scholarly journals Role of Mycoplasma Chaperone DnaK in Cellular Transformation

2020 ◽  
Vol 21 (4) ◽  
pp. 1311 ◽  
Author(s):  
Francesca Benedetti ◽  
Fiorenza Cocchi ◽  
Olga S. Latinovic ◽  
Sabrina Curreli ◽  
Selvi Krishnan ◽  
...  
Keyword(s):  
Dna Damage ◽  
Critical Role ◽  
Human Microbiome ◽  
Bacterial Pathogen ◽  
Cellular Transformation ◽  
Tumor Formation ◽  
Dna Damage And Repair ◽  
In Vivo Experiments ◽  
Apoptotic Pathways

Studies of the human microbiome have elucidated an array of complex interactions between prokaryotes and their hosts. However, precise bacterial pathogen–cancer relationships remain largely elusive, although several bacteria, particularly those establishing persistent intra-cellular infections, like mycoplasmas, can alter host cell cycles, affect apoptotic pathways, and stimulate the production of inflammatory substances linked to DNA damage, thus potentially promoting abnormal cell growth and transformation. Consistent with this idea, in vivo experiments in several chemically induced or genetically deficient mouse models showed that germ-free conditions reduce colonic tumor formation. We demonstrate that mycoplasma DnaK, a chaperone protein belonging to the Heath shock protein (Hsp)-70 family, binds Poly-(ADP-ribose) Polymerase (PARP)-1, a protein that plays a critical role in the pathways involved in recognition of DNA damage and repair, and reduces its catalytic activity. It also binds USP10, a key p53 regulator, reducing p53 stability and anti-cancer functions. Finally, we showed that bystander, uninfected cells take up exogenous DnaK—suggesting a possible paracrine function in promoting cellular transformation, over and above direct mycoplasma infection. We propose that mycoplasmas, and perhaps certain other bacteria with closely related DnaK, may have oncogenic activity, mediated through the inhibition of DNA repair and p53 functions, and may be involved in the initiation of some cancers but not necessarily involved nor necessarily even be present in later stages.

scholarly journals Impact of G-Quadruplexes on the Regulation of Genome Integrity, DNA Damage and Repair

Biomolecules ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1284
Author(s):  
Anzhela V. Pavlova ◽  
Elena A. Kubareva ◽  
Mayya V. Monakhova ◽  
Maria I. Zvereva ◽  
Nina G. Dolinnaya
Keyword(s):  
Dna Damage ◽  
Genome Instability ◽  
Critical Role ◽  
Dna Lesions ◽  
Genome Integrity ◽  
Dna Breaks ◽  
Dna Damage And Repair ◽  
Repair Processes

DNA G-quadruplexes (G4s) are known to be an integral part of the complex regulatory systems in both normal and pathological cells. At the same time, the ability of G4s to impede DNA replication plays a critical role in genome integrity. This review summarizes the results of recent studies of G4-mediated genomic and epigenomic instability, together with associated DNA damage and repair processes. Although the underlying mechanisms remain to be elucidated, it is known that, among the proteins that recognize G4 structures, many are linked to DNA repair. We analyzed the possible role of G4s in promoting double-strand DNA breaks, one of the most deleterious DNA lesions, and their repair via error-prone mechanisms. The patterns of G4 damage, with a focus on the introduction of oxidative guanine lesions, as well as their removal from G4 structures by canonical repair pathways, were also discussed together with the effects of G4s on the repair machinery. According to recent findings, there must be a delicate balance between G4-induced genome instability and G4-promoted repair processes. A broad overview of the factors that modulate the stability of G4 structures in vitro and in vivo is also provided here.

scholarly journals The role of the PZP domain of AF10 in acute leukemia driven by AF10 translocations

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Brianna J. Klein ◽  
Anagha Deshpande ◽  
Khan L. Cox ◽  
Fan Xuan ◽  
Mohamad Zandian ◽  
...  
Keyword(s):  
Critical Role ◽  
Cellular Transformation ◽  
Acute Leukemias ◽  
Hematopoietic Stem ◽  
Nucleosome Core ◽  
Stem And Progenitor Cells ◽  
Transforming Activity

