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Chen X, Yang Y, Zhou Z, Yu H, Zhang S, Huang S, Wei Z, Ren K, Jin Y. Unraveling the complex interplay between Mitochondria-Associated Membranes (MAMs) and cardiovascular Inflammation: Molecular mechanisms and therapeutic implications. Int Immunopharmacol 2024; 141:112930. [PMID: 39146786 DOI: 10.1016/j.intimp.2024.112930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2024] [Revised: 07/26/2024] [Accepted: 08/10/2024] [Indexed: 08/17/2024]
Abstract
Cardiovascular diseases (CVDs) represent a significant public health concern because of their associations with inflammation, oxidative stress, and abnormal remodeling of the heart and blood vessels. In this review, we discuss the intricate interplay between mitochondria-associated membranes (MAMs) and cardiovascular inflammation, highlighting their role in key cellular processes such as calcium homeostasis, lipid metabolism, oxidative stress management, and ERS. We explored how these functions impact the pathogenesis and progression of various CVDs, including myocardial ischemia-reperfusion injury, atherosclerosis, diabetic cardiomyopathy, cardiovascular aging, heart failure, and pulmonary hypertension. Additionally, we examined current therapeutic strategies targeting MAM-related pathways and proteins, emphasizing the potential of MAMs as therapeutic targets. Our review aims to provide new insights into the mechanisms of cardiovascular inflammation and propose novel therapeutic approaches to improve cardiovascular health outcomes.
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Affiliation(s)
- Xing Chen
- Department of Translational Medicine Center, the First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, PR China
| | - Yang Yang
- Department of Translational Medicine Center, the First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, PR China
| | - Zheng Zhou
- Department of Geriatric Endocrinology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, PR China
| | - Haihan Yu
- Department of Neurology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, PR China
| | - Shuwei Zhang
- Department of Translational Medicine Center, the First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, PR China
| | - Siyuan Huang
- Department of Translational Medicine Center, the First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, PR China
| | - Ziqing Wei
- Department of Neurology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, PR China.
| | - Kaidi Ren
- Department of Pharmacy, the First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, PR China.
| | - Yage Jin
- Department of Cardiology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, PR China.
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Hirose S, Mashima T, Yuan X, Yamashita M, Kitano S, Torii S, Migita T, Seimiya H. Interleukin-4 induced 1-mediated resistance to an immune checkpoint inhibitor through suppression of CD8 + T cell infiltration in melanoma. Cancer Sci 2024; 115:791-803. [PMID: 38258342 PMCID: PMC10921010 DOI: 10.1111/cas.16073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 12/29/2023] [Accepted: 01/04/2024] [Indexed: 01/24/2024] Open
Abstract
Cancer cells adopt multiple strategies to escape tumor surveillance by the host immune system and aberrant amino acid metabolism in the tumor microenvironment suppresses the immune system. Among the amino acid-metabolizing enzymes is an L-amino-acid oxidase called interleukin-4 induced 1 (IL4I1), which depletes essential amino acids in immune cells and is associated with a poor prognosis in various cancer types. Although IL4I1 is involved in immune metabolism abnormalities, its effect on the therapeutic efficacy of immune checkpoint inhibitors is unknown. In this study, we established murine melanoma cells overexpressing IL4I1 and investigated their effects on the intratumor immune microenvironment and the antitumor efficacy of anti-programmed death-ligand 1 (PD-L1) antibodies (Abs) in a syngeneic mouse model. As a result, we found that IL4I1-overexpressing B16-F10-derived tumors showed resistance to anti-PD-L1 Ab therapy. Transcriptome analysis revealed that immunosuppressive genes were globally upregulated in the IL4I1-overexpressing tumors. Consistently, we showed that IL4I1-overexpressing tumors exhibited an altered subset of lymphoid cells and particularly significant suppression of cytotoxic T cell infiltration compared to mock-infected B16-F10-derived tumors. After treatment with anti-PD-L1 Abs, we also found a more prominent elevation of tumor-associated macrophage (TAM) marker, CD68, in the IL4I1-overexpressing tumors than in the mock tumors. Consistently, we confirmed an enhanced TAM infiltration in the IL4I1-overexpressing tumors and a functional involvement of TAMs in the tumor growth. These observations indicate that IL4I1 reprograms the tumor microenvironment into an immunosuppressive state and thereby confers resistance to anti-PD-L1 Abs.
