CONCLUSIONS

Our findings suggest that the expression of GME is independent from the deposition of stromal components. KPC mice are most appropriate to study stromal composition whereas PDX mice maintain GME expression of the corresponding hPRT and could be best suited for pharmacokinetic studies.

Elucidation of the Gemcitabine Transporters of Escherichia coli K-12 and Gamma-Proteobacteria Linked to Gemcitabine-Related Chemoresistance

Gemcitabine (2',2'-difluoro-2'-deoxycytidine), a widely used anticancer drug, is considered a gold standard in treating aggressive pancreatic cancers. Gamma-proteobacteria that colonize the pancreatic tumors contribute to chemoresistance against gemcitabine by metabolizing the drug to a less active and deaminated form. The gemcitabine transporters of these bacteria are unknown to date. Furthermore, there is no complete knowledge of the gemcitabine transporters in Escherichia coli or any other related proteobacteria. In this study, we investigate the complement of gemcitabine transporters in E. coli K-12 and two common chemoresistance-related bacteria (Klebsiella pneumoniae and Citrobacter freundii). We found that E. coli K-12 has two high-affinity gemcitabine transporters with distinct specificity properties, namely, NupC and NupG, whereas the gemcitabine transporters of C. freundii and K. pneumoniae include the NupC and NupG orthologs, functionally indistinguishable from their counterparts, and, in K. pneumoniae, one additional NupC variant, designated KpNupC2. All these bacterial transporters have a higher affinity for gemcitabine than their human counterparts. The highest affinity (KM 2.5-3.0 μΜ) is exhibited by NupGs of the bacteria-specific nucleoside-H+ symporter (NHS) family followed by NupCs (KM 10-13 μΜ) of the concentrative nucleoside transporter (CNT) family, 15-100 times higher than the affinities reported for the human gemcitabine transporter hENT1/SLC29A1, which is primarily associated with gemcitabine uptake in the pancreatic adenocarcinoma cells. Our results offer a basis for further insight into the role of specific bacteria in drug availability within tumors and for understanding the structure-function differences of bacterial and human drug transporters.

Gemcitabine-Lipid Conjugate and ONC201 Combination Therapy Effectively Treats Orthotopic Pancreatic Tumor-Bearing Mice

Gemcitabine (GEM) is a nucleoside analogue approved as a first line of therapy for pancreatic ductal adenocarcinoma (PDAC). However, rapid metabolism by plasma cytidine deaminase leading to the short half-life, intricate intracellular metabolism, ineffective cell uptake, and swift development of chemoresistance downgrades the clinical efficacy of GEM. ONC201 is a small molecule that inhibits the Akt and ERK pathways and upregulates the TNF-related apoptosis-inducing ligand (TRAIL), which leads to the reversal of both intrinsic and acquired GEM resistance in PDAC treatment. Moreover, the pancreatic cancer cells that were able to bypass apoptosis after treatment of ONC201 get arrested in the G1-phase, which makes them highly sensitive to GEM. To enhance the in vivo stability of GEM, we first synthesized a disulfide bond containing stearate conjugated GEM (lipid-GEM), which makes it sensitive to the redox tumor microenvironment (TME) comprising high glutathione levels. In addition, with the help of colipids 1,2-dioleoyl-glycero-3-phosphocholine (DOPC), cholesterol, and 1,2-distearoyl-glycero-3-phosphoethanolamine-poly(ethylene glycol)-2000 (DSPE-PEG 2000), we were able to synthesize the lipid-GEM conjugate and ONC201 releasing liposomes. A cumulative drug release study confirmed that both ONC201 and GEM showed sustained release from the formulation. Since MUC1 is highly expressed in 70-90% PDAC, we conjugated a MUC1 binding peptide in the liposomes which showed higher cytotoxicity, apoptosis, and cellular internalization by MIA PaCa-2 cells. A biodistribution study further confirmed that the systemic delivery of the liposomes through the tail vein resulted in a higher accumulation of drugs in orthotopic PDAC tumors in NSG mice. The IHC of the excised tumor grafts further confirmed the higher apoptosis and lower metastasis and cell proliferation. Thus, our MUC1 targeting binary drug-releasing liposomal formulation showed higher drug payload, enhanced plasma stability, and accumulation of drugs in the pancreatic orthotopic tumor and thus is a promising therapeutic alternative for the treatment of PDAC.

