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.

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.

ENT1 blockade by CNX-774 overcomes resistance to DHODH inhibition in pancreatic cancer.

Inhibitors of dihydroorotate dehydrogenase (DHODH), a key enzyme for de novo synthesis of pyrimidine nucleotides, have failed in clinical trials for various cancers despite robust efficacy in preclinical animal models. To probe for druggable mediators of DHODH inhibitor resistance, we performed a combination screen with a small molecule library against pancreatic cancer cell lines that are highly resistant to the DHODH inhibitor brequinar (BQ). The screen revealed that CNX-774, a preclinical Bruton tyrosine kinase (BTK) inhibitor, sensitizes resistant cell lines to BQ. Mechanistic studies showed that this effect is independent of BTK and instead results from inhibition of equilibrative nucleoside transporter 1 (ENT1) by CNX-774. We show that ENT1 mediates BQ resistance by taking up extracellular uridine, which is salvaged to generate pyrimidine nucleotides in a DHODH-independent manner. In BQ-resistant cell lines, BQ monotherapy slowed proliferation and caused modest pyrimidine nucleotide depletion, whereas combination treatment with BQ and CNX-774 led to profound cell viability loss and pyrimidine starvation. We also identify N-acetylneuraminic acid accumulation as a potential marker of the therapeutic efficacy of DHODH inhibitors. In an aggressive, immunocompetent pancreatic cancer mouse model, combined targeting of DHODH and ENT1 dramatically suppressed tumor growth and prolonged mouse survival. Overall, our study defines CNX-774 as a previously uncharacterized ENT1 inhibitor and provides strong proof of concept support for dual targeting of DHODH and ENT1 in pancreatic cancer.

Retrospective Observational Study to Evaluate Causality, Preventability and Severity of Adverse Drug Reaction Associated with Anticancer Drugs in a Tertiary Care Hospital in Northern India.

BACKGROUND: Chemotherapy has high efficacy, but it is associated with several adverse drug reactions (ADRs). OBJECTIVES: A retrospective observational study to explore the prevalence, causality, and preventability of ADRs of anticancer agents was conducted. METHODS: The study was carried out at Punjab Institute of Medical Sciences Jalandhar, Punjab after obtaining IEC approval. The data was collected from cancer patients undergoing treatment at the hospital. The causality assessment of the collected data was done by using WHO causality assessment criteria. The preventability and severity of the reported ADRs were also assessed. RESULTS: From 50 medical records, a total of 47 ADRs were recorded among 25 patients, out of which 16 were females and the rest were males. The cancer cases observed were breast carcinoma, leukaemia, lung, colon, and ovarian cancer. The highest number of ADRs were observed with alkylating agents, followed by taxanes, antimetabolites, kinase inhibitors, and monoclonal antibodies. The most affected organ systems were the gastrointestinal system, blood, and lymphatic system. According to the causality assessment, the majority of the ADRs were of the "possible" category. Preventability analysis showed that 85.11% of ADRs were unavoidable reactions, while 14.89% of ADRs were possibly avoidable. Severity analysis of ADRs showed that 87.23% of ADRs were mild and 12.77% were of moderate severity. The majority of the ADRs were unavoidable and mild to moderate in severity. CONCLUSION: Since the majority of the ADRs were of the unavoidable category, it indicates that the treatment regimens are acceptable as per the current clinical management of cancer patients.

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.

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.

Molecular Subtypes of Pancreatic Cancer: A Proteomics Approach.

Through molecular subtyping, therapeutic vulnerabilities can be exploited for developing personalized medicine. The real utility of molecular subtyping lies in the clinical translation for disease characterization. Proteomic methods with defined marker sets hold great promise for improving therapy outcomes by improving the speed of predictions for devising treatment strategies.See related article by Son et al., p. 3370.

Clinical profile of patients presenting with dysphagia - an experience from a tertiary care center in North India.

