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Abstract
Pre-clinical and on-going trials have indicated the advantage of using metformin as an anticancer drug alone or in combination with other chemotherapeutics for the treatment of patients with breast cancer. However, the mechanisms by which metformin attenuates tumorigenesis remain to be further elucidated. The present study investigated the anticancer effects of metformin in breast cancer and identified potential molecular targets of metformin using western blotting and immunohistochemical analysis. Metformin significantly decreased tumor cell proliferation in vitro and suppressed tumor growth in vivo. Moreover, it induced the activation of AMP-induced protein kinase and suppression of phosphorylated-eukaryotic translation initiation factor 4E-binding protein 1 (p-4E-BP1), a downstream effector of the mTOR signaling pathway, and decreased cyclin D1 levels in in vitro and in vivo experimental models. Additionally, metformin inhibited cyclooxygenase (COX)-2 expression. Clinically, high expression levels of COX-2 and p-4E-BP1 in tissues of patients with breast cancer were significantly associated with enhanced lymphatic metastasis and distant metastasis. Thus, the current data suggested that metformin may have potential value as a synergistic therapy targeting both the COX-2 and mTOR signaling pathways.
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Affiliation(s)
- Bin Shi
- Department of Medical Oncology, Fuzhou General Hospital of Fujian Medical University, East Hospital Affiliated to Xiamen University (The 900th Hospital of The Joint Logistics Support Force of The Chinese PLA), Dongfang Hospital, Xiamen University, Fuzhou, Fujian 350025, P.R. China.,Department of Medical Oncology, Longyan People's Hospital, Longyan, Fujian 364000, P.R. China
| | - Xinyu Hu
- Department of Medical Oncology, Fuzhou General Hospital of Fujian Medical University, East Hospital Affiliated to Xiamen University (The 900th Hospital of The Joint Logistics Support Force of The Chinese PLA), Dongfang Hospital, Xiamen University, Fuzhou, Fujian 350025, P.R. China
| | - Huimin He
- Department of Medical Oncology, Fuzhou General Hospital of Fujian Medical University, East Hospital Affiliated to Xiamen University (The 900th Hospital of The Joint Logistics Support Force of The Chinese PLA), Dongfang Hospital, Xiamen University, Fuzhou, Fujian 350025, P.R. China
| | - Wenzheng Fang
- Department of Medical Oncology, Fuzhou General Hospital of Fujian Medical University, East Hospital Affiliated to Xiamen University (The 900th Hospital of The Joint Logistics Support Force of The Chinese PLA), Dongfang Hospital, Xiamen University, Fuzhou, Fujian 350025, P.R. China
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Wood MP, Wood LF, Templeton M, Fisher B, Lippy A, Jones CI, Lindestam Arlehamn CS, Sette A, Fuller JT, Murapa P, Jaspan HB, Fuller DH, Sodora DL. Transient Immune Activation in BCG-Vaccinated Infant Rhesus Macaques Is Not Sufficient to Influence Oral Simian Immunodeficiency Virus Infection. J Infect Dis 2021; 222:44-53. [PMID: 31605528 DOI: 10.1093/infdis/jiz382] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 07/22/2019] [Indexed: 12/20/2022] Open
Abstract
BCG vaccination has been demonstrated to increase levels of activated CD4+ T cells, thus potentially influencing mother-to-child transmission of human immunodeficiency virus (HIV). To assess the risk of BCG vaccination in HIV infection, we randomly assigned newborn rhesus macaques to receive BCG vaccine or remain unvaccinated and then undergo oral simian immunodeficiency virus (SIV) challenges 3 weeks later. We observed elevated levels of activated peripheral CD4+ T cells (ie, HLA-DR+CD38+CCR5+ CD4+ T cells) by week 3 after vaccination. BCG was also associated with an altered immune gene expression profile, as well as with monocyte activation in both peripheral blood and the draining axillary lymph node, indicating significant BCG vaccine-induced immune activation. Despite these effects, BCG vaccination did not increase the rate of SIV oral transmission or disease progression. Our findings therefore identify patterns of T-cell and monocyte activation that occur after BCG vaccination but do not support the hypothesis that BCG vaccination is a risk factor for postnatal HIV transmission or increased pathogenesis in infants.