Sugar ring alignment and dynamics underline cytarabine and gemcitabine inhibition on Pol η catalyzed DNA synthesis

Nucleoside analogue drugs are pervasively used as antiviral and chemotherapy agents. Cytarabine and gemcitabine are anti-cancer nucleoside analogue drugs that contain C2' modifications on the sugar ring. Despite carrying all the required functional groups for DNA synthesis, these two compounds inhibit DNA extension once incorporated into DNA. It remains unclear how the C2' modifications on cytarabine and gemcitabine affect the polymerase active site during substrate binding and DNA extension. Using steady-state kinetics, static and time-resolved X-ray crystallography with DNA polymerase η (Pol η) as a model system, we showed that the sugar ring C2' chemical groups on cytarabine and gemcitabine snugly fit within the Pol η active site without occluding the steric gate. During DNA extension, Pol η can extend past gemcitabine but with much lower efficiency past cytarabine. The Pol η crystal structures show that the -OH modification in the β direction on cytarabine locks the sugar ring in an unfavorable C2'-endo geometry for product formation. On the other hand, the addition of fluorine atoms on gemcitabine alters the proper conformational transition of the sugar ring for DNA synthesis. Our study illustrates mechanistic insights into chemotherapeutic drug inhibition and resistance and guides future optimization of nucleoside analogue drugs.

Pulse and CW EPR Oximetry Using Oxychip in Gemcitabine-Treated Murine Pancreatic Tumors

PURPOSE

The goal of this work was to compare pO2 measured using both continuous wave (CW) and pulse electron paramagnetic resonance (EPR) spectroscopy. The Oxychip particle spin probe enabled longitudinal monitoring of pO2 in murine pancreatic tumor treated with gemcitabine during the course of therapy.

PROCEDURES

Pancreatic PanO2 tumors were growing in the syngeneic mice, in the leg. Five doses of saline in control animals or gemcitabine were administered every 3 days, and pO2 was measured after each dose at several time points. Oxygen partial pressure was determined from the linewidth of the CW EPR signal (Bruker E540L) or from the T2 measured using the electron spin echo sequence (Jiva-25™).

RESULTS

The oxygen sensitivity was determined from a calibration curve as 6.1 mG/mm Hg in CW EPR and 68.5 ms-1/mm Hg in pulse EPR. A slight increase in pO2 of up to 20 mm Hg was observed after the third dose of gemcitabine compared to the control. The maximum delta pO2 during the therapy correlated with better survival.

CONCLUSIONS

Both techniques offer fast and reliable oximetry in vivo, allowing to follow the effects of pharmaceutic intervention.

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.

Methyltransferase-like 3 modifications of RNAs: Implications for the pathology in the endocrine system

Methyltransferase-like 3 (METTL3) is the most well-known element of N6-methyladenosine modification on RNAs. METTL3 deposits a methyl group onto target RNAs to modify their expression, ultimately regulating various physiological and pathological events. Numerous studies have suggested the significant role of METTL3 in endocrine dysfunction and related disorders. However, reviews that summarize and interpret these studies are lacking. In this review, we systematically analyze such studies, including obesity, type 2 diabetes mellitus (T2DM), T2DM-induced diseases, pancreatic cancer, and thyroid carcinoma. This review indicates that METTL3 contributes remarkably to the endocrine dysfunction and progression of obesity, T2DM, T2DM-induced diseases, pancreatic cancer, and thyroid carcinoma. In conclusion, this review provides a comprehensive interpretation of the mechanism via which METTL3 functions on RNAs and regulates various endocrine dysfunction events and suggest potential associated correlations. Our review, thus, provides a valuable reference for further fundamental studies and clinical applications.

Emerging Therapeutic Options in Pancreatic Cancer Management

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with a 5-year survival rate of <8% [...].

