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Cell Death & Disease Jul 2020DNA damage triggers cell death mechanisms contributing to neuronal loss and cognitive decline in neurological disorders, including traumatic brain injury (TBI), and as a...
DNA damage triggers cell death mechanisms contributing to neuronal loss and cognitive decline in neurological disorders, including traumatic brain injury (TBI), and as a side effect of chemotherapy. Mithramycin, which competitively targets chromatin-binding sites of specificity protein 1 (Sp1), was used to examine previously unexplored neuronal cell death regulatory mechanisms via rat primary neurons in vitro and after TBI in mice (males). In primary neurons exposed to DNA-damage-inducing chemotherapy drugs in vitro we showed that DNA breaks sequentially initiate DNA-damage responses, including phosphorylation of ATM, HAX and tumor protein 53 (p53), transcriptional activation of pro-apoptotic BH3-only proteins, and mitochondrial outer membrane permeabilization (MOMP), activating caspase-dependent and caspase-independent intrinsic apoptosis. Mithramycin was highly neuroprotective in DNA-damage-dependent neuronal cell death, inhibiting chemotherapeutic-induced cell death cascades downstream of ATM and p53 phosphorylation/activation but upstream of p53-induced expression of pro-apoptotic molecules. Mithramycin reduced neuronal upregulation of BH3-only proteins and mitochondrial dysfunction, attenuated caspase-3/7 activation and caspase substrates' cleavage, and limited c-Jun activation. Chromatin immunoprecipitation indicated that mithramycin attenuates Sp1 binding to pro-apoptotic gene promoters without altering p53 binding suggesting it acts by removing cofactors required for p53 transactivation. In contrast, the DNA-damage-independent neuronal death models displayed caspase initiation in the absence of p53/BH3 activation and were not protected even when mithramycin reduced caspase activation. Interestingly, experimental TBI triggers a multiplicity of neuronal death mechanisms. Although markers of DNA-damage/p53-dependent intrinsic apoptosis are detected acutely in the injured cortex and are attenuated by mithramycin, these processes may play a reduced role in early neuronal death after TBI, as caspase-dependent mechanisms are repressed in mature neurons while other, mithramycin-resistant mechanisms are active. Our data suggest that Sp1 is required for p53-mediated transactivation of neuronal pro-apoptotic molecules and that mithramycin may attenuate neuronal cell death in conditions predominantly involving DNA-damage-induced p53-dependent intrinsic apoptosis.
Topics: Animals; Apoptosis; Biomarkers; Brain Injuries, Traumatic; Cell Death; DNA Damage; Etoposide; Male; Mice, Inbred C57BL; Mitochondria; Models, Biological; Neurons; Neuroprotective Agents; Plicamycin; Proto-Oncogene Proteins c-jun; Rats, Sprague-Dawley; Signal Transduction; Transcription, Genetic; Tumor Suppressor Protein p53
PubMed: 32719328
DOI: 10.1038/s41419-020-02774-6 -
Applied Microbiology and Biotechnology Sep 2020The aureolic acid-type polyketide mithramycin (MTM) has a remarkable cytotoxicity against a variety of human tumors and has been used for the treatment of several types... (Review)
Review
The aureolic acid-type polyketide mithramycin (MTM) has a remarkable cytotoxicity against a variety of human tumors and has been used for the treatment of several types of cancer, including chronic and acute myeloid leukemia, testicular carcinoma, hypercalcemia, and Paget's disease. However, its clinical use is quite limited due to its toxicity. Recently, interest in MTM has been renewed after its identification as a top candidate for the inhibition of the aberrant fusion transcription factor EWS-FLI1, associated with malignant transformation and progression of Ewing sarcoma tumor family. The mechanism of MTM inhibition involves its reversible non-intercalative interaction with GC-rich DNA regions. As a result of this binding, MTM blocks binding of transcription factors (such as Sp1) to their GC-rich promoters and inhibits transcription of several proto-oncogenes and thus suppresses various types of cancer. Knowledge of the biosynthesis of MTM and its gene cluster has enabled genetic modifications of the gene cluster and combinatorial biosynthesis to produce new modified MTM molecules ("mithralogues") with improved efficacy and lower toxicity, which has also renewed interest in the clinical development of MTM. However, production yields of MTM and its analogues are low in the natural production strains. Recent developments in genetic engineering approaches have made it possible to increase MTM production through more rational strategies based on genetic manipulations and heterologous expression in optimized chassis. Recent construction of various genetically modified strains of Streptomyces lividans has shown their use for efficient heterologous production of various biologically active secondary metabolites including MTM. KEY POINTS: • Discovery a novel bifunctional glycosyl hydrolase from uncultured microorganism. • Heterologous production of MTM in engineered S. lividans strains is efficient.