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Affiliation(s)
- Matthew P Wood
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington
| | - Lianna F Wood
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington
| | - Megan Templeton
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington
| | - Bridget Fisher
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington
| | - Adriana Lippy
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington
| | - Chloe I Jones
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington
| | | | - Alessandro Sette
- Division of Vaccine Discovery, La Jolla Institute for Immunology, San Diego.,Department of Medicine, University of California-San Diego, La Jolla, California
| | - James T Fuller
- Department of Microbiology, Seattle, Washington; and University of Washington.,Washington National Primate Research Center, Seattle, Washington
| | - Patience Murapa
- Department of Microbiology, Seattle, Washington; and University of Washington.,Washington National Primate Research Center, Seattle, Washington
| | - Heather B Jaspan
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington
| | - Deborah H Fuller
- Department of Microbiology, Seattle, Washington; and University of Washington.,Washington National Primate Research Center, Seattle, Washington
| | - Donald L Sodora
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington
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Kalscheuer R, Palacios A, Anso I, Cifuente J, Anguita J, Jacobs WR Jr, Guerin ME, Prados-Rosales R. The Mycobacterium tuberculosis capsule: a cell structure with key implications in pathogenesis. Biochem J 2019; 476:1995-2016. [PMID: 31320388 DOI: 10.1042/BCJ20190324] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 06/19/2019] [Accepted: 06/20/2019] [Indexed: 01/17/2023]
Abstract
Bacterial capsules have evolved to be at the forefront of the cell envelope, making them an essential element of bacterial biology. Efforts to understand the Mycobacterium tuberculosis (Mtb) capsule began more than 60 years ago, but the relatively recent development of mycobacterial genetics combined with improved chemical and immunological tools have revealed a more refined view of capsule molecular composition. A glycogen-like α-glucan is the major constituent of the capsule, with lower amounts of arabinomannan and mannan, proteins and lipids. The major Mtb capsular components mediate interactions with phagocytes that favor bacterial survival. Vaccination approaches targeting the mycobacterial capsule have proven successful in controlling bacterial replication. Although the Mtb capsule is composed of polysaccharides of relatively low complexity, the concept of antigenic variability associated with this structure has been suggested by some studies. Understanding how Mtb shapes its envelope during its life cycle is key to developing anti-infective strategies targeting this structure at the host-pathogen interface.
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Malik DES, David RM, Gooderham NJ. Mechanistic evidence that benzo[a]pyrene promotes an inflammatory microenvironment that drives the metastatic potential of human mammary cells. Arch Toxicol 2018; 92:3223-3239. [PMID: 30155724 PMCID: PMC6132703 DOI: 10.1007/s00204-018-2291-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 08/16/2018] [Indexed: 12/21/2022]
Abstract
Benzo[a]pyrene (B(a)P) is a major cancer-causing contaminant present in food such as cooked meats and cereals, and is ubiquitous in the environment in smoke derived from the combustion of organic material. Exposure to B(a)P is epidemiologically linked with the incidence of breast cancer. Although B(a)P is recognized as a complete genotoxic carcinogen, thought to act primarily via CYP-mediated metabolic activation to DNA-damaging species, there is also evidence that B(a)P exposure elicits other biological responses that promote development of the cancer phenotype. Here in mechanistic studies using human mammary cells MCF-7 and MDA-MB-231, we have explored mechanisms whereby B(a)P (10- 8 to 10- 5M) promotes inflammation pathways via TNF-α and NFκB leading to IL-6 upregulation, microRNA (Let7a, miR21 and miR29b) dysregulation and activation of VEGF. The miRNA dysregulation is associated with altered expression of inflammation mediators and increased migration and invasive potential of human mammary cancer cells. Our data suggest that mammary cell exposure to B(a)P results in perturbation of inflammation mediators and dysregulation of tumorigenic miRNAs, leading to an inflammation microenvironment that facilitates migration and invasion of mammary epithelial cells. These properties of B(a)P, together with its well-established metabolic activation to DNA-damaging species, offer mechanistic insights into its carcinogenic mode of action.
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Affiliation(s)
- Durr-E-Shahwar Malik
- Computational and Systems Medicine, Imperial College London, London, SW7 2AZ, UK
| | - Rhiannon M David
- Computational and Systems Medicine, Imperial College London, London, SW7 2AZ, UK
- Genetic Toxicology, Drug Safety and Metabolism, MSAS Unit, AstraZeneca, Cambridge, UK
| | - Nigel J Gooderham
- Computational and Systems Medicine, Imperial College London, London, SW7 2AZ, UK.
