MUC1 and HIF-1alpha Signaling Crosstalk Induces Anabolic Glucose Metabolism to Impart Gemcitabine Resistance to Pancreatic Cancer

Exploring the metabolic landscape of pancreatic ductal adenocarcinoma cells using genome-scale metabolic modeling

Pancreatic ductal adenocarcinoma (PDAC) is a major research focus because of its poor therapy response and dismal prognosis. PDAC cells adapt their metabolism to the surrounding environment, often relying on diverse nutrient sources. Because traditional experimental techniques appear exhaustive to find a viable therapeutic strategy, a highly curated and omics-informed PDAC genome-scale metabolic model was reconstructed using patient-specific transcriptomics data. From the model-predictions, several new metabolic functions were explored as potential therapeutic targets in addition to the known metabolic hallmarks of PDAC. Significant downregulation in the peroxisomal beta oxidation pathway, flux modulation in the carnitine shuttle system, and upregulation in the reactive oxygen species detoxification pathway reactions were observed. These unique metabolic traits of PDAC were correlated with potential drug combinations targeting genes with poor prognosis in PDAC. Overall, this study provides a better understanding of the metabolic vulnerabilities in PDAC and will lead to novel effective therapeutic strategies.

Association of mucin family members with prognostic significance in pancreatic cancer patients: A meta-analysis

OBJECTIVE

The role of biomarkers in the early diagnosis and prognosis prediction of tumors has been paid more and more attention by researchers. Mucins are markers that have been found to have an abnormal expression in many tumors in recent years, which have been proved to have a predictive effect on the prognosis of tumors such as cholangiocarcinoma and colon cancer. However, whether it can predict the prognosis of pancreatic cancer remains unknown. The purpose of our study is to investigate whether the mucins and their subtypes are related to the prognosis of patients with pancreatic cancer.

METHODS

We systematically searched the Pubmed, Embase, and Cochrane Library for all eligible studies on the relationship between mucin and the prognosis of patients with pancreatic cancer up to November 2021. We used R 4.12 to calculate the combined risk ratio (HR) and 95% confidence interval (CI). For studies that did not provide HR values, we used scientific methods to calculate their values as accurately as possible. We used fixed effect model due to low heterogeneity. Subgroup analysis and sensitivity analysis were used to study heterogeneity. The funnel plot and Egger test were used to test whether the publication bias existed. The trim and filling method were used to evaluate the impact of publication bias on the results of the study.

RESULTS

A total of 18 studies were included in this meta-analysis, including 4 subtypes of mucin family members and 1643 patients. There was a slight heterogeneity between studies (I2 = 24.4%, P = 0.14). Meta-analysis showed that MUC4 (HR = 2.04, 95%CI 1.21;3.45), MUC16 (HR = 2.10, 95%CI 1.31;3.37), and whole mucin (HR = 1.32, 95%CI 1.07;1.63). The expression level was negatively correlated with the prognosis of pancreatic cancer patients, MUC1 (HR = 1.09, 95%CI 0.77;1.54), MUC5 (HR = 1.03, 95%CI 0.47;2.25) The expression level was not related to the prognosis of pancreatic cancer patients.

CONCLUSION

The meta-analysis demonstrated that the overall expression level of mucin and the expression levels of MUC4 and MUC16 were important prognostic predictors for pancreatic cancer patients. MUC1 and MUC5 had no predictive value for the prognosis of pancreatic cancer patients. Future studies should validate these and other promising biomarkers.

TRIAL REGISTRATION

PROSPERO registration number is CRD42021291962. https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021291962.

HIF-1-dependent heme synthesis promotes gemcitabine resistance in human non-small cell lung cancers via enhanced ABCB6 expression

Gemcitabine is commonly used to treat various cancer types, including human non-small cell lung cancer (NSCLC). However, even cases that initially respond rapidly commonly develop acquired resistance, limiting our ability to effectively treat advanced NSCLC. To gain insight for developing a strategy to overcome gemcitabine resistance, the present study investigated the mechanism of gemcitabine resistance in NSCLC according to the involvement of ATP-binding cassette subfamily B member 6 (ABCB6) and heme biosynthesis. First, an analysis of ABCB6 expression in human NSCLCs was found to be associated with poor prognosis and gemcitabine resistance in a hypoxia-inducible factor (HIF)-1-dependent manner. Further experiments showed that activation of HIF-1α/ABCB6 signaling led to intracellular heme metabolic reprogramming and a corresponding increase in heme biosynthesis to enhance the activation and accumulation of catalase. Increased catalase levels diminished the effective levels of reactive oxygen species, thereby promoting gemcitabine-based resistance. In a mouse NSCLC model, inhibition of HIF-1α or ABCB6, in combination with gemcitabine, strongly restrained tumor proliferation, increased tumor cell apoptosis, and prolonged animal survival. These results suggest that, in combination with gemcitabine-based chemotherapy, targeting HIF-1α/ABCB6 signaling could result in enhanced tumor chemosensitivity and, thus, may improve outcomes in NSCLC patients.

β-Escin reduces cancer progression in aggressive MDA-MB-231 cells by inhibiting glutamine metabolism through downregulation of c-myc oncogene

BACKGROUND

The c-myc oncogene, which causes glutamine dependence in triple negative breast cancers (TNBC), is also the target of one of the signaling pathways affected by β-Escin.

METHODS AND RESULTS

We sought to determine how c-myc protein affects glutamine metabolism and the proteins, glutamine transporter alanine-serine-cysteine 2 (ASCT2) and glutaminase (GLS1), in β-Escin-treated MDA-MB-231 cells using glutamine uptake and western blot analysis. Cell viability, colony formation, migration and apoptosis were also evaluated in MDA-MB-231 cells in response to β-Escin treatment using MTS, colony forming, wound healing, and Annexin-V assay. We determined that β-Escin decreased glutamine uptake and reduced c-myc and GLS1 protein expressions and increased the expression of ASCT2. In addition, this inhibition of glutamine metabolism decreased cell proliferation, colony formation and migration, and induced apoptosis.

CONCLUSIONS

In this study, it was suggested that β-Escin inhibits glutamine metabolism via c-myc in MDA-MB-231 cells, and it is thought that as a result of interrupting the energy supply in these cells via c-myc, it results in a decrease in the carcinogenic properties of the cells. Consequently, β-Escin may be promising as a therapeutic agent for glutamine-dependent cancers.

Stromal HIF2 Regulates Immune Suppression in the Pancreatic Cancer Microenvironment

BACKGROUND & AIMS

Pancreatic ductal adenocarcinoma (PDAC) has a hypoxic, immunosuppressive stroma that contributes to its resistance to immune checkpoint blockade therapies. The hypoxia-inducible factors (HIFs) mediate the cellular response to hypoxia, but their role within the PDAC tumor microenvironment remains unknown.

METHODS

We used a dual recombinase mouse model to delete Hif1α or Hif2α in α-smooth muscle actin-expressing cancer-associated fibroblasts (CAFs) arising within spontaneous pancreatic tumors. The effects of CAF HIF2α expression on tumor progression and composition of the tumor microenvironment were evaluated by Kaplan-Meier analysis, reverse transcription quantitative real-time polymerase chain reaction, histology, immunostaining, and by both bulk and single-cell RNA sequencing. CAF-macrophage crosstalk was modeled ex vivo using conditioned media from CAFs after treatment with hypoxia and PT2399, an HIF2 inhibitor currently in clinical trials. Syngeneic flank and orthotopic PDAC models were used to assess whether HIF2 inhibition improves response to immune checkpoint blockade.

RESULTS

CAF-specific deletion of Hif2α, but not Hif1α, suppressed PDAC tumor progression and growth, and improved survival of mice by 50% (n = 21-23 mice/group, Log-rank P = .0009). Deletion of CAF-HIF2 modestly reduced tumor fibrosis and significantly decreased the intratumoral recruitment of immunosuppressive M2 macrophages and regulatory T cells. Treatment with the clinical HIF2 inhibitor PT2399 significantly reduced in vitro macrophage chemotaxis and M2 polarization, and improved tumor responses to immunotherapy in both syngeneic PDAC mouse models.

CONCLUSIONS

Together, these data suggest that stromal HIF2 is an essential component of PDAC pathobiology and is a druggable therapeutic target that could relieve tumor microenvironment immunosuppression and enhance immune responses in this disease.

Nanoparticle-based therapeutic strategies targeting major clinical challenges in pancreatic cancer treatment

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers due to its aggressiveness and the challenges for early diagnosis and treatment. Recently, nanotechnology has demonstrated relevant strategies to overcome some of the major clinical issues in the treatment of PDAC. This review is focused on the pathological hallmarks of PDAC and the impact of nanotechnology to find solutions. It describes the use of nanoparticle-based systems designed for the delivery of chemotherapeutic agents and combinatorial alternatives that address the chemoresistance associated with PDAC, the development of combination therapies targeting the molecular heterogeneity in PDAC, the investigation of novel therapies dealing with the improvement of immunotherapy and handling the desmoplastic stroma in PDAC by remodeling the tumor microenvironment. A special section is dedicated to the design of nanoparticles for unique non-traditional modalities that could be promising in the future for the improvement in the dismal prognosis of PDAC.