AbstractChromosomal translocations of the AF10 (or MLLT10) gene are frequently found in acute leukemias. Here, we show that the PZP domain of AF10 (AF10PZP), which is consistently impaired or deleted in leukemogenic AF10 translocations, plays a critical role in blocking malignant transformation. Incorporation of functional AF10PZP into the leukemogenic CALM-AF10 fusion prevents the transforming activity of the fusion in bone marrow-derived hematopoietic stem and progenitor cells in vitro and in vivo and abrogates CALM-AF10-mediated leukemogenesis in vivo. Crystallographic, biochemical and mutagenesis studies reveal that AF10PZP binds to the nucleosome core particle through multivalent contacts with the histone H3 tail and DNA and associates with chromatin in cells, colocalizing with active methylation marks and discriminating against the repressive H3K27me3 mark. AF10PZP promotes nuclear localization of CALM-AF10 and is required for association with chromatin. Our data indicate that the disruption of AF10PZP function in the CALM-AF10 fusion directly leads to transformation, whereas the inclusion of AF10PZP downregulates Hoxa genes and reverses cellular transformation. Our findings highlight the molecular mechanism by which AF10 targets chromatin and suggest a model for the AF10PZP-dependent CALM-AF10-mediated leukemogenesis.

scholarly journals A Critical Role for Fas Ligand in the Active Suppression of Systemic Immune Responses by Ultraviolet Radiation

1999 ◽  
Vol 189 (8) ◽  
pp. 1285-1294 ◽  
Author(s):  
Laurie L. Hill ◽  
Vijay K. Shreedhar ◽  
Margaret L. Kripke ◽  
Laurie B. Owen-Schaub
Keyword(s):  
Dna Damage ◽  
Immune Responses ◽  
Immune Suppression ◽  
Fas Ligand ◽  
Critical Role ◽  
Cell Activity ◽  
Contact Hypersensitivity ◽  
Delayed Type Hypersensitivity ◽  
Intact Cells

Induction of antigen-specific suppression elicited by environmental insults, such as ultraviolet (UV)-B radiation in sunlight, can inhibit an effective immune response in vivo and may contribute to the outgrowth of UV-induced skin cancer. Although UV-induced DNA damage is known to be an initiating event in the immune suppression of most antigen responses, the underlying mechanism(s) of such suppression remain undefined. In this report, we document that Fas ligand (FasL) is critical for UV-induced systemic immune suppression. Normal mice acutely exposed to UV exhibit a profound suppression of both contact hypersensitivity and delayed type hypersensitivity (DTH) reactions and the development of transferable antigen-specific suppressor cells. FasL-deficient mice exposed to UV lack both transferable suppressor cell activity and primary suppression to all antigens tested, with the exception of the DTH response to allogeneic spleen cells. Interestingly, suppression of this response is also known to occur independently of UV-induced DNA damage. Delivery of alloantigen as protein, rather than intact cells, restored the requirement for FasL in UV-induced immune suppression of this response. These results substantiate that FasL/Fas interactions are essential for systemic UV-induced suppression of immune responses that involve host antigen presentation and suggest an interrelationship between UV-induced DNA damage and FasL in this phenomenon. Collectively, our results suggest a model whereby UV-induced DNA damage disarms the immune system in a manner similar to that observed in immunologically privileged sites.

Abstract 19363: Migration of MicroRNAs From Cardiomyocytes to Cancer Cells Interferes With Tumor Formation in the Adult Heart

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Laura Graciotti ◽  
Toru Hosoda ◽  
Fumihiro Sanada ◽  
Giulia Borghetti ◽  
Christian Arranto ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Critical Role ◽  
Tumor Formation ◽  
Molecular Characteristics ◽  
Cardiac Tumors ◽  
Mcf7 Cells ◽  
Tissue Pressure ◽  
Intramyocardial Injection

The low incidence of cardiac tumors has been attributed to tissue pressure dictated by myocardial mechanics and large coronary blood flow. These variables, however, have failed to consider the possibility that the rare occurrence of heart neoplasms may be dictated by the molecular characteristics of cardiomyocytes. We have shown that miR-1, miR-133a, and miR-499 translocate from myocytes to co-cultured MCF7 breast cancer cells, inhibiting their growth. The transfer of miRs is mediated by gap junction channels and is abolished by Cx43 and Cx45 silencing. Although these in vitro results provided important information on the inhibitory function of miRs in cell proliferation, co-culture of myocytes and cancer cells does not mimic the in vivo organization of the myocardium that allows the formation of multiple sites of coupling between myocytes and tumor cells. To reproduce, at least in part, the in vivo condition, we developed first a physiological model of organ culture. Thick vibratome-cut myocardial slices were placed on a multiwell plate containing an oxygen-saturated sponge. At 24-48 hours, the cultured tissue was viable and myocytes showed a well organized sarcomere structure. Two hours after plating of the organ slices, control MCF7 cells or MCF7 cells in which Cx43 and Cx45 were silenced (MCF7-shCx43-shCx45) were seeded on the myocardium. Control MCF7 cells showed a slower growth rate than MCF7-shCx43-shCx45 cells, a finding consistent with miR translocation and its blockade, respectively. Second, 1 x 106 MCF7 or MCF7 cells overexpressing miR-1, miR-133a, and miR-499 (MCF7-miRs) were injected subcutaneously in NOD-SCID mice; ~45 days later, the tumors developed from MCF7 cells were more than 10-fold larger and 3-fold heavier than those originated from MCF7-miRs cells. Third, these studies were complemented with the intramyocardial injection of 1 x 105 control MCF7 cells. Five weeks later, no neoplastic lesions were identified. However, when an excessive number of MCF7 cells were injected, 1 x 106, tumor formation was apparent. In conclusion, our results indicate that transfer of miR-1, miR-133a, and miR-499 from cardiomyocytes to cancer cells plays a critical role in preventing the generation of tumors in the myocardium.