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Ghorpade DS, Holla S, Kaveri SV, Bayry J, Patil SA, Balaji KN. Sonic hedgehog-dependent induction of microRNA 31 and microRNA 150 regulates Mycobacterium bovis BCG-driven toll-like receptor 2 signaling. Mol Cell Biol 2013; 33:543-56. [PMID: 23166298 DOI: 10.1128/MCB.01108-12] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Hedgehog (HH) signaling is a significant regulator of cell fate decisions during embryogenesis, development, and perpetuation of various disease conditions. Testing whether pathogen-specific HH signaling promotes unique innate recognition of intracellular bacteria, we demonstrate that among diverse Gram-positive or Gram-negative microbes, Mycobacterium bovis BCG, a vaccine strain, elicits a robust activation of Sonic HH (SHH) signaling in macrophages. Interestingly, sustained tumor necrosis factor alpha (TNF-α) secretion by macrophages was essential for robust SHH activation, as TNF-α(-/-) macrophages exhibited compromised ability to activate SHH signaling. Neutralization of TNF-α or blockade of TNF-α receptor signaling significantly reduced the infection-induced SHH signaling activation both in vitro and in vivo. Intriguingly, activated SHH signaling downregulated M. bovis BCG-mediated Toll-like receptor 2 (TLR2) signaling events to regulate a battery of genes associated with divergent functions of M1/M2 macrophages. Genome-wide expression profiling as well as conventional gain-of-function or loss-of-function analysis showed that SHH signaling-responsive microRNA 31 (miR-31) and miR-150 target MyD88, an adaptor protein of TLR2 signaling, thus leading to suppression of TLR2 responses. SHH signaling signatures could be detected in vivo in tuberculosis patients and M. bovis BCG-challenged mice. Collectively, these investigations identify SHH signaling to be what we believe is one of the significant regulators of host-pathogen interactions.
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Castro-Garza J, Swords WE, Karls RK, Quinn FD. Dual mechanism for Mycobacterium tuberculosis cytotoxicity on lung epithelial cells. Can J Microbiol 2012; 58:909-16. [PMID: 22720783 DOI: 10.1139/w2012-067] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mycobacterium tuberculosis strains CDC1551 and Erdman were used to assess cytotoxicity in infected A549 human alveolar epithelial cell monolayers. Strain CDC1551 was found to induce qualitatively greater disruption of A549 monolayers than was strain Erdman, although total intracellular and cell-associated bacterial growth rates over the course of the infections were not significantly different. Cell-free culture supernatants from human monocytic cells infected with either of the 2 M. tuberculosis strains produced a cytotoxic effect on A549 cells, correlating with the amount of tumor necrosis factor alpha (TNF-α) released by the infected monocytes. The addition of TNF-α-neutralizing antibodies to the supernatants from infected monocyte cultures did prevent the induction of a cytotoxic effect on A549 cells overlaid with this mixture but did not prevent the death of epithelial cells when added prior to infection with M. tuberculosis bacilli. Thus, these data agree with previous observations that lung epithelial cells infected with M. tuberculosis bacilli are rapidly killed in vitro. In addition, the data indicate that some of the observed epithelial cell killing may be collateral damage; the result of TNF-α released from M. tuberculosis-infected monocytes.
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Affiliation(s)
- Jorge Castro-Garza
- Centro de Investigación Biomédica del Noreste, Instituto Mexicano del Seguro Social, Monterrey, Mexico.
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Ghorpade DS, Leyland R, Kurowska-Stolarska M, Patil SA, Balaji KN. MicroRNA-155 is required for Mycobacterium bovis BCG-mediated apoptosis of macrophages. Mol Cell Biol 2012; 32:2239-53. [PMID: 22473996 DOI: 10.1128/MCB.06597-11] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Pathogenic mycobacteria, including Mycobacterium tuberculosis and Mycobacterium bovis, cause significant morbidity and mortality worldwide. However, the vaccine strain Mycobacterium bovis BCG, unlike virulent strains, triggers extensive apoptosis of infected macrophages, a step necessary for the elicitation of robust protective immunity. We here demonstrate that M. bovis BCG triggers Toll-like receptor 2 (TLR2)-dependent microRNA-155 (miR-155) expression, which involves signaling cross talk among phosphatidylinositol 3-kinase (PI3K), protein kinase Cδ (PKCδ), and mitogen-activated protein kinases (MAPKs) and recruitment of NF-κB and c-ETS to miR-155 promoter. Genetic and signaling perturbations presented the evidence that miR-155 regulates PKA signaling by directly targeting a negative regulator of PKA, protein kinase inhibitor alpha (PKI-α). Enhanced activation of PKA signaling resulted in the generation of PKA C-α; phosphorylation of MSK1, cyclic AMP response element binding protein (CREB), and histone H3; and recruitment of phospho-CREB to the apoptotic gene promoters. The miR-155-triggered activation of caspase-3, BAK1, and cytochrome c translocation involved signaling integration of MAPKs and epigenetic or posttranslational modification of histones or CREB. Importantly, M. bovis BCG infection-induced apoptosis was severely compromised in macrophages derived from miR-155 knockout mice. Gain-of-function and loss-of-function studies validated the requirement of miR-155 for M. bovis BCG's ability to trigger apoptosis. Overall, M. bovis BCG-driven miR-155 dictates cell fate decisions of infected macrophages, strongly implicating a novel role for miR-155 in orchestrating cellular reprogramming during immune responses to mycobacterial infection.
