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Schiavoni V, Emanuelli M, Campagna R, Cecati M, Sartini D, Milanese G, Galosi AB, Pozzi V, Salvolini E. Paraoxonase-2 shRNA-mediated gene silencing suppresses proliferation and migration, while promotes chemosensitivity in clear cell renal cell carcinoma cell lines. J Cell Biochem 2024. [PMID: 38706121 DOI: 10.1002/jcb.30572] [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: 12/23/2023] [Revised: 03/27/2024] [Accepted: 04/15/2024] [Indexed: 05/07/2024]
Abstract
Clear cell renal cell carcinoma (ccRCC) represents the most common subtype of renal tumor. Despite recent advances in identifying novel target molecules, the prognosis of patients with ccRCC continues to be poor, mainly due to the lack of sensitivity to chemo- and radiotherapy and because of one-third of renal cell carcinoma patients displays metastatic disease at diagnosis. Thus, identifying new molecules for early detection and for developing effective targeted therapies is mandatory. In this work, we focused on paraoxonase-2 (PON2), an intracellular membrane-bound enzyme ubiquitously expressed in human tissues, whose upregulation has been reported in a variety of malignancies, thus suggesting its possible role in cancer cell survival and proliferation. To investigate PON2 involvement in tumor cell metabolism, human ccRCC cell lines were transfected with plasmid vectors coding short harpin RNAs targeting PON2 transcript and the impact of PON2 silencing on cell viability, migration, and response to chemotherapeutic treatment was then explored. Our results showed that PON2 downregulation was able to trigger a decrease in proliferation and migration of ccRCC cells, as well as an enhancement of cell sensitivity to chemotherapy. Thus, taken together, data reported in this study suggest that the enzyme may represent an interesting therapeutic target for ccRCC.
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Affiliation(s)
- Valentina Schiavoni
- Department of Clinical Sciences, Polytechnic University of Marche, Ancona, Italy
| | - Monica Emanuelli
- Department of Clinical Sciences, Polytechnic University of Marche, Ancona, Italy
- New York-Marche Structural Biology Center (NY-MaSBiC), Polytechnic University of Marche, Ancona, Italy
| | - Roberto Campagna
- Department of Clinical Sciences, Polytechnic University of Marche, Ancona, Italy
| | - Monia Cecati
- Department of Clinical Sciences, Polytechnic University of Marche, Ancona, Italy
| | - Davide Sartini
- Department of Clinical Sciences, Polytechnic University of Marche, Ancona, Italy
| | - Giulio Milanese
- Department of Clinical Sciences, Polytechnic University of Marche, Ancona, Italy
| | | | - Valentina Pozzi
- Department of Clinical Sciences, Polytechnic University of Marche, Ancona, Italy
| | - Eleonora Salvolini
- Department of Clinical Sciences, Polytechnic University of Marche, Ancona, Italy
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Campagna R, Serritelli EN, Salvolini E, Schiavoni V, Cecati M, Sartini D, Pozzi V, Emanuelli M. Contribution of the Paraoxonase-2 Enzyme to Cancer Cell Metabolism and Phenotypes. Biomolecules 2024; 14:208. [PMID: 38397445 PMCID: PMC10886763 DOI: 10.3390/biom14020208] [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: 12/08/2023] [Revised: 01/10/2024] [Accepted: 01/12/2024] [Indexed: 02/25/2024] Open
Abstract
Paraoxonase-2 (PON2) is a ubiquitously expressed intracellular protein that is localized in the perinuclear region, the endoplasmic reticulum (ER), and mitochondria, and is also associated with the plasma membrane. PON2 functions as an antioxidant enzyme by reducing the levels of reactive oxygen species (ROS) in the mitochondria and ER through different mechanisms, thus having an anti-apoptotic effect and preventing the formation of atherosclerotic lesions. While the antiatherogenic role played by this enzyme has been extensively explored within endothelial cells in association with vascular disorders, in the last decade, great efforts have been made to clarify its potential involvement in both blood and solid tumors, where PON2 was reported to be overexpressed. This review aims to deeply and carefully examine the contribution of this enzyme to different aspects of tumor cells by promoting the initiation, progression, and spread of neoplasms.