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

Pancreatic ductal adenocarcinoma (PDAC) is a very aggressive tumor with a poor prognosis and inadequate response to treatment. Many factors contribute to this therapeutic failure: lack of symptoms until the tumor reaches an advanced stage, leading to late diagnosis; early lymphatic and hematic spread; advanced age of patients; important development of a pro-tumoral and hyperfibrotic stroma; high genetic and metabolic heterogeneity; poor vascular supply; a highly acidic matrix; extreme hypoxia; and early development of resistance to the available therapeutic options. In most cases, the disease is silent for a long time, andwhen it does become symptomatic, it is too late for ablative surgery; this is one of the major reasons explaining the short survival associated with the disease. Even when surgery is possible, relapsesare frequent, andthe causes of this devastating picture are the low efficacy ofand early resistance to all known chemotherapeutic treatments. Thus, it is imperative to analyze the roots of this resistance in order to improve the benefits of therapy. PDAC chemoresistance is the final product of different, but to some extent, interconnected factors. Surgery, being the most adequate treatment for pancreatic cancer and the only one that in a few selected cases can achieve longer survival, is only possible in less than 20% of patients. Thus, the treatment burden relies on chemotherapy in mostcases. While the FOLFIRINOX scheme has a slightly longer overall survival, it also produces many more adverse eventsso that gemcitabine is still considered the first choice for treatment, especially in combination with other compounds/agents. This review discusses the multiple causes of gemcitabine resistance in PDAC.

Exploration of the System-Level Mechanisms of the Herbal Drug FDY003 for Pancreatic Cancer Treatment: A Network Pharmacological Investigation

Pancreatic cancer (PC) is the most lethal cancer with the lowest survival rate globally. Although the prescription of herbal drugs against PC is gaining increasing attention, their polypharmacological therapeutic mechanisms are yet to be fully understood. Based on network pharmacology, we explored the anti-PC properties and system-level mechanisms of the herbal drug FDY003. FDY003 decreased the viability of human PC cells and strengthened their chemosensitivity. Network pharmacological analysis of FDY003 indicated the presence of 16 active phytochemical components and 123 PC-related pharmacological targets. Functional enrichment analysis revealed that the PC-related targets of FDY003 participate in the regulation of cell growth and proliferation, cell cycle process, cell survival, and cell death. In addition, FDY003 was shown to target diverse key pathways associated with PC pathophysiology, namely, the PIK3-Akt, MAPK, FoxO, focal adhesion, TNF, p53, HIF-1, and Ras pathways. Our network pharmacological findings advance the mechanistic understanding of the anti-PC properties of FDY003 from a system perspective.

Transformer 2 alpha homolog is a downstream gene of hypoxia-inducible factor 1 subunit alpha and is involved in the progression of pancreatic cancer

Intratumoral hypoxia is a common feature of pancreatic cancer (PC) and also plays a role in its progression. However, hypoxia-regulated signatures in PC are still not completely understood. This study aimed to identify core hypoxia-associated genes and determine their underlying molecular mechanisms in PC cells. Transformer 2 alpha homolog (TRA2A) was found to be an important hypoxia-associated gene, which was upregulated in PC tissues and in PC cells cultured under hypoxia. High TRA2A expression was associated with advanced stage, poor differentiation, and lymph node metastasis. Under normoxic and hypoxic conditions, knockdown of TRA2A both markedly suppressed PC cell proliferation and motility in vitro and in vivo, as well as activation of the AKT pathway. Hypoxia-inducible factor 1 subunit alpha (HIF1α) upregulated the transcription of TRA2A by directly binding to its promoter. TRA2A showed a co-expression relationship with HIF1α in PC tissues. Overexpression of TRA2A alleviated the pro-inhibitive functions of HIF1α-inhibition on PC cell proliferation and motility under hypoxia. In conclusion, TRA2A is a crucial downstream gene of HIF1α that accelerates the proliferation and motility of PC cells. TRA2A may be a novel and practical molecular target for investigating the hypoxic response of PC cells.Abbreviations: TRA2A, transformer 2A protein; PC, pancreatic cancer; HIF1α, hypoxia-inducible factor 1-alpha; GEO, Gene Expression Omnibus; IHC, immunohistochemical staining.

The Interplay Between Inflammation and Stromal Components in Pancreatic Cancer

Inflammation involves interactions between various immune cells, inflammatory cells, chemokines and cytokines in pancreatic cancer. Cancer cells as well as surrounding stromal and inflammatory cells establish an inflammatory tumor microenvironment (TME). Inflammation is closely associated with immunity. Meanwhile, immune cells are involved in both inflammation and immune response. Tumor-promoting inflammation and tumor-suppressive immunity are two main characteristics of the tumor microenvironment in pancreatic cancer. Yet, the mechanism of inflammation and immune response in pancreatic cancer development is still unclear due to the dual role of some cytokines and the complicated crosstalk between tumor and stromal components in TME. In this review, we outline the principal cytokines and stromal cells in the pancreatic TME that are involved in the tumor-promoting and immunosuppressive effects of inflammation, and discuss the interaction between inflammation and stromal components in pancreatic cancer progression. Moreover, the clinical approaches based on targeting TME in pancreatic cancer are also summarized. Defining the mechanisms of interplay between inflammation and stromal components will be essential for further development of anti-cancer therapies.

BZW1 Facilitates Glycolysis and Promotes Tumor Growth in Pancreatic Ductal Adenocarcinoma Through Potentiating eIF2α Phosphorylation

BACKGROUND & AIMS

Pancreatic ductal adenocarcinoma (PDAC) is characterized by severe metabolic stress due to fibrosis and poor vascularization. BZW1 is an eIF5-mimic protein involved in tumorigenesis and progression. The aim of this study was to investigate the role of BZW1 in metabolic stress resistance in PDAC.

METHODS

BZW1 expression was evaluated in human PDAC tissue microarray and PDAC cells. Glycolysis regulation of BZW1 and its correlation with glycolysis-related genes was analyzed. Tumor growth, cell proliferation, and apoptosis were evaluated in mice xenograft tumors and patient-derived organoids.

RESULTS

The results of bioinformatic screening identified that BZW1 was 1 of the top 3 genes favorable for tumor progression in PDAC. The analysis of our cohort confirmed that BZW1 was overexpressed in human PDAC tissues compared with nontumor tissues, and its abnormal expression was correlated with large tumor size and poor prognosis. BZW1 promoted cell proliferation and inhibited apoptosis in both mouse xenograft models and PDAC-derived organoids via facilitating glycolysis in the oxygen-glucose-deprivation condition. Mechanically, BZW1 served as an adaptor for PKR-like endoplasmic reticulum (ER) kinase (PERK), facilitated the phosphorylation of eIF2α, promoted internal ribosome entry site-dependent translation of HIF1α and c-Myc, and thereby boosted the Warburg effect. In organoid-based xenografts with high BZW1 levels, both the PERK/eIF2α phosphorylation inhibitor GSK2606414 and ISRIB significantly suppressed tumor growth and prolonged animal survival.

CONCLUSIONS

BZW1 is a key molecule in the internal ribosome entry site-dependent translation of HIF1α/c-Myc and plays crucial roles in the glycolysis of PDAC. BZW1 might serve as a therapeutic target for patients with pancreatic cancer.

Combination of Electrochemistry and Mass Spectrometry to Study Nitric Oxide Metabolism and Its Modulation by Compound K in Breast Cancer Cells

The levels of l-arginine and asymmetric dimethylarginine (ADMA) and the amount of the nitric oxide (NO) production have recently been linked to breast cancer and pharmaceutical effect evaluation. Herein, a method combining electrochemistry and high-resolution mass spectrometry (HRMS) was established and used to study NO metabolism and its modulation by ginsenoside compound K (CK) in breast cancer cells. Platinum nanoparticles-decorated fluorine tin oxide was employed as an electrochemical sensor for in situ detection of NO release, while HRMS was used for the analysis of the NO-related metabolites. Through the combination of the electrochemical and HRMS results, decreases in arginine and NO and increases in ADMA and ornithine were observed after modulation by CK, and two highly correlated metabolic pathways including arginine and proline metabolism and vascular smooth muscle contraction were found. This method offers a new strategy for fast evaluation of pharmaceutical efficacy based on NO metabolism.

Induction of Synthetic Lethality by Activation of Mitochondrial ClpP and Inhibition of HDAC1/2 in Glioblastoma

PURPOSE

Novel therapeutic targets are critical to unravel for the most common primary brain tumor in adults, glioblastoma (GBM). We have identified a novel synthetic lethal interaction between ClpP activation and HDAC1/2 inhibition that converges on GBM energy metabolism.

