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

MUC1 promotes cervical squamous cell carcinoma through ERK phosphorylation-mediated regulation of ITGA2/ITGA3

In contrast to the decreasing trends in developed countries, the incidence and mortality rates of cervical squamous cell carcinoma in China have increased significantly. The screening and identification of reliable biomarkers and candidate drug targets for cervical squamous cell carcinoma are urgently needed to improve the survival rate and quality of life of patients. In this study, we demonstrated that the expression of MUC1 was greater in neoplastic tissues than in non-neoplastic tissues of the cervix, and cervical squamous cell carcinoma patients with high MUC1 expression had significantly worse overall survival than did those with low MUC1 expression, indicating its potential for early diagnosis of cervical squamous cell carcinoma. Next, we explored the regulatory mechanism of MUC1 in cervical squamous cell carcinoma. MUC1 could upregulate ITGA2 and ITGA3 expression via ERK phosphorylation, promoting the proliferation and metastasis of cervical cancer cells. Further knockdown of ITGA2 and ITGA3 significantly inhibited the tumorigenesis of cervical cancer cells. Moreover, we designed a combination drug regimen comprising MUC1-siRNA and a novel ERK inhibitor in vivo and found that the combination of these drugs achieved better results in animals with xenografts than did MUC1 alone. Overall, we discovered a novel regulatory pathway, MUC1/ERK/ITGA2/3, in cervical squamous cell carcinoma that may serve as a potential biomarker and therapeutic target in the future.

Hypoxia, hypoxia-inducible factors and inflammatory bowel diseases

Adequate oxygen supply is essential for maintaining the body's normal physiological function. In chronic inflammatory conditions such as inflammatory bowel disease (IBD), insufficient oxygen reaching the intestine triggers the regulatory system in response to environmental changes. However, the pathogenesis of IBD is still under investigation. Recent research has highlighted the significant role of hypoxia in IBD, particularly the involvement of hypoxia-inducible factors (HIF) and their regulatory mechanisms, making them promising therapeutic targets for IBD. This review will delve into the role of hypoxia, HIF, and the associated hypoxia-inflammatory microenvironment in the context of IBD. Potential interventions for addressing these challenging gastrointestinal inflammatory diseases will also be discussed within this framework.

GPRC5A promotes paclitaxel resistance and glucose content in NSCLC

Lung cancer is one of the most common and malignant cancers worldwide. Chemotherapy has been widely used in the clinical setting, and paclitaxel is the first-line therapy for lung cancer patients but paclitaxel resistance is the main problem. First, we successfully established paclitaxel-resistant lung cancer cells treated with elevated doses of paclitaxel for 3 months, as confirmed by the CCK-8 assay. Paclitaxel-resistant cancer cells increased glucose content. Second, Gtex, Oncomine, and gene expression omnibus database data mining identified GPRC5A, G protein-coupled receptor, as the most prominent differentially expressed gene in drug-resistant datasets including gemcitabine, paclitaxel, and gefitinib overlapped with the microarray data from cancer cell metabolism. Third, qPCR analysis and western blot technique showed that GPRC5A mRNA and protein levels were significantly enhanced in paclitaxel-resistant lung cancer cells. Fourth, functional analysis was conducted by siRNA-mediated transient knockdown of GPRC5A. Silencing GPRC5A significantly decreased paclitaxel resistance and glucose content. In the end, retinoic acid substantially upregulated GPRC5A proteins and promoted glucose content in two lung cancer cells. Kaplan-Meier plot also confirmed that lung cancer patients with high expression of GPRC5A had a relatively lower survival rate. Our study provided a potential drug target GPRC5A, which may benefit lung cancer patients with acquired paclitaxel resistance in the future and a theoretical basis for future preclinical trials.

The MUC1-HIF-1α signaling axis regulates pancreatic cancer pathogenesis through polyamine metabolism remodeling

Dysregulation of polyamine metabolism has been implicated in cancer initiation and progression; however, the mechanism of polyamine dysregulation in cancer is not fully understood. In this study, we investigated the role of MUC1, a mucin protein overexpressed in pancreatic cancer, in regulating polyamine metabolism. Utilizing pancreatic cancer patient data, we noted a positive correlation between MUC1 expression and the expression of key polyamine metabolism pathway genes. Functional studies revealed that knockdown of spermidine/spermine N1-acetyltransferase 1 (SAT1), a key enzyme involved in polyamine catabolism, attenuated the oncogenic functions of MUC1, including cell survival and proliferation. We further identified a regulatory axis whereby MUC1 stabilized hypoxia-inducible factor (HIF-1α), leading to increased SAT1 expression, which in turn induced carbon flux into the tricarboxylic acid cycle. MUC1-mediated stabilization of HIF-1α enhanced the promoter occupancy of the latter on SAT1 promoter and corresponding transcriptional activation of SAT1, which could be abrogated by pharmacological inhibition of HIF-1α or CRISPR/Cas9-mediated knockout of HIF1A. MUC1 knockdown caused a significant reduction in the levels of SAT1-generated metabolites, N1-acetylspermidine and N8-acetylspermidine. Given the known role of MUC1 in therapy resistance, we also investigated whether inhibiting SAT1 would enhance the efficacy of FOLFIRINOX chemotherapy. By utilizing organoid and orthotopic pancreatic cancer mouse models, we observed that targeting SAT1 with pentamidine improved the efficacy of FOLFIRINOX, suggesting that the combination may represent a promising therapeutic strategy against pancreatic cancer. This study provides insights into the interplay between MUC1 and polyamine metabolism, offering potential avenues for the development of treatments against pancreatic cancer.

Cancer-associated fibroblast-derived acetate promotes pancreatic cancer development by altering polyamine metabolism via the ACSS2-SP1-SAT1 axis

The ability of tumour cells to thrive in harsh microenvironments depends on the utilization of nutrients available in the milieu. Here we show that pancreatic cancer-associated fibroblasts (CAFs) regulate tumour cell metabolism through the secretion of acetate, which can be blocked by silencing ATP citrate lyase (ACLY) in CAFs. We further show that acetyl-CoA synthetase short-chain family member 2 (ACSS2) channels the exogenous acetate to regulate the dynamic cancer epigenome and transcriptome, thereby facilitating cancer cell survival in an acidic microenvironment. Comparative H3K27ac ChIP-seq and RNA-seq analyses revealed alterations in polyamine homeostasis through regulation of SAT1 gene expression and enrichment of the SP1-responsive signature. We identified acetate/ACSS2-mediated acetylation of SP1 at the lysine 19 residue that increased SP1 protein stability and transcriptional activity. Genetic or pharmacologic inhibition of the ACSS2-SP1-SAT1 axis diminished the tumour burden in mouse models. These results reveal that the metabolic flexibility imparted by the stroma-derived acetate enabled cancer cell survival under acidosis via the ACSS2-SP1-SAT1 axis.

Liensinine inhibits progression of intrahepatic cholangiocarcinoma by regulating TGF-β1 /P-smad3 signaling through HIF-1a

Intrahepatic cholangiocarcinoma (ICC) is a high-grade malignant digestive system tumor with an insidious onset and unfavorable prognosis. Liensinine, a small molecule derived from plants, has been proven to have significant tumor suppressor activity in other cancers. However, there are no reports on whether liensinine can inhibit the proliferation or metastasis of ICC. This study aimed to explore the tumor-suppressive activity of liensinine in ICC and its underlying mechanisms. The phenotypic changes in ICC cells were monitored in vitro using cell function tests. Western blot and immunofluorescence analyses verified the efficacy of liensinine. Tumor-bearing nude mice were used to explore the effect of liensinine on tumors and its toxicity and side effects in vivo. Liensinine suppressed ICC cell proliferation and arrested the cell cycle at the G1 phase. The epithelial-mesenchymal transition (EMT) of ICC cells was also inhibited, thereby restraining their invasion and migration of tumor cells. In addition, this study found that the potential mechanism of liensinine inhibiting EMT may be via suppression of the TGF-β1/P-smad3 signaling pathway through hypoxia-inducible factor 1 alpha (HIF-1a). In vivo experiments showed that liensinine inhibited the growth of Hucc-T1 transplanted tumors in nude mice. Liensinine restrained the proliferation of ICC cells and suppressed EMT in ICC via the HIF-1a-mediated TGF-β1/P-smad3 signaling pathway.