Overcoming Microbiome-Acquired Gemcitabine Resistance in Pancreatic Ductal Adenocarcinoma

Gastrointestinal cancers (GICs) are one of the most recurrent diseases in the world. Among all GICs, pancreatic cancer (PC) is one of the deadliest and continues to disrupt people's lives worldwide. The most frequent pancreatic cancer type is pancreatic ductal adenocarcinoma (PDAC), representing 90 to 95% of all pancreatic malignancies. PC is one of the cancers with the worst prognoses due to its non-specific symptoms that lead to a late diagnosis, but also due to the high resistance it develops to anticancer drugs. Gemcitabine is a standard treatment option for PDAC, however, resistance to this anticancer drug develops very fast. The microbiome was recently classified as a cancer hallmark and has emerged in several studies detailing how it promotes drug resistance. However, this area of study still has seen very little development, and more answers will help in developing personalized medicine. PC is one of the cancers with the highest mortality rates; therefore, it is crucial to explore how the microbiome may mold the response to reference drugs used in PDAC, such as gemcitabine. In this article, we provide a review of what has already been investigated regarding the impact that the microbiome has on the development of PDAC in terms of its effect on the gemcitabine pathway, which may influence the response to gemcitabine. Therapeutic advances in this type of GIC could bring innovative solutions and more effective therapeutic strategies for other types of GIC, such as colorectal cancer (CRC), due to its close relation with the microbiome.

Acquired and intrinsic gemcitabine resistance in pancreatic cancer therapy: Environmental factors, molecular profile and drug/nanotherapeutic approaches

A high number of cancer patients around the world rely on gemcitabine (GEM) for chemotherapy. During local metastasis of cancers, surgery is beneficial for therapy, but dissemination in distant organs leads to using chemotherapy alone or in combination with surgery to prevent cancer recurrence. Therapy failure can be observed as a result of GEM resistance, threatening life of pancreatic cancer (PC) patients. The mortality and morbidity of PC in contrast to other tumors are increasing. GEM chemotherapy is widely utilized for PC suppression, but resistance has encountered its therapeutic impacts. The purpose of current review is to bring a broad concept about role of biological mechanisms and pathways in the development of GEM resistance in PC and then, therapeutic strategies based on using drugs or nanostructures for overcoming chemoresistance. Dysregulation of the epigenetic factors especially non-coding RNA transcripts can cause development of GEM resistance in PC and miRNA transfection or using genetic tools such as siRNA for modulating expression level of these factors for changing GEM resistance are suggested. The overexpression of anti-apoptotic proteins and survival genes can contribute to GEM resistance in PC. Moreover, supportive autophagy inhibits apoptosis and stimulates GEM resistance in PC cells. Increase in metabolism, glycolysis induction and epithelial-mesenchymal transition (EMT) stimulation are considered as other factors participating in GEM resistance in PC. Drugs can suppress tumorigenesis in PC and inhibit survival factors and pathways in increasing GEM sensitivity in PC. More importantly, nanoparticles can increase pharmacokinetic profile of GEM and promote its blood circulation and accumulation in cancer site. Nanoparticles mediate delivery of GEM with genes and drugs to suppress tumorigenesis in PC and increase drug sensitivity. The basic research displays significant connection among dysregulated pathways and GEM resistance, but the lack of clinical application is a drawback that can be responded in future.

Antiproliferative Activity of Piceamycin by Regulating Alpha-Actinin-4 in Gemcitabine-Resistant Pancreatic Cancer Cells