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Affiliation(s)
- Roberto Campagna
- Department of Clinical Sciences, Polytechnic University of Marche, 60126 Ancona, Italy; (R.C.); (E.N.S.); (E.S.); (V.S.); (M.C.); (V.P.); (M.E.)
| | - Emma Nicol Serritelli
- Department of Clinical Sciences, Polytechnic University of Marche, 60126 Ancona, Italy; (R.C.); (E.N.S.); (E.S.); (V.S.); (M.C.); (V.P.); (M.E.)
| | - Eleonora Salvolini
- Department of Clinical Sciences, Polytechnic University of Marche, 60126 Ancona, Italy; (R.C.); (E.N.S.); (E.S.); (V.S.); (M.C.); (V.P.); (M.E.)
| | - Valentina Schiavoni
- Department of Clinical Sciences, Polytechnic University of Marche, 60126 Ancona, Italy; (R.C.); (E.N.S.); (E.S.); (V.S.); (M.C.); (V.P.); (M.E.)
| | - Monia Cecati
- Department of Clinical Sciences, Polytechnic University of Marche, 60126 Ancona, Italy; (R.C.); (E.N.S.); (E.S.); (V.S.); (M.C.); (V.P.); (M.E.)
| | - Davide Sartini
- Department of Clinical Sciences, Polytechnic University of Marche, 60126 Ancona, Italy; (R.C.); (E.N.S.); (E.S.); (V.S.); (M.C.); (V.P.); (M.E.)
| | - Valentina Pozzi
- Department of Clinical Sciences, Polytechnic University of Marche, 60126 Ancona, Italy; (R.C.); (E.N.S.); (E.S.); (V.S.); (M.C.); (V.P.); (M.E.)
| | - Monica Emanuelli
- Department of Clinical Sciences, Polytechnic University of Marche, 60126 Ancona, Italy; (R.C.); (E.N.S.); (E.S.); (V.S.); (M.C.); (V.P.); (M.E.)
- New York-Marche Structural Biology Center (NY-MaSBiC), Polytechnic University of Marche, 60131 Ancona, Italy
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Mutchler SM, Whelan SCM, Marciszyn A, Chen J, Kleyman TR, Shi S. Role of paraoxonase 3 in regulating ENaC-mediated Na + transport in the distal nephron. J Physiol 2024; 602:737-757. [PMID: 38345534 PMCID: PMC10940207 DOI: 10.1113/jp285034] [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: 05/16/2023] [Accepted: 01/11/2024] [Indexed: 02/18/2024] Open
Abstract
Paraoxonase 3 (PON3) is expressed in the aldosterone-sensitive distal nephron, where filtered Na+ is reabsorbed mainly via the epithelial Na+ channel (ENaC) and Na+ -coupled co-transporters. We previously showed that PON3 negatively regulates ENaC through a chaperone mechanism. The present study aimed to determine the physiological role of PON3 in renal Na+ and K+ homeostasis. Pon3 knockout (KO) mice had higher amiloride-induced natriuresis and lower plasma [K+ ] at baseline. Single channel recordings in split-open tubules showed that the number of active channels per patch was significantly higher in KO mice, resulting in a higher channel activity in the absence of PON3. Although whole kidney abundance of ENaC subunits was not altered in Pon3 KOs, ENaC gamma subunit was more apically distributed within the connecting tubules and cortical collecting ducts of Pon3 KO kidneys. Additionally, small interfering RNA-mediated knockdown of PON3 in cultured mouse cortical collecting duct cells led to an increased surface abundance of ENaC gamma subunit. As a result of lower plasma [K+ ], sodium chloride co-transporter phosphorylation was enhanced in the KO kidneys, a phenotype that was corrected by a high K+ diet. Finally, PON3 expression was upregulated in mouse kidneys under dietary K+ restriction, potentially providing a mechanism to dampen ENaC activity and associated K+ secretion. Taken together, our results show that PON3 has a role in renal Na+ and K+ homeostasis through regulating ENaC functional expression in the distal nephron. KEY POINTS: Paraoxonase 3 (PON3) is expressed in the distal nephron of mouse kidneys and functions as a molecular chaperone to reduce epithelial Na+ channel (ENaC) expression and activity in heterologous expression systems. We examined the physiological role of PON3 in renal Na+ and K+ handling using a Pon3 knockout (KO) mouse model. At baseline, Pon3 KO mice had lower blood [K+ ], more functional ENaC in connecting tubules/cortical collecting ducts, higher amiloride-induced natriuresis, and enhanced sodium chloride co-transporter (NCC) phosphorylation. Upon challenge with a high K+ diet, Pon3 KO mice had normalized blood [K+ ] and -NCC phosphorylation but lower circulating aldosterone levels compared to their littermate controls. Kidney PON3 abundance was altered in mice under dietary K+ loading or K+ restriction, providing a potential mechanism for regulating ENaC functional expression and renal Na+ and K+ homeostasis in the distal nephron.