Exosome-Derived MicroRNA-221-3p Desensitizes Breast Cancer Cells to Adriamycin by Regulating PIK3r1-Mediated Glycose Metabolism

Background: Cancer-derived exosomes facilitate chemoresistance by transferring RNAs, yet their role in exosomal microRNA-221-3p (miR-221-3p) regulation of Adriamycin resistance in breast cancer (BC) remains unclear. Methods: Adriamycin-resistant BC cells were developed from MCF-7 and MDA-MB-231 cells by incremental Adriamycin exposure. The miR-221-3p levels were quantified by quantitative reverse transcription-polymerase chain reaction. Subsequently, exosomes were isolated and incubated with BC cells, and exosome-mediated Adriamycin sensitivity was evaluated using Cell Counting Kit-8, colony formation, and flow cytometry assays. Sensitive cells were cocultured with miR-221-3p inhibitor-treated cells to assess Adriamycin resistance. Moreover, the interaction between miR-221-3p and phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1) was validated using a dual luciferase reporter gene assay. Mimics and inhibitors were used to determine the effects of miR-221-3p on Adriamycin resistance. Results: Elevated levels of miR-221-3p expression were observed in Adriamycin-resistant BC cells and exosomes. Sensitive cells were cocultured with exosomes from resistant cells, resulting in increased half-maximal inhibitory concentration value and proliferation, and reduced Adriamycin-induced apoptosis. However, the effects of coculturing sensitive cells with Adriamycin-resistant cells were significantly weakened by miR-221-3p inhibitor transfection in Adriamycin-resistant cells. PIK3R1 was found to be a target of miR-221-3p, and miR-221-3p mimics enhanced Adriamycin resistance in sensitive cells. miR-221-3p inhibitors increased the expression of PIK3R1, p-AKT, c-Myc, HK2, and PKM2, decreased FOXO3 expression, and weakened the Adriamycin resistance in resistant cells. Conclusions: miR-221-3p can be transferred between BC cells through exosomes. High levels of miR-221-3p were found to target PIK3R1 and promoted Adriamycin resistance in BC cells. [Figure: see text].

PRMT1 promotes pancreatic cancer development and resistance to chemotherapy

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal types of cancer, and novel treatment regimens are direly needed. Epigenetic regulation contributes to the development of various cancer types, but its role in the development of and potential as a therapeutic target for PDAC remains underexplored. Here, we show that PRMT1 is highly expressed in murine and human pancreatic cancer and is essential for cancer cell proliferation and tumorigenesis. Deletion of PRMT1 delays pancreatic cancer development in a KRAS-dependent mouse model, and multi-omics analyses reveal that PRMT1 depletion leads to global changes in chromatin accessibility and transcription, resulting in reduced glycolysis and a decrease in tumorigenic capacity. Pharmacological inhibition of PRMT1 in combination with gemcitabine has a synergistic effect on pancreatic tumor growth in vitro and in vivo. Collectively, our findings implicate PRMT1 as a key regulator of pancreatic cancer development and a promising target for combination therapy.

Deciphering cellular plasticity in pancreatic cancer for effective treatments

Cellular plasticity and therapy resistance are critical features of pancreatic cancer, a highly aggressive and fatal disease. The pancreas, a vital organ that produces digestive enzymes and hormones, is often affected by two main types of cancer: the pre-dominant ductal adenocarcinoma and the less common neuroendocrine tumors. These cancers are difficult to treat due to their complex biology characterized by cellular plasticity leading to therapy resistance. Cellular plasticity refers to the capability of cancer cells to change and adapt to different microenvironments within the body which includes acinar-ductal metaplasia, epithelial to mesenchymal/epigenetic/metabolic plasticity, as well as stemness. This plasticity allows heterogeneity of cancer cells, metastasis, and evasion of host's immune system and develops resistance to radiation, chemotherapy, and targeted therapy. To overcome this resistance, extensive research is ongoing exploring the intrinsic and extrinsic factors through cellular reprogramming, chemosensitization, targeting metabolic, key survival pathways, etc. In this review, we discussed the mechanisms of cellular plasticity involving cellular adaptation and tumor microenvironment and provided a comprehensive understanding of its role in therapy resistance and ways to overcome it.

Human papillomavirus type 16 E6 promotes cervical cancer proliferation by upregulating transketolase enzymatic activity through the activation of protein kinase B

Over 99% of precancerous cervical lesions are associated with human papillomavirus (HPV) infection, with HPV types 16 and 18 (especially type 16) found in over 70% of cervical cancer cases globally. E6, a critical HPV gene, triggers malignant proliferation by degrading p53; however, this mechanism alone cannot fully explain the oncogenic effects of HPV16 E6. Therefore, we aimed to investigate new targets of HPV oncogenic mechanisms. Our results revealed significant changes in nonoxidative pentose phosphate pathway (PPP) metabolites in HPV16-positive cells. However, the role of nonoxidative PPP in HPV-associated cell transformation and tumor development remained unexplored. In this study, we investigated the impact and mechanisms of HPV16 E6 on cervical cancer proliferation using the HPV-negative cervical cancer cell line (C33A). HPV16 E6 was found to promote cervical cancer cell proliferation both in vitro and in vivo, activating the nonoxidative PPP. Transketolase (TKT), a key enzyme in the nonoxidative PPP, is highly expressed in cervical cancer tissues and associated with poor prognosis. HPV16 E6 promotes cervical cancer cell proliferation by upregulating TKT activity through the activation of AKT. In addition, oxythiamine (OT), a TKT inhibitor, hindered tumor growth, with enhanced effects when combined with cisplatin (DDP). In conclusion, HPV16 E6 promotes cervical cancer proliferation by upregulating TKT activity through the activation of AKT. OT demonstrates the potential to inhibit HPV16-positive cervical cancer growth, and when combined with DDP, could further enhance the tumor-suppressive effect of DDP.

MUC1 and MUC16: critical for immune modulation in cancer therapeutics

The Mucin (MUC) family, a range of highly glycosylated macromolecules, is ubiquitously expressed in mammalian epithelial cells. Such molecules are pivotal in establishing protective mucosal barriers, serving as defenses against pathogenic assaults. Intriguingly, the aberrant expression of specific MUC proteins, notably Mucin 1 (MUC1) and Mucin 16 (MUC16), within tumor cells, is intimately associated with oncogenesis, proliferation, and metastasis. This association involves various mechanisms, including cellular proliferation, viability, apoptosis resistance, chemotherapeutic resilience, metabolic shifts, and immune surveillance evasion. Due to their distinctive biological roles and structural features in oncology, MUC proteins have attracted considerable attention as prospective targets and biomarkers in cancer therapy. The current review offers an exhaustive exploration of the roles of MUC1 and MUC16 in the context of cancer biomarkers, elucidating their critical contributions to the mechanisms of cellular signal transduction, regulation of immune responses, and the modulation of the tumor microenvironment. Additionally, the article evaluates the latest advances in therapeutic strategies targeting these mucins, focusing on innovations in immunotherapies and targeted drugs, aiming to enhance customization and accuracy in cancer treatments.

Neuromedin U regulates the anti-tumor activity of CD8+ T cells and glycolysis of tumor cells in the tumor microenvironment of pancreatic ductal adenocarcinoma in an NMUR1-dependent manner

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with a poor prognosis, which is lethal in approximately 90% of cases despite advanced standard therapies. A typical feature of PDAC is the immunosuppressive tumor microenvironment with multiple immunosuppressive factors including neurotransmitters. Recently, neuromedin U (NMU), a highly conserved neuropeptide with many physiological functions, has attracted attention for its roles in tumorigenesis and metastasis in several types of cancers. However, whether NMU affects PDAC progression remains unclear. In this study, using an orthotopic mouse model of PDAC in combination with bioinformatics analysis, we found that NMU was upregulated in tumor tissues from the patients with PDAC and positively correlated with a poor prognosis of the disease. Interestingly, knockout of the Nmu gene in mice enhanced the anti-tumor functions of tumor-infiltrating CD8+ T cells in an NMU receptor 1-dependent manner. Additionally, NMU promoted the glycolytic metabolism of mouse PDAC tumors. The activities of pyruvate kinase (PK) and lactate dehydrogenase (LDH), pivotal enzymes involved in the regulation of lactate production, were markedly reduced in tumor tissues from NMU-knockout mice. In vitro the presence of LDHA inhibitor can reduce the production of lactic acid stimulated by NMU, which can increase the anti-tumor activity of CD8+ T cells. Moreover, treatment of the pancreatic cancer cells with a phosphoinositide 3-kinase (PI3K) inhibitor diminished NMU-induced lactate production and the activities of PK and LDH, suggesting that NMU might regulate glycolysis via the PI3K/AKT pathway.