Although gemcitabine-based regimens are widely used as an effective treatment for pancreatic cancer, acquired resistance to gemcitabine has become an increasingly common problem. Therefore, a novel therapeutic strategy to treat gemcitabine-resistant pancreatic cancer is urgently required. Piceamycin has been reported to exhibit antiproliferative activity against various cancer cells; however, its underlying molecular mechanism for anticancer activity in pancreatic cancer cells remains unexplored. Therefore, the present study evaluated the antiproliferation activity of piceamycin in a gemcitabine-resistant pancreatic cancer cell line and patient-derived pancreatic cancer organoids. Piceamycin effectively inhibited the proliferation and suppressed the expression of alpha-actinin-4, a gene that plays a pivotal role in tumorigenesis and metastasis of various cancers, in gemcitabine-resistant cells. Long-term exposure to piceamycin induced cell cycle arrest at the G0/G1 phase and caused apoptosis. Piceamycin also inhibited the invasion and migration of gemcitabine-resistant cells by modulating focal adhesion and epithelial-mesenchymal transition biomarkers. Moreover, the combination of piceamycin and gemcitabine exhibited a synergistic antiproliferative activity in gemcitabine-resistant cells. Piceamycin also effectively inhibited patient-derived pancreatic cancer organoid growth and induced apoptosis in the organoids. Taken together, these findings demonstrate that piceamycin may be an effective agent for overcoming gemcitabine resistance in pancreatic cancer.

Selective and Concentrative Enteropancreatic Recirculation of Antibiotics by Pigs

Antibiotics that are efficacious for infectious pancreatitis are present in pancreatic exocrine secretion (PES) after intravenous administration and above minimal inhibitory concentrations. We measured concentrations of four antibiotics by tandem liquid chromatography-mass spectroscopy in plasma and PES after enteral administration to juvenile pigs with jugular catheters and re-entrant pancreatic-duodenal catheters. Nystatin, which is not absorbed by the intestine nor used for infectious pancreatitis (negative control), was not detected in plasma or PES. Concentrations of amoxicillin increased in plasma after administration (p = 0.035), but not in PES (p = 0.51). Metronidazole and enrofloxacin that are used for infectious pancreatitis increased in plasma after enteral administration and even more so in PES, with concentrations in PES averaging 3.1 (±0.5)- and 2.3 (±0.6)-fold higher than in plasma, respectively (p's < 0.001). The increase in enrofloxacin in PES relative to plasma was lower after intramuscular administration (1.8 ± 0.5; p = 0.001). The present results demonstrate the presence of a selective and concentrative enteropancreatic pathway of secretion for some antibiotics. Unlike the regulated secretion of bile, the constitutive secretion of PES and intestinal reabsorption may provide a continuous exposure of pancreas tissue and the small intestine to recirculated antibiotics and potentially other therapeutic molecules. There is a need to better understand the enteropancreatic recirculation of antibiotics and the associated mechanisms.

TRPV6 Channel Is Involved in Pancreatic Ductal Adenocarcinoma Aggressiveness and Resistance to Chemotherapeutics

Pancreatic ductal adenocarcinoma (PDAC) stands as a highly aggressive and lethal cancer, characterized by a grim prognosis and scarce treatment alternatives. Within this context, TRPV6, a calcium-permeable channel, emerges as a noteworthy candidate due to its overexpression in various cancers, capable of influencing the cell behavior in different cancer entities. Nonetheless, the exact expression pattern and functional significance of TRPV6 in the context of PDAC remains enigmatic. This study scrutinizes the expression of TRPV6 in tissue specimens obtained from 46 PDAC patients across distinct stages and grades. We manipulated TRPV6 expression (knockdown, overexpression) in the human PDAC cell lines Panc-1 and Capan-1. Subsequently, we analyzed its impact on multiple facets, encompassing Ca2+ influx, proliferation, apoptosis, migration, chemoresistance, and tumor growth, both in vitro and in vivo. Notably, the data indicate a direct correlation between TRPV6 expression levels, tumor stage, and grade, establishing a link between TRPV6 and PDAC proliferation in tissue samples. Decreasing TRPV6 expression via knockdown hampered Ca2+ influx, resulting in diminished proliferation and viability in both cell lines, and cell cycle progression in Panc-1. The knockdown simultaneously led to an increase in apoptotic rates and increased the susceptibility of cells to 5-FU and gemcitabine treatments. Moreover, it accelerated migration and promoted collective movement among Panc-1 cells. Conversely, TRPV6 overexpression yielded opposing outcomes in terms of proliferation in Panc-1 and Capan-1, and the migration of Panc-1 cells. Intriguingly, both TRPV6 knockdown and overexpression diminished the process of tumor formation in vivo. This intricate interplay suggests that PDAC aggressiveness relies on a fine-tuned TRPV6 expression, raising its profile as a putative therapeutic target.

