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Slapak EJ, El Mandili M, Ten Brink MS, Kros A, Bijlsma MF, Spek CA. CAPN2-responsive mesoporous silica nanoparticles: A promising nanocarrier for targeted therapy of pancreatic cancer. Cancer Lett 2024; 590:216845. [PMID: 38589004 DOI: 10.1016/j.canlet.2024.216845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 02/29/2024] [Accepted: 03/28/2024] [Indexed: 04/10/2024]
Abstract
Pancreatic adenocarcinoma (PDAC) is highly resistant to conventional chemotherapeutic interventions, resulting in exceptionally low survival rates. The limited efficacy can in part be attributed to dose limitations and treatment cessation urged by toxicity of currently used chemotherapy. The advent of targeted delivery strategies has kindled hope for circumventing off-target toxicity. We have previously reported a PDAC-specific mesoporous silica nanoparticle (MSN) containing a protease linker responsive to ADAM9, a PDAC-enriched extracellularly deposited protease. Upon loading with paclitaxel these ADAM9-MSNs reduced side effects both in vitro and in vivo, however, disappointing antitumor efficacy was observed in vivo. Here, we propose that an efficient uptake of MSNs by tumor cells might underlie the lack of antitumor efficacy of MSNs functionalized with linker responsive to extracellular proteases. Harnessing this premise to improve antitumor efficacy, we performed an in silico analysis to identify PDAC-enriched intracellular proteases. We report the identification of BACE2, CAPN2 and DPP3 as PDAC enriched intracellular proteases, and report the synthesis of BACE2-, CAPN2- and DPP3-responsive MSNs. Extensive preclinical assessments revealed that paclitaxel-loaded CAPN2- and DPP3-MSNs exhibit high PDAC specificity in vitro as opposed to free paclitaxel. The administration of paclitaxel-loaded CAPN2- and DPP3-MSNs in vivo confirmed the reduction of leukopenia and induced no organ damage. Promisingly, in two mouse models CAPN2-MSNs reduced tumor growth at least as efficiently as free paclitaxel. Taken together, our results pose CAPN2-MSNs as a promising nanocarrier for the targeted delivery of chemotherapeutics in PDAC.
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Affiliation(s)
- Etienne J Slapak
- Amsterdam UMC Location University of Amsterdam, Center of Experimental and Molecular Medicine, Meibergdreef 9, Amsterdam, the Netherlands; Cancer Center Amsterdam, Cancer Biology, Amsterdam, the Netherlands.
| | - Mouad El Mandili
- Amsterdam UMC Location University of Amsterdam, Center of Experimental and Molecular Medicine, Meibergdreef 9, Amsterdam, the Netherlands.
| | - Marieke S Ten Brink
- Amsterdam UMC Location University of Amsterdam, Center of Experimental and Molecular Medicine, Meibergdreef 9, Amsterdam, the Netherlands.
| | - Alexander Kros
- Department of Supramolecular & Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, Leiden, the Netherlands.
| | - Maarten F Bijlsma
- Amsterdam UMC Location University of Amsterdam, Center of Experimental and Molecular Medicine, Meibergdreef 9, Amsterdam, the Netherlands; Cancer Center Amsterdam, Cancer Biology, Amsterdam, the Netherlands.
| | - C Arnold Spek
- Amsterdam UMC Location University of Amsterdam, Center of Experimental and Molecular Medicine, Meibergdreef 9, Amsterdam, the Netherlands; Cancer Center Amsterdam, Cancer Biology, Amsterdam, the Netherlands.