GPX3-Mediated Oxidative Stress Affects Pyrimidine Metabolism Levels in Stomach Adenocarcinoma via the AMPK/mTOR Pathway

Background

Amino acid metabolism, including ATP production, nucleotide synthesis, and redox homeostatic processes, are associated with proliferation and differentiation of tumor cells. This study aimed to identify novel prognostic biomarkers and potential therapeutic targets of amino acid metabolism-related genes for stomach adenocarcinoma (STAD).

Methods

RNA sequencing transcriptome data in the TCGA-STAD (training set) and GTEx datasets (validation set) were used. The LIMMA R program enabled the differentially expressed amino acid metabolism-related genes (AAMRGs) to be found. A prognostic risk score model based on clinical phenotypic features was built using LASSO regression and step multi-Cox analyses. Gene set enrichment analysis (GSEA) was used to find potential molecular pathways associated with STAD. Hierarchical cluster analysis was used to evaluate pyrimidine metabolism. Cultured STAD cells assessed the proliferation of STAD and upregulation of GPX3 expression by CCK8 and flow cytometry. Transwell and wound healing assays assessed the impact of GPX3 on invasion and migration of STAD cells. Western blot and qRT-PCR were used to measure changes in pyrimidine metabolism-related markers and active molecules involved in the AMPK/mTOR signaling pathway.

Results

Three AAMRGs, DNMT1, F2R, and GPX3, could independently predict the course of STAD. Pyrimidine metabolism appeared to be significantly associated with these by GSEA and clustering analyses. Pyrimidine metabolism was negatively correlated with GPX3. Functional studies using an overexpressed GPX3 plasmid showed an enhanced migration and invasion of STAD cells as well as the expression of genes associated with pyrimidine metabolism and the AMPK/mTOR signaling pathway. By using a CAD siRNA, it was found that that GPX3 affected 5-fluorouracil resistance during de novo synthesis of pyrimidine through the CAD-UMPS signaling axis.

Conclusions

GPX3 which regulates the level of pyrimidine metabolism through the AMPK/mTOR pathway was found to be closely associated with STAD. Our findings demonstrate GPX3 is a reliable biomarker for the prognosis of amino acid metabolism and a probable target for STAD therapy.

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.

Advances in macrophage and T cell metabolic reprogramming and immunotherapy in the tumor microenvironment

Macrophages and T cells in the tumor microenvironment (TME) play an important role in tumorigenesis and progression. However, TME is also characterized by metabolic reprogramming, which may affect macrophage and metabolic activity of T cells and promote tumor escape. Immunotherapy is an approach to fight tumors by stimulating the immune system in the host, but requires support and modulation of cellular metabolism. In this process, the metabolic roles of macrophages and T cells become increasingly important, and their metabolic status and interactions play a critical role in the success of immunotherapy. Therefore, understanding the metabolic state of T cells and macrophages in the TME and the impact of metabolic reprogramming on tumor therapy will help optimize subsequent immunotherapy strategies.

DHODH inhibition enhances the efficacy of immune checkpoint blockade by increasing cancer cell antigen presentation

Pyrimidine nucleotide biosynthesis is a druggable metabolic dependency of cancer cells, and chemotherapy agents targeting pyrimidine metabolism are the backbone of treatment for many cancers. Dihydroorotate dehydrogenase (DHODH) is an essential enzyme in the de novo pyrimidine biosynthesis pathway that can be targeted by clinically approved inhibitors. However, despite robust preclinical anticancer efficacy, DHODH inhibitors have shown limited single-agent activity in phase 1 and 2 clinical trials. Therefore, novel combination therapy strategies are necessary to realize the potential of these drugs. To search for therapeutic vulnerabilities induced by DHODH inhibition, we examined gene expression changes in cancer cells treated with the potent and selective DHODH inhibitor brequinar (BQ). This revealed that BQ treatment causes upregulation of antigen presentation pathway genes and cell surface MHC class I expression. Mechanistic studies showed that this effect is 1) strictly dependent on pyrimidine nucleotide depletion, 2) independent of canonical antigen presentation pathway transcriptional regulators, and 3) mediated by RNA polymerase II elongation control by positive transcription elongation factor B (P-TEFb). Furthermore, BQ showed impressive single-agent efficacy in the immunocompetent B16F10 melanoma model, and combination treatment with BQ and dual immune checkpoint blockade (anti-CTLA-4 plus anti-PD-1) significantly prolonged mouse survival compared to either therapy alone. Our results have important implications for the clinical development of DHODH inhibitors and provide a rationale for combination therapy with BQ and immune checkpoint blockade.

Vitamin B6 Competition in the Tumor Microenvironment Hampers Antitumor Functions of NK Cells

Nutritional factors play crucial roles in immune responses. The tumor-caused nutritional deficiencies are known to affect antitumor immunity. Here, we demonstrate that pancreatic ductal adenocarcinoma (PDAC) cells can suppress NK-cell cytotoxicity by restricting the accessibility of vitamin B6 (VB6). PDAC cells actively consume VB6 to support one-carbon metabolism, and thus tumor cell growth, causing VB6 deprivation in the tumor microenvironment. In comparison, NK cells require VB6 for intracellular glycogen breakdown, which serves as a critical energy source for NK-cell activation. VB6 supplementation in combination with one-carbon metabolism blockage effectively diminishes tumor burden in vivo. Our results expand the understanding of the critical role of micronutrients in regulating cancer progression and antitumor immunity, and open new avenues for developing novel therapeutic strategies against PDAC.

SIGNIFICANCE

The nutrient competition among the different tumor microenvironment components drives tumor growth, immune tolerance, and therapeutic resistance. PDAC cells demand a high amount of VB6, thus competitively causing NK-cell dysfunction. Supplying VB6 with blocking VB6-dependent one-carbon metabolism amplifies the NK-cell antitumor immunity and inhibits tumor growth in PDAC models. This article is featured in Selected Articles from This Issue, p. 5.

Metabolomic Investigations into Hypoxia-Mediated Metabolic Reprogramming of Pancreatic Cancer Cells

Hypoxia is a crucial microenvironmental factor that defines tumor cell growth and aggressiveness. Cancer cells adapt to hypoxia by altering their metabolism. These alterations impact various cellular and physiological functions, including energy metabolism, vascularization, invasion and metastasis, genetic instability, cell immortalization, stem cell maintenance, and resistance to chemotherapy (Li et al. Technol Cancer Res Treat 20:15330338211036304, 2021). Hypoxia-inducible factor-1α (HIF-1α) is known to be a critical regulator of glycolysis that directly regulates the transcription of multiple key enzymes of the glycolysis pathway. Moreover, HIF-1α stabilization can be directly modulated by TCA-derived metabolites, including 2-ketoglutarate and succinate (Infantino et al, Int J Mol Sci 22(22), https://doi.org/10.3390/ijms22115703 , 2021). Overall, the molecular mechanisms underlying the adaptation of cellular metabolism to hypoxia impact the metabolic phenotype of cancer cells. Such adaptations include increased glucose uptake, increased lactate production, and increased levels of other metabolites that stabilize HIF-1α, leading to a vicious circle of hypoxia-induced tumor growth.

Mucin1 as a potential molecule for cancer immunotherapy and targeted therapy

Mucin1 is a highly glycosylated type 1 transmembrane mucin that ranks second among 75 tumor-related antigens published by the National Cancer Institute, and has been identified as a possible therapeutic target over the past 30 years. MUC1 plays an important role in malignant transformation and disease evolution, including cell proliferation, survival, self-renewal, and metastatic invasion. MUC1 has been shown to interact with diverse effectors such as β-catenin, receptor tyrosine kinases, and cellular-abelsongene, which are of importance in the pathogenesis of various malignant tumors. Targeting MUC1 has been shown to be an effective way to induce tumor cell death in vivo and in vitro models. In recent years, a number of therapeutic strategies targeting MUC1 have been developed and their value for tumor therapy have been demonstrated experimentally. This review summarizes recent findings on the structure of MUC1, its expression in different tumors and its involved mechanism pathways, with emphasis on new progress in cancer therapy which related MUC1 in the past decade and evaluates their therapeutic effect.