AUM302, a novel triple kinase PIM/PI3K/mTOR inhibitor, is a potent in vitro pancreatic cancer growth inhibitor

Pancreatic cancer is one of the leading causes of cancer deaths, with pancreatic ductal adenocarcinoma (PDAC) being the most common subtype. Advanced stage diagnosis of PDAC is common, causing limited treatment opportunities. Gemcitabine is a frequently used chemotherapeutic agent which can be used as a monotherapy or in combination. However, tumors often develop resistance to gemcitabine. Previous studies show that the proto-oncogene PIM kinases (PIM1 and PIM3) are upregulated in PDAC compared to matched normal tissue and are related to chemoresistance and PDAC cell growth. The PIM kinases are also involved in the PI3K/AKT/mTOR pathway to promote cell survival. In this study, we evaluate the effect of the novel multikinase PIM/PI3K/mTOR inhibitor, AUM302, and commercially available PIM inhibitor, TP-3654. Using five human PDAC cell lines, we found AUM302 to be a potent inhibitor of cell proliferation, cell viability, cell cycle progression, and phosphoprotein expression, while TP-3654 was less effective. Significantly, AUM302 had a strong impact on the viability of gemcitabine-resistant PDAC cells. Taken together, these results demonstrate that AUM302 exhibits antitumor activity in human PDAC cells and thus has the potential to be an effective drug for PDAC therapy.

Matrix stiffness triggers chemoresistance through elevated autophagy in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) has a signature of extremely high matrix stiffness caused by a special desmoplastic reaction, which dynamically stiffens along with the pathological process. The poor prognosis and low five-year survival rate of PDAC are partly owing to chemoresistance triggered by substrate stiffness. Understanding the potential mechanisms of matrix stiffness causing PDAC chemoresistance is of great significance. In this study, methacrylated gelatin hydrogel was used as platform for PANC-1 and MIA-PaCa2 cell culture. The results indicated that compared to soft substrate, stiff substrate distinctively reduced the gemcitabine sensitivity of pancreatic cancer. Intriguingly, transmission electron microscopy, immunofluorescence staining, western blot and qRT-PCR assay showcased that the number of autophagosomes and the expression of LC3 were elevated. The observations indicate that matrix stiffness may regulate the autophagy level, which plays a vital role during chemoresistance. In brief, soft substrate exhibited low autophagy level, while the counterpart displayed elevated autophagy level. In order to elucidate the underlying interaction between matrix stiffness-mediated cell autophagy and chemoresistance, rescue experiments with rapamycin and chloroquine were conducted. We found that inhibiting cell autophagy dramatically increased the sensitivity of pancreatic cancer cells to gemcitabine in the stiff group, while promoting autophagy-driven chemoresistance in the soft group, demonstrating that matrix stiffness modulated chemoresistance via autophagy. Furthermore, RNA-seq results showed that miR-1972 may regulate autophagy level in response to matrix stiffness. Overall, our research shed light on the synergistic therapy of PDAC combined with gemcitabine and chloroquine, which is conducive to promoting a therapeutic effect.