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Ashrafizadeh M, Luo K, Zhang W, Reza Aref A, Zhang X. Acquired and intrinsic gemcitabine resistance in pancreatic cancer therapy: Environmental factors, molecular profile and drug/nanotherapeutic approaches. ENVIRONMENTAL RESEARCH 2024; 240:117443. [PMID: 37863168 DOI: 10.1016/j.envres.2023.117443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 09/17/2023] [Accepted: 10/17/2023] [Indexed: 10/22/2023]
Abstract
A high number of cancer patients around the world rely on gemcitabine (GEM) for chemotherapy. During local metastasis of cancers, surgery is beneficial for therapy, but dissemination in distant organs leads to using chemotherapy alone or in combination with surgery to prevent cancer recurrence. Therapy failure can be observed as a result of GEM resistance, threatening life of pancreatic cancer (PC) patients. The mortality and morbidity of PC in contrast to other tumors are increasing. GEM chemotherapy is widely utilized for PC suppression, but resistance has encountered its therapeutic impacts. The purpose of current review is to bring a broad concept about role of biological mechanisms and pathways in the development of GEM resistance in PC and then, therapeutic strategies based on using drugs or nanostructures for overcoming chemoresistance. Dysregulation of the epigenetic factors especially non-coding RNA transcripts can cause development of GEM resistance in PC and miRNA transfection or using genetic tools such as siRNA for modulating expression level of these factors for changing GEM resistance are suggested. The overexpression of anti-apoptotic proteins and survival genes can contribute to GEM resistance in PC. Moreover, supportive autophagy inhibits apoptosis and stimulates GEM resistance in PC cells. Increase in metabolism, glycolysis induction and epithelial-mesenchymal transition (EMT) stimulation are considered as other factors participating in GEM resistance in PC. Drugs can suppress tumorigenesis in PC and inhibit survival factors and pathways in increasing GEM sensitivity in PC. More importantly, nanoparticles can increase pharmacokinetic profile of GEM and promote its blood circulation and accumulation in cancer site. Nanoparticles mediate delivery of GEM with genes and drugs to suppress tumorigenesis in PC and increase drug sensitivity. The basic research displays significant connection among dysregulated pathways and GEM resistance, but the lack of clinical application is a drawback that can be responded in future.
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Affiliation(s)
- Milad Ashrafizadeh
- Department of General Surgery and Institute of Precision Diagnosis and Treatment of Digestive System Tumors, Carson International Cancer Center, Shenzhen University General Hospital, Shenzhen University, Shenzhen, Guangdong, 518055, China; International Association for Diagnosis and Treatment of Cancer, Shenzhen, Guangdong, 518055, China; Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai, 200032, China.
| | - Kuo Luo
- Department of Oncology, Chongqing Hyheia Hospital, Chongqing, 4001331, China
| | - Wei Zhang
- Department of General Surgery and Institute of Precision Diagnosis and Treatment of Digestive System Tumors, Carson International Cancer Center, Shenzhen University General Hospital, Shenzhen University, Shenzhen, Guangdong, 518055, China
| | - Amir Reza Aref
- Belfer Center for Applied Cancer Science, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - Xianbin Zhang
- Department of General Surgery and Institute of Precision Diagnosis and Treatment of Digestive System Tumors, Carson International Cancer Center, Shenzhen University General Hospital, Shenzhen University, Shenzhen, Guangdong, 518055, China.
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Duan H, Li L, He S. Advances and Prospects in the Treatment of Pancreatic Cancer. Int J Nanomedicine 2023; 18:3973-3988. [PMID: 37489138 PMCID: PMC10363367 DOI: 10.2147/ijn.s413496] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 07/11/2023] [Indexed: 07/26/2023] Open
Abstract
Pancreatic cancer is a highly malignant and incurable disease, characterized by its aggressive nature and high fatality rate. The most common type is pancreatic ductal adenocarcinoma (PDAC), which has poor prognosis and high mortality rate. Current treatments for pancreatic cancer mainly encompass surgery, chemotherapy, radiotherapy, targeted therapy, and combination regimens. However, despite efforts to improve prognosis, and the 5-year survival rate for pancreatic cancer remains very low. Therefore, it's urgent to explore novel therapeutic approaches. With the rapid development of therapeutic strategies in recent years, new ideas have been provided for treating pancreatic cancer. This review expositions the advancements in nano drug delivery system, molecular targeted drugs, and photo-thermal treatment combined with nanotechnology for pancreatic cancer. It comprehensively analyzes the prospects of combined drug delivery strategies for treating pancreatic cancer, aiming at a deeper understanding of the existing drugs and therapeutic approaches, promoting the development of new therapeutic drugs, and attempting to enhance the therapeutic effect for patients with this disease.