Measurement of Metabolic Alteration in Immune Cells Under Hypoxia

The hypoxic microenvironment in solid tumors affects the metabolism of tumor cells and infiltrating immune cells, which aids in robust tumor growth and expansion. Myeloid-derived suppressor cells (MDSCs) are heterogenous immature myeloid cells in the TME, which play an essential role in immune evasion by subverting T/NK cell-mediated killing. The immunosuppressive function of MDSCs is tightly regulated to the metabolic pathways, in which hypoxia plays a critical role. In this chapter, we describe the isolation of murine MDSCs from bone marrows and the measurement of the transcriptomic changes of essential metabolic enzymes under hypoxic conditions. This method can be applied to study MDSCs function, mimicking the hypoxic environment in vitro. This method can be utilized to investigate the critical metabolic alterations under a given tumor context and help evaluate the efficacy of metabolic-targeted therapies in the long run.

CTPS1 is a novel therapeutic target in multiple myeloma which synergizes with inhibition of CHEK1, ATR or WEE1

Targeting nucleotide biosynthesis is a proven strategy for the treatment of cancer but is limited by toxicity, reflecting the fundamental nucleotide requirement of dividing cells. The rate limiting step in de novo pyrimidine synthesis is of interest, being catalyzed by two homologous enzymes, CTP synthase 1 (CTPS1) and CTPS2, that could be differentially targeted. Herein, analyses of publicly available datasets identified an essential role for CTPS1 in multiple myeloma (MM), linking high expression of CTPS1 (but not CTPS2) with advanced disease and poor outcomes. In cellular experiments, CTPS1 knockout induced apoptosis of MM cell lines. Exposure of MM cells to STP-B, a novel and highly selective pharmacological inhibitor of CTPS1, inhibited proliferation, induced S phase arrest and led to cell death by apoptosis. Mechanistically, CTPS1 inhibition by STP-B activated DNA damage response (DDR) pathways and induced double-strand DNA breaks which accumulated in early S phase. Combination of STP-B with pharmacological inhibitors of key components of the DDR pathway (ATR, CHEK1 or WEE1) resulted in synergistic growth inhibition and early apoptosis. Taken together, these findings identify CTPS1 as a promising new target in MM, either alone or in combination with DDR pathway inhibition.

Nuclear GRP78 Promotes Metabolic Reprogramming and Therapeutic Resistance in Pancreatic Ductal Adenocarcinoma

PURPOSE

Stromal fibrosis limits nutritional supply and disarrays metabolism in pancreatic cancer (PDA, pancreatic ductal adenocarcinoma). Understanding of the molecular basis underlying metabolic cues would improve PDA management. The current study determined the interaction between glucose-regulated proteins 78 (GRP78) and hypoxia-inducible factor 1α (HIF-1α) and its mechanistic roles underlying PDA response to oxygen and glucose restrains.

EXPERIMENTAL DESIGN

Gene expression and its association with clinicopathologic characteristics of patients with PDA and mouse models were analyzed using IHC. Protein expression and their regulation were measured by Western blot and immunoprecipitation analyses. Protein interactions were determined using gain- and loss-of-function assays and molecular methods, including chromatin immunoprecipitation, co-immunoprecipitation, and dual luciferase reporter.

RESULTS

There was concomitant overexpression of both GRP78 and HIF-1α in human and mouse PDA tissues and cells. Glucose deprivation increased the expression of GRP78 and HIF-1α, particularly colocalization in nucleus. Induction of HIF-1α expression by glucose deprivation in PDA cells depended on the expression of and its own interaction with GRP78. Mechanistically, increased expression of both HIF-1α and LDHA under glucose deprivation was caused by the direct binding of GRP78 and HIF-1α protein complexes to the promoters of HIF-1α and LDHA genes and transactivation of their transcriptional activity.

CONCLUSIONS

Protein complex of GRP78 and HIF-1α directly binds to HIF-1α own promoter and LDHA promoter, enhances the transcription of both HIF-1α and LDHA, whereas glucose deprivation increases GRP78 expression and further enhances HIF-1α and LDHA transcription. Therefore, crosstalk and integration of hypoxia- and hypoglycemia-responsive signaling critically impact PDA metabolic reprogramming and therapeutic resistance.

Wild-type IDH1 maintains NSCLC stemness and chemoresistance through activation of the serine biosynthetic pathway

Tumor-initiating cells (TICs) reprogram their metabolic features to meet their bioenergetic, biosynthetic, and redox demands. Our previous study established a role for wild-type isocitrate dehydrogenase 1 (IDH1WT) as a potential diagnostic and prognostic biomarker for non-small cell lung cancer (NSCLC), but how IDH1WT modulates NSCLC progression remains elusive. Here, we report that IDH1WT activates serine biosynthesis by enhancing the expression of phosphoglycerate dehydrogenase (PHGDH) and phosphoserine aminotransferase 1 (PSAT1), the first and second enzymes of de novo serine synthetic pathway. Augmented serine synthesis leads to GSH/ROS imbalance and supports pyrimidine biosynthesis, maintaining tumor initiation capacity and enhancing gemcitabine chemoresistance. Mechanistically, we identify that IDH1WT interacts with and stabilizes PHGDH and fragile X-related protein-1 (FXR1) by impeding their association with the E3 ubiquitin ligase parkin by coimmunoprecipitation assay and proximity ligation assay. Subsequently, stabilized FXR1 supports PSAT1 mRNA stability and translation, as determined by actinomycin D chase experiment and in vitro translation assay. Disrupting IDH1WT-PHGDH and IDH1WT-FXR1 interactions synergistically reduces NSCLC stemness and sensitizes NSCLC cells to gemcitabine and serine/glycine-depleted diet therapy in lung cancer xenograft models. Collectively, our findings offer insights into the role of IDH1WT in serine metabolism, highlighting IDH1WT as a potential therapeutic target for eradicating TICs and overcoming gemcitabine chemoresistance in NSCLC.

NOP58 induction potentiates chemoresistance of colorectal cancer cells through aerobic glycolysis as evidenced by proteomics analysis

Introduction: The majority of individuals diagnosed with advanced colorectal cancer (CRC) will ultimately acquire resistance to 5-FU treatment. An increasing amount of evidence indicates that aerobic glycolysis performs a significant function in the progression and resistance of CRC. Nevertheless, the fundamental mechanisms remain to be fully understood. Methods: Proteomic analysis of 5-FU resistant CRC cells was implemented to identify and determine potential difference expression protein. Results: These proteins may exhibit resistance mechanisms that are potentially linked to the process of aerobic glycolysis. Herein, we found that nucleolar protein 58 (NOP58) has been overexpressed within two 5-FU resistant CRC cells, 116-5FuR and Lovo-5FuR. Meanwhile, the glycolysis rate of drug-resistant cancer cells has increased. NOP58 knockdown decreased glycolysis and enhanced the sensitivity of 116-5FuR and Lovo-5FuR cells to 5FU. Conclusion: The proteomic analysis of chemoresistance identifies a new target involved in the cellular adaption to 5-FU and therefore highlights a possible new therapeutic strategy to overcome this resistance.

Impact of Hypoxia-Induced miR-210 on Pancreatic Cancer

Pancreatic cancer (PC) poses significant clinical challenges, with late-stage diagnosis and limited therapeutic options contributing to its dismal prognosis. A hallmark feature of PC is the presence of a profoundly hypoxic tumour microenvironment, resulting from various factors such as fibrotic stroma, rapid tumour cell proliferation, and poor vascularization. Hypoxia plays a crucial role in promoting aggressive cancer behaviour, therapeutic resistance, and immunosuppression. Previous studies have explored the molecular mechanisms behind hypoxia-induced changes in PC, focusing on the role of hypoxia-inducible factors (HIFs). Among the myriad of molecules affected by hypoxia, microRNA-210 (miR-210) emerges as a central player. It is highly responsive to hypoxia and regulated by HIF-dependent and HIF-independent pathways. miR-210 influences critical cellular processes, including angiogenesis, metastasis, and apoptosis, all of which contribute to PC progression and resistance to treatment. Understanding these pathways provides insights into potential therapeutic targets. Furthermore, investigating the role of miR-210 and its regulation in hypoxia sheds light on the potential development of early diagnostic strategies, which are urgently needed to improve outcomes for PC patients. This review delves into the complexities of PC and introduces the roles of hypoxia and miR-210 in the progression of PC.