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Affiliation(s)
| | | | - Allison Marciszyn
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jingxin Chen
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Thomas R. Kleyman
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Shujie Shi
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
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Whitt AG, Neely AM, Sarkar OS, Meng S, Arumugam S, Yaddanapudi K, Li C. Paraoxonase 2 (PON2) plays a limited role in murine lung tumorigenesis. Sci Rep 2023; 13:9929. [PMID: 37337025 PMCID: PMC10279720 DOI: 10.1038/s41598-023-37146-5] [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: 11/15/2022] [Accepted: 06/16/2023] [Indexed: 06/21/2023] Open
Abstract
Paraoxonase 2 (PON2) is a multifunctional intracellular enzyme that has received growing attention for its ability to modulate various aspects of normal and malignant cellular physiology. Recent research has revealed that PON2 is upregulated in tissues from patients with various types of solid tumors and hematologic cancers, likely due to its ability to suppress oxidative stress and evade apoptosis. However, the effects of PON2 on pulmonary oncogenesis are unknown. Here, we conducted studies to investigate how PON2 influences lung cancer cell proliferation in vitro and lung tumorigenesis in vivo using a variety of cellular and animal models. It was found that PON2 expression deficiency hampered the proliferation of cultured lung cancer cells with concomitant cell cycle arrest at the G1 phase. In addition, the loss of endogenous PON2 expression impaired key aspects of oxidative metabolism in lung adenocarcinoma cells. Moreover, we investigated how the interplay between PON2 expression in lung tumors and host mice influences lung tumor initiation and progression. PON2 status in both transplanted tumor cells and mice failed to influence the development of subcutaneously grafted Lewis lung carcinoma (LLC) tumors, orthotopically implanted LLC tumors, and oncogenic Kras-driven primary lung adenocarcinoma tumors. Importantly, the frequencies of tumor-infiltrating myeloid subsets that include myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages were not impacted by PON2 expression in LLC tumor-bearing mice. Overall, our studies indicate that PON2 plays a limited role in murine lung tumorigenesis.
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Affiliation(s)
- Aaron G Whitt
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY, 40202, USA
- Experimental Therapeutics Group, Brown Cancer Center, Department of Medicine, University of Louisville, Louisville, KY, 40202, USA
| | - Aaron M Neely
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY, 40202, USA
- Experimental Therapeutics Group, Brown Cancer Center, Department of Medicine, University of Louisville, Louisville, KY, 40202, USA
- Department of Translational Genomics, University of Southern California, Los Angeles, CA, USA
| | - Omar Sadi Sarkar
- Department of Microbiology and Immunology, University of Louisville, Louisville, KY, USA
| | - Shuhan Meng
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY, 40202, USA
- Experimental Therapeutics Group, Brown Cancer Center, Department of Medicine, University of Louisville, Louisville, KY, 40202, USA
| | - Sengodagounder Arumugam
- NMR Facility, Brown Cancer Center, Department of Medicine, University of Louisville, Louisville, KY, USA
| | - Kavitha Yaddanapudi
- Department of Microbiology and Immunology, University of Louisville, Louisville, KY, USA
- Immuno-Oncology Program, Brown Cancer Center, Department of Medicine, University of Louisville, Louisville, KY, USA
- Division of Immunotherapy, Department of Surgery, University of Louisville, Louisville, KY, USA
| | - Chi Li
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY, 40202, USA.
- Experimental Therapeutics Group, Brown Cancer Center, Department of Medicine, University of Louisville, Louisville, KY, 40202, USA.
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Que F, Zhang L, Wang T, Xu M, Li W, Zang S. RHOA G17V induces T follicular helper cell specification and involves angioimmunoblastic T-cell lymphoma via upregulating the expression of PON2 through an NF-κB-dependent mechanism. Oncoimmunology 2022; 11:2134536. [PMID: 36249275 PMCID: PMC9559328 DOI: 10.1080/2162402x.2022.2134536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Angioimmunoblastic T-cell lymphoma (AITL) is a malignant hematologic tumor arising from T follicular helper (Tfh) cells. High-throughput genomic sequencing studies have shown that AITL is characterized by a novel highly recurring somatic mutation in RHOA, encoding p.Gly17Val (RHOA G17V). However, the specific role of RHOA G17V in AITL remains unknown. Here, we demonstrated that expression of Rhoa G17V in CD4+ T cells increased cell proliferation and induces Tfh cell specification associated with Pon2 upregulation through an NF-κB-dependent mechanism. Further, loss of Pon2 attenuated oncogenic function induced by genetic lesions in Rhoa. In addition, an abnormality of RHOA G17V mutation and PON2 expression is also detected in patients with AITL. Our findings suggest that PON2 associated with RHOA G17V mutation might control the direction of the molecular agents-based AITL and provide a new therapeutic target in AITL.