High-Load Gemcitabine Inorganic-Organic Hybrid Nanoparticles as an Image-Guided Tumor-Selective Drug-Delivery System to Treat Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) has a devastating prognosis without effective treatment options. Thus, there is an urgent need for more effective and safe therapies. Here, inorganic-organic hybrid nanoparticles (GMP-IOH-NPs) are presented as a novel drug-delivery system for the selective delivery of extraordinarily high concentrations of gemcitabine monophosphate (GMP), not only to the primary tumor but also to metastatic sites. GMP-IOH-NPs have a composition of [ZrO]2+ [GMP]2 - with GMP as drug anion (76% of total IOH-NP mass). Multiscale fluorescence imaging confirms an efficient uptake in tumor cells, independent of the activity of the human-equilibrative-nucleoside transporter (hENT1), being responsible for gemcitabine (GEM) transport into cells and a key factor for GEM resistance. Delivering already phosphorylated GMP via GMP-IOH-NPs into tumor cells also allows the cellular resistance induced by the downregulation of deoxycytidine kinase to be overcome. GMP-IOH-NPs show high accumulation in tumor lesions and only minor liver trapping when given intraperitoneally. GMP-IOH-NPs result in a higher antitumor efficacy compared to free GEM, which is further enhanced applying cetuximab-functionalized GMP-CTX-IOH-NPs. By maximizing the therapeutic benefits with high drug load, tumor-specific delivery, minimizing undesired side effects, overcoming mechanisms of chemoresistance, and preventing systemic GEM inactivation, GMP-IOH-NPs are anticipated to have a high chance to significantly improve current PDAC-patient outcome.

Single-Cell Lipidomics Using Analytical Flow LC-MS Characterizes the Response to Chemotherapy in Cultured Pancreatic Cancer Cells

In this work, we demonstrate the development and first application of nanocapillary sampling followed by analytical flow liquid chromatography-mass spectrometry for single-cell lipidomics. Around 260 lipids were tentatively identified in a single cell, demonstrating remarkable sensitivity. Human pancreatic ductal adenocarcinoma cells (PANC-1) treated with the chemotherapeutic drug gemcitabine can be distinguished from controls solely on the basis of their single-cell lipid profiles. Notably, the relative abundance of LPC(0:0/16:0) was significantly affected in gemcitabine-treated cells, in agreement with previous work in bulk. This work serves as a proof of concept that live cells can be sampled selectively and then characterized using automated and widely available analytical workflows, providing biologically relevant outputs.

Anti-tumor effect of avadomide in gemcitabine-resistant pancreatic ductal adenocarcinoma

PURPOSE

Although gemcitabine-based chemotherapy is most recommended for pancreatic ductal adenocarcinoma (PDAC), its effectiveness is limited because of drug resistance. Given thalidomide's anti-tumor effects in solid tumors, we investigated the effect of avadomide, a novel thalidomide analog, on PDAC and explored its anti-tumor mechanisms.

METHODS

PDAC cell lines, including gemcitabine-resistant (GR) clones derived from MiaPaCa2 cells, were used to evaluate the effects of avadomide. An annexin V assay, a cell cycle assay, and western blot analysis were performed to explain the mechanism of avadomide as an anti-tumor reagent. Moreover, we investigated the anti-tumor effect on tumor growth using a subcutaneous xenograft murine model.

RESULTS

Avadomide showed anti-tumor effects in human PDAC cell lines. The proportion of apoptotic cells and G0/G1 phase cells after avadomide treatment increased, especially in the GR PDAC clones. Western blot analysis also showed the induction of the apoptotic pathway by inhibiting the NF-κB process and G1 phase cell cycle arrest. The xenograft murine model revealed that the proportion of viable cells in the avadomide-treated group was lower than that in the untreated group.

CONCLUSION

Our findings suggest that avadomide could be a novel therapeutic option to overcome gemcitabine resistance in patients with PDAC.

Co-delivery of three synergistic chemotherapeutics in a core-shell nanoscale coordination polymer for the treatment of pancreatic cancer

The combination chemotherapy regimen FOLFIRINOX comprising folinic acid, 5-fluorouracil, irinotecan, and oxaliplatin is the first-line treatment for patients with advanced pancreatic cancer, but its use remains prohibitive for the majority of patients due to severe side effects. Here, we report a core-shell nanoscale coordination polymer (NCP) nanoparticle co-delivering a potent and synergistic combination of oxaliplatin, gemcitabine, and SN38 (OGS), for the treatment of pancreatic cancer in mouse models. OGS contains key synergistic components of FOLFIRINOX in a controllable drug ratio., It exhibited particle stability in blood circulation and enhanced deposition of the drugs in acidic tumor environments. In vitro, OGS showed superior cytotoxicity over free drug combinations and robust cytotoxic synergism among its three components. In vivo, OGS improved drug circulation, increased tumor deposition, and exhibited superior antitumor efficacy over the free drug combination in both subcutaneous and orthotopic pancreatic tumor models. OGS treatment achieved 75-91% tumor growth inhibition and prolonged mouse survival by 1.6- to 2.8-folds while minimizing systemic toxicities such as neutropenia, hepatotoxicity, and renal toxicity. This work uncovers a novel and clinically relevant nanomedicine strategy to co-deliver synergistic combination chemotherapies for difficult-to-treat cancers.