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Affiliation(s)
- Shiho Hirose
- Division of Molecular Biotherapy, Cancer Chemotherapy CenterJapanese Foundation for Cancer ResearchTokyoJapan
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier SciencesUniversity of TokyoTokyoJapan
| | - Tetsuo Mashima
- Division of Molecular Biotherapy, Cancer Chemotherapy CenterJapanese Foundation for Cancer ResearchTokyoJapan
| | - Xunmei Yuan
- Division of Molecular Biotherapy, Cancer Chemotherapy CenterJapanese Foundation for Cancer ResearchTokyoJapan
| | - Makiko Yamashita
- Division of Cancer Immunotherapy Development, Department of Advanced Medical DevelopmentThe Cancer Institute Hospital of JFCRTokyoJapan
| | - Shigehisa Kitano
- Division of Cancer Immunotherapy Development, Department of Advanced Medical DevelopmentThe Cancer Institute Hospital of JFCRTokyoJapan
| | - Shinichi Torii
- Division of Neuropathology and Neuroscience, Graduate School of Pharmaceutical SciencesUniversity of TokyoTokyoJapan
- Vermilion Therapeutics Inc.TokyoJapan
| | - Toshiro Migita
- Division of Cancer Cell BiologyInstitute of Medical Science, University of TokyoTokyoJapan
| | - Hiroyuki Seimiya
- Division of Molecular Biotherapy, Cancer Chemotherapy CenterJapanese Foundation for Cancer ResearchTokyoJapan
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier SciencesUniversity of TokyoTokyoJapan
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Wu J, Wang X, Zhang M, Mathews P, Kang Y. RXR Agonists Enhance Lenalidomide Anti-Myeloma Activity and T Cell Functions while Retaining Glucose-Lowering Effect. Cells 2023; 12:1993. [PMID: 37566072 PMCID: PMC10417536 DOI: 10.3390/cells12151993] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 07/29/2023] [Accepted: 08/01/2023] [Indexed: 08/12/2023] Open
Abstract
Retinoid X receptor (RXR) heterodimerizes with the PPAR nuclear hormone receptor and regulates its downstream events. We investigated the effects of RXR agonists (LG100754, bexarotene, AGN194204, and LG101506) on lenalidomide's anti-myeloma activity, T cell functions, and the level of glucose and lipids in vivo. Genetic overexpression and CRISPR/Cas9 knockout experiments were conducted in multiple myeloma (MM) cell lines and Jurkat T cell lines to determine the roles of CRBN in RXR-agonist mediated effects. A xenograft mouse model of MM was established to determine the combination effect of LG100754 and lenalidomide. The combination of RXR agonists and lenalidomide demonstrated synergistic activity in increasing CRBN expression and killing myeloma cells. Mechanistically, the RXR agonists reduced the binding of PPARs to the CRBN promoter, thereby relieving the repressor effect of PPARs on CRBN transcription. RXR agonists downregulated the exhaustion markers and increased the activation markers of Jurkat T cells and primary human T cells. Co-administration of LG100754 and lenalidomide showed enhanced anti-tumor activity in vivo. LG100754 retained its glucose- and lipid-lowering effects. RXR agonists demonstrate potential utility in enhancing drug sensitivity and T-cell function in the treatment of myeloma.
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Affiliation(s)
| | | | | | | | - Yubin Kang
- Division of Hematologic Malignancies and Cellular Therapy, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA; (J.W.); (X.W.)
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4
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Pandit M, Kil YS, Ahn JH, Pokhrel RH, Gu Y, Mishra S, Han Y, Ouh YT, Kang B, Jeong MS, Kim JO, Nam JW, Ko HJ, Chang JH. Methionine consumption by cancer cells drives a progressive upregulation of PD-1 expression in CD4 T cells. Nat Commun 2023; 14:2593. [PMID: 37147330 PMCID: PMC10162977 DOI: 10.1038/s41467-023-38316-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 04/25/2023] [Indexed: 05/07/2023] Open
Abstract
Programmed cell death protein 1 (PD-1), expressed on tumor-infiltrating T cells, is a T cell exhaustion marker. The mechanisms underlying PD-1 upregulation in CD4 T cells remain unknown. Here we develop nutrient-deprived media and a conditional knockout female mouse model to study the mechanism underlying PD-1 upregulation. Reduced methionine increases PD-1 expression on CD4 T cells. The genetic ablation of SLC43A2 in cancer cells restores methionine metabolism in CD4 T cells, increasing the intracellular levels of S-adenosylmethionine and yielding H3K79me2. Reduced H3K79me2 due to methionine deprivation downregulates AMPK, upregulates PD-1 expression and impairs antitumor immunity in CD4 T cells. Methionine supplementation restores H3K79 methylation and AMPK expression, lowering PD-1 levels. AMPK-deficient CD4 T cells exhibit increased endoplasmic reticulum stress and Xbp1s transcript levels. Our results demonstrate that AMPK is a methionine-dependent regulator of the epigenetic control of PD-1 expression in CD4 T cells, a metabolic checkpoint for CD4 T cell exhaustion.