scholarly journals A cell type-selective apoptosis-inducing small molecule for the treatment of brain cancer

2019 ◽  
Vol 116 (13) ◽  
pp. 6435-6440 ◽  
Author(s):  
Natasha C. Lucki ◽  
Genaro R. Villa ◽  
Naja Vergani ◽  
Michael J. Bollong ◽  
Brittney A. Beyer ◽  
...  
Keyword(s):  
Small Molecule ◽  
Brain Cancer ◽  
Critical Role ◽  
Tumor Formation ◽  
Tumor Xenograft ◽  
Drug Candidate ◽  
Cell Type ◽  
Caspase 1 ◽  
A Cell

Glioblastoma multiforme (GBM; grade IV astrocytoma) is the most prevalent and aggressive form of primary brain cancer. A subpopulation of multipotent cells termed GBM cancer stem cells (CSCs) play a critical role in tumor initiation, tumor maintenance, metastasis, drug resistance, and recurrence following surgery. Here we report the identification of a small molecule, termed RIPGBM, from a cell-based chemical screen that selectively induces apoptosis in multiple primary patient-derived GBM CSC cultures. The cell type-dependent selectivity of this compound appears to arise at least in part from redox-dependent formation of a proapoptotic derivative, termed cRIPGBM, in GBM CSCs. cRIPGBM induces caspase 1-dependent apoptosis by binding to receptor-interacting protein kinase 2 (RIPK2) and acting as a molecular switch, which reduces the formation of a prosurvival RIPK2/TAK1 complex and increases the formation of a proapoptotic RIPK2/caspase 1 complex. In an orthotopic intracranial GBM CSC tumor xenograft mouse model, RIPGBM was found to significantly suppress tumor formation in vivo. Our chemical genetics-based approach has identified a drug candidate and a potential drug target that provide an approach to the development of treatments for this devastating disease.

scholarly journals Targeting SKA3 suppresses the proliferation and chemoresistance of laryngeal squamous cell carcinoma via impairing PLK1–AKT axis-mediated glycolysis

2020 ◽  
Vol 11 (10) ◽  
Author(s):  
Wei Gao ◽  
Yuliang Zhang ◽  
Hongjie Luo ◽  
Min Niu ◽  
Xiwang Zheng ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Squamous Cell Carcinoma ◽  
Cell Carcinoma ◽  
Squamous Cell ◽  
Laryngeal Squamous Cell Carcinoma ◽  
Critical Role ◽  
In Vivo Experiments ◽  
Potential Strategy

Abstract Spindle and kinetochore-associated complex subunit 3 (SKA3) is a well-known regulator of chromosome separation and cell division, which plays an important role in cell proliferation. However, the mechanism of SKA3 regulating tumor proliferation via reprogramming metabolism is unknown. Here, SKA3 is identified as an oncogene in laryngeal squamous cell carcinoma (LSCC), and high levels of SKA3 are closely associated with malignant progression and poor prognosis. In vitro and in vivo experiments demonstrate that SKA3 promotes LSCC cell proliferation and chemoresistance through a novel role of reprogramming glycolytic metabolism. Further studies reveal the downstream mechanisms of SKA3, which can bind and stabilize polo-like kinase 1 (PLK1) protein via suppressing ubiquitin-mediated degradation. The accumulation of PLK1 activates AKT and thus upregulates glycolytic enzymes HK2, PFKFB3, and PDK1, resulting in enhancement of glycolysis. Furthermore, our data reveal that phosphorylation at Thr360 of SKA3 is critical for its binding to PLK1 and the increase in glycolysis. Collectively, the novel oncogenic signal axis “SKA3-PLK1-AKT” plays a critical role in the glycolysis of LSCC. SKA3 may serve as a prognostic biomarker and therapeutic target, providing a potential strategy for proliferation inhibition and chemosensitization in tumors, especially for LSCC patients with PLK1 inhibitor resistance.