Gemcitabine effects on tumor microenvironment of pancreatic ductal adenocarcinoma: Special focus on resistance mechanisms and metronomic therapies

Pancreatic ductal adenocarcinoma (PDAC) is considered one of the deadliest malignancies, with dismal survival rates and extremely prevalent chemoresistance. Gemcitabine is one of the primary treatments used in treating PDACs, but its benefits are limited due to chemoresistance, which could be attributed to interactions between the tumor microenvironment (TME) and intracellular processes. In preclinical models, certain schedules of administration of gemcitabine modulate the TME in a manner that does not promote resistance. Metronomic therapy constitutes a promising strategy to overcome some barriers associated with current PDAC treatments. This review will focus on gemcitabine's mechanism in treating PDAC, combination therapies, gemcitabine's interactions with the TME, and gemcitabine in metronomic therapies.

Earlier Diagnosis of Pancreatic Cancer: Is It Possible?

Pancreatic ductal adenocarcinoma has a very high mortality rate which has been only minimally improved in the last 30 years. This high mortality is closely related to late diagnosis, which is usually made when the tumor is large and has extensively infiltrated neighboring tissues or distant metastases are already present. This is a paradoxical situation for a tumor that requires nearly 15 years to develop since the first founding mutation. Response to chemotherapy under such late circumstances is poor, resistance is frequent, and prolongation of survival is almost negligible. Early surgery has been, and still is, the only approach with a slightly better outcome. Unfortunately, the relapse percentage after surgery is still very high. In fact, early surgery clearly requires early diagnosis. Despite all the advances in diagnostic methods, the available tools for improving these results are scarce. Serum tumor markers permit a late diagnosis, but their contribution to an improved therapeutic result is very limited. On the other hand, effective screening methods for high-risk populations have not been fully developed as yet. This paper discusses the difficulties of early diagnosis, evaluates whether the available diagnostic tools are adequate, and proposes some simple and not-so-simple measures to improve it.

Nanoparticle-Mediated Therapy with miR-198 Sensitizes Pancreatic Cancer to Gemcitabine Treatment through Downregulation of VCP-Mediated Autophagy

Pancreatic ductal adenocarcinoma (PDAC) remains an extremely aggressive disease characterized by rapidly acquired multi-drug resistance, including to first-line chemotherapeutic agent gemcitabine. Autophagy is a process that is often exploited by cancer and is one of several intrinsic factors associated with resistance to gemcitabine. We have previously found that miR-198 acts as a tumor suppressor in PDAC through the targeting of factors including Valosin-containing protein (VCP). VCP has been reported to play an important role in autophagic flux. In this study, we investigated whether the repression of VCP through miR-198 administration disrupts the autophagy process and sensitizes PDAC cells to gemcitabine treatment in vitro. Moreover, we used LGA-PEI (LPNP) nanoparticles to effectively administer miR-198 to tumors in vivo, inducing tumor sensitization to gemcitabine and leading to a significant reduction in tumor burden and metastases and a concomitant downregulation of VCP expression and autophagy maturation. Our results indicate a potential therapeutic strategy for targeting gemcitabine resistant PDAC and establishes the use of LPNPs for effective therapeutic delivery of nucleic acids in vitro and in vivo.

