Tumor Hypoxia Research Articles

Anaerobic bacterial metabolism responsive microspheres for bacterial embolization cancer therapy

Anaerobic bacteriolytic cancer therapy, whether delivered locally or systemically, frequently encounters challenges related to limited colonization within hypoxic pockets of central tumors and activation of innate immunity. Herein we have developed trans-arterial bacteria embolization therapy using bacterial embolic microspheres. C. novyi-NT spores loaded calcium alginate embolic microspheres demonstrated C. novyi-NT metabolites-mediated microsphere degradation, releasing vegetative C. novyi-NT bacterial in hypoxic condition. Transcatheter directed bacterial microsphere embolization therapy occludes tumor feeding vessels with infused bacterial embolic microspheres and enhances tumoral hypoxia. Notably, anaerobic bacterial metabolism responsive microsphere-bacterial embolization therapy achieved a complete tumor response with enhanced tumor-specific bacterial delivery and colonization, resulting in cancer cell killing across the entire tumor. In vivo tumor response and immunological profiling revealed that bacterial embolization uniquely enhances anti-cancer response, effectively engaging direct anaerobic bacterial oncolysis and adaptive and innate immune responses in a cooperative manner.

Tumor Hypoxia on 18F-fluoromisonidazole Positron Emission Tomography and Distant Metastasis From Head and Neck Squamous Cell Carcinoma.

Given high rates of locoregional control after definitive management of head and neck squamous cell carcinoma (HNSCC), better methods are needed to project distant metastasis (DM) risk. Tumor hypoxia on 18F-fluoromisonidazole (FMISO) positron emission tomography (PET) is associated with locoregional failure, but data demonstrating an association with DM are limited. To determine whether tumor hypoxia on FMISO PET is associated with DM risk after chemoradiotherapy (CRT) for HNSCC. This cohort study assessed patients with HNSCC enrolled in 2 prospective clinical trials at a single academic referral center from 2004 to 2021 in which participants received FMISO PET before and during CRT. Data analysis occurred from May 2023 to May 2024. FMISO PET scans before and 1 to 2 weeks after starting CRT were evaluated for tumor hypoxia by nuclear medicine physicians. The primary outcome was DM, defined as biopsy-proven HNSCC outside the primary site and regional lymph nodes. Time to DM was modeled with competing risk regression, with death as a competing risk. Overall survival (OS) was assessed secondarily and modeled with Cox regression. Among 281 patients (median [range] age at CRT, 58.7 [25.5-85.6] years; 251 male [89.3%]) included in this study, 242 (86.1%) had oropharyngeal primary cancer, and 266 (94.7%) had human papillomavirus-positive disease. Of all patients, 217 (77.2%) had T stage 1 or 2, and 231 patients (82.2%) had N stage 2b or less. De-escalated 30 Gy CRT was delivered to 144 patients (51.2%), and the remainder received standard 70 Gy CRT. On FMISO PET examination, 73 patients (26.0%) had hypoxia-negative disease before CRT, 138 patients (49.1%) had hypoxia-positive disease before CRT and then hypoxia-negative disease during CRT, and 70 patients (24.9%) persistently had hypoxia-positive disease before and during CRT. At a median (IQR) 58 (46-91) months of follow-up, 12 DM events and 22 deaths were observed. Persistent intratreatment hypoxia was associated with increased DM risk (hazard ratio, 3.51; 95% CI, 1.05-11.79; P = .04) and worse OS (hazard ratio, 2.66; 95% CI, 1.14-6.19; P = .02). No patients with hypoxia-negative disease before CRT experienced DM. In this cohort study using pooled analysis of prospective nonrandomized clinical trials incorporating FMISO PET in the definitive management of HNSCC, persistent intratreatment hypoxia was associated with increased risk of DM and worse OS. Conversely, all patients with hypoxia-negative disease before treatment remained free of DM. These findings suggest that pretreatment and intratreatment FMISO PET results may serve as biomarkers for DM risk and aid in identifying candidates for escalated therapeutic strategies.