Single-cell sequencing in pancreatic cancer research: A deeper understanding of heterogeneity and therapy

Pancreatic cancer, including pancreatic ductal adenocarcinomas (PDACs), is a malignant tumor with characteristics of tumor-stroma interactions. Patients often have a poor prognosis and a poor long-term survival rate. In recent years, rapidly-developing single-cell sequencing techniques have been used to analyze cell populations at a single-cell resolution, so that it is now possible to have a more in-depth and clearer understanding of the genetic composition of pancreatic cancer. In this review, we provide an overview of the current single-cell sequencing techniques and their applications in the exploration of intratumoral heterogeneity, the tumor microenvironment, therapy resistance, and novel treatments. Our hope is to provide new insight into the potential of precision therapy, which will perhaps one day lead to significant advances in PDAC treatment.

Supraphysiological glutamine as a means of depleting intracellular amino acids to enhance pancreatic cancer chemosensitivity

Limited efficacy of systemic therapy for pancreatic ductal adenocarcinoma (PDAC) patients contributes to high mortality. Cancer cells develop strategies to secure nutrients in nutrient-deprived conditions and chemotherapy treatment. Despite the dependency of PDAC on glutamine (Gln) for growth and survival, strategies designed to suppress Gln metabolism have limited effects. Here, we demonstrated that supraphysiological concentrations of glutamine (SPG) could produce paradoxical responses leading to tumor growth inhibition alone and in combination with chemotherapy. Integrated metabolic and transcriptomic analysis revealed that the growth inhibitory effect of SPG was the result of a decrease in intracellular amino acid and nucleotide pools. Mechanistically, disruption of the sodium gradient, plasma membrane depolarization, and competitive inhibition of amino acid transport mediated amino acid deprivation. Among standard chemotherapies given to PDAC patients, gemcitabine treatment resulted in a significant enrichment of amino acid and nucleoside pools, exposing a metabolic vulnerability to SPG-induced metabolic alterations. Further analysis highlighted a superior anticancer effect of D-glutamine, a non-metabolizable enantiomer of the L-glutamine, by suppressing both amino acid uptake and glutaminolysis, in gemcitabine-treated preclinical models with no apparent toxicity. Our study suggests supraphysiological glutamine could be a means of inhibiting amino acid uptake and nucleotide biosynthesis, potentiating gemcitabine sensitivity in PDAC.

Advances in MUC1 resistance to chemotherapy in pancreatic cancer

The incidence of pancreatic cancer (PC), a highly fatal malignancy, is increasing every year. Chemotherapy is an important treatment for it in addition to surgery, yet most patients become resistant to chemotherapeutic agents within a few weeks of treatment initiation.​ MUC1 is a highly glycosylated transmembrane protein, and studies have shown that aberrantly glycosylated overexpression of MUC1 is involved in regulating the biology of chemoresistance in cancer cells. This article summarizes the mechanism of MUC1 in PC chemoresistance and reviews MUC1-based targeted therapies.

MUC1-C integrates aerobic glycolysis with suppression of oxidative phosphorylation in triple-negative breast cancer stem cells

Activation of the MUC1-C protein promotes lineage plasticity, epigenetic reprogramming, and the cancer stem cell (CSC) state. The present studies performed on enriched populations of triple-negative breast cancer (TNBC) CSCs demonstrate that MUC1-C is essential for integrating activation of glycolytic pathway genes with self-renewal and tumorigenicity. MUC1-C further integrates the glycolytic pathway with suppression of mitochondrial DNA (mtDNA) genes encoding components of mitochondrial Complexes I-V. The repression of mtDNA genes is explained by MUC1-C-mediated (i) downregulation of the mitochondrial transcription factor A (TFAM) required for mtDNA transcription and (ii) induction of the mitochondrial transcription termination factor 3 (mTERF3). In support of pathogenesis that suppresses mitochondrial ROS production, targeting MUC1-C increases (i) mtDNA gene transcription, (ii) superoxide levels, and (iii) loss of self-renewal capacity. These findings and scRNA-seq analysis of CSC subpopulations indicate that MUC1-C regulates self-renewal and redox balance by integrating activation of glycolysis with suppression of oxidative phosphorylation.

An intravenous pancreatic cancer therapeutic: Characterization of CRISPR/Cas9n-modified Clostridium novyi-Non Toxic

Clostridium novyi has demonstrated selective efficacy against solid tumors largely due to the microenvironment contained within dense tumor cores. The core of a solid tumor is typically hypoxic, acidic, and necrotic-impeding the penetration of current therapeutics. C. novyi is attracted to the tumor microenvironment and once there, can both lyse and proliferate while simultaneously re-activating the suppressed immune system. C. novyi systemic toxicity is easily mitigated by knocking out the phage DNA plasmid encoded alpha toxin resulting in C. novyi-NT; but, after intravenous injection spores are quickly cleared by phagocytosis before accomplishing significant tumor localization. C. novyi-NT could be designed to accomplish intravenous delivery with the potential to target all solid tumors and their metastases in a single dose. This study characterizes CRISPR/Cas9 modified C. novyi-NT to insert the gene for RGD, a tumor targeting peptide, expressed within the promoter region of a spore coat protein. Expression of the RGD peptide on the outer spore coat of C. novyi-NT indicates an increased capacity for tumor localization of C. novyi upon intravenous introduction based on the natural binding of RGD with the αvβ3 integrin commonly overexpressed on the epithelial tissue surrounding a tumor, and lead to immune stimulation.

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.

Black Phosphorus as a Targeting PPAR-γ Agonist to Reverse Chemoresistance in Patient-derived Organoids, Mice, and Pancreatic Tumor Cells

Black phosphorus (BP) exhibits significant potential for clinical applications. However, further research is necessary to uncover the unknown biological functions of BP and broaden its applications across various fields. This study investigates the potential of BP as a targeting PPAR-γ agonist to overcome chemoresistance in the treatment of pancreatic adenocarcinoma (PAAD) using 2D and 3D cell lines, patient-derived organoids (PDOs), and mouse models. RNA-sequencing analysis shows that BP treatment enriches differentially expressed genes in the PPAR pathway, and molecular modeling predicts the potential docking site between BP and PPAR-γ. Transcriptional activity assays are further to verify the activation of PPAR-γ. BP-activated PPAR-γ inhibits cancer stem cell (CSC) properties and expression of biomarkers such as CD44 and c-Myc, which are involved in chemoresistance. Notably, CD44 overexpression in tumor cells renders them susceptible to BP while insensitive to gemcitabine. This indicates that BP preferentially targets stem-like cells, which exhibit heightened resistance to chemotherapeutic drugs. A combination treatment strategy involving BP and gemcitabine is developed, demonstrating enhanced treatment efficacy of PAAD in both in vitro and in vivo models. Thus, BP serves as a PPAR-γ agonist capable of reversing chemoresistance, establishing it as a potent anti-tumor approach for the treatment of PAAD.

Regulation of nucleotide metabolism in cancers and immune disorders

Nucleotides are the foundational elements of life. Proliferative cells acquire nutrients for energy production and the synthesis of macromolecules, including proteins, lipids, and nucleic acids. Nucleotides are continuously replenished through the activation of the nucleotide synthesis pathways. Despite the importance of nucleotides in cell physiology, there is still much to learn about how the purine and pyrimidine synthesis pathways are regulated in response to intracellular and exogenous signals. Over the past decade, evidence has emerged that several signaling pathways [Akt, mechanistic target of rapamycin complex I (mTORC1), RAS, TP53, and Hippo-Yes-associated protein (YAP) signaling] alter nucleotide synthesis activity and influence cell function. Here, we examine the mechanisms by which these signaling networks affect de novo nucleotide synthesis in mammalian cells. We also discuss how these molecular links can be targeted in diseases such as cancers and immune disorders.

Activation of Glycolysis by MCM10 Increases Stemness and Paclitaxel Resistance in Gastric Cancer Cells

BACKGROUND/AIMS

Chemotherapy is an essential avenue for curing malignancies; however, tumor cells acquire resistance to chemotherapeutic agents, eventually leading to chemotherapy failure. At present, paclitaxel (PTX) resistance seriously hinders the therapeutic efficacy of gastric cancer (GC). Investigating the molecular mechanism of PTX resistance in GC is critical. This study attempted to delineate the impact of MCM10 on GC resistance to PTX and its mechanism in GC.