EXPERIMENTAL DESIGN

Transcriptome, metabolite, and U-13C-glucose tracing analyses were utilized in patient-derived xenograft (PDX) models of GBM. Orthotopic GBM models were used for in vivo studies.

RESULTS

We showed that activation of the mitochondrial ClpP protease by mutant ClpP (Y118A) or through utilization of second-generation imipridone compounds (ONC206 and ONC212) in combination with genetic interference of HDAC1 and HDAC2 as well as with global (panobinostat) or selective (romidepsin) HDAC inhibitors caused synergistic reduction of viability in GBM model systems, which was mediated by interference with tricarboxylic acid cycle activity and GBM cell respiration. This effect was partially mediated by activation of apoptosis along with activation of caspases regulated chiefly by Bcl-xL and Mcl-1. Knockdown of the ClpP protease or ectopic expression of a ClpP D190A mutant substantially rescued from the inhibition of oxidative energy metabolism as well as from the reduction of cellular viability by ClpP activators and the combination treatment, respectively. Finally, utilizing GBM PDX models, we demonstrated that the combination treatment of HDAC inhibitors and imipridones prolonged host survival more potently than single treatments or vehicle in vivo.

CONCLUSIONS

Collectively, these observations suggest that the efficacy of HDAC inhibitors might be significantly enhanced through ClpP activators in model systems of human GBM.

Dielectrophoresis-Based Biosensor for Detection of the Cancer Biomarkers CEA and CA 242 in Serum

We show that dielectrophoresis (DEP) spectroscopy is an effective transduction mechanism for detection of the concentration levels of the pancreatic cancer biomarkers cancer antigen (CA) 242 and carcinoembryonic antigen (CEA) in serum. We noticed a frequency dependence of the negative DEP force applied by interdigitated electrodes on functionalized polystyrene microspheres (PM) with respect to changes in the number of these cancer antigens bound to the PM. An electrode array with a well-defined gradient of the electric field was designed and used, which enabled the automation of the signal processing and reproducibility of the signal acquired by the biosensor.

USP33 deubiquitinates and stabilizes HIF-2alpha to promote hypoxia response in glioma stem cells

Hypoxia regulates tumor angiogenesis, metabolism, and therapeutic response in malignant cancers including glioblastoma, the most lethal primary brain tumor. The regulation of HIF transcriptional factors by the ubiquitin-proteasome system is critical in the hypoxia response, but hypoxia-inducible deubiquitinases that counteract the ubiquitination remain poorly defined. While the activation of ERK1/2 also plays an important role in hypoxia response, the relationship between ERK1/2 activation and HIF regulation remains elusive. Here, we identified USP33 as essential deubiquitinase that stabilizes HIF-2alpha protein in an ERK1/2-dependent manner to promote hypoxia response in cancer cells. USP33 is preferentially induced in glioma stem cells by hypoxia and interacts with HIF-2alpha, leading to its stabilization through deubiquitination. The activation of ERK1/2 upon hypoxia promoted HIF-2alpha phosphorylation, enhancing its interaction with USP33. Silencing of USP33 disrupted glioma stem cells maintenance, reduced tumor vascularization, and inhibited glioblastoma growth. Our findings highlight USP33 as an essential regulator of hypoxia response in cancer stem cells, indicating a novel potential therapeutic target for brain tumor treatment.

A new era: tumor microenvironment in chemoresistance of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a solid malignant tumor with an extremely poor prognosis. Gemcitabine (GEM)-based chemotherapy remains one of the most important treatment choices for PDAC. However, either as monotherapy or as a part of the combination chemotherapy, GEM achieved only limited success in improving the survival of patients with advanced PDAC, primarily due to GEM resistance. PDAC is characterized by an extensive desmoplasia in the tumor microenvironment (TME). Increasing evidence indicates that this fibrotic TME not only actively participates in the tumor growth and spread of PDAC but also contributes to the induction of GEM resistance. Here we review the current advances of how TME components are involved in the induction of GEM resistance.

The Emerging Roles of Circular RNAs in the Chemoresistance of Gastrointestinal Cancer

Gastrointestinal (GI) cancer represents a major global health problem due to its aggressive characteristics and poor prognosis. Despite the progress achieved in the development of treatment regimens, the clinical outcomes and therapeutic responses of patients with GI cancer remain unsatisfactory. Chemoresistance arising throughout the clinical intervention is undoubtedly a critical barrier for the successful treatment of GI cancer. However, the precise mechanisms associated with chemoresistance in GI cancer remain unclear. In the past decade, accumulating evidence has indicated that circular RNAs (circRNAs) play a key role in regulating cancer progression and chemoresistance. Notably, circRNAs function as molecular sponges that sequester microRNAs (miRNAs) and/or proteins, and thus indirectly control the expression of specific genes, which eventually promote or suppress drug resistance in GI cancer. Therefore, circRNAs may represent potential therapeutic targets for overcoming drug resistance in patients with GI cancer. This review comprehensively summarizes the regulatory roles of circRNAs in the development of chemoresistance in different GI cancers, including colorectal cancer, gastric cancer and esophageal cancer, as well as deciphers the underlying mechanisms and key molecules involved. Increasing knowledge of the important functions of circRNAs underlying drug resistance will provide new opportunities for developing efficacious therapeutic strategies against GI cancer.

Macrophage C/EBPδ Drives Gemcitabine, but Not 5-FU or Paclitaxel, Resistance of Pancreatic Cancer Cells in a Deoxycytidine-Dependent Manner

Treatment of pancreatic ductal adenocarcinoma (PDAC), a dismal disease with poor survival rates, is hampered by the high prevalence of chemotherapy resistance. Resistance is accompanied by macrophage infiltration into the tumor microenvironment, and infiltrated macrophages are key players in chemotherapy resistance. In the current manuscript, we identify CCAAT/enhancer-binding protein delta (C/EBPδ) as an important transcription factor driving macrophage-dependent gemcitabine resistance. We show that conditioned medium obtained from wild type macrophages largely diminishes gemcitabine-induced cytotoxicity of PDAC cells, whereas conditioned medium obtained from C/EBPδ-deficient macrophages only minimally affects gemcitabine-induced PDAC cell death. Subsequent analysis of RNA-Seq data identified the pyrimidine metabolism pathway amongst the most significant pathways down-regulated in C/EBPδ-deficient macrophages and size filtration experiments indeed showed that the low molecular weight and free metabolite fraction most effectively induced gemcitabine resistance. In line with a role for pyrimidines, we next show that supplementing macrophage conditioned medium with deoxycytidine overruled the effect of macrophage conditioned media on gemcitabine resistance. Consistently, macrophage C/EBPδ-dependent resistance is specific for gemcitabine and does not affect paclitaxel or 5-FU-induced cytotoxicity. Overall, we thus show that C/EBPδ-dependent deoxycytidine biosynthesis in macrophages induces gemcitabine resistance of pancreatic cancer cells.

CD73 induces GM-CSF/MDSC-mediated suppression of T cells to accelerate pancreatic cancer pathogenesis

Metabolic alterations regulate cancer aggressiveness and immune responses. Given the poor response of pancreatic ductal adenocarcinoma (PDAC) to conventional immunotherapies, we investigated the link between metabolic alterations and immunosuppression. Our metabolic enzyme screen indicated that elevated expression of CD73, an ecto-5'-nucleotidase that generates adenosine, correlates with increased aggressiveness. Correspondingly, we observed increased interstitial adenosine levels in tumors from spontaneous PDAC mouse models. Diminishing CD73 by genetic manipulations ablated in vivo tumor growth, and decreased myeloid-derived suppressor cells (MDSC) in orthotopic mouse models of PDAC. A high-throughput cytokine profiling demonstrated decreased GM-CSF in mice implanted with CD73 knockdowns. Furthermore, we noted increased IFN-γ expression by intratumoral CD4⁺ and CD8⁺ T cells in pancreatic tumors with CD73 knockdowns. Depletion of CD4⁺ T cells, but not CD8⁺ T cells abrogated the beneficial effects of decreased CD73. We also observed that splenic MDSCs from Nt5e knockdown tumor-bearing mice were incompetent in suppressing T cell activation in the ex vivo assays. Replenishing GM-CSF restored tumor growth in Nt5e knockout tumors, which was reverted by MDSC depletion. Finally, anti-CD73 antibody treatment significantly improved gemcitabine efficacy in orthotopic models. Thus, targeting the adenosine axis presents a novel therapeutic opportunity for improving the anti-tumoral immune response against PDAC.

ROS/PI3K/Akt and Wnt/β-catenin signalings activate HIF-1α-induced metabolic reprogramming to impart 5-fluorouracil resistance in colorectal cancer

Background

Acquired resistance of 5-fluorouracil (5-FU) remains a clinical challenge in colorectal cancer (CRC), and efforts to develop targeted agents to reduce resistance have not yielded success. Metabolic reprogramming is a key cancer hallmark and confers several tumor phenotypes including chemoresistance. Glucose metabolic reprogramming events of 5-FU resistance in CRC has not been evaluated, and whether abnormal glucose metabolism could impart 5-FU resistance in CRC is also poorly defined.