Targeting Hypoxia-Inducible Factor-1α in Pancreatic Cancer: siRNA Delivery Using Hyaluronic Acid-Displaying Nanoparticles

Background/Objectives: Conventional anticancer therapies often lack specificity, targeting both cancerous and normal cells, which reduces efficacy and leads to undesired off-target effects. An additional challenge is the presence of hypoxic regions in tumors, where the Hypoxia Inducible Factor (HIF) transcriptional system drives the expression of pro-survival and drug resistance genes, leading to radio- and chemo-resistance. This study aims to explore the efficacy of targeted nanoparticle (NP)-based small interfering RNA (siRNA) therapies in downregulating these genes to enhance treatment outcomes in pancreatic cancer, a tumor type characterized by high CD44 expression and hypoxia. Methods: We utilized hyaluronic acid (HA)-displaying nanoparticles composed of positively charged chitosan (CS) complexed with siRNA to target and knock down HIF-1α in pancreatic cancer cells. Two NP formulations were prepared using either low molecular weight (LMW) or high molecular weight (HMW) CS. These formulations were evaluated for their internalization by cells and their effectiveness in gene silencing, both in vitro and in vivo. Results: The study found that the molecular weight (MW) of CS influenced the interaction between HA and CD44, as well as the release of siRNA upon internalization. The LMW CS formulation shows faster uptake kinetics, while HMW CS is more effective in gene knockdown across different cell lines in vitro. In vivo, both were able to significantly knockdown HIF-1α and some of its downstream genes. Conclusions: The results suggest that HMW and LMW CS-based NPs exhibit distinct characteristics, showing that both MWs have potential for targeted pancreatic cancer therapy by influencing different aspects of delivery and gene silencing, particularly in the hypoxic tumor microenvironment.

Necrosis area, Tumor Size, and Lymph Node of Breast Cancer

Background: Breast cancer is the leading cause of cancer deaths in women worldwide in 2020. The high mortality rate is often influenced by various reasons, one of which is patients's prognosis. One of the prognostic factors is necrosis area, caused by hypoxic tumor tissue that can affect tumor growth and metastasis. Therefore, this study aims to determine the relationship between necrosis area with tumor size and lymph node metastasis in breast cancer patients. Methods: This study was an observational analytic with a cross-sectional approach. This research was conducted at the Anatomical Pathology Laboratory of Dr Soedarso Pontianak General Hospital and the Microscopy Laboratory of the Faculty of Medicine Tanjungpura University from September until November 2022. The study sample was 55 slides of Formalin-Fixed Paraffin-Embedded (FFPE). The study was conducted by observing the preparations under a microscope and then analyzed using ImageJ and SPSS software. The independent variable in this study was the necrosis area in the tumor microenvironment, and the dependent variables were tumor size and lymph node metastasis in breast tissue. Results: All study samples were female patients with invasive ductal carcinoma. Breast cancer tends to occur in patients aged 48-55 years. The highest percentage of necrosis area was 21% and the most diagnosed breast tumor size and lymph node metastasis were stage T4 and stage N2. Spearman's rho correlation test showed that there was no relationship between necrosis area and tumor size (p = 0.122; r = 0.16) and lymph node metastasis (p = 0.637; r = 0.18). Conclusions: There is no correlation between necrosis area with tumor size and lymph node metastasis of breast cancer patients in the Anatomical Pathology Laboratory at Dr Soedarso Pontianak General Hospital.

Construction and validation of a pancreatic cancer prognostic model based on genes related to the hypoxic tumor microenvironment.

Pancreatic cancer is one of the most lethal malignancies, characterized by poor prognosis and low survival rates. Traditional prognostic factors for pancreatic cancer offer inadequate predictive accuracy, often failing to capture the complexity of the disease. The hypoxic tumor microenvironment has been recognized as a significant factor influencing cancer progression and resistance to treatment. This study aims to develop a prognostic model based on key hypoxia-related molecules to enhance prediction accuracy for patient outcomes and to guide more effective treatment strategies in pancreatic cancer. To develop and validate a prognostic model for predicting outcomes in patients with pancreatic cancer using key hypoxia-related molecules. This pancreatic cancer prognostic model was developed based on the expression levels of the hypoxia-associated genes CAPN2, PLAU, and CCNA2. The results were validated in an independent dataset. This study also examined the correlations between the model risk score and various clinical features, components of the immune microenvironment, chemotherapeutic drug sensitivity, and metabolism-related pathways. Real-time quantitative PCR verification was conducted to confirm the differential expression of the target genes in hypoxic and normal pancreatic cancer cell lines. The prognostic model demonstrated significant predictive value, with the risk score showing a strong correlation with clinical features: It was significantly associated with tumor grade (G) (b P < 0.01), moderately associated with tumor stage (T) (a P < 0.05), and significantly correlated with residual tumor (R) status (b P < 0.01). There was also a significant negative correlation between the risk score and the half-maximal inhibitory concentration of some chemotherapeutic drugs. Furthermore, the risk score was linked to the enrichment of metabolism-related pathways in pancreatic cancer. The prognostic model based on hypoxia-related genes effectively predicts pancreatic cancer outcomes with improved accuracy over traditional factors and can guide treatment selection based on risk assessment.