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Affiliation(s)
- Mahesh Pandit
- College of Pharmacy, Yeungnam University, Gyeongsan-si, Gyeongsangbukdo, 38541, Republic of Korea
| | - Yun-Seo Kil
- College of Pharmacy, Yeungnam University, Gyeongsan-si, Gyeongsangbukdo, 38541, Republic of Korea
| | - Jae-Hee Ahn
- Department of Pharmacy, Kangwon National University, Chuncheon, 24341, Republic of Korea
| | - Ram Hari Pokhrel
- College of Pharmacy, Yeungnam University, Gyeongsan-si, Gyeongsangbukdo, 38541, Republic of Korea
| | - Ye Gu
- College of Pharmacy, Yeungnam University, Gyeongsan-si, Gyeongsangbukdo, 38541, Republic of Korea
| | - Sunil Mishra
- College of Pharmacy, Yeungnam University, Gyeongsan-si, Gyeongsangbukdo, 38541, Republic of Korea
| | - Youngjoo Han
- Department of Pharmacy, Kangwon National University, Chuncheon, 24341, Republic of Korea
| | - Yung-Taek Ouh
- Department of Obstetrics and Gynecology, School of medicine, Kangwon National University, Chuncheon, 24289, Republic of Korea
| | - Ben Kang
- Department of Pediatrics, School of Medicine, Kyungpook National University, 68-Gukchaebosang-ro, Jung-gu, Daegu, 41944, Republic of Korea
| | - Myeong Seon Jeong
- Chuncheon Center, Korea Basic Science Institute (KBSI), Chuncheon, 24341, Republic of Korea
- Department of Biochemistry, Kangwon National University, Chuncheon, 24341, Republic of Korea
| | - Jong-Oh Kim
- College of Pharmacy, Yeungnam University, Gyeongsan-si, Gyeongsangbukdo, 38541, Republic of Korea
| | - Joo-Won Nam
- College of Pharmacy, Yeungnam University, Gyeongsan-si, Gyeongsangbukdo, 38541, Republic of Korea
| | - Hyun-Jeong Ko
- Department of Pharmacy, Kangwon National University, Chuncheon, 24341, Republic of Korea.
| | - Jae-Hoon Chang
- College of Pharmacy, Yeungnam University, Gyeongsan-si, Gyeongsangbukdo, 38541, Republic of Korea.
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Zhu T, Wang R, Jiang H, Shi A, Chai M, Huang C, Yang S, Zhong W, Cai Y. Fibroblast Programmed Cell Death Ligand 1 Promotes Osteoclastogenesis in Odontogenic Keratocysts. THE AMERICAN JOURNAL OF PATHOLOGY 2023; 193:286-295. [PMID: 36509120 DOI: 10.1016/j.ajpath.2022.11.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Revised: 11/18/2022] [Accepted: 11/22/2022] [Indexed: 12/13/2022]
Abstract
Local aggressive growth of odontogenic keratocysts (OKCs) can cause serious bone destruction, even resulting in pathologic fractures of the mandible. The mechanism of osteoclastogenesis in OKCs was explored by investigating the role of programmed cell death ligand 1 (PD-L1), a key immune checkpoint, in OKCs and its relationship with the M2 isoform of pyruvate kinase (PKM2), a key enzyme of glycolysis. The data from immunohistochemistry, real-time quantitative PCR, Western blot, and flow cytometry indicated that the expression level of PD-L1 was significantly increased in the stroma and fibroblasts of OKCs (OKC-Fs) when compared with oral mucosa. Double-labeling staining demonstrated that osteoclasts in OKCs spatially interacted with PD-L1-positive OKC-Fs. Exogenous expression of PD-L1 in OKC-Fs promoted osteoclastogenesis when OKC-Fs were co-cultured with osteoclast precursors (RAW264.7 cells). Because OKC-Fs exhibit energy dependency and acquire energy from PKM2-mediated glycolysis, this study generated stable PKM2 knockdown OKC-Fs using shRNAs against PKM2, and found that PD-L1 expression level was decreased by PKM2 knockdown. Furthermore, Spearman rank correlation analysis showed that there was a positive correlation between the immunostaining of PKM2 and PD-L1 in OKC samples. In addition, double-labeling immunofluorescence showed colocalizations between PKM2 and PD-L1 in the fibrous tissue walls of OKCs. In conclusion, PD-L1 in fibroblasts promotes osteoclastogenesis in OKCs, which is regulated by PKM2.