Topics: Anti-Bacterial Agents; Antibiotics, Antineoplastic; Humans; Plicamycin; Polyketides; Sarcoma, Ewing
PubMed: 32686008
DOI: 10.1007/s00253-020-10782-x -
Biochemical Pharmacology Mar 2022Mithramycin A (MIT) has reacquired extensive research attention due to its anti-solid tumor activity and improved pharmacological production. Mechanismly, MIT was...
Mithramycin A (MIT) has reacquired extensive research attention due to its anti-solid tumor activity and improved pharmacological production. Mechanismly, MIT was broadly used as a c-Myc inhibitor, and c-Myc regulated CD47 and PD-L1 expression which has been demonstrated. However, how MIT affects immune check-point molecules remains unknown. In this study, we found CD47 expression was higher in melanoma of pan-tissue array. MIT inhibited CD47 expression both in mRNA and protein level in melanoma cells (SK-MEL-28 and B16). MIT inhibited c-Myc, Sp-1 and CD47 expression in a concentration-dependent way. MIT inhibited the surface CD47 expression and promoted the phagocytosis of SK-MEL-28 cells by THP-1 cells. We found MIT inhibited tumor growth in melanoma allograft mice and CD47 expression in tumor mass. We also found MIT upregulated PD-L1 expression in cancer cells possibly via inhibiting PD-L1 ubiquitination, increasing ROS and IFN-γ. Combination of MIT and anti-PD-1 antibody showed enhanced antitumor activity compared to MIT and anti-PD-1 antibody alone in MC38 allograft mice. Using immune checkpoint array we found MIT inhibited expression of FasL and Galectin3. These results suggest that MIT inhibits CD47 expression, while improves PD-L1 expression. Furthermore, the combination of MIT and anti-PD-1 antibody exerts potent antitumor effect.
Topics: Animals; Antibiotics, Antineoplastic; B7-H1 Antigen; CD47 Antigen; Dose-Response Relationship, Drug; Female; Gene Expression; Humans; Melanoma, Experimental; Mice; Mice, Inbred C57BL; Plicamycin; THP-1 Cells; Xenograft Model Antitumor Assays
PubMed: 34968486
DOI: 10.1016/j.bcp.2021.114894 -
Journal of Pharmacological Sciences 2013Mithramycin A (MTM) has been shown to inhibit cancer growth by blocking the binding of Sp-family transcription factors to gene regulatory elements and is used for the... (Review)
Review
Mithramycin A (MTM) has been shown to inhibit cancer growth by blocking the binding of Sp-family transcription factors to gene regulatory elements and is used for the treatment of leukemia and testicular cancer in the United States. In contrast, MTM has also been shown to exert neuroprotective effects in normal cells. An earlier study showed that MTM protected primary cortical neurons against oxidative stress-induced cell death. Recently, we demonstrated that MTM suppressed endoplasmic reticulum (ER) stress-induced neuronal death in organotypic hippocampal slice cultures and cultured hippocampal cells through attenuation of ER stress-associated signal proteins. We also found that MTM decreased neuronal death in area CA1 of the hippocampus after transient global ischemia/reperfusion in mice and restored the ischemia/reperfusion-induced impairment of long-term potentiation in this area. MTM has been shown to prolong the survival of Huntington's disease model mice and to attenuate dopaminergic neurotoxicity in mice after repeated administration of methamphetamine. In this review, we provide an up to date overview of neuroprotective effects of MTM and less toxic MTM analogs, MTM SK and MTM SDK, on some of the neurodegenerative diseases and discuss the promise of MTM as an agent for developing new therapeutic drugs for such diseases.
Topics: Animals; Cell Death; Cells, Cultured; Cerebral Cortex; Disease Models, Animal; Endoplasmic Reticulum Stress; Hippocampus; Humans; Huntington Disease; Long-Term Potentiation; Methamphetamine; Mice; Molecular Targeted Therapy; Neurodegenerative Diseases; Neurons; Neuroprotective Agents; Oxidative Stress; Plicamycin; Reperfusion Injury
PubMed: 23902990
DOI: 10.1254/jphs.13r02cp -
EMBO Molecular Medicine Feb 2021Rhabdoid tumor (RT) is a pediatric cancer characterized by the inactivation of SMARCB1, a subunit of the SWI/SNF chromatin remodeling complex. Although this deletion is...