Regulating Manganese-Site Electronic Structure via Reconstituting Nitrogen Coordination for Efficient Non-Oxygen-Dependent Sonocatalytic Therapy against Orthotopic Breast Cancer.

Sonocatalytic therapy (SCT) has emerged as a promising noninvasive modality for tumor treatment but is hindered by the insufficient generation of ultrasound-induced reactive oxygen species (ROS) and the hypoxic tumor microenvironments. Herein, we fabricated a carbon nanoframe-confined N-coordinated manganese single-atom sonocatalyst with a five-coordinated structure (MnN5 SA/CNF) using a phthalocyanine-mediated pyrolysis strategy. The precise coordination structure was identified by synchrotron X-ray absorption fine structure analyses. The MnN5 SA/CNF exhibits superior and nonoxygen-dependent sonocatalytic activity owing to the optimized coordination structure and cavitation effect enhanced by defects. Additionally, density functional theory studies reveal that the five-coordination structure downshifts the d-band center of Mn from -0.547 to -0.829 eV and enhances the desorption capacity for oxygen-containing intermediates, thus accelerating the catalytic process. Finally, the as-synthesized MnN5 SA/CNF demonstrates a significantly enhanced antitumor effect through mitochondrial apoptosis in an orthotopic breast cancer mouse model. This work explores the potential of SAzymes-supported biomedical interventions by leveraging enzymatic activity with sonocatalytic properties.

Cancer cell membrane-coated siRNA-Decorated Au/MnO2 nanosensitizers for synergistically enhanced radio-immunotherapy of breast cancer

Radiotherapy plays a critical role in the clinical treatment of breast cancer. However, the efficacy of traditional X-ray radiotherapy is greatly limited by its low tumor specificity and treatment tolerance mediated by the tumor microenvironment. Herein, we proposed a novel nano-radiotherapy sensitization strategy to design and construct a cancer cell membrane-coated siRNA-decorated Au/MnO2 nanosensitizer (R&F@Au/MnO2-CM) to synergistically enhance radio-immunotherapy for breast cancer. In the integrated nanosensitizer, the cancer cell membrane (CM) derived from 4T1 breast cancer cells is utilized for targeted functionality, while Au/MnO2 is designed to improve X-ray absorption and alleviate tumor hypoxia. Additionally, PD-L1 siRNA (R) is used to downregulate PD-L1 expression in tumor cells. In an in situ mouse model of 4T1 breast cancer, R&F@Au/MnO2-CM demonstrated accurate tumor identification via CM-mediated homologous targeting after intravenous injection, which was monitored in real-time through NIR-II fluorescence imaging of NIR-935 (F). Subsequently, the radiotherapy sensitivity was achieved due to the strong radiation absorption properties and oxygen generation through catalysis of Au/MnO2 upon X-ray irradiation. Furthermore, the immunosuppressive microenvironment of the tumor is improved by downregulating PD-L1, enhancing synergistic anti-tumor effect. Our findings demonstrate a promising approach for tumor treatment by combining targeted enhanced radiotherapy with immune activation.

A Study on Overcoming Post-TACE Drug Resistance in HCC Based on Controllable Oxygen Release-Magnetic Hyperthermia Therapy.

Drug-eluting bead transcatheter arterial chemoembolization (D-TACE) is one of the first-line treatment for intermediate hepatocellular carcinoma (HCC). However, the dual hypoxia microenvironment, due to inherent tumor hypoxia and TACE-induced hypoxia, triggers drug resistance in HCC. To address this challenge, the study develops multicavitary microspheres capable of encapsulating oxygen and harnessing magnetic hyperthermia to enhance oxygen permeability. The novel multicavitary oxygen-encapsulated magnetothermal drug-eluting microspheres (OTD-Ms) effectively reduce hypoxia-related proteins (HIF-1α, VEGF-A) and drug resistance (P-gp) both in vitro and in vivo. Moreover, these microspheres demonstrate improved TACE efficacy and enhance survival rates in a rabbit VX-2 tumor model, suggesting their potential for HCC treatment.