MATERIALS AND METHODS

The expression of minichromosome maintenance complex component 10 (MCM10) in GC tissues, its enrichment pathways, and its correlation with glycolysis marker genes and stemness index (mRNAsi) were analyzed in a bioinformatics effort. Real-time quantitative polymerase chain reaction was used to assay the expression of MCM10 in cells. Cell counting kit-8 (CCK-8) was used to analyze cell viability and calculate the 50% inhibitor concentration (IC50) value. Western blot was used to measure the expression of MCM10, Hexokinase 2 (HK2) and stemness-related factors in cells. Sphere-forming assay was performed to study cell sphere-forming ability. Seahorse XF 96 was utilized to measure cell extracellular acidification and oxygen consumption rates. The content of glycolysisrelated products was tested with corresponding kits.

RESULTS

MCM10 was significantly upregulated in GC and enriched in the glycolysis pathway, and it was positively correlated with both glycolysis-related genes and stemness index. High expression of MCM10 increased sphere-forming ability of drug-resistant cells and GC resistance to PTX. The stimulation of PTX resistance and drug-resistant cell stemness in GC by high MCM10 expression was mediated by the glycolysis pathway.

CONCLUSION

MCM10 was upregulated in GC and drove stemness and PTX resistance in GC cells by activating glycolysis. These findings generated new insights into the development of PTX resistance in GC, implicating that targeting MCM10 may be a novel approach to improve GC sensitivity to PTX chemotherapy.

Pancreatic Ductal Adenocarcinoma: The Characteristics of Contrast-Enhanced Ultrasound Are Correlated with the Hypoxic Microenvironment

A hypoxic microenvironment is associated with an increased risk of metastasis, treatment resistance and poor prognosis of pancreatic ductal adenocarcinoma (PDAC). This study aimed to identify contrast-enhanced ultrasound (CEUS) characteristics that could predict the hypoxic microenvironment of PDAC. A total of 102 patients with surgically resected PDAC who underwent CEUS were included. CEUS qualitative and quantitative characteristics were analyzed. The expression of hypoxia-inducible factor-1α (HIF-1) and glucose transporter-1 (GLUT1) were demonstrated by immunohistochemistry. The associations between CEUS characteristics and the HIF-1α and GLUT1 expression of PDACs were evaluated. We found that HIF-1α-high PDACs and GLUT1-high PDACs had a larger tumor size and were more prone to lymph node metastasis. There was a significant positive linear correlation between the expression of HIF-1α and GLUT1. CEUS qualitative characteristics including completeness of enhancement and peak enhancement degree (PED) were related to the expression of HIF-1α and GLUT1. A logistic regression analysis showed that tumor size, lymph node metastasis, incomplete enhancement and iso-enhancement of PED were independent predictors for HIF-1α-high PDACs and GLUT1-high PDACs. As for quantitative characteristics, HIF-1α-high PDACs and GLUT1-high PDACs showed higher peak enhancement (PE) and wash-in rate (WIR). CEUS can effectively reflect the hypoxia microenvironment of PDAC, which may become a noninvasive imaging biomarker for prognosis prediction and individualized treatment.

ERRα promotes glycolytic metabolism and targets the NLRP3/caspase-1/GSDMD pathway to regulate pyroptosis in endometrial cancer

BACKGROUND

Tumor cells can resist chemotherapy-induced pyroptosis through glycolytic reprogramming. Estrogen-related receptor alpha (ERRα) is a central regulator of cellular energy metabolism associated with poor cancer prognosis. Herein, we refine the oncogenic role of ERRα in the pyroptosis pathway and glycolytic metabolism.

METHODS

The interaction between ERRα and HIF-1α was verified using co-immunoprecipitation. The transcriptional binding sites of ERRα and NLRP3 were confirmed using dual-luciferase reporter assay and cleavage under targets and tagmentation (CUT&Tag). Flow cytometry, transmission electron microscopy, scanning electron microscopy, cell mito stress test, and extracellular acidification rate analysis were performed to investigate the effects of ERRα on the pyroptosis pathway and glycolytic metabolism. The results of these experiments were further confirmed in endometrial cancer (EC)-derived organoids and nude mice. In addition, the expression of ERRα-related pyroptosis genes was analyzed using The Cancer Genome Atlas and Gene Expression Omnibus database.

RESULTS

Triggered by a hypoxic microenvironment, highly expressed ERRα could bind to the promoter of NLRP3 and inhibit caspase-1/GSDMD signaling, which reduced inflammasome activation and increased pyroptosis resistance, thereby resulting in the resistance of cancer cells to cisplatin. Moreover, ERRα activated glycolytic rate-limiting enzyme to bridge glycolytic metabolism and pyroptosis in EC. This phenomenon was further confirmed in EC-derived organoids and nude mice. CUT & Tag sequencing and The Cancer Genome Atlas database analysis showed that ERRα participated in glycolysis and programmed cell death, which resulted in EC progression.

CONCLUSIONS

ERRα inhibits pyroptosis in an NLRP3-dependent manner and induces glycolytic metabolism, resulting in cisplatin resistance in EC cells.

Metabolic classification suggests the GLUT1/ALDOB/G6PD axis as a therapeutic target in chemotherapy-resistant pancreatic cancer

Metabolic reprogramming is known as an emerging mechanism of chemotherapy resistance, but the metabolic signatures of pancreatic ductal adenocarcinomas (PDACs) remain unclear. Here, we characterize the metabolomic profile of PDAC organoids and classify them into glucomet-PDAC (high glucose metabolism levels) and lipomet-PDAC (high lipid metabolism levels). Glucomet-PDACs are more resistant to chemotherapy than lipomet-PDACs, and patients with glucomet-PDAC have a worse prognosis. Integrated analyses reveal that the GLUT1/aldolase B (ALDOB)/glucose-6-phosphate dehydrogenase (G6PD) axis induces chemotherapy resistance by remodeling glucose metabolism in glucomet-PDAC. Increased glycolytic flux, G6PD activity, and pyrimidine biosynthesis are identified in glucomet-PDAC with high GLUT1 and low ALDOB expression, and these phenotypes could be reversed by inhibiting GLUT1 expression or by increasing ALDOB expression. Pharmacological inhibition of GLUT1 or G6PD enhances the chemotherapy response of glucomet-PDAC. Our findings uncover potential metabolic heterogeneity related to differences in chemotherapy sensitivity in PDAC and develop a promising pharmacological strategy for patients with chemotherapy-resistant glucomet-PDAC through the combination of chemotherapy and GLUT1/ALDOB/G6PD axis inhibitors.

Bifunctional Cascading Nanozymes Based on Carbon Dots Promotes Photodynamic Therapy by Regulating Hypoxia and Glycolysis

Photodynamic therapy (PDT) still faces great challenges with suitable photosensitizers, oxygen supply, and reactive oxygen species (ROS) accumulation, especially in the tumor microenvironment, feathering hypoxia, and high glucose metabolism. Herein, a carbon dots (CDs)-based bifunctional nanosystem (MnZ@Au), acting as photosensitizer and nanozyme with cascading glucose oxidase (GOx)- and catalase (CAT)-like reactivity, was developed for improving hypoxia and regulating glucose metabolism to enhance PDT. The MnZ@Au was constructed using Mn-doped CDs (Mn-CDs) as a core and zeolitic imidazolate framework-8 (ZIF-8) as a shell to form a hybrid (MnZ), followed by anchoring ultrasmall Au nanoparticles (AuNPs) onto the surface of MnZ through the ion exchange and in situ reduction methods. MnZ@Au catalyzed glucose consumption and oxygen generation by cascading GOx- and CAT-like nanozyme reactions, which was further enhanced by its own photothermal properties. In vitro and in vivo studies also confirmed that MnZ@Au greatly improved CDs penetration, promoted ROS accumulation, and enhanced PDT efficacy, leading to efficient tumor growth inhibition in the breast tumor model. Besides, MnZ@Au enabled photoacoustic (PA) imaging to provide a mapping of Mn-CDs distribution and oxygen saturation, showing the real-time catalytic process of MnZ@Au in vivo. 18F-Fluorodeoxyglucose positron emission tomography (18F-FDG PET) imaging also validated the decreased glucose uptake in tumors treated by MnZ@Au. Therefore, the integrated design provided a promising strategy to utilize and regulate the tumor microenvironment, promote penetration, enhance PDT, and finally prevent tumor deterioration.