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Conradie F, Foulkes AS, Ive P, Yin X, Roussos K, Glencross DK, Lawrie D, Stevens W, Montaner LJ, Sanne I, Azzoni L. Natural killer cell activation distinguishes Mycobacterium tuberculosis-mediated immune reconstitution syndrome from chronic HIV and HIV/MTB coinfection. J Acquir Immune Defic Syndr 2011; 58:309-18. [PMID: 21826013 DOI: 10.1097/QAI.0b013e31822e0d15] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND With increased access to antiretroviral treatment (ART), immune reconstitution inflammatory syndrome (IRIS) in Mycobacterium tuberculosis (MTB)-infected populations remains a clinical challenge. We studied a cross-sectional cohort of HIV-infected subjects in Johannesburg (South Africa) to help define the immune correlates that best distinguish IRIS from ongoing MTB cases. METHODS We studied HIV+ subjects developing MTB-related unmasking tuberculosis-related immune reconstitution inflammatory syndrome (uTB-IRIS) after ART initiation; control groups were subjects with HIV and HIV/tuberculosis-coinfected subjects with comparable ART treatment. Testing was conducted with whole blood-based 4-color flow cytometry and plasma-based Luminex cytokine assessment. RESULTS Natural killer cell activation, C-reactive protein, and interleukin 8 serum concentration were significantly higher in uTB-IRIS subjects compared with both control groups. In addition, all MTB-coinfected subjects, independent of clinical presentation, had higher neutrophils and T-cell activation, together with lower lymphocytes, CD4⁺ T-cell, and myeloid dendritic cell counts. Using conditional inference tree analysis, we show that elevated natural killer cell activation in combination with lymphocyte count characterizes the immunological profile of uTB-IRIS. CONCLUSION Our results support a role for innate immune effectors in the immunopathogenesis of unmasking MTB-related IRIS and identify new immune parameters defining this pathology.
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Chaturvedi R, Bansal K, Narayana Y, Kapoor N, Sukumar N, Togarsimalemath SK, Chandra N, Mishra S, Ajitkumar P, Joshi B, Katoch VM, Patil SA, Balaji KN. The multifunctional PE_PGRS11 protein from Mycobacterium tuberculosis plays a role in regulating resistance to oxidative stress. J Biol Chem 2010; 285:30389-403. [PMID: 20558725 DOI: 10.1074/jbc.m110.135251] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mycobacterium tuberculosis utilizes unique strategies to survive amid the hostile environment of infected host cells. Infection-specific expression of a unique mycobacterial cell surface antigen that could modulate key signaling cascades can act as a key survival strategy in curtailing host effector responses like oxidative stress. We demonstrate here that hypothetical PE_PGRS11 ORF encodes a functional phosphoglycerate mutase. The transcriptional analysis revealed that PE_PGRS11 is a hypoxia-responsive gene, and enforced expression of PE_PGRS11 by recombinant adenovirus or Mycobacterium smegmatis imparted resistance to alveolar epithelial cells against oxidative stress. PE_PGRS11-induced resistance to oxidative stress necessitated the modulation of genetic signatures like induced expression of Bcl2 or COX-2. This modulation of specific antiapoptotic molecular signatures involved recognition of PE_PGRS11 by TLR2 and subsequent activation of the PI3K-ERK1/2-NF-κB signaling axis. Furthermore, PE_PGRS11 markedly diminished H(2)O(2)-induced p38 MAPK activation. Interestingly, PE_PGRS11 protein was exposed at the mycobacterial cell surface and was involved in survival of mycobacteria under oxidative stress. Furthermore, PE_PGRS11 displayed differential B cell responses during tuberculosis infection. Taken together, our investigation identified PE_PGRS11 as an in vivo expressed immunodominant antigen that plays a crucial role in modulating cellular life span restrictions imposed during oxidative stress by triggering TLR2-dependent expression of COX-2 and Bcl2. These observations clearly provide a mechanistic basis for the rescue of pathogenic Mycobacterium-infected lung epithelial cells from oxidative stress.
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Affiliation(s)
- Rashmi Chaturvedi
- Department of Microbiology and Cell Biology, Supercomputer Education and Research Centre, Indian Institute of Science, Bangalore 560012, India
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