Methods

Three separate acquired 5-FU resistance CRC cell line models were generated, and glucose metabolism was assessed by measuring glucose and lactate utilization, RNA and protein expressions of glucose metabolism-related enzymes and changes of intermediate metabolites of glucose metabolite pool. The protein levels of hypoxia inducible factor 1α (HIF-1α) in primary tumors and circulating tumor cells of CRC patients were detected by immunohistochemistry and immunofluorescence. Stable HIF1A knockdown in cell models was established with a lentiviral system. The influence of both HIF1A gene knockdown and pharmacological inhibition on 5-FU resistance in CRC was evaluated in cell models in vivo and in vitro.

Results

The abnormality of glucose metabolism in 5-FU-resistant CRC were described in detail. The enhanced glycolysis and pentose phosphate pathway in CRC were associated with increased HIF-1α expression. HIF-1α-induced glucose metabolic reprogramming imparted 5-FU resistance in CRC. HIF-1α showed enhanced expression in 5-FU-resistant CRC cell lines and clinical specimens, and increased HIF-1α levels were associated with failure of fluorouracil analog-based chemotherapy in CRC patients and poor survival. Upregulation of HIF-1α in 5-FU-resistant CRC occurred through non-oxygen-dependent mechanisms of reactive oxygen species-mediated activation of PI3K/Akt signaling and aberrant activation of β-catenin in the nucleus. Both HIF-1α gene knock-down and pharmacological inhibition restored the sensitivity of CRC to 5-FU.

Conclusions

HIF-1α is a potential biomarker for 5-FU-resistant CRC, and targeting HIF-1a in combination with 5-FU may represent an effective therapeutic strategy in 5-FU-resistant CRC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02229-6.

Mucin 5AC Serves as the Nexus for β-Catenin/c-Myc Interplay to Promote Glutamine Dependency During Pancreatic Cancer Chemoresistance

BACKGROUND & AIMS

A major clinical challenge for patients with pancreatic cancer (PC) is metabolic adaptation. Neoplastic cells harboring molecular perturbations suffice for their increased anabolic demand and nucleotide biosynthesis to acquire chemoresistance. The mucin 5AC expressed de novo in malignant pancreas promotes cancer cell stemness and is significantly associated with poor patient survival. Identification of MUC5AC-associated drivers of chemoresistance through metabolic alterations may facilitate the sculpting of a new combinatorial regimen.

METHODS

The contributions of MUC5AC to glutaminolysis and gemcitabine resistance were examined by The Cancer Genome Atlas data analysis, RNA sequencing, and immunohistochemistry analysis on pancreatic tissues of KrasG12D;Pdx1-Cre (KC) and KrasG12D;Pdx1-Cre;Muc5ac-/- mice. These were followed by metabolite flux assays as well as biochemical and xenograft studies on MUC5AC-depleted human and murine PC cells. Murine and human pancreatic 3-dimensional tumoroids were used to evaluate the efficacy of gemcitabine in combination with β-catenin and glutaminolysis inhibitors.

RESULTS

Transcriptional analysis showed that high MUC5AC-expressing human and autochthonous murine PC tumors exhibit higher resistance to gemcitabine because of enhanced glutamine use and nucleotide biosynthesis. Gemcitabine treatment led to MUC5AC overexpression, resulting in disruption of E-cadherin/β-catenin junctions and the nuclear translocation of β-catenin, which increased c-Myc expression, with a concomitant rise in glutamine uptake and glutamate release. MUC5AC depletion and glutamine deprivation sensitized human PC cells to gemcitabine, which was obviated by glutamine replenishment in MUC5AC-expressing cells. Coadministration of β-catenin and glutaminolysis inhibitors with gemcitabine abrogated the MUC5AC-mediated resistance in murine and human tumoroids.

CONCLUSIONS

The MUC5AC/β-catenin/c-Myc axis increases the uptake and use of glutamine in PC cells, and cotargeting this axis along with gemcitabine may improve therapeutic efficacy in PC.

Nanocarriers for pancreatic cancer imaging, treatments, and immunotherapies

Pancreatic tumors are highly desmoplastic and immunosuppressive. Delivery and distribution of drugs within pancreatic tumors are compromised due to intrinsic physical and biochemical stresses that lead to increased interstitial fluid pressure, vascular compression, and hypoxia. Immunotherapy-based approaches, including therapeutic vaccines, immune checkpoint inhibition, CAR-T cell therapy, and adoptive T cell therapies, are challenged by an immunosuppressive tumor microenvironment. Together, extensive fibrosis and immunosuppression present major challenges to developing treatments for pancreatic cancer. In this context, nanoparticles have been extensively studied as delivery platforms and adjuvants for cancer and other disease therapies. Recent advances in nanotechnology have led to the development of multiple nanocarrier-based formulations that not only improve drug delivery but also enhance immunotherapy-based approaches for pancreatic cancer. This review discusses and critically analyzes the novel nanoscale strategies that have been used for drug delivery and immunomodulation to improve treatment efficacy, including newly emerging immunotherapy-based approaches. This review also presents important perspectives on future research directions that will guide the rational design of novel and robust nanoscale platforms to treat pancreatic tumors, particularly with respect to targeted therapies and immunotherapies. These insights will inform the next generation of clinical treatments to help patients manage this debilitating disease and enhance survival rates.

Hsa_circ_0019054 up-regulates HIF1A through sequestering miR-340-5p to promote the tumorigenesis of intrahepatic cholangiocarcinoma

BACKGROUND

Circular RNAs (circRNAs) have been uncovered to play an important regulatory function in the tumorigenesis of intrahepatic cholangiocarcinoma (ICC). Hsa_circ_0,019,054 was found to be increased in ICC. Here, we aimed to explore the action and mechanism of hsa_circ_0,019,054 in ICC carcinogenesis.

METHODS

Quantitative real-time PCR (qRT-PCR) and western blotting were used to detect the levels of genes and proteins. The functional experiments were performed using in vitro 5-ethynyl-2'-deoxyuridine (EdU) assay, cell counting Kit-8 (CCK-8) assay, flow cytometry, and in vivo murine xenograft model. The glycolysis was analyzed by detecting glucose uptake and lactate level. The binding between miR-340-5 p and hsa_circ_0,019,054 or HIF1A (Hypoxia-inducible factor 1-alpha) was validated using pull-down, dual-luciferase reporter and RNA immunoprecipitation assays.

RESULTS

Hsa_circ_0,019,054 expression was higher in ICC tissues and cells. Functionally, hsa_circ_0,019,054 silencing could suppress ICC cell proliferation and glycolysis active, as well as induce apoptosis. Mechanistically, hsa_circ_0,019,054 was demonstrated to act as a sponge for miR-340-5 p, which directly targeted HIF1A. Hsa_circ_0,019,054/miR-340-5 p/HIF1A formed a feedback loop. HIF1A was up-regulated, while miR-340-5 p was decreased in ICC tissues and cells. MiR-340-5 p re-expression attenuated ICC cell growth. Besides that, rescue experiments suggested that HIF1A overexpression or miR-340-5 p knockdown reversed the anti-proliferation and glycolysis arrest effects mediated by hsa_circ_0,019,054 silencing. Importantly, hsa_circ_0,019,054 silencing also impeded the growth of ICC in nude mice.

CONCLUSION

Hsa_circ_0,019,054 deficiency could attenuate the proliferation and glycolysis of ICC cells via miR-340-5 p/HIF1A axis.

Are we still on the right path(way)?: the altered expression of the pentose phosphate pathway in solid tumors and the potential of its inhibition in combination therapy

INTRODUCTION

The pentose phosphate pathway (PPP) branches from glycolysis and is crucial for cell growth, since it provides necessary compounds for anabolic reactions, nucleotide synthesis, and detoxification of reactive-oxygen-species (ROS). Overexpression of PPP enzymes has been reported in multiple cancer types and linked to therapy resistance, making their inhibition interesting targets for anti-cancer therapies.

AREAS COVERED

This review summarizes the extent of PPP upregulation across different cancer types, and the non-metabolic functions that PPP-enzymes might contribute to cancer initiation and maintenance. The effects of PPP-inhibition and their combinations with chemotherapeutics are summarized. We searched the databases provided by the University of Amsterdam to characterize the altered expression of the PPP across different cancer types, and to identify the effects of PPP-inhibition.

EXPERT OPINION

It can be concluded that there are synergistic and additive effects of PPP-inhibition and various classes of chemotherapeutics. These effects may be attributed to the increased susceptibility to ROS. However, the toxicity, low efficacy, and off-target effects of PPP-inhibitors make application in clinical practice challenging. Novel inhibitors are currently being developed, which could make PPP-inhibition a potential therapeutic strategy in the future, especially in combination with conventional chemotherapeutics and the inhibition of other metabolic pathways.