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Affiliation(s)
- Tianshuang Zhu
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China; Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Rong Wang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Hao Jiang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Alex Shi
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Maosheng Chai
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Congfa Huang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China; Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Shaodong Yang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Wenqun Zhong
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China; Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
| | - Yu Cai
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China; Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
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6
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Fan R, De Beule N, Maes A, De Bruyne E, Menu E, Vanderkerken K, Maes K, Breckpot K, De Veirman K. The prognostic value and therapeutic targeting of myeloid-derived suppressor cells in hematological cancers. Front Immunol 2022; 13:1016059. [PMID: 36304465 PMCID: PMC9592826 DOI: 10.3389/fimmu.2022.1016059] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 09/16/2022] [Indexed: 11/22/2022] Open
Abstract
The success of immunotherapeutic approaches in hematological cancers is partially hampered by the presence of an immunosuppressive microenvironment. Myeloid-derived suppressor cells (MDSC) are key components of this suppressive environment and are frequently associated with tumor cell survival and drug resistance. Based on their morphology and phenotype, MDSC are commonly subdivided into polymorphonuclear MDSC (PMN-MDSC or G-MDSC) and monocytic MDSC (M-MDSC), both characterized by their immunosuppressive function. The phenotype, function and prognostic value of MDSC in hematological cancers has been intensively studied; however, the therapeutic targeting of this cell population remains challenging and needs further investigation. In this review, we will summarize the prognostic value of MDSC and the different attempts to target MDSC (or subtypes of MDSC) in hematological cancers. We will discuss the benefits, challenges and opportunities of using MDSC-targeting approaches, aiming to enhance anti-tumor immune responses of currently used cellular and non-cellular immunotherapies.
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Affiliation(s)
- Rong Fan
- Department of Hematology and Immunology-Myeloma Center Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Nathan De Beule
- Department of Clinical Hematology, Universitair Ziekenhuis Brussel, Brussels, Belgium
| | - Anke Maes
- Department of Hematology and Immunology-Myeloma Center Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Elke De Bruyne
- Department of Hematology and Immunology-Myeloma Center Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Eline Menu
- Department of Hematology and Immunology-Myeloma Center Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Karin Vanderkerken
- Department of Hematology and Immunology-Myeloma Center Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Ken Maes
- Center for Medical Genetics, Vrije Universiteit Brussel, Universitair Ziekenhuis Brussel, Brussels, Belgium
| | - Karine Breckpot
- Laboratory for Molecular and Cellular Therapy, Department of Biomedical Sciences Vrije Universiteit Brussel, Brussels, Belgium
| | - Kim De Veirman
- Department of Hematology and Immunology-Myeloma Center Brussels, Vrije Universiteit Brussel, Brussels, Belgium
- *Correspondence: Kim De Veirman,
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Cho J, Tae N, Ahn JH, Chang SY, Ko HJ, Kim DH. Bispecific Antibody-Bound T Cells as a Novel Anticancer Immunotherapy. Biomol Ther (Seoul) 2022; 30:418-426. [PMID: 35577765 PMCID: PMC9424331 DOI: 10.4062/biomolther.2022.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 04/01/2022] [Accepted: 04/13/2022] [Indexed: 11/05/2022] Open
Abstract
Chimeric antigen receptor T (CAR-T) cell therapy is one of the promising anticancer treatments. It shows a high overall response rate with complete response to blood cancer. However, there is a limitation to solid tumor treatment. Additionally, this currently approved therapy exhibits side effects such as cytokine release syndrome and neurotoxicity. Alternatively, bispecific antibody is an innovative therapeutic tool that simultaneously engages specific immune cells to disease-related target cells. Since programmed death ligand 1 (PD-L1) is an immune checkpoint molecule highly expressed in some cancer cells, in the current study, we generated αCD3xαPD-L1 bispecific antibody (BiTE) which can engage T cells to PD-L1+ cancer cells. We observed that the BiTE-bound OT-1 T cells effectively killed cancer cells in vitro and in vivo. They substantially increased the recruitment of effector memory CD8+ T cells having CD8+CD44+CD62Llow phenotype in tumor. Interestingly, we also observed that BiTE-bound polyclonal T cells showed highly efficacious tumor killing activity in vivo in comparison with the direct intravenous treatment of bispecific antibody, suggesting that PD-L1-directed migration and engagement of activated T cells might increase cancer cell killing. Additionally, BiTE-bound CAR-T cells which targets human Her-2/neu exhibited enhanced killing effect on Her-2-expressing cancer cells in vivo, suggesting that this could be a novel therapeutic regimen. Collectively, our results suggested that engaging activated T cells with cancer cells using αCD3xαPD-L1 BiTE could be an innovative next generation anticancer therapy which exerts simultaneous inhibitory functions on PD-L1 as well as increasing the infiltration of activated T cells having effector memory phenotype in tumor site.