Rhabdoid tumor (RT) is a pediatric cancer characterized by the inactivation of SMARCB1, a subunit of the SWI/SNF chromatin remodeling complex. Although this deletion is the known oncogenic driver, there are limited effective therapeutic options for these patients. Here we use unbiased screening of cell line panels to identify a heightened sensitivity of rhabdoid tumor to mithramycin and the second-generation analogue EC8042. The sensitivity of MMA and EC8042 was superior to traditional DNA damaging agents and linked to the causative mutation of the tumor, SMARCB1 deletion. Mithramycin blocks SMARCB1-deficient SWI/SNF activity and displaces the complex from chromatin to cause an increase in H3K27me3. This triggers chromatin remodeling and enrichment of H3K27ac at chromHMM-defined promoters to restore cellular differentiation. These effects occurred at concentrations not associated with DNA damage and were not due to global chromatin remodeling or widespread gene expression changes. Importantly, a single 3-day infusion of EC8042 caused dramatic regressions of RT xenografts, recapitulated the increase in H3K27me3, and cellular differentiation described in vitro to completely cure three out of eight mice.
Topics: Animals; Cell Differentiation; Chromosomal Proteins, Non-Histone; Humans; Mice; Plicamycin; Rhabdoid Tumor; Transcription Factors
PubMed: 33332735
DOI: 10.15252/emmm.202012640 -
Journal of Nanobiotechnology Sep 2021Sarcomas comprise a group of aggressive malignancies with very little treatment options beyond standard chemotherapy. Reposition of approved drugs represents an...
BACKGROUND
Sarcomas comprise a group of aggressive malignancies with very little treatment options beyond standard chemotherapy. Reposition of approved drugs represents an attractive approach to identify effective therapeutic compounds. One example is mithramycin (MTM), a natural antibiotic which has demonstrated a strong antitumour activity in several tumour types, including sarcomas. However, its widespread use in the clinic was limited by its poor toxicity profile.
RESULTS
In order to improve the therapeutic index of MTM, we have loaded MTM into newly developed nanocarrier formulations. First, polylactide (PLA) polymeric nanoparticles (NPs) were generated by nanoprecipitation. Also, liposomes (LIP) were prepared by ethanol injection and evaporation solvent method. Finally, MTM-loaded hydrogels (HG) were obtained by passive loading using a urea derivative non-peptidic hydrogelator. MTM-loaded NPs and LIP display optimal hydrodynamic radii between 80 and 105 nm with a very low polydispersity index (PdI) and encapsulation efficiencies (EE) of 92 and 30%, respectively. All formulations show a high stability and different release rates ranging from a fast release in HG (100% after 30 min) to more sustained release from NPs (100% after 24 h) and LIP (40% after 48 h). In vitro assays confirmed that all assayed MTM formulations retain the cytotoxic, anti-invasive and anti-stemness potential of free MTM in models of myxoid liposarcoma, undifferentiated pleomorphic sarcoma and chondrosarcoma. In addition, whole genome transcriptomic analysis evidenced the ability of MTM, both free and encapsulated, to act as a multi-repressor of several tumour-promoting pathways at once. Importantly, the treatment of mice bearing sarcoma xenografts showed that encapsulated MTM exhibited enhanced therapeutic effects and was better tolerated than free MTM.
CONCLUSIONS
Overall, these novel formulations may represent an efficient and safer MTM-delivering alternative for sarcoma treatment.
Topics: Animals; Anti-Bacterial Agents; Antineoplastic Agents; Chondrosarcoma; Drug Compounding; Female; Humans; Hydrogels; Liposomes; Mice; Mice, Nude; Nanoparticles; Plicamycin; Polyesters; Sarcoma
PubMed: 34488783
DOI: 10.1186/s12951-021-01008-x -
ChemMedChem Feb 2023DNA coordinating platinum (Pt) containing compounds cisplatin and carboplatin have been used for the treatment of ovarian cancer therapy for four decades. However,...
DNA coordinating platinum (Pt) containing compounds cisplatin and carboplatin have been used for the treatment of ovarian cancer therapy for four decades. However, recurrent Pt-resistant cancers are a major cause of mortality. To combat Pt-resistant ovarian cancers, we designed and synthesized a conjugate of an anticancer drug mithramycin with a reactive Pt(II) bearing moiety, which we termed mithplatin. The conjugates displayed both the Mg -dependent noncovalent DNA binding characteristic of mithramycin and the covalent crosslinking to DNA of the Pt. The conjugate was three times as potent as cisplatin against ovarian cancer cells. The DNA lesions caused by the conjugate led to the generation of DNA double-strand breaks, as also observed with cisplatin. Nevertheless, the conjugate was highly active against both Pt-sensitive and Pt-resistant ovarian cancer cells. This study paves the way to developing mithplatins to combat Pt-resistant ovarian cancers.