Unveiling tumor immune evasion mechanisms: abnormal expression of transporters on immune cells in the tumor microenvironment

The tumor microenvironment (TME) is a crucial driving factor for tumor progression and it can hinder the body's immune response by altering the metabolic activity of immune cells. Both tumor and immune cells maintain their proliferative characteristics and physiological functions through transporter-mediated regulation of nutrient acquisition and metabolite efflux. Transporters also play an important role in modulating immune responses in the TME. In this review, we outline the metabolic characteristics of the TME and systematically elaborate on the effects of abundant metabolites on immune cell function and transporter expression. We also discuss the mechanism of tumor immune escape due to transporter dysfunction. Finally, we introduce some transporter-targeted antitumor therapeutic strategies, with the aim of providing new insights into the development of antitumor drugs and rational drug usage for clinical cancer therapy.

Oncogenic SRSF3 in health and diseases

Serine/arginine rich splicing factor 3 (SRSF3) is an important multi-functional splicing factor, and has attracted increasing attentions in the past thirty years. The importance of SRSF3 is evidenced by its impressively conserved protein sequences in all animals and alternative exon 4 which represents an autoregulatory mechanism to maintain its proper cellular expression level. New functions of SRSF3 have been continuously discovered recently, especially its oncogenic function. SRSF3 plays essential roles in many cellular processes by regulating almost all aspects of RNA biogenesis and processing of many target genes, and thus, contributes to tumorigenesis when overexpressed or disregulated. This review updates and highlights the gene, mRNA, and protein structure of SRSF3, the regulatory mechanisms of SRSF3 expression, and the characteristics of SRSF3 targets and binding sequences that contribute to SRSF3's diverse molecular and cellular functions in tumorigenesis and human diseases.

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.

Correlating Basal Gene Expression across Chemical Sensitivity Data to Screen for Novel Synergistic Interactors of HDAC Inhibitors in Pancreatic Carcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive and lethal malignancies. Development of the chemoresistance in the PDAC is one of the key contributors to the poor survival outcomes and the major reason for urgent development of novel pharmacological approaches in a treatment of PDAC. Systematically tailored combination therapy holds the promise for advancing the treatment of PDAC. However, the number of possible combinations of pharmacological agents is too large to be explored experimentally. In respect to the many epigenetic alterations in PDAC, epigenetic drugs including histone deacetylase inhibitors (HDACi) could be seen as the game changers especially in combined therapy settings. In this work, we explored a possibility of using drug-sensitivity data together with the basal gene expression of pancreatic cell lines to predict combinatorial options available for HDACi. Developed bioinformatics screening protocol for predictions of synergistic drug combinations in PDAC identified the sphingolipid signaling pathway with associated downstream effectors as a promising novel targets for future development of multi-target therapeutics or combined therapy with HDACi. Through the experimental validation, we have characterized novel synergism between HDACi and a Rho-associated protein kinase (ROCK) inhibitor RKI-1447, and between HDACi and a sphingosine 1-phosphate (S1P) receptor agonist fingolimod.

LncRNA SNHG6 Upregulates KPNA5 to Overcome Gemcitabine Resistance in Pancreatic Cancer via Sponging miR-944

Gemcitabine (GEM) is the gold-standard therapeutic regimen for patients with pancreatic cancer (PC); however, patients may receive limited benefits due to the drug resistance of GEM. LncRNA SNHG6 is reported to play key roles in drug resistance, but its role and molecular mechanism in PC remain incompletely understood. We found that LncRNA SNHG6 is drastically downregulated in GEM-resistant PC and is positively correlated with the survival of PC patients. With the help of bioinformatic analysis and molecular approaches, we show that LncRNA SNHG6 can sponge miR-944, therefore causing the upregulation of the target gene KPNA5. In vitro experiments showed that LncRNA SNHG6 and KPNA5 suppress PC cell proliferation and colony formation. The Upregulation of LncRNA SNHG6 and KPNA5 increases the response of GEM-resistant PANC-1 cells to GEM. We also show that the expression of KPNA5 is higher in patients without GEM resistance than in those who developed GEM resistance. In summary, our findings indicate that the LncRNA SNHG6/miR944/KPNA5 axis plays a pivotal role in overcoming GEM resistance, and targeting this axis may contribute to an increasing of the benefits of PC patients from GEM treatment.