Gelatin-coated glutathione depletion and oxygen generators in potentiated chemotherapy for pancreatic cancer

Chemotherapy is generally acknowledged as an effective method for pancreatic cancer (PC). However, its treatment efficacy is often compromised due to inefficient drug delivery and drug resistance propensity of tumor tissues. The purpose of this study is to design and develop a novel drug delivery system (Manganese-doped mesoporous silica nanoparticles, Mn-MSN) in which paclitaxel (PTX), a conventional chemotherapeutic agent used to effectively treat pancreatic cancer clinically. Through cross-linking with glutaraldehyde, gelatin (Ge) was encapsulated on the carrier surface, endowing the nanoparticles (Ge-Mn-MSN@PTX) with excellent biocompatibility, low hemolytic activity, and enzyme-responsive degradation. Mn was added for the following purposes: (1) catalyzing hydrogen peroxide (H2O2) to generate oxygen (O2), thereby alleviating tumor hypoxia and drug resistance; (2) depleting glutathione (GSH), inducing intracellular lipid peroxidation and ferroptosis; (3) enabling real-time monitoring of the therapeutic efficacy of the nanoparticles via magnetic resonance imaging (MRI). The experimental results demonstrated that Ge-Mn-MSN@PTX has satisfactory biosafety, antitumor activity, controlled drug release as well as imaging tracking capabilities. In the SW1990 nude mice model, the Ge-Mn-MSN@PTX effectively inhibited tumor growth by suppressing the expression of the resistance protein P-glycoprotein (P-gp) and inducing ferroptosis. In conclusion, the designed gelatin-coated Mn-MSN shows potential for application in future pancreatic cancer therapy.

Hypoxia-Induced Adaptations of N-Glycomes and Proteomes in Breast Cancer Cells and Their Secreted Extracellular Vesicles.

The hypoxic tumor microenvironment significantly impacts cellular behavior and intercellular communication, with extracellular vesicles (EVs) playing a crucial role in promoting angiogenesis, metastasis, and host immunosuppression, and presumed cancer progression and metastasis are closely associated with the aberrant surface N-glycan expression in EVs. We hypothesize that hypoxic tumors synthesize specific hypoxia-induced N-glycans in response to or as a consequence of hypoxia. This study utilized nano-LC-MS/MS to integrate quantitative proteomic and N-glycomic analyses of both cells and EVs derived from the MDA-MB-231 breast cancer cell line cultured under normoxic and hypoxic conditions. Whole N-glycome and proteome profiling revealed that hypoxia has an impact on the asparagine N-linked glycosylation patterns and on the glycolysis/gluconeogenesis proteins in cells in terms of altered N-glycosylation for their adaptation to low-oxygen conditions. Distinct N-glycan types, high-mannose glycans like Man3 and Man9, were highly abundant in the hypoxic cells. On the other hand, alterations in the sialylation and fucosylation patterns were observed in the hypoxic cells. Furthermore, hypoxia-induced EVs exhibit a signature consisting of mono-antennary structures and specific N-glycans (H4N3F1S2, H3N3F1S0, and H7N4F3S2; H8N4F1S0 and H8N6F1S2), which are significantly associated with poor prognoses for breast tumors, presumably altering the interactions within the tumor microenvironment to promote tumorigenesis and metastasis. Our findings provide an overview of the N-glycan profiles, particularly under hypoxic conditions, and offer insights into the potential biomarkers for tracking tumor microenvironment dynamics and for developing precision medicine approaches in oncology.

Abstract C121: Racial differences in expression of the oxygen-sensor BACH1 in breast cancer