Prognostic Stratification Based on HIF-1 Signaling for Evaluating Hypoxic Status and Immune Infiltration in Pancreatic Ductal Adenocarcinomas

Pancreatic ductal adenocarcinoma (PDAC) has a hypoxic and desmoplastic tumor microenvironment (TME), leading to treatment failure. We aimed to develop a prognostic classifier to evaluate hypoxia status and hypoxia-related molecular characteristics of PDAC. In this study, we classified PDAC into three clusters based on 16 known hypoxia-inducible factor 1 (HIF-1)-related genes. Nine differentially expressed genes were identified to construct an HIF-1 score system, whose predictive efficacy was evaluated. Furthermore, we investigated oncogenic pathways and immune-cell infiltration status of PDAC with different scores. The C-index of the HIF-1score system for OS prediction in the meta-PDAC cohort and the other two validation cohorts were 0.67, 0.63, and 0.65, respectively, indicating that it had a good predictive value for patient survival. Furthermore, the area under the curve (AUC) of the receiver operating characteristic (ROC) curve of the HIF-1α score system for predicting 1-, 3-, and 4-year OS indicated the HIF-1α score system had an optimal discrimination of prognostic prediction for PDAC. Importantly, our model showed superior predictive ability compared to previous hypoxia signatures. We also classified PDAC into HIF-1 scores of low, medium, and high groups. Then, we found high enrichment of glycolysis, mTORC1 signaling, and MYC signaling in the HIF-1 score high group, whereas the cGMP metabolic process was activated in the low score group. Of note, analysis of public datasets and our own dataset showed a high HIF-1 score was associated with high immunosuppressive TME, evidenced by fewer infiltrated CD8⁺ T cells, B cells, and type 1 T-helper cells and reduced cytolytic activity of CD8⁺ T cells. In summary, we established a specific HIF-1 score system to discriminate PDAC with various hypoxia statuses and immune microenvironments. For highly hypoxic and immunosuppressive tumors, a combination treatment strategy should be considered in the future.

Microfluidic-Assisted Preparation of Targeted pH-Responsive Polymeric Micelles Improves Gemcitabine Effectiveness in PDAC: In Vitro Insights

Simple Summary

This research suggests a new potential therapeutic approach to pancreatic ductal adenocarcinoma to improve drug effectiveness and overcome drug resistance. A double actively targeted gemcitabine delivery system, consisting of polymeric micelles, was developed by microfluidic technique to ensure a narrow size distribution, a good colloidal stability, and drug-encapsulation efficiency for the selective and controlled release of the loaded drug, in response to the pH variations and uPAR expression in tumors. In vitro studies assessed that the release of the drug in the acidic environment was higher than in the neutral one, and that the pH-responsive and uPAR-targeted polymeric micelles enhanced the antitumor properties of gemcitabine in models resembling the pancreatic tumor microenvironment.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) represents a great challenge to the successful delivery of the anticancer drugs. The intrinsic characteristics of the PDAC microenvironment and drugs resistance make it suitable for therapeutic approaches with stimulus-responsive drug delivery systems (DDSs), such as pH, within the tumor microenvironment (TME). Moreover, the high expression of uPAR in PDAC can be exploited for a drug receptor-mediated active targeting strategy. Here, a pH-responsive and uPAR-targeted Gemcitabine (Gem) DDS, consisting of polymeric micelles (Gem@TpHResMic), was formulated by microfluidic technique to obtain a preparation characterized by a narrow size distribution, good colloidal stability, and high drug-encapsulation efficiency (EE%). The Gem@TpHResMic was able to perform a controlled Gem release in an acidic environment and to selectively target uPAR-expressing tumor cells. The Gem@TpHResMic displayed relevant cellular internalization and greater antitumor properties than free Gem in 2D and 3D models of pancreatic cancer, by generating massive damage to DNA, in terms of H2AX phosphorylation and apoptosis induction. Further investigation into the physiological model of PDAC, obtained by a co-culture of tumor spheroids and cancer-associated fibroblast (CAF), highlighted that the micellar system enhanced the antitumor potential of Gem, and was demonstrated to overcome the TME-dependent drug resistance. In vivo investigation is warranted to consider this new DDS as a new approach to overcome drug resistance in PDAC.

Impact of cancer metabolism on therapy resistance - Clinical implications

Despite an increasing arsenal of anticancer therapies, many patients continue to have poor outcomes due to the therapeutic failures and tumor relapses. Indeed, the clinical efficacy of anticancer therapies is markedly limited by intrinsic and/or acquired resistance mechanisms that can occur in any tumor type and with any treatment. Thus, there is an urgent clinical need to implement fundamental changes in the tumor treatment paradigm by the development of new experimental strategies that can help to predict the occurrence of clinical drug resistance and to identify alternative therapeutic options. Apart from mutation-driven resistance mechanisms, tumor microenvironment (TME) conditions generate an intratumoral phenotypic heterogeneity that supports disease progression and dismal outcomes. Tumor cell metabolism is a prototypical example of dynamic, heterogeneous, and adaptive phenotypic trait, resulting from the combination of intrinsic [(epi)genetic changes, tissue of origin and differentiation dependency] and extrinsic (oxygen and nutrient availability, metabolic interactions within the TME) factors, enabling cancer cells to survive, metastasize and develop resistance to anticancer therapies. In this review, we summarize the current knowledge regarding metabolism-based mechanisms conferring adaptive resistance to chemo-, radio-and immunotherapies as well as targeted therapies. Furthermore, we report the role of TME-mediated intratumoral metabolic heterogeneity in therapy resistance and how adaptations in amino acid, glucose, and lipid metabolism support the growth of therapy-resistant cancers and/or cellular subpopulations. We also report the intricate interplay between tumor signaling and metabolic pathways in cancer cells and discuss how manipulating key metabolic enzymes and/or providing dietary changes may help to eradicate relapse-sustaining cancer cells. Finally, in the current era of personalized medicine, we describe the strategies that may be applied to implement metabolic profiling for tumor imaging, biomarker identification, selection of tailored treatments and monitoring therapy response during the clinical management of cancer patients.

The Metabolism Symbiosis Between Pancreatic Cancer and Tumor Microenvironment

Complex interactions occur between tumor cells and the tumor microenvironment. Studies have focused on the mechanism of metabolic symbiosis between tumors and the tumor microenvironment. During tumor development, the metabolic pattern undergoes significant changes, and the optimal metabolic mode of the tumor is selected on the basis of its individual environment. Tumor cells can adapt to a specific microenvironment through metabolic adjustment to achieve compatibility. In this study, the effects of tumor glucose metabolism, lipid metabolism, and amino acid metabolism on the tumor microenvironment and related mechanisms were reviewed. Selective targeting of tumor cell metabolic reprogramming is an attractive direction for tumor therapy. Understanding the mechanism of tumor metabolic adaptation and determining the metabolism symbiosis mechanism between tumor cells and the surrounding microenvironment may provide a new approach for treatment, which is of great significance for accelerating the development of targeted tumor metabolic drugs and administering individualized tumor metabolic therapy.

Positive Reciprocal Feedback of lncRNA ZEB1-AS1 and HIF-1α Contributes to Hypoxia-Promoted Tumorigenesis and Metastasis of Pancreatic Cancer

Background

Many studies have reported the roles of the extracellular hypoxia microenvironment in the tumorigenesis and metastasis of multiple cancers. However, long noncoding RNAs (lncRNAs) that induce cancer oncogenicity and metastasis of pancreatic cancer (PC) under hypoxia conditions remain unclear.

Methods

In PC cells, the expression levels of lncRNAs in different conditions (normoxia or hypoxia) were compared through RNA sequencing (RNA-seq). The effects of the zinc finger E-box-binding homeobox 1 (ZEB1-AS1) antisense lncRNA on PC cells cultured in normoxia/hypoxia medium were measured through gain and loss-of-function experiments. Fluorescence in situ hybridization and luciferase reporter assays in addition to in vivo studies were utilized to explore the adaptive mechanisms of ZEB1-AS1 in the hypoxia-promoted proliferation, migration, and invasion ability of PC cells. Moreover, the level of ZEB1-AS1 and its associated targets or pathways were investigated in both PC and pancreatic normal tissues.

Results

RNA-seq revealed that ZEB1-AS1 was significantly upregulated in PC cells under hypoxia conditions. The ZEB1-AS1 expression level was closely associated with poor prognosis of PC patients. Knockdown of ZEB1-AS1 suppressed the proliferation, migration, and invasion of PC cells in vitro as well as PC xenograft tumor growth in vivo. In PC cells, RNAi-mediated reduction of ZEB1-AS1 inhibited zinc finger E-box-binding homeobox 1 (ZEB1), while ZEB1-AS1 overexpression rescued ZEB1 expression, indicating that ZEB1-AS1 promotes ZEB1 expression. Moreover, hypoxia-inducible factor-1α (HIF-1α)induced the expression of ZEB1-AS1 by binding to the ZEB1-AS1 promoter, which contains a putative hypoxia response element (HRE). Mechanistically, ZEB1-AS1 scaffolded the interaction among HIF-1α, ZEB1, and histone deacetylase 1 (HDAC1), leading to deacetylation-mediated stabilization of HIF-1α. We further revealed that ZEB1 induced the deacetylase capacity of HDAC1 to suppress the acetylation or degradation of HIF-1α, improving HIF-1α assembly. Thus, hypoxia-induced ZEB1-AS1 facilitated ZEB1 transcription and the stability of HIF-1α, which promoted the metastasis of PC cells. Clinically, dysregulated ZEB1 and HIF-1α expression was significantly correlated with histological grade, lymphatic metastasis, and distant metastasis in PC patients.