Therapeutic Targeting of Mitochondrial Plasticity and Redox Control to Overcome Cancer Chemoresistance

Significance: Mitochondria are subcellular organelles performing essential metabolic functions contributing to cellular bioenergetics and regulation of cell growth or death. The basic mitochondrial function in fulfilling the need for cell growth and vitality is evidenced whereby cancer cells with depleted mitochondrial DNA (rho zero, p0 cells) no longer form tumors until newly recruited mitochondria are internalized into the rho zero cells. Herein lies the absolute dependency on mitochondria for tumor growth. Hence, mitochondria are key regulators of cell death (by apoptosis, necroptosis, or other forms of cell death) and are, therefore, important targets for anticancer therapy. Recent Advances: Mitochondrial plasticity regulating their state of fusion or fission is key to the chemoresistance properties of cancer cells by promoting pro-survival pathways, enabling the mitochondria to mitigate against the cellular stresses and extreme conditions within the tumor microenvironment caused by chemotherapy, hypoxia, or oxidative stress. Critical Issues: This review discusses many characteristics of mitochondria, the processes and pathways controlling the dynamic changes occurring in the morphology of mitochondria, the roles of reactive oxygen species, and their relationship with mitochondrial fission or fusion. It also examines the relationship of redox to mitophagy when mitochondria become compromised and its effect on cancer cell survival, stemness, and the changes accompanying malignant progression from primary tumors to metastatic disease. Future Directions: A challenging question that arises is whether the changes in mitochondrial dynamics and their regulation can provide opportunities for improving drug targeting during cancer treatment and enhancing survival outcomes. Antioxid. Redox Signal. 39, 591-619.

Therapeutic advances targeting tumor angiogenesis in pancreatic cancer: Current dilemmas and future directions

Pancreatic cancer (PC) is one of the most lethal malignancies, which is generally resistant to various treatments. Tumor angiogenesis is deemed to be a pivotal rate-determining step for tumor growth and metastasis. Therefore, anti-angiogenetic therapy is a rational strategy to treat various cancers. However, numerous clinical trials on anti-angiogenetic therapies for PC are overwhelmingly disappointing. The unique characteristics of tumor blood vessels in PC, which are desperately lacking and highly compressed by the dense desmoplastic stroma, are reconsidered to explore some optimized strategies. In this review, we mainly focus on its specific characteristics of tumor blood vessels, discuss the current dilemmas of anti-angiogenic therapy in PC and their underlying mechanisms. Furthermore, we point out the future directions, including remodeling the abnormal vasculature or even reshaping the whole tumor microenvironment in which they are embedded to improve tumor microcirculation, and then create therapeutic vulnerabilities to the current available therapeutic strategies.

Evofosfamide and Gemcitabine Act Synergistically in Pancreatic Cancer Xenografts by Dual Action on Tumor Vasculature and Inhibition of Homologous Recombination DNA Repair

Aims: Pancreatic ductal adenocarcinomas (PDACs) form hypovascular and hypoxic tumors, which are difficult to treat with current chemotherapy regimens. Gemcitabine (GEM) is often used as a first-line treatment for PDACs but has issues with chemoresistance and penetration in the interior of the tumor. Evofosfamide, a hypoxia-activated prodrug, has been shown to be effective in combination with GEM, although the mechanism of each drug on the other has not been established. We used mouse xenografts from two cell lines (MIA Paca-2 and SU.86.86) with different tumor microenvironmental characteristics to probe the action of each drug on the other. Results: GEM treatment enhanced survival times in mice with SU.86.86 leg xenografts (hazard ratio [HR] = 0.35, p = 0.03) but had no effect on MIA Paca-2 mice (HR = 0.91, 95% confidence interval = 0.37-2.25, p = 0.84). Conversely, evofosfamide did not improve survival times in SU.86.86 mice to a statistically significant degree (HR = 0.57, p = 0.22). Electron paramagnetic resonance imaging showed that oxygenation worsened in MIA Paca-2 tumors when treated with GEM, providing a direct mechanism for the activation of the hypoxia-activated prodrug evofosfamide by GEM. Sublethal amounts of either treatment enhanced the toxicity of other treatment in vitro in SU.86.86 but not in MIA Paca-2. By the biomarker γH2AX, combination treatment increased the number of double-stranded DNA lesions in vitro for SU.86.86 but not MIA Paca-2. Innovation and Conclusion: The synergy between GEM and evofosfamide appears to stem from the dual action of GEMs effect on tumor vasculature and inhibition by GEM of the homologous recombination DNA repair process. Antioxid. Redox Signal. 39, 432-444.

The multifaceted role of MUC1 in tumor therapy resistance

Tumor therapeutic resistances are frequently linked to the recurrence and poor prognosis of cancers and have been a key bottleneck in clinical tumor treatment. Mucin1 (MUC1), a heterodimeric transmembrane glycoprotein, exhibits abnormally overexpression in a variety of human tumors and has been confirmed to be related to the formation of therapeutic resistance. In this review, the multifaceted roles of MUC1 in tumor therapy resistance are summarized from aspects of pan-cancer principles shared among therapies and individual mechanisms dependent on different therapies. Concretely, the common mechanisms of therapy resistance across cancers include interfering with gene expression, promoting genome instability, modifying tumor microenvironment, enhancing cancer heterogeneity and stemness, and activating evasion and metastasis. Moreover, the individual mechanisms of therapy resistance in chemotherapy, radiotherapy, and biotherapy are introduced. Last but not least, MUC1-involved therapy resistance in different types of cancers and MUC1-related clinical trials are summarized.

Hypoxia-responsive lncRNA G077640 promotes ESCC tumorigenesis via the H2AX-HIF1α-glycolysis axis

Long noncoding RNAs (lncRNAs) contribute to esophageal squamous cell carcinoma (ESCC) progression, but the underlying mechanisms remain elusive. In this study, we verified a hitherto uncharacterized hypoxia-responsive lncRNA, G077640, which is upregulated in human ESCC cells and tissues, supporting the proliferation and migration of ESCC cells. Mechanistically, G077640 prevented hypoxia-inducible factor-1α (HIF1α) from being degraded by directly interacting with histone H2AX and further modulated the interaction of HIF1α and H2AX. In addition, G077640 reprogrammed glycolytic metabolism by regulating the expression of glucose transporter 4 (GLUT4), hexokinase 2 (HK2) and pyruvate dehydrogenase kinase 1 (PDK1) for ESCC proliferation and migration. Clinically, G077640 was associated with poor prognosis in ESCC patients. Taken together, our findings identified a hypoxia-responsive lncRNA that contributes to ESCC cells proliferation and migration, and targeting G077640 and its pathway might be a potential therapeutic strategy for ESCC.

Methyltransferase like 3 inhibition limits intrahepatic cholangiocarcinoma metabolic reprogramming and potentiates the efficacy of chemotherapy

N6-methyladenosine (m6A) RNA methylation and its associated methyltransferase like 3 (METTL3) are involved in the development and maintenance of various tumors. The present study aimed to evaluate the cross-talk of METTL3 with glucose metabolism and reveal a novel mechanism for intrahepatic cholangiocarcinoma (ICC) progression. Real-time quantitative PCR, western blotting, and immunohistochemistry analyses suggested that METTL3 was highly expressed in ICC, which was correlated with poor patient prognosis. Immunoprecipitation sequencing of m6A-RNA showed that METTL3 upregulated m6A modification of NFAT5, which recruited IGF2BP1 for NFAT5 mRNA stabilization. Elevated expression of NFAT5 increased the expression of the gluconeogenesis-related genes GLUT1 and PGK1, resulting in enhanced aerobic glycolysis, proliferation, and tumor metastasis of ICC. Moreover, higher METTL3 expression was observed in tumor tissues of ICC patients with activated ICC glucose metabolism. Importantly, STM2457, a highly potent METTL3 inhibitor, which inhibited METTL3 activity and acted synergistically with gemcitabine, suggests that reprogramming RNA epigenetic modifications may serve as a potential therapeutic strategy. Overall, our findings highlighted the role of METTL3-mediated m6A modification of NFAT5 in activating glycolytic reprogramming in ICC and proposed that the METTL3/NFAT5 axis was a clinical target for the management of ICC chemoresistance by targeting cancer glycolysis.