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Affiliation(s)
- Huaiyu Duan
- School of Integrated Chinese and Western Medicine, Anhui University of Chinese Medicine, Hefei, People’s Republic of China
| | - Li Li
- Department of Hepatobiliary Pancreatic Oncology, Hefei Cancer Hospital, Chinese Academy of Sciences, Hefei, People’s Republic of China
| | - Shiming He
- School of Integrated Chinese and Western Medicine, Anhui University of Chinese Medicine, Hefei, People’s Republic of China
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Slapak EJ, El Mandili M, Brink MST, Kros A, Bijlsma MF, Spek CA. Preclinical Assessment of ADAM9-Responsive Mesoporous Silica Nanoparticles for the Treatment of Pancreatic Cancer. Int J Mol Sci 2023; 24:10704. [PMID: 37445886 DOI: 10.3390/ijms241310704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 06/20/2023] [Accepted: 06/24/2023] [Indexed: 07/15/2023] Open
Abstract
Pancreatic adenocarcinoma (PDAC) remains largely refractory to chemotherapeutic treatment regimens and, consequently, has the worst survival rate of all cancers. The low efficacy of current treatments results largely from toxicity-dependent dose limitations and premature cessation of therapy. Recently, targeted delivery approaches that may reduce off-target toxicities have been developed. In this paper, we present a preclinical evaluation of a PDAC-specific drug delivery system based on mesoporous silica nanoparticles (MSNs) functionalized with a protease linker that is specifically cleaved by PDAC cells. Our previous work demonstrated that ADAM9 is a PDAC-enriched protease and that paclitaxel-loaded ADAM9-responsive MSNs effectively kill PDAC cells in vitro. Here, we show that paclitaxel-loaded ADAM9-MSNs result in off-target cytotoxicity in clinically relevant models, which spurred the development of optimized ADAM9-responsive MSNs (OPT-MSNs). We found that these OPT-MSNs still efficiently kill PDAC cells but, as opposed to free paclitaxel, do not induce death in neuronal or bone marrow cells. In line with these in vitro data, paclitaxel-loaded OPT-MSNs showed reduced organ damage and leukopenia in a preclinical PDAC xenograft model. However, no antitumor response was observed upon OPT-MSN administration in vivo. The poor in vivo antitumor activity of OPT-MSNs despite efficient antitumor effects in vitro highlights that although MSN-based tumor-targeting strategies may hold therapeutic potential, clinical translation does not seem as straightforward as anticipated.
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Affiliation(s)
- Etienne J Slapak
- Laboratory of Experimental Oncology and Radiobiology, Center for Experimental and Molecular Medicine, Amsterdam UMC Location University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
- Oncode Institute, 3521 AZ Amsterdam, The Netherlands
- Cancer Center Amsterdam, Cancer Biology, 1081 HV Amsterdam, The Netherlands
| | - Mouad El Mandili
- Laboratory of Experimental Oncology and Radiobiology, Center for Experimental and Molecular Medicine, Amsterdam UMC Location University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
- Oncode Institute, 3521 AZ Amsterdam, The Netherlands
| | - Marieke S Ten Brink
- Laboratory of Experimental Oncology and Radiobiology, Center for Experimental and Molecular Medicine, Amsterdam UMC Location University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - Alexander Kros
- Department of Supramolecular & Biomaterials Chemistry, Leiden Institute of Chemistry, Leiden University, 2333 CC Leiden, The Netherlands
| | - Maarten F Bijlsma
- Laboratory of Experimental Oncology and Radiobiology, Center for Experimental and Molecular Medicine, Amsterdam UMC Location University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
- Oncode Institute, 3521 AZ Amsterdam, The Netherlands
- Cancer Center Amsterdam, Cancer Biology, 1081 HV Amsterdam, The Netherlands
| | - C Arnold Spek
- Laboratory of Experimental Oncology and Radiobiology, Center for Experimental and Molecular Medicine, Amsterdam UMC Location University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
- Cancer Center Amsterdam, Cancer Biology, 1081 HV Amsterdam, The Netherlands
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Ma B, Yu R. Pan-cancer analysis of ADAMs: A promising biomarker for prognosis and response to chemotherapy and immunotherapy. Front Genet 2023; 14:1105900. [PMID: 37082201 PMCID: PMC10110990 DOI: 10.3389/fgene.2023.1105900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 03/20/2023] [Indexed: 04/07/2023] Open
Abstract
Background: Members of a disintegrin and metalloproteinase (ADAM) family play a vital role in cancer development. However, a comprehensive analysis of the landscape of the ADAM family in pan-cancer remains to be performed.Methods: The correlation of the expression level and prognostic value with ADAMs in a pan-cancer cohort and the relationship between ADAMs and the stemness score, tumour microenvironment (TME), chemotherapy-related drug sensitivity, immune subtype, and immunotherapy outcome were investigated.Results: ADAMs were differentially expressed between tumour and para-carcinoma tissues in the pan-cancer cohort, and the expression of ADAMs was significantly correlated with patient prognosis. Furthermore, ADAMs were significantly correlated with the stromal score and immune score based on the TME analysis. Additionally, ADAMs were also correlated with DNAss and RNAss in the pan-cancer cohort. On investigating the CellMiner database, ADAMs were revealed to be significantly correlated with the sensitivity of various drugs, including raloxifene and tamoxifen. Moreover, in the IMvigor210 and GSE78220 cohorts, ADAMs were correlated with immunotherapy response and immune activation genes. Furthermore, quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC) were utilised to determine the differential level of ADAM9 in cancer and para-carcinoma tissues in patients’ samples.Conclusion: This study elucidates the importance of ADAMs in cancer progression and lays a foundation for further exploration of ADAMs as potential pan-cancer targets.