Conclusions

Our results emphasized that the positive reciprocal loop of HIF-1α/ZEB1-AS1/ZEB1/HDAC1 contributes to hypoxia-promoted oncogenicity and PC metastasis, indicating that it might be a novel therapeutic target for PC.

Improving therapeutic resistance: beginning with targeting the tumor microenvironment

Cancer is a serious threat to human health and life. The tumor microenvironment (TME) not only plays a key role in the occurrence, development and metastasis of cancer, but also has a profound impact on treatment resistance. To improve and solve this problem, an increasing number of strategies targeting the TME have been proposed, and great progress has been made in recent years. This article reviews the characteristics and functions of the main matrix components of the TME and the mechanisms by which each component affects drug resistance. Furthermore, this article elaborates on targeting the TME as a strategy to treat acquired drug resistance, reduce tumor metastasis, recurrence, and improve efficacy.

NeuroD1 promotes tumor cell proliferation and tumorigenesis by directly activating the pentose phosphate pathway in colorectal carcinoma

Tumor metabolic reprogramming ensures that cancerous cells obtain sufficient building blocks, energy, and antioxidants to sustain rapid growth and for coping with oxidative stress. Neurogenic differentiation factor 1 (NeuroD1) is upregulated in various types of tumors; however, its involvement in tumor cell metabolic reprogramming remains unclear. In this study, we report that NeuroD1 is positively correlated with glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme in the pentose phosphate pathway (PPP), in colorectal cancer cells. In addition, the regulation of G6PD by NeuroD1 alters tumor cell metabolism by stimulating the PPP, leading to enhanced production of nucleotides and NADPH. These, in turn, promote DNA and lipid biosynthesis in tumor cells, while decreasing intracellular levels of reactive oxygen species. Mechanistically, we showed that NeuroD1 binds directly to the G6PD promoter to activate G6PD transcription. Consequently, tumor cell proliferation and colony formation are enhanced, leading to increased tumorigenic potential in vitro and in vivo. These findings reveal a novel function of NeuroD1 as a regulator of G6PD, whereby its oncogenic activity is linked to tumor cell metabolic reprogramming and regulation of the PPP. Furthermore, NeuroD1 represents a potential target for metabolism-based anti-tumor therapeutic strategies.

Epigenetic activation of the elongator complex sensitizes gallbladder cancer to gemcitabine therapy

Background

Gallbladder cancer (GBC) is known for its high malignancy and multidrug resistance. Previously, we uncovered that impaired integrity and stability of the elongator complex leads to GBC chemotherapy resistance, but whether its restoration can be an efficient therapeutic strategy for GBC remains unknown.

Methods

RT-qPCR, MS-qPCR and ChIP-qPCR were used to evaluate the direct association between ELP5 transcription and DNA methylation in tumour and non-tumour tissues of GBC. EMSA, chromatin accessibility assays, and luciferase assays were utilized to analysis the DNA methylation in interfering PAX5-DNA interactions. The functional experiments in vitro and in vivo were performed to investigate the effects of DNA demethylating agent decitabine (DAC) on the transcription activation of elongator complex and the enhanced sensitivity of gemcitabine in GBC cells. Tissue microarray contains GBC tumour tissues was used to evaluate the association between the expression of ELP5, DNMT3A and PAX5.

Results

We demonstrated that transcriptional repression of ELP5 in GBC was highly correlated with hypermethylation of the promoter. Mechanistically, epigenetic analysis revealed that DNA methyltransferase DNMT3A-catalysed hypermethylation blocked transcription factor PAX5 activation of ELP5 by disrupting PAX5-DNA interaction, resulting in repressed ELP5 transcription. Pharmacologically, the DNA demethylating agent DAC eliminated the hypermethylated CpG dinucleotides in the ELP5 promoter and then facilitated PAX5 binding and reactivated ELP5 transcription, leading to the enhanced function of the elongator complex. To target this mechanism, we employed a sequential combination therapy of DAC and gemcitabine to sensitize GBC cells to gemcitabine-therapy through epigenetic activation of the elongator complex.

Conclusions

Our findings suggest that ELP5 expression in GBC is controlled by DNA methylation-sensitive induction of PAX5. The sequential combination therapy of DAC and gemcitabine could be an efficient therapeutic strategy to overcome chemotherapy resistance in GBC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02186-0.

OXCT1 Enhances Gemcitabine Resistance Through NF-κB Pathway in Pancreatic Ductal Adenocarcinoma

Background

Pancreatic ductal adenocarcinoma (PDAC) is a type of malignant tumor with a five-year survival rate of less than 10%. Gemcitabine (GEM) is the most commonly used drug for PDAC chemotherapy. However, a vast majority of patients with PDAC develop resistance after GEM treatment.

Methods

We screened for GEM resistance genes through bioinformatics analysis. We used immunohistochemistry to analyze 3-oxoacid CoA-transferase 1 (OXCT1) expression in PDAC tissues. The survival data were analyzed using the Kaplan–Meier curve. The expression levels of the genes related to OXCT1 and the NF-κB signaling pathway were quantified using real−time quantitative PCR and western blot analyses. We performed flow cytometry to detect the apoptosis rate. Colony formation assay was performed to measure the cell proliferation levels. The cytotoxicity assays of cells were conducted using RTCA. The downstream pathway of OXCT1 was identified via the Gene Set Enrichment Analysis. Tumor growth response to GEM in vivo was also determined in mouse models.

Results

Bioinformatics analysis revealed that OXCT1 is the key gene leading to GEM resistance. Patients with high OXCT1 expression exhibited short relapse-free survival under GEM treatment. OXCT1 overexpression in PDAC cell lines exerted inhibitory effect on apoptosis after GEM treatment. However, the down-regulation of OXCT1 showed the opposite effect. Blocking the NF-κB signaling pathway also reduced GEM resistance of PDAC cells. Tumor growth inhibition induced by GEM in vivo reduced after OXCT1 overexpression. Moreover, the effect of OXCT1 on GEM refractoriness in PDAC cell lines was reversed through using an NF-κB inhibitor.

Conclusion

OXCT1 promoted GEM resistance in PDAC via the NF-κB signaling pathway both in vivo and in vitro. Our results suggest that OXCT1 could be used as a potential therapeutic target for patients with PDAC.

Metabolic characterization and metabolism-score of tumor to predict the prognosis in prostate cancer

Tumor metabolism patterns have been reported to be associated with the prognosis of many cancers. However, the metabolic mechanisms underlying prostate cancer (PCa) remain unknown. This study aimed to explore the metabolic characteristics of PCa. First, we downloaded mRNA expression data and clinical information of PCa samples from multiple databases and quantified the metabolic pathway activity level using single-sample gene set enrichment analysis (ssGSEA). Through unsupervised clustering and principal component analyses, we explored metabolic characteristics and constructed a metabolic score for PCa. Then, we independently validated the prognostic value of our metabolic score and the nomogram based on the metabolic score in multiple databases. Next, we found the metabolic score to be closely related to the tumor microenvironment and DNA mutation using multi-omics data and ssGSEA. Finally, we found different features of drug sensitivity in PCa patients in the high/low metabolic score groups. In total, 1232 samples were analyzed in the present study. Overall, an improved understanding of tumor metabolism through the characterization of metabolic clusters and metabolic score may help clinicians predict prognosis and aid the development of more personalized anti-tumor therapeutic strategies for PCa.

One-shot dual gene editing for drug-resistant pancreatic cancer therapy

It is challenging to diagnose patients with pancreatic ductal adenocarcinoma (PDAC) early on, and their treatment is often complex. Gemcitabine (GEM) is the first-line treatment for PDAC, but its efficacy is limited in most patients due to the GEM resistance from KRAS and P53 gene mutations. We describe the correction of a double gene mutation and therapeutic effect for the GEM resistant PDAC. Bio-available nanoliposomes (NL) possessing Cas9-ribonucleoproteins and adenine-base editors were developed to conduct KRAS and P53 mutation gene editing directly. NLs were conjugated with EGFR antibodies to tumor-specific delivery, and the anti-cancer effect was verified in vitro and in vivo Model. Our GEM-combinatorial therapeutic strategies using double gene editing systems with one-shot may be a potent therapy for PDAC, overcoming chemoresistance.

The biological role of metabolic reprogramming in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease and highly resistant to all forms of therapy. PDAC cells reprogram their metabolism extensively to promote their survival and growth. Reflecting the vital role of altered metabolism, experimental and clinical trials targeting the rewired metabolism are currently underway. In this review, we summarize the vital role of metabolic reprogramming in the development of PDAC and the future of novel therapeutic applications.