Abstract Hypoxia is an important hallmark of aggressive solid tumors and a key driver of metastasis and resistance to therapy. Hypoxic stress induces the activation of various factors, such as hypoxia- inducible factors (HIFs), which facilitate cellular adaptation and promote tumorigenesis. Given the complexity of this mechanism, identifying novel targets that sensitize hypoxic tumors to therapy could have significant clinical impact. We demonstrate HIF-independent induction of BACH1 within multiple TNBC (Triple-Negative Breast Cancer) cell lines and patient-derived organoids under hypoxic conditions. Utilizing ChIP-seq, bulk, single-cell and spatial transcriptomics across diverse BACH1 knockout tumor models, our study revealed that BACH1 selectively and directly modulates the transcriptional response associated with hypoxia and stress in TNBC. TGCA analysis reveals racial disparities in BACH1 mRNA expression in TNBC BACH1 mRNA and activity across all breast cancer subtypes (Basal, Her, LumA, LumB). Our findings suggest that BACH1 is an oxygen-sensitive mediator of hypoxia and a promising therapeutic target for mitigating hypoxia-induced pro-metastatic signaling and treatment resistance. These results also highlight the necessity of accounting for racial differences in BACH1 expression and function as a means of developing targeted therapy that takes into account racial disparities in TNBC. Citation Format: Long C. Nguyen, Christopher Dann, Dongbo Yang, Madeline Henn, Emily Shi, Thomas Li, Kent Schechter, Letícia Stock, Wenchao Liu, Margarite Matossian, Andrea Valdespino, Yoo Jane Han, Jing Zhang, Geetha Priyanka Yerradoddi, Yan Li, Mitsuyo Matsumoto, Olufunmilayo I Olopade, Kazuhiko Igarashi, Marsha R Rosner. Racial differences in expression of the oxygen-sensor BACH1 in breast cancer [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C121.

FTO-mediated DSP m6A demethylation promotes an aggressive subtype of growth hormone-secreting pituitary neuroendocrine tumors

BackgroundGrowth hormone-secreting pituitary neuroendocrine tumors can be pathologically classified into densely granulated (DGGH) and sparsely granulated types (SGGH). SGGH is more aggressive and associated with a poorer prognosis. While epigenetic regulation is vital in tumorigenesis and progression, the role of N6-methyladenosine (m6A) in aggressive behavior has yet to be elucidated.MethodsWe performed m6A-sequencing on tumor samples from 8 DGGH and 8 SGGH patients, complemented by a suite of assays including ELISA, immuno-histochemistry, -blotting and -fluorescence, qPCR, MeRIP, RIP, and RNA stability experiments, aiming to delineate the influence of m6A on tumor behavior. We further assessed the therapeutic potential of targeted drugs using cell cultures, organoid models, and animal studies.ResultsWe discovered a significant reduction of m6A levels in SGGH compared to DGGH, with an elevated expression of fat mass and obesity-associated protein (FTO), an m6A demethylase, in SGGH subtype. Series of in vivo and in vitro experiments demonstrated that FTO inhibition in tumor cells robustly diminishes hypoxia resistance, attenuates growth hormone secretion, and augments responsiveness to octreotide. Mechanically, FTO-mediated m6A demethylation destabilizes desmoplakin (DSP) mRNA, mediated by the m6A reader FMR1, leading to prohibited desmosome integrity and enhanced tumor hypoxia tolerance. Targeting the FTO-DSP-SSTR2 axis curtailed growth hormone secretion, therefor sensitizing tumors to octreotide therapy.ConclusionOur study reveals the critical role of FTO in the aggressive growth hormone-secreting pituitary neuroendocrine tumors subtype and suggests FTO may represent a new therapeutic target for refractory/persistent SGGH.

Privileged Scaffold Hybridization in the Design of Carbonic Anhydrase Inhibitors.

Human Carbonic Anhydrases (hCA) are enzymes that contribute to cancer's development and progression. Isoforms IX and XII have been identified as potential anticancer targets, and, more specifically, hCA IX is overexpressed in hypoxic tumor cells, where it plays an important role in reprogramming the metabolism. With the aim to find new inhibitors towards IX and XII isoforms, the hybridization of the privileged scaffolds isatin, dihydrothiazole, and benzenesulfonamide was investigated in order to explore how it may affect the activity and selectivity of the hCA isoforms. In this respect, a series of isatin thiazolidinone hybrids have been designed and synthesized and their biological activity and selectivity on hCA I, hCA II, hCA IX, and hCA XII explored. The new compounds exhibited promising inhibitory activity results on isoforms IX and XII in the nanomolar range, which has highlighted the importance of substituents in the isatin ring and in position 3 and 5 of thiazolidinone. In particular, compound 5g was the most active toward hCA IX, while 5f was the most potent inhibitor of hCA XII within the series. When both potency and selectivity were considered, compound 5f appeared as one of the most promising. Additionally, our investigations were supported by molecular docking experiments, which have highlighted the putative binding poses of the most promising compound.