scholarly journals Suppression of MicroRNA 200 Family Expression by Oncogenic KRAS Activation Promotes Cell Survival and Epithelial-Mesenchymal Transition in KRAS-Driven Cancer

2016 ◽  
Vol 36 (21) ◽  
pp. 2742-2754 ◽  
Author(s):  
Xiaomin Zhong ◽  
Lan Zheng ◽  
Jianfeng Shen ◽  
Dongmei Zhang ◽  
Minmin Xiong ◽  
...  
Keyword(s):  
Epithelial Mesenchymal Transition ◽  
Protein Translation ◽  
Cellular Transformation ◽  
Tumor Formation ◽  
Regulate Gene Expression ◽  
Mesenchymal Transition ◽  
Pancreatic Cancers ◽  
Mcf10a Cells

Oncogenic KRAS contributes to malignant transformation, antiapoptosis, and metastasis in multiple human cancers, such as lung, colon, and pancreatic cancers and melanoma. MicroRNAs (miRNAs) are endogenous 18- to 25-nucleotide noncoding small RNAs that regulate gene expression in a sequence-specific manner via the degradation of target mRNAs or inhibition of protein translation. In the present study, using array-based miRNA profiling in IMR90 and MCF10A cells expressing oncogenic KRAS, we identified that the expression of the microRNA 200 (mir-200) family was suppressed by KRAS activation and that this suppression was mediated by the transcription factors JUN and SP1 in addition to ZEB1. Restoration of mir-200 expression compromised KRAS-induced cellular transformationin vitroand tumor formationin vivo. In addition, we found that enforced expression of mir-200 abrogated KRAS-induced resistance to apoptosis by directly targeting the antiapoptotic geneBCL2. Finally, mir-200 was able to antagonize the epithelial-mesenchymal transition (EMT) driven by mutant KRAS. Collectively, our results suggest that repression of endogenous mir-200 expression is one of the important cellular responses to KRAS activation during tumor initiation and progression.

scholarly journals KALRN mutations promote antitumor immunity and immunotherapy response in cancer

2020 ◽  
Vol 8 (2) ◽  
pp. e000293
Author(s):  
Mengyuan Li ◽  
Yuxiang Ma ◽  
You Zhong ◽  
Qian Liu ◽  
Canping Chen ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cell Death ◽  
Immune Checkpoint ◽  
Antitumor Immunity ◽  
Immune Checkpoint Blockade ◽  
Patients With Cancer ◽  
In Vivo Experiments ◽  
Damage Repair

Backgroundkalirin RhoGEF kinase (KALRN) is mutated in a wide range of cancers. Nevertheless, the association between KALRN mutations and the pathogenesis of cancer remains unexplored. Identification of biomarkers for cancer immunotherapy response is crucial because immunotherapies only show beneficial effects in a subset of patients with cancer.MethodsWe explored the correlation between KALRN mutations and antitumor immunity in 10 cancer cohorts from The Cancer Genome Atlas program by the bioinformatics approach. Moreover, we verified the findings from the bioinformatics analysis with in vitro and in vivo experiments. We explored the correlation between KALRN mutations and immunotherapy response in five cancer cohorts receiving immune checkpoint blockade therapy.ResultsAntitumor immune signatures were more enriched in KALRN-mutated than KALRN-wildtype cancers. Moreover, KALRN mutations displayed significant correlations with increased tumor mutation burden and the microsatellite instability or DNA damage repair deficiency genomic properties, which may explain the high antitumor immunity in KALRN-mutated cancers. Also, programmed cell death 1 ligand (PD-L1) expression was markedly upregulated in KALRN-mutated versus KALRN-wildtype cancers. The increased antitumor immune signatures and PD-L1 expression in KALRN-mutated cancers may favor the response to immune checkpoint blockade therapy in this cancer subtype, as evidenced in five cancer cohorts receiving antiprogrammed cell death protein 1 (PD-1)/PD-L1/cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) immunotherapy. Furthermore, the significant association between KALRN mutations and increased antitumor immunity was associated with the fact that KALRN mutations compromised the function of KALRN in targeting Rho GTPases for the regulation of DNA damage repair pathways. In vitro and in vivo experiments validated the association of KALRN deficiency with antitumor immunity and the response to immune checkpoint inhibitors.ConclusionsThe KALRN mutation is a useful biomarker for predicting the response to immunotherapy in patients with cancer.

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