BACKGROUND AND AIM: Dysphagia can lead to substantial morbidity and mortality, especially in the elderly. It has both benign and malignant causes. Despite having a varied etiology, there have been few studies in India. Therefore, a study was undertaken to evaluate the clinical profile and various etiologies of dysphagia. METHODS: A prospective study was conducted on 220 patients with a complaint of dysphagia. Detailed history and examination, endoscopy and biopsies, and barium swallow were performed. Computed tomography and magnetic resonance imaging were performed wherever required. Patients who had an oropharyngeal or neurological cause of dysphagia were excluded. RESULTS: The mean age of patients was 57.2 years, with the male: female ratio being 1.7:1. Of the patients, 35% (78 patients) had malignant etiology, with a mean age of 65.2 years, and 65% (142 patients) had a benign etiology, with a mean age of 51 years. Among the patients with malignancy, 56 had squamous cell carcinoma of esophagus (71.7%), 20 had adenocarcinoma of esophagus (25.7%), and 2 had gastric cardia adenocarcinoma (2.6%). Malignancy was most commonly located in distal esophagus (48 patients), and among the cases, 18 had involvement of the gastroesophageal junction. The most common benign cause was esophagitis secondary to reflux in 25.5% (56 patients), followed by esophageal ulcer in 5.9%, achalasia in 5%, corrosive stricture in 4.5%, and peptic stricture in 3.6%. CONCLUSION: Dysphagia has diverse etiology, and a majority can be diagnosed by endoscopy and barium swallow. Malignancy is an important cause of dysphagia in elderly. Esophageal squamous cell carcinoma remains the most common malignancy, but the incidence of gastroesophageal junctional adenocarcinoma is increasing.

SIRT1-NOX4 signaling axis regulates cancer cachexia.

Approximately one third of cancer patients die due to complexities related to cachexia. However, the mechanisms of cachexia and the potential therapeutic interventions remain poorly studied. We observed a significant positive correlation between SIRT1 expression and muscle fiber cross-sectional area in pancreatic cancer patients. Rescuing Sirt1 expression by exogenous expression or pharmacological agents reverted cancer cell-induced myotube wasting in culture conditions and mouse models. RNA-seq and follow-up analyses showed cancer cell-mediated SIRT1 loss induced NF-κB signaling in cachectic muscles that enhanced the expression of FOXO transcription factors and NADPH oxidase 4 (Nox4), a key regulator of reactive oxygen species production. Additionally, we observed a negative correlation between NOX4 expression and skeletal muscle fiber cross-sectional area in pancreatic cancer patients. Knocking out Nox4 in skeletal muscles or pharmacological blockade of Nox4 activity abrogated tumor-induced cachexia in mice. Thus, we conclude that targeting the Sirt1-Nox4 axis in muscles is an effective therapeutic intervention for mitigating pancreatic cancer-induced cachexia.

Computational Design of Biologically Active Anticancer Peptides and Their Interactions with Heterogeneous POPC/POPS Lipid Membranes.

Over the last few decades, anticancer peptides (ACPs) have turned into potential warheads against cancer. Apart from small molecules and monoclonal antibodies, ACPs have been proven to be effective against cancer cells. ACPs are small cationic peptides that selectively bind to the negatively charged cancer cell membrane and kill them by various mechanisms. In the present study, we prepared a random scrambled library of 1200 peptides from the 100 known ACPs and virtually screened them for their anticancer properties. From in silico-predicted ACPs, 27 peptides were prioritized based on their support vector machine (SVM) score. Based on the SVM score and properties such as hydrophobicity, size, overall net charge, secondary structure, and synthetic feasibility, finally, four peptides were synthesized and screened for their biological activities. Cancer cell membrane-deforming potential of two most active peptides, peptide1 and peptide2 was assessed with molecular dynamics simulation. We found that peptide1 remains adsorbed to the membrane surface, while peptide2 has membrane penetration capability. The present study will be helpful in the computational design of ACPs and understanding their interaction with the cancerous cell's membrane.

Novel Tetrahydroquinazolinamines as Selective Histamine 3 Receptor Antagonists for the Treatment of Obesity.

The histamine 3 receptor (H3R) is a presynaptic receptor, which modulates several neurotransmitters including histamine and various essential physiological processes, such as feeding, arousal, cognition, and pain. The H3R is considered as a drug target for the treatment of several central nervous system disorders. We have synthesized and identified a novel series of 4-aryl-6-methyl-5,6,7,8-tetrahydroquinazolinamines that act as selective H3R antagonists. Among all the synthesized compounds, in vitro and docking studies suggested that the 4-methoxy-phenyl-substituted tetrahydroquinazolinamine compound 4c has potent and selective H3R antagonist activity (IC50 < 0.04 µM). Compound 4c did not exhibit any activity on the hERG ion channel and pan-assay interference compounds liability. Pharmacokinetic studies showed that 4c crosses the blood brain barrier, and in vivo studies demonstrated that 4c induces anorexia and weight loss in obese, but not in lean mice. These data reveal the therapeutic potential of 4c as an anti-obesity candidate drug via antagonizing the H3R.