Photothermal and enhanced chemodynamic reinforced anti-tumor therapy based on PDA@POM nanocomposites

Chemodynamic therapy (CDT) and photothermal therapy (PTT) have both demonstrated considerable efficacy in the tumor treatment individually, owing to their non-invasive nature and excellent selectivity. However, due to the propensity of tumors for metastasis and recurrence, a singular therapeutic approach falls short of achieving optimal treatment outcomes. Polydopamine (PDA) has excellent photothermal conversion ability and polyoxometalates (POMs) possess diverse enzymatic activities. Here, we synthesized PDA@POM nanospheres comprising polydopamine-coated Tungsten-based polyoxometalate (W-POM). These nanospheres leverage dual enzymatic activities that synergistically enhance both chemodynamic and photothermal therapies for tumor treatment. The PDA-mediated PTT effect enables precise tumor cell destruction, while the W-POM nanozymes catalyzes the generation of highly toxic reactive oxygen species (ROS) from hydrogen peroxide within tumor cells through a Fenton-like reaction, which mitigates tumor hypoxia and induces tumor cell death. This synergistic photothermal catalytic therapy shows enhanced efficacy in tumor suppression, providing a promising new approach for tumor treatment.

Pericyte phenotype switching alleviates immunosuppression and sensitizes vascularized tumors to immunotherapy in preclinical models.

T cell-based immunotherapies are a promising therapeutic approach for multiple malignancies, but their efficacy is limited by tumor hypoxia arising from dysfunctional blood vessels. Here, we report that cell-intrinsic properties of a single vascular component, namely the pericyte, contribute to the control of tumor oxygenation, macrophage polarization, vessel inflammation, and T cell infiltration. Switching pericyte phenotype from a synthetic to a differentiated state reverses immune suppression and sensitizes tumors to adoptive T cell therapy, leading to regression of melanoma in mice. In melanoma patients, improved survival is correlated with enhanced pericyte maturity. Importantly, pericyte plasticity is regulated by signaling pathways converging on Rho kinase activity, with pericyte maturity being inducible by selective low-dose therapeutics that suppress pericyte MEK, AKT, or notch signaling. We also show that low-dose targeted anticancer therapy can durably change the tumor microenvironment without inducing adaptive resistance, creating a highly translatable pathway for redosing anticancer targeted therapies in combination with immunotherapy to improve outcome.

Synergistic effect of Gemcitabin-loaded metal organic frameworks nanoparticles with particle therapy

Combination of nanoagents with radiations has opened up new perspectives in cancer treatment, improving both tumor diagnosis and therapeutic index. This work presents the first investigation of an innovative strategy that combines porous metal–organic frameworks (nanoMOFs) loaded with the anti-cancer drug Gemcitabine monophosphate (GemMP) and particle therapy-a globally emerging technique that offers more precise radiation targeting and enhanced biological efficacy compared to conventional radiotherapy. This radiochemotherapy has been confronted with two major obstacles limiting the efficacy of therapeutics when tested in vivo: (i) the presence of hypoxia, one of the most important causes for radiotherapy failure and (ii) the presence of a microenvironment, main biological barrier to the direct penetration of nanoparticles into cancer cells.On the one hand, this study explore the effects of hypoxia on drug delivery systems in combination with radiation, demonstrating that GemMP-loaded nanoMOFs significantly enhance the anticancer efficacy of particle therapy under both normoxic (pO2 = 20 %) and hypoxic (pO2 = 0.5 %) conditions. Notably, the presence of GemMP-loaded nanoMOFs allows the irradiation dose to be reduced by 1.4-fold in normoxia and at least 1.6-fold in hypoxia, achieving the same cytotoxic effect (SF=10 %) as carbon or helium ions alone. Synergistic effects between GemMP-loaded nanoMOFs and radiations have been observed and quantified. On the other hand, we also highlighted the ability of the nanoMOFs to diffuse through an extracellular matrix and accumulate in cells. An higher effect of the encapsulated GemMP than the free drug was observed, confirming the key role of the nanoMOFs in transporting the active substance to the cancer cells as a Trojan horse. This paves the way to the design of “all-in-one” nanodrugs where each component plays a role in the optimization of cancer therapy to maximize cytotoxic effects on hypoxic tumor cells while minimizing toxicity on healthy tissue.