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Affiliation(s)
- Bo Ma
- *Correspondence: Bo Ma, ; Riyue Yu,
| | - Riyue Yu
- *Correspondence: Bo Ma, ; Riyue Yu,
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Tanaka HY, Nakazawa T, Enomoto A, Masamune A, Kano MR. Therapeutic Strategies to Overcome Fibrotic Barriers to Nanomedicine in the Pancreatic Tumor Microenvironment. Cancers (Basel) 2023; 15:cancers15030724. [PMID: 36765684 PMCID: PMC9913712 DOI: 10.3390/cancers15030724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/19/2023] [Accepted: 01/21/2023] [Indexed: 01/26/2023] Open
Abstract
Pancreatic cancer is notorious for its dismal prognosis. The enhanced permeability and retention (EPR) effect theory posits that nanomedicines (therapeutics in the size range of approximately 10-200 nm) selectively accumulate in tumors. Nanomedicine has thus been suggested to be the "magic bullet"-both effective and safe-to treat pancreatic cancer. However, the densely fibrotic tumor microenvironment of pancreatic cancer impedes nanomedicine delivery. The EPR effect is thus insufficient to achieve a significant therapeutic effect. Intratumoral fibrosis is chiefly driven by aberrantly activated fibroblasts and the extracellular matrix (ECM) components secreted. Fibroblast and ECM abnormalities offer various potential targets for therapeutic intervention. In this review, we detail the diverse strategies being tested to overcome the fibrotic barriers to nanomedicine in pancreatic cancer. Strategies that target the fibrotic tissue/process are discussed first, which are followed by strategies to optimize nanomedicine design. We provide an overview of how a deeper understanding, increasingly at single-cell resolution, of fibroblast biology is revealing the complex role of the fibrotic stroma in pancreatic cancer pathogenesis and consider the therapeutic implications. Finally, we discuss critical gaps in our understanding and how we might better formulate strategies to successfully overcome the fibrotic barriers in pancreatic cancer.
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Affiliation(s)
- Hiroyoshi Y. Tanaka
- Department of Pharmaceutical Biomedicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Kita-ku, Okayama-shi 700-8530, Okayama, Japan
| | - Takuya Nakazawa
- Department of Pharmaceutical Biomedicine, Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, 1-1-1 Tsushima-naka, Kita-ku, Okayama-shi 700-8530, Okayama, Japan
| | - Atsushi Enomoto
- Department of Pathology, Graduate School of Medicine, Nagoya University, 65 Tsurumai-cho, Showa-ku, Nagoya-shi 466-8550, Aichi, Japan
| | - Atsushi Masamune
- Division of Gastroenterology, Graduate School of Medicine, Tohoku University, 1-1 Seiryo-machi, Aoba-ku, Sendai-shi 980-8574, Miyagi, Japan
| | - Mitsunobu R. Kano
- Department of Pharmaceutical Biomedicine, Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, 1-1-1 Tsushima-naka, Kita-ku, Okayama-shi 700-8530, Okayama, Japan
- Correspondence:
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Recent developments of nanomedicine delivery systems for the treatment of pancreatic cancer. J Drug Deliv Sci Technol 2022. [DOI: 10.1016/j.jddst.2022.104042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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pH-Responsive Drug Delivery and Imaging Study of Hybrid Mesoporous Silica Nanoparticles. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27196519. [PMID: 36235055 PMCID: PMC9572296 DOI: 10.3390/molecules27196519] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/24/2022] [Accepted: 09/28/2022] [Indexed: 11/05/2022]
Abstract
A system of pH-responsive and imaging nanocarriers was developed using mesoporous silica nanoparticles (MSNs), in which gadolinium (Gd) was doped through in situ doping (Gd2O3@MSN). Sodium alginate (SA) was attached to the surfaces of the amino groups of MSNs (NH2-Gd2O3@MSN) through the electrostatic adsorption between the amino groups and the carboxyl groups with the formation of hybrid SA-Gd2O3@MSN nanoparticles (NPs). The SA-coated NPs were spherical or near-spherical in shape with an average size of nearly 83.2 ± 8.7 nm. The in vitro drug release experiments of a model rhodamine B (RhB) cargo were performed at different pH values. The result confirmed the pH-responsiveness of the nanocarriers. The results of the cytotoxicity studies indicated that the SA-Gd2O3@MSN NPs were not cytotoxic by themselves. The results of the in vivo safety evaluation and the hemolysis assay confirmed that the system is highly biocompatible. It is noteworthy that the T1 contrast of the system was significantly enhanced by the Gd, as indicated by the result of the MR imaging. This study confirms that the synthesized hybrid nanosystem is promising for pH-responsive drug delivery and MR imaging for cancer diagnosis and treatment.