Topics: Humans; Female; Cisplatin; Plicamycin; Antineoplastic Agents; Ovarian Neoplasms; DNA; Cell Line, Tumor; Drug Resistance, Neoplasm
PubMed: 36342449
DOI: 10.1002/cmdc.202200368 -
Advances in Pharmacology and... 1975
Comparative Study Review
Topics: Animals; Chemical Phenomena; Chemistry; Chromomycins; Dogs; Female; Humans; Kinetics; Lethal Dose 50; Male; Mice; Neoplasms; Neoplasms, Experimental; Olivomycins; Plicamycin; Rabbits; Rats
PubMed: 125531
DOI: 10.1016/s1054-3589(08)60218-5 -
International Journal of Radiation... Feb 2018Specificity protein 1 (SP1) is involved in the transcription of several genes implicated in tumor maintenance. We investigated the effects of mithramycin A (MTA), an...
PURPOSE
Specificity protein 1 (SP1) is involved in the transcription of several genes implicated in tumor maintenance. We investigated the effects of mithramycin A (MTA), an inhibitor of SP1 DNA binding, on radiation response.
METHODS AND MATERIALS
Clonogenic survival after irradiation was assessed in 2 tumor cell lines (A549, UM-UC-3) and 1 human fibroblast line (BJ) after SP1 knockdown or MTA treatment. DNA damage repair was evaluated using γH2AX foci formation, and mitotic catastrophe was assessed using nuclear morphology. Gene expression was evaluated using polymerase chain reaction arrays. In vivo tumor growth delay was used to evaluate the effects of MTA on radiosensitivity.
RESULTS
Targeting of SP1 with small interfering RNA or MTA sensitized A549 and UM-UC-3 to irradiation, with no effect on the BJ radiation response. MTA did not alter γH2AX foci formation after irradiation in tumor cells but did enhance mitotic catastrophe. Treatment with MTA suppressed transcription of genes involved in cell death. MTA administration to mice bearing A549 and UM-UC-3 xenografts enhanced radiation-induced tumor growth delay.
CONCLUSIONS
These results support SP1 as a target for radiation sensitization and confirm MTA as a radiation sensitizer in human tumor models.
Topics: Animals; Apoptosis; Cell Cycle; Cell Line, Tumor; DNA Damage; DNA Repair; Humans; Mice; Mitosis; Neoplasms, Experimental; Plicamycin; Radiation-Sensitizing Agents; Sp1 Transcription Factor
PubMed: 29157749
DOI: 10.1016/j.ijrobp.2017.09.049 -
Cancer Letters Sep 2020The dependency of prostate cancer (PCa) growth on androgen receptor (AR) signaling has been harnessed to develop first-line therapies for high-risk localized and...
The dependency of prostate cancer (PCa) growth on androgen receptor (AR) signaling has been harnessed to develop first-line therapies for high-risk localized and metastatic PCa treatment. However, the occurrence of aberrant expression, mutated or splice variants of AR confers resistance to androgen ablation therapy (ADT), radiotherapy or chemotherapy in AR-positive PCa. Therapeutic strategies that effectively inhibit the expression and/or transcriptional activity of full-length AR, mutated AR and AR splice variants have remained elusive. In this study, we report that mithramycin (MTM), an antineoplastic antibiotic, suppresses cell proliferation and exhibits dual inhibitory effects on expression and transcriptional activity of AR and AR splice variants. MTM blocks AR recruitment to its genomic targets by occupying AR enhancers and causes downregulation of AR target genes, which includes key DNA repair factors in DNA damage repair (DDR). We show that MTM significantly impairs DDR and enhances the effectiveness of ionizing radiation or the radiomimetic agent Bleomycin in PCa. Thus, the combination of MTM treatment with RT or radiomimetic agents, such as bleomycin, may present a novel effective therapeutic strategy for patients with high-risk, clinically localized PCa.
Topics: Antibiotics, Antineoplastic; Cell Line, Tumor; DNA Damage; DNA Repair; Humans; Male; Plicamycin; Prostatic Neoplasms, Castration-Resistant; Receptors, Androgen
PubMed: 32485222
DOI: 10.1016/j.canlet.2020.05.027