Abstract B036: Hypoxic cancer cells condition immunosuppressive macrophages via secreted non-protein mediators in pancreatic ductal adenocarcinoma

Abstract INTRODUCTION: Hypoxia is a defining feature of pancreatic ductal adenocarcinoma (PDAC) that contributes to the immunosuppressive microenvironment defined by increased tumor-associated macrophages (TAMs). However, there is an unmet need to define mechanisms by which hypoxia drives the immunosuppressive macrophage phenotype. We hypothesize that hypoxic cancer cells secrete non-protein metabolites to induce immunosuppressive phenotypes in macrophages. METHODS: We generated conditioned media (CM) by culturing the pancreatic adenocarcinoma cell line KPC under normoxia (21% O2) or hypoxia (0.5% O2) conditions for 48 hours. We treated bone marrow-derived macrophages (BMDMs) or the macrophage line RAW264.7 with CM. We assessed immunosuppressive gene expression using RNAseq and qRT-PCR. Proteins in CM were depleted using Sera-Mag Magnetic Carboxylate Modified Beads or denatured by boiling at 100°C for 15 minutes. We identified changes in metabolites between hypoxic and normoxic CM using HPLC. RESULTS: Compared to BMDMs treated with normoxic CM, we observed that BMDMs treated with hypoxic CM induced multiple immunosuppressive proteins (Arg1), cytokines (Ccl22, Cxcl3) and interleukins (Il1b, Il1a, Il6). Similarly, GSEA analysis demonstrated that hypoxic CM induced TNFa signaling via NfkB and IL6-JAK-STAT3 signaling. Consistent with RNA-seq analysis, qRT-PCR measured Arg1 expression 53 times higher in hypoxic CM-treated BMDMs compared to nomoxic CM (p=0.0286). Compared to normoxic CM, hypoxic CM stimulated macrophage migration, a marker for macrophage infiltration, as measured by transwell assays (p&amp;lt;0.0001). An increase in Arg1 expression in RAW264.7 cells was still observed when treated with protein depleted or boiled hypoxic CM, excluding proteins as soluble factor(s) mediating immunosuppression. To identify non-protein mediators of immune suppression, mass spectrometry quantified lipids and metabolites enriched in HCM. Metabolomic analysis identified 40 metabolites increased in hypoxic CM including the monounsaturated or polyunsaturated fatty acids linoelaidic acid, DGLA, and arachidonic acid. Similarly, lipidomic analysis revealed that multiple PC (phosphatidylcholine) and LPC (lysophosphatidylcholine) lipid species were enriched in HCM. CONCLUSION: We observe that hypoxic tumor cells induce immunosuppressive changes in macrophages likely via secreted non-protein metabolites. The hypoxic metabolome of PDAC tumor cells may be a key driver of the accumulation of immunosuppressive tumor associated macrophages. We are currently characterizing the role of individual lipids or metabolites in macrophage polarization. Citation Format: Matthew T Cribb, Sahar Fattani, Ayeisha Colon-Ortiz, Dadi Jiang, Michael Spiotto, Albert Koong. Hypoxic cancer cells condition immunosuppressive macrophages via secreted non-protein mediators in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B036.

Abstract A038: The hypoxic regulation of macrophage function in pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) is marked by an extensive fibroinflammatory stroma and a low-oxygen (hypoxic) microenvironment, which contribute to disease progression and therapeutic resistance. Within the PDAC stroma, macrophages and cancer-associated fibroblasts (CAFs) are the predominant cell types. Macrophages are a major immunosuppressive population in PDAC. These cells are highly plastic and, as a result, their environment plays an important role in regulating their function. Macrophages adapt to hypoxia primarily by stabilizing hypoxia-inducible factors (HIFs), which are oxygen-labile transcription factors. Although PDAC is profoundly hypoxic and both the tumor cells and stromal cells experience hypoxia, the effects of hypoxia and HIFs on macrophages and their interactions with other stromal cells in PDAC are not yet fully understood. We found that hypoxia promotes the acquisition of inflammatory cancer-associated fibroblasts (inflammatory CAFs), a fibroblast subtype that produces high levels of cytokines and chemokines. Utilizing a hypoxia marker in mouse models of PDAC, we have observed that inflammatory CAFs and macrophages are predominantly situated in hypoxic tumor regions compared with normoxic regions, while T cells are largely absent from these oxygen-poor regions. These preliminary data raise the possibility that inflammatory fibroblasts induced by hypoxia promote macrophage infiltration into hypoxic tumor regions and facilitate an immunosuppressive macrophage phenotype. We have also found that when macrophages are exposed to conditioned media derived from fibroblast cultures under either hypoxic or normoxic conditions, factors secreted from the hypoxia-exposed fibroblasts promote an immunosuppressive macrophage phenotype. We are currently identifying the factors released from hypoxic fibroblasts that drive the immunosuppressive macrophage phenotype. Future work will focus on evaluating the effects of macrophage-intrinsic responses to hypoxia through HIFs on pancreatic tumorigenesis in vivo. Citation Format: Sean Hannifin, Ashley M Mello, Tenzin Ngodup, Katelyn L Donahue, Marina Pasca di Magliano, Kyoung Eun Lee. The hypoxic regulation of macrophage function in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr A038.