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Mesoporous Silica Nanoparticle-Based Drug Delivery Systems for the Treatment of Pancreatic Cancer: A Systematic Literature Overview. Pharmaceutics 2022; 14:pharmaceutics14020390. [PMID: 35214121 PMCID: PMC8876630 DOI: 10.3390/pharmaceutics14020390] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/02/2022] [Accepted: 02/07/2022] [Indexed: 12/23/2022] Open
Abstract
Pancreatic cancer is a devastating disease with the worst outcome of any human cancer. Despite significant improvements in cancer treatment in general, little progress has been made in pancreatic cancer (PDAC), resulting in an overall 5-year survival rate of less than 10%. This dismal prognosis can be attributed to the limited clinical efficacy of systemic chemotherapy due to its high toxicity and consequent dose reductions. Targeted delivery of chemotherapeutic drugs to PDAC cells without affecting healthy non-tumor cells will largely reduce collateral toxicity leading to reduced morbidity and an increased number of PDAC patients eligible for chemotherapy treatment. To achieve targeted delivery in PDAC, several strategies have been explored over the last years, and especially the use of mesoporous silica nanoparticles (MSNs) seem an attractive approach. MSNs show high biocompatibility, are relatively easy to surface modify, and the porous structure of MSNs enables high drug-loading capacity. In the current systematic review, we explore the suitability of MSN-based targeted therapies in the setting of PDAC. We provide an extensive overview of MSN-formulations employed in preclinical PDAC models and conclude that MSN-based tumor-targeting strategies may indeed hold therapeutic potential for PDAC, although true clinical translation has lagged behind.
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Macrophage C/EBPδ Drives Gemcitabine, but Not 5-FU or Paclitaxel, Resistance of Pancreatic Cancer Cells in a Deoxycytidine-Dependent Manner. Biomedicines 2022; 10:biomedicines10020219. [PMID: 35203429 PMCID: PMC8869168 DOI: 10.3390/biomedicines10020219] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/17/2022] [Accepted: 01/19/2022] [Indexed: 02/04/2023] Open
Abstract
Treatment of pancreatic ductal adenocarcinoma (PDAC), a dismal disease with poor survival rates, is hampered by the high prevalence of chemotherapy resistance. Resistance is accompanied by macrophage infiltration into the tumor microenvironment, and infiltrated macrophages are key players in chemotherapy resistance. In the current manuscript, we identify CCAAT/enhancer-binding protein delta (C/EBPδ) as an important transcription factor driving macrophage-dependent gemcitabine resistance. We show that conditioned medium obtained from wild type macrophages largely diminishes gemcitabine-induced cytotoxicity of PDAC cells, whereas conditioned medium obtained from C/EBPδ-deficient macrophages only minimally affects gemcitabine-induced PDAC cell death. Subsequent analysis of RNA-Seq data identified the pyrimidine metabolism pathway amongst the most significant pathways down-regulated in C/EBPδ-deficient macrophages and size filtration experiments indeed showed that the low molecular weight and free metabolite fraction most effectively induced gemcitabine resistance. In line with a role for pyrimidines, we next show that supplementing macrophage conditioned medium with deoxycytidine overruled the effect of macrophage conditioned media on gemcitabine resistance. Consistently, macrophage C/EBPδ-dependent resistance is specific for gemcitabine and does not affect paclitaxel or 5-FU-induced cytotoxicity. Overall, we thus show that C/EBPδ-dependent deoxycytidine biosynthesis in macrophages induces gemcitabine resistance of pancreatic cancer cells.
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