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Planta Medica Oct 2015Mithramycin is an antitumor compound of the aureolic acid family produced by Streptomyces argillaceus. It has been used to treat several types of cancer including... (Review)
Review
Expanding the Chemical Diversity of the Antitumoral Compound Mithramycin by Combinatorial Biosynthesis and Biocatalysis: The Quest for Mithralogs with Improved Therapeutic Window.
Mithramycin is an antitumor compound of the aureolic acid family produced by Streptomyces argillaceus. It has been used to treat several types of cancer including testicular carcinoma, chronic and acute myeloid leukemia as well as hypercalcemias and Paget's disease. Although the use of mithramycin in humans has been limited because its side effects, in recent years a renewed interest has arisen since new uses and activities have been ascribed to it. Chemically, mithramycin is characterized by a tricyclic aglycone bearing two aliphatic side chains attached at C3 and C7, and disaccharide and trisaccharide units attached at positions 2 and 6, respectively. The mithramycin gene cluster has been characterized. This has allowed for the development of several mithramycin analogs ("mithralogs") by combinatorial biosynthesis and/or biocatalysis. The combinatorial biosynthesis strategies include gene inactivation and/or the use of sugar biosynthesis plasmids for sugar modification. In addition, lipase-based biocatalysis enabled selective modifications of the hydroxyl groups, providing further mithramycin analogs. As a result, new mithramycin analogs with higher antitumor activity and/or less toxicity have been generated. One, demycarosyl-3D-β-D-digitoxosyl-mithramycin SK (EC-8042), is being tested in regulatory preclinical assays, representing an opportunity to open the therapeutic window of this promising molecular scaffold.
Topics: Animals; Antibiotics, Antineoplastic; Biocatalysis; Combinatorial Chemistry Techniques; Humans; Plicamycin; Streptomyces
PubMed: 26393942
DOI: 10.1055/s-0035-1557876 -
Mithramycin A Radiosensitizes EWS:Fli1 Ewing Sarcoma Cells by Inhibiting Double Strand Break Repair.International Journal of Radiation... Apr 2021The oncogenic EWS:Fli1 fusion protein is a key transcriptional mediator of Ewing sarcoma initiation, progression, and therapeutic resistance. Mithramycin A (MithA) is a...
PURPOSE
The oncogenic EWS:Fli1 fusion protein is a key transcriptional mediator of Ewing sarcoma initiation, progression, and therapeutic resistance. Mithramycin A (MithA) is a potent and specific inhibitor of transcription mediated by the EWS:Fli1. We tested the hypothesis that pretreatment with MithA could selectively radiosensitize EWS:Fli1 tumor cells by altering the transcriptional response to radiation injury.
METHODS AND MATERIALS
A panel of 4 EWS:Fli1 and 3 EWS:Fli1 Ewing sarcoma cell lines and 1 nontumor cell line were subjected to MithA dose-response viability assays to determine the relative potency of MithA in cells possessing or lacking the EWS:Fli1 fusion. Radiosensitization by MithA was evaluated by clonogenic survival assays in vitro and in a murine xenograft model. DNA damage was evaluated by comet assay and γ-H2Ax flow cytometry. Immunoblotting, flow cytometry, and reverse-transcription, polymerase chain reaction were used to evaluate DNA damage-induced signaling and repair processes and apoptosis.
RESULTS
We found that MithA alone could potently and selectively inhibit the growth of EWS:Fli1 tumor cells, but not cells lacking this fusion. Pretreatment with MithA for 24 hours before irradiation significantly reduced clonogenic survival in vitro and delayed tumor regrowth in vivo, prolonging survival of EWS:Fli1 tumor-bearing mice. Although MithA did not increase the level of DNA double-strand breaks, mechanistic studies revealed that MithA pretreatment selectively inhibited DNA double-strand break repair through downregulation of EWS:Fli1-mediated transcription, leading to tumor cell death by apoptosis.
CONCLUSIONS
Our data indicate that MithA is an effective radiosensitizer of EWS:Fli1 tumors and may achieve better local control at lower doses of radiation.
Topics: Animals; Apoptosis; Cell Line, Tumor; Cell Proliferation; Cell Survival; Comet Assay; DNA Breaks, Double-Stranded; DNA Repair; Dose-Response Relationship, Drug; Down-Regulation; Histones; Mice; Oncogene Proteins, Fusion; Plicamycin; Proto-Oncogene Protein c-fli-1; RNA-Binding Protein EWS; Radiation Tolerance; Radiation-Sensitizing Agents; Reverse Transcriptase Polymerase Chain Reaction; Sarcoma, Ewing; Xenograft Model Antitumor Assays
PubMed: 33373655
DOI: 10.1016/j.ijrobp.2020.12.010 -
Journal of Experimental & Clinical... Aug 2023Gemcitabine resistance (GR) is a significant clinical challenge in pancreatic adenocarcinoma (PAAD) treatment. Macrophages in the tumor immune-microenvironment are...