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Affiliation(s)
- Fenglian Que
- Department of Endocrinology, the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, 510260, China
| | - Lihong Zhang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, 510060, China
- Department of Pathology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, China
| | - Taoli Wang
- Department of Pathology, Zhuzhou Central Hospital, Zhuzhou, Hunan, 412007, China
| | - Meifang Xu
- Department of Pathology, Fujian Medical University Union Hospital, Fuzhou, Fujian, 350001, China
| | - Wangen Li
- Department of Endocrinology, the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, 510260, China
| | - Shengbing Zang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, 510060, China
- Department of Pathology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, 510060, China
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Effects of Antioxidant Gene Overexpression on Stress Resistance and Malignization In Vitro and In Vivo: A Review. Antioxidants (Basel) 2022; 11:antiox11122316. [PMID: 36552527 PMCID: PMC9774954 DOI: 10.3390/antiox11122316] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 11/17/2022] [Accepted: 11/21/2022] [Indexed: 11/25/2022] Open
Abstract
Reactive oxygen species (ROS) are normal products of a number of biochemical reactions and are important signaling molecules. However, at the same time, they are toxic to cells and have to be strictly regulated by their antioxidant systems. The etiology and pathogenesis of many diseases are associated with increased ROS levels, and many external stress factors directly or indirectly cause oxidative stress in cells. Within this context, the overexpression of genes encoding the proteins in antioxidant systems seems to have become a viable approach to decrease the oxidative stress caused by pathological conditions and to increase cellular stress resistance. However, such manipulations unavoidably lead to side effects, the most dangerous of which is an increased probability of healthy tissue malignization or increased tumor aggression. The aims of the present review were to collect and systematize the results of studies devoted to the effects resulting from the overexpression of antioxidant system genes on stress resistance and carcinogenesis in vitro and in vivo. In most cases, the overexpression of these genes was shown to increase cell and organism resistances to factors that induce oxidative and genotoxic stress but to also have different effects on cancer initiation and promotion. The last fact greatly limits perspectives of such manipulations in practice. The overexpression of GPX3 and SOD3 encoding secreted proteins seems to be the "safest" among the genes that can increase cell resistance to oxidative stress. High efficiency and safety potential can also be found for SOD2 overexpression in combinations with GPX1 or CAT and for similar combinations that lead to no significant changes in H2O2 levels. Accumulation, systematization, and the integral analysis of data on antioxidant gene overexpression effects can help to develop approaches for practical uses in biomedical and agricultural areas. Additionally, a number of factors such as genetic and functional context, cell and tissue type, differences in the function of transcripts of one and the same gene, regulatory interactions, and additional functions should be taken into account.
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Shi S, Buck TM, Nickerson AJ, Brodsky JL, Kleyman TR. Paraoxonase 2 is an ER chaperone that regulates the epithelial Na + channel. Am J Physiol Cell Physiol 2022; 322:C111-C121. [PMID: 34852210 PMCID: PMC8759969 DOI: 10.1152/ajpcell.00335.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The mammalian paraoxonases (PONs) have been linked to protection against oxidative stress. However, the physiological roles of members in this family (PON1, PON2, and PON3) are still being characterized. PON2 and PON3 are expressed in the aldosterone-sensitive distal nephron of the kidney and have been shown to negatively regulate expression of the epithelial sodium channel (ENaC), a trimeric ion channel that orchestrates salt and water homeostasis. To date, the nature of this phenomenon has not been explored. Therefore, to investigate the mechanism by which PON2 regulates ENaC, we expressed PON2 along with the ENaC subunits in fisher rat thyroid (FRT) cells, a system that is amenable to biochemical analyses of ENaC assembly and trafficking. We found that PON2 primarily resides in the endoplasmic reticulum (ER) in FRT cells, and its expression reduces the abundance of each ENaC subunit, reflecting enhanced subunit turnover. In contrast, no effect on the levels of mRNAs encoding the ENaC subunits was evident. Inhibition of lysosome function with chloroquine or NH4Cl did not alter the inhibitory effect of PON2 on ENaC expression. In contrast, PON2 accelerates ENaC degradation in a proteasome-dependent manner and acts before ENaC subunit ubiquitination. As a result of enhanced ENaC subunit ubiquitination and degradation, both channel surface expression and ENaC-mediated Na+ transport in FRT cells were reduced by PON2. Together, our data suggest that PON2 functions as an ER chaperone to monitor ENaC biogenesis and redirects the channel for ER-associated degradation.