Abstract A036: The role of hypoxia in CD8+ T cell localization and function in pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a deadly malignancy characterized by poor response to existing therapeutic options. This resistance to treatment is partly due to its extensive inflammatory, desmoplastic stromal response, along with a hypoxic microenvironment. Although tumor hypoxia induces adaptive responses in both cancer cells and the surrounding stroma, most studies on the role of hypoxia in tumorigenesis have focused on cancer cell-intrinsic properties. The impact of hypoxia on stromal cells themselves and their interactions with cancer cells has remained largely unknown. We previously showed that inflammatory cancer-associated fibroblasts (iCAFs), which express high levels of cytokines and chemokines, are preferentially located in hypoxic regions of PDAC, and that hypoxia promotes an inflammatory fibroblast phenotype. The iCAF phenotype has been correlated with highly immunosuppressive features of PDAC. These findings and our preliminary observation that CD8+ T cells are largely excluded from hypoxic PDAC regions, raise the possibility that hypoxia suppresses the infiltration and activation of CD8+ T cells by modulating their interactions with inflammatory fibroblasts. By culturing CD8+ T cells under hypoxia with conditioned media from co-cultures of pancreatic cancer cells and fibroblasts, we have found that cancer cells and fibroblasts decrease CD8+ T cell proliferation and cytotoxic activity under low oxygen conditions. We are working to elucidate the mechanism by which hypoxia regulates CD8+ T cell infiltration and activation through cancer cell-fibroblast crosstalk. Citation Format: Ashley M. Mello, Tenzin Ngodup, Katelyn L. Donahue, Marina Pasca Di Magliano, Kyoung Eun Lee. The role of hypoxia in CD8+ T cell localization and function in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr A036.

Photostimulated Anticancer Activity of Mitochondria Localized Rhenium(I) Tricarbonyl Complexes Bearing 1H-imidazo[4,5-f][1,10]phenanthroline Ligands Against MDA-MB-231 Cancer Cells.

We have introduced Re(I) tricarbonyl complexes (ReL1 - ReL6) [Re(CO)3(N^N)Cl] where N^N = extensive π conjugated imidazo-[4,5-f]1,10-phenanthroline derivatives that helps in strong DNA intercalation, enhanced photophysical behavior, increase the 3π-π* character of T1 state for PDT and high value of lipophilicity for cell membrane penetration. These complexes exhibited prominent intraligand/ligand-centered (π - π*/ 1LC) absorption bands at λ 260 - 350 nm and relatively weak metal-to-ligand charge-transfer (1MLCT) bands within the λ 350 - 550 nm range. Among the six synthesized complexes, [(CO)3ReICl(K2-N,N-2-(4-(1-benzyl-1H-tetrazol-5-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline] (ReL6) exhibited outstanding potency (IC50 ~ 6 µM, PI > 9) under yellow light irradiation compared to dark conditions. Importantly, extremely lipophilic complex ReL6 showed effective penetration through the cell membrane and localized primarily in mitochondria (Pearson's correlation coefficient, PCC = 0.918) of MDA-MB-231 cells. Complex ReL6 exhibited more than 9 times higher photo-toxicity in normoxic and hypoxic environment of tumor by inducing 1O2 generation (type II PDT), radical generation triggered by NADH oxidation (type I PDT). This complex is a promising candidate for TNBC treatment in hypoxic tumors, with efficacy comparable to photofrin and have demonstrated CO release ability under UV light irradiation.