Molecular aspects of pancreatic cancer: focus on reprogrammed metabolism in a nutrient-deficient environment and potential therapeutic targets

Pancreatic ductal adenocarcinoma (PDAC) is still burdened with high mortality (5-year survival rate < 9%) due to late diagnosis, aggressiveness, and a lack of more effective treatment methods. Early diagnosis and new therapeutic approaches based on the reprogrammed metabolism of the tumor in a nutrient-deficient environment are expected to improve the future treatment of PDAC patients. Research results suggest that genetic and metabolic disorders may precede the onset of neoplastic changes, which should allow for earlier appropriate treatment. Glycolysis and glutaminolysis are the most investigated pathways associated with the highest aggressiveness of pancreatic tumors. Blocking of selected metabolic pathways related to the local adaptive metabolic activity of pancreatic cancer cells improving nutrient acquisition and metabolic crosstalk within the microenvironment to sustain proliferation may inhibit cancer development, increase cancer cells death, and increase sensitivity to other forms of treatment (e.g., chemotherapy). Depriving cancer cells of important nutrients (glucose, glutamine) revealed tumor “checkpoints” for the mechanisms that drive cell proliferation and metastasis formation in order to determine its accuracy for individualization of the therapeutic approach. The present review highlights selected metabolic signaling pathways and their regulators aimed at inhibiting the neoplastic process. Particular attention has been paid to the adaptive metabolism of pancreatic cancer, which promotes its development in an oxygen-deficient and nutrient-poor environment.

Drosophila intestinal homeostasis requires CTP synthase

CTP synthase (CTPS) senses all four nucleotides and forms filamentous structures termed cytoophidia in all three domains of life. How CTPS and cytoophidia function in a developmental context, however, remains underexplored. We report that CTPS forms cytoophidia in a subset of cells in the Drosophila midgut. We found that cytoophidia exist in intestinal stem cells (ISC) and enteroblasts in similar proportions. Both refeeding after starvation and feeding with dextran sulfate sodium (DSS) induce ISC proliferation and elongate cytoophidia. Knockdown of CTPS inhibits ISC proliferation. Remarkably, disruption of CTPS cytoophidia inhibits DSS-induced ISC proliferation. Taken together, these data suggest that both the expression level and the filament-form property of CTPS are crucial for intestinal homeostasis in Drosophila.

Metabolic Rewiring by Loss of Sirt5 Promotes Kras-Induced Pancreatic Cancer Progression

BACKGROUND & AIMS

SIRT5 plays pleiotropic roles via post-translational modifications, serving as a tumor suppressor, or an oncogene, in different tumors. However, the role SIRT5 plays in the initiation and progression of pancreatic ductal adenocarcinoma (PDAC) remains unknown.

METHODS

Published datasets and tissue arrays with SIRT5 staining were used to investigate the clinical relevance of SIRT5 in PDAC. Furthermore, to define the role of SIRT5 in the carcinogenesis of PDAC, we generated autochthonous mouse models with conditional Sirt5 knockout. Moreover, to examine the mechanistic role of SIRT5 in PDAC carcinogenesis, SIRT5 was knocked down in PDAC cell lines and organoids, followed by metabolomics and proteomics studies. A novel SIRT5 activator was used for therapeutic studies in organoids and patient-derived xenografts.

RESULTS

SIRT5 expression negatively regulated tumor cell proliferation and correlated with a favorable prognosis in patients with PDAC. Genetic ablation of Sirt5 in PDAC mouse models promoted acinar-to-ductal metaplasia, precursor lesions, and pancreatic tumorigenesis, resulting in poor survival. Mechanistically, SIRT5 loss enhanced glutamine and glutathione metabolism via acetylation-mediated activation of GOT1. A selective SIRT5 activator, MC3138, phenocopied the effects of SIRT5 overexpression and exhibited antitumor effects on human PDAC cells. MC3138 also diminished nucleotide pools, sensitizing human PDAC cell lines, organoids, and patient-derived xenografts to gemcitabine.

CONCLUSIONS

Collectively, we identify SIRT5 as a key tumor suppressor in PDAC, whose loss promotes tumorigenesis through increased noncanonic use of glutamine via GOT1, and that SIRT5 activation is a novel therapeutic strategy to target PDAC.

Role of human nucleoside transporters in pancreatic cancer and chemoresistance

The prognosis of pancreatic cancer is poor with the overall 5-year survival rate of less than 5% changing minimally over the past decades and future projections predicting it developing into the second leading cause of cancer related mortality within the next decade. Investigations into the mechanisms of pancreatic cancer development, progression and acquired chemoresistance have been constant for the past few decades, thus resulting in the identification of human nucleoside transporters and factors affecting cytotoxic uptake via said transporters. This review summaries the aberrant expression and role of human nucleoside transports in pancreatic cancer, more specifically human equilibrative nucleoside transporter 1/2 (hENT1, hENT2), and human concentrative nucleoside transporter 1/3 (hCNT1, hCNT3), while briefly discussing the connection and importance between these nucleoside transporters and mucins that have also been identified as being aberrantly expressed in pancreatic cancer. The review also discusses the incidence, current diagnostic techniques as well as the current therapeutic treatments for pancreatic cancer. Furthermore, we address the importance of chemoresistance in nucleoside analogue drugs, in particular, gemcitabine and we discuss prospective therapeutic treatments and strategies for overcoming acquired chemoresistance in pancreatic cancer by the enhancement of human nucleoside transporters as well as the potential targeting of mucins using a combination of mucolytic compounds with cytotoxic agents.

Anti-cancer efficacy including Rb-deficient tumors and VHL-independent HIF1α proteasomal destabilization by dual targeting of CDK1 or CDK4/6 and HSP90

A prevalent characteristic of solid tumors is intra-tumoral hypoxia. Hypoxia-inducible factor 1α (HIF1α) predominantly mediates the adaptive response to O₂ oscillation and is linked to multiple malignant hallmarks. Here we describe a strategy to robustly target HIF1α by dual inhibition of CDK(s) and heat shock protein 90 (HSP90). We show that CDK1 may contribute to HSP90-mediated HIF1α stabilization. CDK1 knockdown enhances the decrease of HIF1α by HSP90 inhibition. Dual inhibition of CDK1 and HSP90 significantly increases apoptosis and synergistically inhibits cancer cell viability. Similarly, targeting CDK4/6 using FDA-approved inhibitors in combination with HSP90 inhibition shows a class effect on HIF1α inhibition and cancer cell viability suppression not only in colorectal but also in various other cancer types, including Rb-deficient cancer cells. Dual inhibition of CDK4/6 and HSP90 suppresses tumor growth in vivo. In summary, combined targeting of CDK(s) (CDK1 or CDK4/6) and HSP90 remarkably inhibits the expression level of HIF1α and shows promising anti-cancer efficacy with therapeutic potential.

Therapeutic resistance in pancreatic ductal adenocarcinoma: Current challenges and future opportunities

Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer-related deaths in the United States. Although chemotherapeutic regimens such as gemcitabine+ nab-paclitaxel and FOLFIRINOX (FOLinic acid, 5-Fluroruracil, IRINotecan, and Oxaliplatin) significantly improve patient survival, the prevalence of therapy resistance remains a major roadblock in the success of these agents. This review discusses the molecular mechanisms that play a crucial role in PDAC therapy resistance and how a better understanding of these mechanisms has shaped clinical trials for pancreatic cancer chemotherapy. Specifically, we have discussed the metabolic alterations and DNA repair mechanisms observed in PDAC and current approaches in targeting these mechanisms. Our discussion also includes the lessons learned following the failure of immunotherapy in PDAC and current approaches underway to improve tumor's immunological response.

Possible Role of Cytochrome P450 1B1 in the Mechanism of Gemcitabine Resistance in Pancreatic Cancer

Patient-derived xenograft models reportedly represent original tumor morphology and gene mutation profiles. In addition, patient-derived xenografts are expected to recapitulate the parental tumor drug responses. In this study, we analyzed the pathways involved in gemcitabine resistance using patient-derived xenograft models of pancreatic cancer. The patient-derived xenograft models were established using samples from patients with pancreatic cancer. The models were treated with gemcitabine to better understand the mechanism of resistance to this anti-cancer drug. We performed comparative gene analysis through the next-generation sequencing of tumor tissues from gemcitabine-treated or non-treated patient-derived xenograft mice and gene set enrichment analysis to analyze mRNA profiling data. Pathway analysis of gemcitabine-treated patient-derived xenografts disclosed the upregulation of multiple gene sets and identified several specific gene pathways that could potentially be related to gemcitabine resistance in pancreatic cancer. Further, we conducted an in vitro analysis to validate these results. The mRNA expression of cytochrome P450 1B1 and cytochrome P450 2A6 was upregulated in a concentration-dependent manner following gemcitabine treatment. Moreover, the sensitivity to gemcitabine increased, and viable cells were decreased by the cytochrome P450 1B1 inhibitor, indicating that the cytochrome P450 1B1 pathway may be related to gemcitabine resistance in pancreatic cancer.