PTEN deficiency facilitates gemcitabine efficacy in cancer by modulating the phosphorylation of PP2Ac and DCK

Gemcitabine is a nucleoside analog that has been successfully used in the treatment of multiple cancers. However, intrinsic or acquired resistance reduces the chemotherapeutic potential of gemcitabine. Here, we revealed a previously unappreciated mechanism by which phosphatase and tensin homolog (PTEN), one of the most frequently mutated genes in human cancers, dominates the decision-making process that is central to the regulation of gemcitabine efficacy in cholangiocarcinoma (CCA). By investigating a gemcitabine-treated CCA cohort, we found that PTEN deficiency was correlated with the improved efficacy of gemcitabine-based chemotherapy. Using cell-based drug sensitivity assays, cell line-derived xenograft, and patient-derived xenograft models, we further confirmed that PTEN deficiency or genetic-engineering down-regulation of PTEN facilitated gemcitabine efficacy both in vitro and in vivo. Mechanistically, PTEN directly binds to and dephosphorylates the C terminus of the catalytic subunit of protein phosphatase 2A (PP2Ac) to increase its enzymatic activity, which further dephosphorylates deoxycytidine kinase (DCK) at Ser⁷⁴ to diminish gemcitabine efficacy. Therefore, PTEN deficiency and high phosphorylation of DCK predict a better response to gemcitabine-based chemotherapy in CCA. We speculate that the combination of PP2A inhibitor and gemcitabine in PTEN-positive tumors could avoid the resistance of gemcitabine, which would benefit a large population of patients with cancer receiving gemcitabine or other nucleoside analogs.

Targeting the metabolism of tumor-infiltrating regulatory T cells

Although targeting the tumor metabolism is performed in cooperation with immunotherapy in the era of precision oncology, ignorance of immune cells' metabolism has resulted in unstable antitumor responses. Tumor-infiltrating regulatory T cells (TI-Tregs) are unique, overcoming the hypoxic, acidic, and nutrient-deficient tumor microenvironments (TMEs) and maintaining immunosuppressive functions. However, secondary autoimmunity caused by systemic Treg depletion remains the 'Sword of Damocles' for current Treg-targeted therapies. In this opinion piece, we propose that metabolically reprogrammed TI-Tregs might represent an obstacle to cancer therapies. Indeed, metabolism-based Treg-targeted therapy might provide higher selectivity for clearing TI-Tregs than traditional kinase/checkpoint inhibitors and chemokine/chemokine receptor blockade; it might also restore the efficacy of targeting the tumor metabolism and eliminate certain metabolic barriers to immunotherapy.

Nuclear PLD1 combined with NPM1 induces gemcitabine resistance through tumorigenic IL7R in pancreatic adenocarcinoma

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant gastrointestinal cancer with a 5-year survival rate of only 9%. Of PDAC patients, 15%-20% are eligible for radical surgery. Gemcitabine is an important chemotherapeutic agent for patients with PDAC; however, the efficacy of gemcitabine is limited due to resistance. Therefore, reducing gemcitabine resistance is essential for improving survival of patients with PDAC. Identifying the key target that determines gemcitabine resistance in PDAC and reversing gemcitabine resistance using target inhibitors in combination with gemcitabine are crucial steps in the quest to improve survival prognosis in patients with PDAC.

METHODS

We constructed a human genome-wide CRISPRa/dCas 9 overexpression library in PDAC cell lines to screen key targets of drug resistance based on sgRNA abundance and enrichment. Then, co-IP, ChIP, ChIP-seq, transcriptome sequencing, and qPCR were used to determine the specific mechanism by which phospholipase D1 (PLD1) confers resistance to gemcitabine.

RESULTS

PLD1 combines with nucleophosmin 1 (NPM1) and triggers NPM1 nuclear translocation, where NPM1 acts as a transcription factor to upregulate interleukin 7 receptor (IL7R) expression. Upon interleukin 7 (IL-7) binding, IL7R activates the JAK1/STAT5 signaling pathway to increase the expression of the anti-apoptotic protein, BCL-2, and induce gemcitabine resistance. The PLD1 inhibitor, Vu0155069, targets PLD1 to induce apoptosis in gemcitabine-resistant PDAC cells.

CONCLUSIONS

PLD1 is an enzyme that has a critical role in PDAC-associated gemcitabine resistance through a non-enzymatic interaction with NPM1, further promoting the downstream JAK1/STAT5/Bcl-2 pathway. Inhibiting any of the participants of this pathway can increase gemcitabine sensitivity.

LXR Signaling-Mediated Cholesterol Metabolism Reprogramming Regulates Cancer Cell Metastasis

Metastasis is a key contributor to mortality in patients with cancer. While many regulators of metastasis have been identified, critical targets to prevent and inhibit metastatic tumor growth remain elusive. A recent study in this issue of Cancer Research by Deng and colleagues compared gene expression signatures between primary esophageal squamous cell carcinoma tumors and metastatic tumors and combined the analysis with genes induced in metastatic cancer cell lines, which identified anoctamin 1 (ANO1) as a key driver of metastasis. ANO1 caused cholesterol accumulation by inhibiting LXR signaling and decreased cholesterol hydroxylation by downregulating the expression of cholesterol hydroxylase CYP27A1. ANO1 also regulated tumor cell-fibroblast cross-talk that contributed to inflammatory cytokine signaling (IL1β) and metastasis. Through in silico analysis, the study identified a novel small-molecule inhibitor of ANO1 that decreased tumor burden at a metastatic site. These studies provide novel insights into the role of ANO1 in cellular cholesterol metabolism and associated signaling in mediating metastasis. See related article by Deng et al., p. 1851.

Mucin 4 Confers Gemcitabine Resistance and an Unfavorable Prognosis in Patients with Cholangiocarcinoma via AKT Activation

Cholangiocarcinoma (CCA) exhibits aggressive biological behavior and a poor prognosis. Gemcitabine (GEM)-based chemotherapy is the first-line chemotherapy for advanced CCA but has a response rate of only 20-30%. Therefore, investigating treatments to overcome GEM resistance in advanced CCA is crucial. Among mucin (MUC) family members, MUC4 showed the greatest increase in the resistant versus parental sublines. MUC4 was upregulated in whole-cell lysates and conditioned media from gemcitabine-resistant (GR) CCA sublines. MUC4 mediated GEM resistance by activating AKT signaling in GR CCA cells. The MUC4-AKT axis induced BAX S184 phosphorylation to inhibit apoptosis and downregulated GEM transporter human equilibrative nucleoside transporter 1 (hENT1) expression. The combination of AKT inhibitors and GEM or afatinib overcame GEM resistance in CCA. In vivo, capivasertib (an AKT inhibitor) increased GEM sensitivity in GR cells. MUC4 promoted EGFR and HER2 activation to mediate GEM resistance. Finally, MUC4 expression in patient plasma correlated with MUC4 expression. Paraffin-embedded specimens from non-responders expressed significantly more MUC4 than did those from responders, and this upregulation was associated with poor progression-free survival and overall survival. In GR CCA, high MUC4 expression promotes sustained EGFR/HER2 signaling and AKT activation. The combination of AKT inhibitors with GEM or afatinib might overcome GEM resistance.

Resistance to Gemcitabine in Pancreatic Cancer Is Connected to Methylglyoxal Stress and Heat Shock Response

Pancreatic ductal adenocarcinoma (PDAC) is a fatal disease with poor prognosis. Gemcitabine is the first-line therapy for PDAC, but gemcitabine resistance is a major impediment to achieving satisfactory clinical outcomes. This study investigated whether methylglyoxal (MG), an oncometabolite spontaneously formed as a by-product of glycolysis, notably favors PDAC resistance to gemcitabine. We observed that human PDAC tumors expressing elevated levels of glycolytic enzymes together with high levels of glyoxalase 1 (GLO1), the major MG-detoxifying enzyme, present with a poor prognosis. Next, we showed that glycolysis and subsequent MG stress are triggered in PDAC cells rendered resistant to gemcitabine when compared with parental cells. In fact, acquired resistance, following short and long-term gemcitabine challenges, correlated with the upregulation of GLUT1, LDHA, GLO1, and the accumulation of MG protein adducts. We showed that MG-mediated activation of heat shock response is, at least in part, the molecular mechanism underlying survival in gemcitabine-treated PDAC cells. This novel adverse effect of gemcitabine, i.e., induction of MG stress and HSR activation, is efficiently reversed using potent MG scavengers such as metformin and aminoguanidine. We propose that the MG blockade could be exploited to resensitize resistant PDAC tumors and to improve patient outcomes using gemcitabine therapy.