Synthesis of isatin based N1-alkylated 3-ß-C-glycoconjugated-oxopropylidene oxindoles as potent antiplasmodial agents.

In an attempt to develop new antimalarial drugs, we have synthesized a new class of N-alkylated 3-glycoconjugated-oxopropylidene oxindoles starting from substituted isatins and glucopyranosyl propanone via a well-known cross-aldol reaction followed by dehydration. The newly synthesized compounds were screened for their in vitro antiplasmodial activity, and among all the compounds 9g, 9f, 9b, 8d, 9d, 9c, and 9e displayed potent activity with the IC50 values in the range of 0.1-0.3 µM against Chloroquine (CQ) sensitive Pf3D7 strain, while compounds 9d, 9b, 9e, 8c, 8f, 9c, and 9a have shown promising activity having IC50 values in 0.1-0.4 µM range against CQ resistant PfK1 strain, which is even better than the standard drug chloroquine with IC50 value of 0.5 µM.

Synthesis and antiplasmodial activity of glyco-conjugate hybrids of phenylhydrazono-indolinones and glycosylated 1,2,3-triazolyl-methyl-indoline-2,3-diones.

A small library of 36 new glycohybrids of phenylhydrazono-indolinones was synthesized employing glycosylated 1,2,3-triazolyl-methyl-indoline-2,3-diones and different phenylhydrazines via acid catalyzed reaction. All the compounds were screened for their antiplasmodial activity in vitro. Compounds 6c, 7c, and 7b showed significant activity with the IC50 values 1.27, 1.64 and 1.96 µM, respectively against CQ sensitive Pf3D7 strain while compounds 7b and 6f showed good activity with IC50 1.61 and 1.93 µM, respectively against CQ resistant PfK1 strain.

ROS mediated pro-apoptotic effects of Tinospora cordifolia on breast cancer cells.

The inevitable development of chemoresistance and unmanageable side effects are the major therapeutic challenges in management of breast cancer imposing an urgent need for identification of novel therapeutic agents. In the present investigation, we report anti-proliferative activity of chloroform fraction of Tinospora cordifolia (TcCF), an Ayurvedic medicinal plant, on breast cancer cells. We found that TcCF inhibited growth of breast cancer cells, MDA-MB-231 and MCF-7. More interestingly, we observed TcCF treatment increased intra-cellular ROS levels, altered expression of pro and anti-apoptotic genes, decreased colony formation ability and induced apoptosis in breast cancer cells. We also found that inhibition of ROS abrogated TcCF induced apoptosis in breast cancer cells, emphasizing the role ROS in TcCF induced breast cancer cell death. Furthermore, we identified the presence of pharmacologically active compounds like rutin and quercetin which account for the anti-cancer property of TcCF against breast cancer cells. These data show TcCF is a promising anti-cancer agent against breast cancer cells.

Matrix reloaded: CCN, tenascin and SIBLING group of matricellular proteins in orchestrating cancer hallmark capabilities.

Matricellular proteins (MCPs) are the non-structural extracellular matrix (ECM) proteins with various regulatory functions. MCPs are critical regulators of ECM homeostasis and are often found dysregulated in various malignancies. They interact with various proteins like ECM structural proteins, integrins, growth factor receptors and growth factors to modulate their availability and activity. Cancer-supporting MCPs are known to induce proliferation, migration and invasion of cancer cells. MCPs also support cancer stem (like) cell growth and induce a drug-resistant state. Apart from their direct effects on cancer cells, they play key roles in angiogenesis, immunomodulation, stromal cell infiltration, stromal proliferation and matrix remodeling. High expression of various MCPs belonging to the tenascin, CCN and SIBLING families is often associated with aggressive tumors and poor patient prognosis. Due to their differential expression and distinct functional role, these MCPs are perceived as attractive therapeutic targets in cancer. Studies on preclinical models have indicated that targeting tumor-supportive MCPs could be a potent avenue for developing anti-cancer therapies. The MCP receptors, like integrins and some associated growth factor receptors, are already being targeted using pharmacological inhibitors and neutralizing antibodies. Neutralizing antibodies against CCNs, tenascins and SIBLINGs have shown promising results in preclinical cancer models, suggesting an opportunity to develop anti-MCP therapies to target cancer. Peptides derived from anti-cancer MCPs could also serve as therapeutic entities. In the present review, in continuation with the expanding horizon of MCP functions and disease association, we focus on (i) their unique domain arrangement, (ii) their association with cancer hallmarks and (iii) available and possible therapeutic interventions.