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Affiliation(s)
- Jaewon Cho
- Department of Pharmacy, Kangwon National University, Chuncheon 24341, Republic of Korea
| | - Nara Tae
- Kangwon Institute of Inclusive Technology, Kangwon National University, Chuncheon 24341, Republic of Korea
| | - Jae-Hee Ahn
- Department of Pharmacy, Kangwon National University, Chuncheon 24341, Republic of Korea
| | - Sun-Young Chang
- College of Pharmacy, Ajou University, Suwon 16499, Republic of Korea
| | - Hyun-Jeong Ko
- Department of Pharmacy, Kangwon National University, Chuncheon 24341, Republic of Korea.,Kangwon Institute of Inclusive Technology, Kangwon National University, Chuncheon 24341, Republic of Korea
| | - Dae Hee Kim
- Department of Pharmacy, Kangwon National University, Chuncheon 24341, Republic of Korea.,Kangwon Institute of Inclusive Technology, Kangwon National University, Chuncheon 24341, Republic of Korea
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Combined Gemcitabine and Immune-Checkpoint Inhibition Conquers Anti-PD-L1 Resistance in Low-Immunogenic Mismatch Repair-Deficient Tumors. Int J Mol Sci 2021; 22:ijms22115990. [PMID: 34206051 PMCID: PMC8199186 DOI: 10.3390/ijms22115990] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 05/28/2021] [Accepted: 05/31/2021] [Indexed: 01/11/2023] Open
Abstract
Tumors arising in the context of Lynch Syndrome or constitutional mismatch repair deficiency are hypermutated and have a good response towards immune-checkpoint inhibitors (ICIs), including α-PD-L1 antibodies. However, in most cases, resistance mechanisms evolve. To improve outcomes and prevent resistance development, combination approaches are warranted. Herein, we applied a combined regimen with an α-PD-L1 antibody and gemcitabine in a preclinical tumor model to activate endogenous antitumor immune responses. Mlh1−/− mice with established gastrointestinal tumors received the α-PD-L1 antibody (clone 6E11; 2.5 mg/kg bw, i.v., q2wx3) and gemcitabine (100 mg/kg bw, i.p., q4wx3) in mono- or combination therapy. Survival and tumor growth were recorded. Immunological changes in the blood were routinely examined via multi-color flow cytometry and complemented by ex vivo frameshift mutation analysis to identify alterations in Mlh1−/−-tumor-associated target genes. The combined therapy of α-PD-L1 and gemcitabine prolonged median overall survival of Mlh1−/− mice from four weeks in the untreated control group to 12 weeks, accompanied by therapy-induced tumor growth inhibition, as measured by [18F]-FDG PET/CT. Plasma cytokine levels of IL13, TNFα, and MIP1β were increased and also higher than in mice receiving either monotherapy. Circulating splenic and intratumoral myeloid-derived suppressor cells (MDSCs), as well as M2 macrophages, were markedly reduced. Besides, residual tumor specimens from combi-treated mice had increased numbers of infiltrating cytotoxic T-cells. Frameshift mutations in APC, Tmem60, and Casc3 were no longer detectable upon treatment, likely because of the successful eradication of single mutated cell clones. By contrast, novel mutations appeared. Collectively, we herein confirm the safe application of combined chemo-immunotherapy by long-term tumor growth control to prevent the development of resistance mechanisms.
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