Pharmacometabolomics by NMR in Oncology: A Systematic Review

Pharmacometabolomics (PMx) studies aim to predict individual differences in treatment response and in the development of adverse effects associated with specific drug treatments. Overall, these studies inform us about how individuals will respond to a drug treatment based on their metabolic profiles obtained before, during, or after the therapeutic intervention. In the era of precision medicine, metabolic profiles hold great potential to guide patient selection and stratification in clinical trials, with a focus on improving drug efficacy and safety. Metabolomics is closely related to the phenotype as alterations in metabolism reflect changes in the preceding cascade of genomics, transcriptomics, and proteomics changes, thus providing a significant advance over other omics approaches. Nuclear Magnetic Resonance (NMR) is one of the most widely used analytical platforms in metabolomics studies. In fact, since the introduction of PMx studies in 2006, the number of NMR-based PMx studies has been continuously growing and has provided novel insights into the specific metabolic changes associated with different mechanisms of action and/or toxic effects. This review presents an up-to-date summary of NMR-based PMx studies performed over the last 10 years. Our main objective is to discuss the experimental approaches used for the characterization of the metabolic changes associated with specific therapeutic interventions, the most relevant results obtained so far, and some of the remaining challenges in this area.

Histone acetyltransferase 1 promotes gemcitabine resistance by regulating the PVT1/EZH2 complex in pancreatic cancer

The poor prognosis of pancreatic cancer is primarily due to the development of resistance to therapies, including gemcitabine. The long noncoding RNA PVT1 (lncRNA PVT1) has been shown to interact with enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2), promoting gemcitabine resistance in pancreatic cancer. In this study, we found histone acetyltransferase 1 (HAT1) enhanced the tolerance of pancreatic cancer cells to gemcitabine and HAT1-mediated resistance mechanisms were regulated by PVT1 and EZH2. Our results showed that the aberrant HAT1 expression promoted gemcitabine resistance, while silencing HAT1 restored gemcitabine sensitivity. Moreover, HAT1 depletion caused a notable increase of gemcitabine sensitivity in gemcitabine-resistant pancreatic cancer cell lines. Further research found that HAT1 increased PVT1 expression to induce gemcitabine resistance, which enhanced the binding of bromodomain containing 4 (BRD4) to the PVT1 promoter, thereby promoting PVT1 transcription. Besides, HAT1 prevented EZH2 degradation by interfering with ubiquitin protein ligase E3 component n-recognin 4 (UBR4) binding to the N-terminal domain of EZH2, thus maintaining EZH2 protein stability to elevate the level of EZH2 protein, which also promoted HAT1-mediated gemcitabine resistance. These results suggested that HAT1 induced gemcitabine resistance of pancreatic cancer cells through regulating PVT1/EZH2 complex. Given this, Chitosan (CS)-tripolyphosphate (TPP)-siHAT1 nanoparticles were developed to block HAT1 expression and improve the antitumor effect of gemcitabine. The results showed that CS-TPP-siHAT1 nanoparticles augmented the antitumor effects of gemcitabine in vitro and in vivo. In conclusion, HAT1-targeted therapy can improve observably gemcitabine sensitivity of pancreatic cancer cells. HAT1 is a promising therapeutic target for pancreatic cancer.

A new pancreatic adenocarcinoma-derived organoid model of acquired chemoresistance to FOLFIRINOX: First insight of the underlying mechanisms

BACKGROUND INFORMATION

Although improvements have been made in the management of pancreatic adenocarcinoma (PDAC) during the past 20 years, the prognosis of this deadly disease remains poor with an overall 5-year survival under 10%. Treatment with FOLFIRINOX, a combined regimen of 5-fluorouracil, irinotecan (SN-38) and oxaliplatin, is nonetheless associated with an excellent initial tumour response and its use has allowed numerous patients to go through surgery while their tumour was initially considered unresectable. These discrepancies between initial tumour response and very low long-term survival are the consequences of rapidly acquired chemoresistance and represent a major therapeutic frontier. To our knowledge, a model of resistance to the combined three drugs has never been described due to the difficulty of modelling the FOLFIRINOX protocol both in vitro and in vivo. Patient-derived tumour organoids (PDO) are the missing link that has long been lacking in the wide range of epithelial cancer models between 2D adherent cultures and in vivo xenografts. In this work we sought to set up a model of PDO with resistance to FOLFIRINOX regimen that we could compare to the paired naive PDO.

RESULTS

We first extrapolated physiological concentrations of the three drugs using previous pharmacodynamics studies and bi-compartmental elimination models of oxaliplatin and SN-38. We then treated PaTa-1818x naive PDAC organoids with six cycles of 72 h-FOLFIRINOX treatment followed by 96 h interruption. Thereafter, we systematically compared treated organoids to PaTa-1818x naive organoids in terms of growth, proliferation, viability and expression of genes involved in cancer stemness and aggressiveness.

CONCLUSIONS

We reproductively obtained resistant organoids FoxR that significantly showed less sensitivity to FOLFORINOX treatment than the PaTa-1818x naive organoids from which they were derived. Our resistant model is representative of the sequential steps of chemoresistance observed in patients in terms of growth arrest (proliferation blockade), residual disease (cell quiescence/dormancy) and relapse.

SIGNIFICANCE

To our knowledge, this is the first genuine in vitro model of resistance to the three drugs in combined therapy. This new PDO model will be a great asset for the discovery of acquired chemoresistance mechanisms, knowledge that is mandatory before offering new therapeutic strategies for pancreatic cancer.

Glycolysis-related gene expression profiling serves as a novel prognosis risk predictor for human hepatocellular carcinoma

Metabolic pattern reconstruction is an important factor in tumor progression. Metabolism of tumor cells is characterized by abnormal increase in anaerobic glycolysis, regardless of high oxygen concentration, resulting in a significant accumulation of energy from glucose sources. These changes promotes rapid cell proliferation and tumor growth, which is further referenced a process known as the Warburg effect. The current study reconstructed the metabolic pattern in progression of cancer to identify genetic changes specific in cancer cells. A total of 12 common types of solid tumors were included in the current study. Gene set enrichment analysis (GSEA) was performed to analyze 9 glycolysis-related gene sets, which are implicated in the glycolysis process. Univariate and multivariate analyses were used to identify independent prognostic variables for construction of a nomogram based on clinicopathological characteristics and a glycolysis-related gene prognostic index (GRGPI). The prognostic model based on glycolysis genes showed high area under the curve (AUC) in LIHC (Liver hepatocellular carcinoma). The findings of the current study showed that 8 genes (AURKA, CDK1, CENPA, DEPDC1, HMMR, KIF20A, PFKFB4, STMN1) were correlated with overall survival (OS) and recurrence-free survival (RFS). Further analysis showed that the prediction model accurately distinguished between high- and low-risk cancer patients among patients in different clusters in LIHC. A nomogram with a well-fitted calibration curve based on gene expression profiles and clinical characteristics showed good discrimination based on internal and external cohorts. These findings indicate that changes in expression level of metabolic genes implicated in glycolysis can contribute to reconstruction of tumor-related microenvironment.

Activated Pancreatic Stellate Cells Enhance the Warburg Effect to Cause the Malignant Development in Chronic Pancreatitis

Chronic pancreatitis (CP) is a precancerous condition associated with pancreatic ductal adenocarcinoma (PDAC), but its evolutionary mechanism is unclear. Pancreatic stellate cells (PSCs) are closely related to the occurrence and development of CP and PDAC, but it is not clear whether PSCs play a key role in this “inflammation-cancer transition”. Our research found that co-culture with activated PSCs promoted the proliferation, migration and invasion of normal pancreatic duct epithelial cells and pancreatic cancer cells. At the same time, activated PSCs had a significant effect on the expression of the glycolysis markers (pyruvate kinase M2, lactate dehydrogenase A, glucose transporter 1, hexokinase-II and monocarboxylate transporter 4; PKM2, LDHA, GLUT1, HK2 and MCT4) in normal pancreatic duct epithelial cells and pancreatic cancer cells and increased lactic acid production and glucose consumption in these two cells. In vivo experiments showed that the expression of the glycolysis markers in pancreatic duct epithelial cells and the marker protein (α-SMA) of activated PSCs in the pancreatic duct peripancreatic interstitium were higher in pancreatic cancer tissues and chronic pancreatitis tissues than in normal pancreatic tissues in both animals and humans. In addition, analysis of human tissue specimens showed that there is a correlation between the expression of glycolysis markers and α-SMA. These findings indicate that activated PSCs play an important role in the development and progression of chronic pancreatitis into pancreatic cancer by regulating and promoting aerobic glycolysis. Our research provides a new theoretical basis for further understanding the mechanism of CP malignancy and the selection of targets for reversing CP malignancy.