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Affiliation(s)
- Shujie Shi
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Teresa M. Buck
- 2Deparment of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Andrew J. Nickerson
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Jeffrey L. Brodsky
- 2Deparment of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Thomas R. Kleyman
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania,3Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania,4Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
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Hui PY, Chen YH, Qin J, Jiang XH. PON2 blockade overcomes dexamethasone resistance in acute lymphoblastic leukemia. Hematology 2021; 27:32-42. [PMID: 34957927 DOI: 10.1080/16078454.2021.2009643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
OBJECTIVES The high frequency of chemotherapy resistance is ultimately responsible for clinical relapse in acute lymphoblastic leukemia (ALL). Nevertheless, the molecular mechanism relevant to glucocorticoid (GC) resistance remains ambiguous. METHODS Quantitative real-time polymerase chain reaction and Western blot were performed to detect the expressions of paraoxonase 2 (PON2), Bcl-2 and Bax. shRNA was used to knockdown PON2 expression in SUP-B15 and REH cell. CCK-8 and flow cytometry assay were conducted to monitor the changes of proliferation and apoptosis in ALL cells. The growth of ALL REH cells in vivo was determined using transplanted tumor model. RESULTS This study was designed to identify GC resistance-associated genes by means of the transcriptome chip from the public Gene Expression Omnibus database, and preliminarily investigation of dexamethasone (DEX)-resistance mechanism in ALL. We disclosed that PON2 expression was elevated in ALL patients and especially higher in DEX-resistance ALL patients. Then, cell apoptosis assay suggested that silencing of PON2 dramatically promoted in DEX-resistant ALL cells apoptosis and the activity of Caspase 3 induced by DEX administration. In xenograft tumor model, PON2 knockdown significantly reduced DEX-resistant ALL cells growth in immunodeficient mice. CONCLUSIONS Collectively, inhibition of PON2 may represent a novel method to restore the sensitivity of treatment-resistant ALL to GC-induced cell death.
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Affiliation(s)
- Pei-Ye Hui
- Pharmacy Department, Shandong Weifang Maternal and Child Health Hospital, Weifang, People's Republic of China
| | - Yan-Hua Chen
- Pharmacy Department, Rizhao people's Hospital, Rizhao, People's Republic of China
| | - Jing Qin
- Pharmacy Department, Rizhao people's Hospital, Rizhao, People's Republic of China
| | - Xiao-Hua Jiang
- Department of Pediatrics, 970 Hospital of Joint Logistics Support Force of Chinese People's Liberation Army, Yantai, People's Republic of China
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Metabolic determinants of B-cell selection. Biochem Soc Trans 2021; 49:1467-1478. [PMID: 34196360 DOI: 10.1042/bst20201316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 06/01/2021] [Accepted: 06/07/2021] [Indexed: 11/17/2022]
Abstract
B-cells are antibody-producing cells of the adaptive immune system. Approximately 75% of all newly generated B-cells in the bone marrow are autoreactive and express potentially harmful autoantibodies. To prevent autoimmune disease, the immune system has evolved a powerful mechanism to eliminate autoreactive B-cells, termed negative B-cell selection. While designed to remove autoreactive clones during early B-cell development, our laboratory recently discovered that transformed B-cells in leukemia and lymphoma are also subject to negative selection. Indeed, besides the risk of developing autoimmune disease, B-cells are inherently prone to malignant transformation: to produce high-affinity antibodies, B-cells undergo multiple rounds of somatic immunoglobulin gene recombination and hypermutation. Reflecting high frequencies of DNA-breaks, adaptive immune protection by B-cells comes with a dramatically increased risk of development of leukemia and lymphoma. Of note, B-cells exist under conditions of chronic restriction of energy metabolism. Here we discuss how these metabolic gatekeeper functions during B-cell development provide a common mechanism for the removal of autoreactive and premalignant B-cells to safeguard against both autoimmune diseases and B-cell malignancies.
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