BACKGROUND
Gemcitabine resistance (GR) is a significant clinical challenge in pancreatic adenocarcinoma (PAAD) treatment. Macrophages in the tumor immune-microenvironment are closely related to GR. Uncovering the macrophage-induced GR mechanism could help devise a novel strategy to improve gemcitabine treatment outcomes in PAAD. Therefore, preclinical models accurately replicating patient tumor properties are essential for cancer research and drug development. Patient-derived organoids (PDOs) represent a promising in vitro model for investigating tumor targets, accelerating drug development, and enabling personalized treatment strategies to improve patient outcomes.
METHODS
To investigate the effects of macrophage stimulation on GR, co-cultures were set up using PDOs from three PAAD patients with macrophages. To identify signaling factors between macrophages and pancreatic cancer cells (PCCs), a 97-target cytokine array and the TCGA-GTEx database were utilized. The analysis revealed CCL5 and AREG as potential candidates. The role of CCL5 in inducing GR was further investigated using clinical data and tumor sections obtained from 48 PAAD patients over three years, inhibitors, and short hairpin RNA (shRNA). Furthermore, single-cell sequencing data from the GEO database were analyzed to explore the crosstalk between PCCs and macrophages. To overcome GR, inhibitors targeting the macrophage-CCL5-Sp1-AREG feedback loop were evaluated in cell lines, PDOs, and orthotopic mouse models of pancreatic carcinoma.
RESULTS
The macrophage-CCL5-Sp1-AREG feedback loop between macrophages and PCCs is responsible for GR. Macrophage-derived CCL5 activates the CCR5/AKT/Sp1/CD44 axis to confer stemness and chemoresistance to PCCs. PCC-derived AREG promotes CCL5 secretion in macrophages through the Hippo-YAP pathway. By targeting the feedback loop, mithramycin improves the outcome of gemcitabine treatment in PAAD. The results from the PDO model were corroborated with cell lines, mouse models, and clinical data.
CONCLUSIONS
Our study highlights that the PDO model is a superior choice for preclinical research and precision medicine. The macrophage-CCL5-Sp1-AREG feedback loop confers stemness to PCCs to facilitate gemcitabine resistance by activating the CCR5/AKT/SP1/CD44 pathway. The combination of gemcitabine and mithramycin shows potential as a therapeutic strategy for treating PAAD in cell lines, PDOs, and mouse models.
Topics: Animals; Mice; Gemcitabine; Pancreatic Neoplasms; Deoxycytidine; Proto-Oncogene Proteins c-akt; Coculture Techniques; Adenocarcinoma; Plicamycin; Drug Resistance, Neoplasm; Cell Line, Tumor; Macrophages; RNA, Small Interfering; Organoids; Tumor Microenvironment
PubMed: 37553567
DOI: 10.1186/s13046-023-02756-4 -
Scientific Reports Oct 2019The pivotal role of cancer initiating stem cells (CSCs) in tumor initiation, growth, metastasis and drug resistance has led to the postulation of a 'total cancer...
The pivotal role of cancer initiating stem cells (CSCs) in tumor initiation, growth, metastasis and drug resistance has led to the postulation of a 'total cancer therapy' paradigm, which involves targeting both cancer cells and CSCs for effective therapy. However, the progress in identifying drugs for total cancer therapy has been limited. Herein, we show for the first time that mithramycin A (Mit-A) can successfully inhibit CSC proliferation, in addition to inhibiting bulk cancer cells in a model of colorectal cancer (CRC), the second leading cause of death among men and women in the United States. To this end, a polymeric nanofiber scaffold culture system was established to develop 3D tumor organoids (tumoroids) from CRC cell lines such as HT29, HCT116, KM12, CT26 and MC38 as well as ex vivo mouse tumors. These tumoroids possessed increased expression of CSC markers and transcription factors, expanded the number of CSCs in culture and increased CSC functional properties measured by aldehyde dehydrogenase activity. Screening of an NCI library of FDA approved drugs led to the identification of Mit-A as a potential total cancer therapy drug. In both sphere and tumoroid culture, Mit-A inhibits cancer growth by reducing the expression of cancer stemness markers. In addition, Mit-A inhibits the expression of SP1, a previously known target in CRCs. Moreover, Mit-A significantly reduces growth of tumoroids in ex vivo cultures and CRC tumor growth in vivo. Finally, a dose-dependent treatment on CRC cells indicate that Mit-A significantly induces the cell death and PARP-cleavage of both CSC and non-CSC cells. Taken together the results of these in vitro, ex vivo and in vivo studies lead to the inference that Mit-A is a promising drug candidate for total cancer therapy of CRCs.
Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Colorectal Neoplasms; HCT116 Cells; HT29 Cells; Humans; Mice, Inbred C57BL; Neoplastic Stem Cells; Plicamycin
PubMed: 31645574
DOI: 10.1038/s41598-019-50917-3 -
Structure (London, England : 1993) May 2021Fusion products with the ETS family of transcription factors play critical roles in the etiology of several cancers. In this issue of Structure, Hou et al. (2020)...
Fusion products with the ETS family of transcription factors play critical roles in the etiology of several cancers. In this issue of Structure, Hou et al. (2020) provide insight into allosteric mechanisms by which mithramycin and its analogs perturb protein-DNA interactions in higher-order complexes at a DNA enhancer site.
Topics: Base Sequence; DNA; Plicamycin; Transcription Factors
PubMed: 33961789
DOI: 10.1016/j.str.2021.03.010 -
International Journal of Molecular... May 2018Osteoarthritis (OA) is the most common and increasing joint disease worldwide. Current treatment for OA is limited to control of symptoms. The purpose of this study was...
Osteoarthritis (OA) is the most common and increasing joint disease worldwide. Current treatment for OA is limited to control of symptoms. The purpose of this study was to determine the effect of specificity protein 1 (SP1) inhibitor Mithramycin A (MitA) on chondrocyte catabolism and OA pathogenesis and to explore the underlying molecular mechanisms involving SP1 and other key factors that are critical for OA. Here, we show that MitA markedly inhibited expressions of matrix-degrading enzymes induced by pro-inflammatory cytokine interleukin-1β (IL-1β) in mouse primary chondrocytes. Intra-articular injection of MitA into mouse knee joint alleviated OA cartilage destruction induced by surgical destabilization of the medial meniscus (DMM). However, modulation of SP1 level in chondrocyte and mouse cartilage did not alter catabolic gene expression or cartilage integrity, respectively. Instead, MitA significantly impaired the expression of HIF-2α known to be critical for OA pathogenesis. Such reduction in expression of HIF-2α by MitA was caused by inhibition of NF-κB activation, at least in part. These results suggest that MitA can alleviate OA pathogenesis by suppressing NF-κB-HIF-2α pathway, thus providing insight into therapeutic strategy for OA.
Topics: Animals; Basic Helix-Loop-Helix Transcription Factors; Cartilage, Articular; Cells, Cultured; Chondrocytes; Disease Progression; Enzyme Induction; Interleukin-1beta; Joints; Male; Matrix Metalloproteinases; Mice, Inbred C57BL; NF-kappa B; Osteoarthritis; Plicamycin; Sp1 Transcription Factor
PubMed: 29747385
DOI: 10.3390/ijms19051411 -
Biochemistry Apr 1991The c-myc protooncogene plays an important role in the regulation of cellular proliferation. Mithramycin, a DNA binding antibiotic which binds G-C-rich DNA, inhibits...
The c-myc protooncogene plays an important role in the regulation of cellular proliferation. Mithramycin, a DNA binding antibiotic which binds G-C-rich DNA, inhibits c-myc expression in both differentiating and nondifferentiating cells. The G-C-rich nature of the c-myc promoter suggests that mithramycin may act by directly inhibiting promoter function. The mithramycin binding sites in the c-myc promoter regions were determined by DNAse I footprinting. Particularly prominent mithramycin binding is noted in the regions just 5' of the P1 and P2 promoter TATA boxes. Gel retardation experiments performed in the presence of mithramycin demonstrate that drug binding can prevent the formation of discrete complexes between HeLa cell nuclear proteins and c-myc promoter DNA fragments. Mithramycin also directly blocks the binding of the transcription factor Sp1 to the P1 promoter region. In vitro run-off transcription demonstrates that mithramycin can completely inhibit the in vitro function of both the P1 and P2 promoters. These data suggest that mithramycin inhibits transcription of the c-myc protooncogene by blocking the binding of important regulatory factors, thus preventing formation of the c-myc transcription initiation complex.
Topics: Base Sequence; Binding Sites; DNA Fingerprinting; DNA Probes; Genes, myc; HeLa Cells; Humans; Molecular Sequence Data; Plasmids; Plicamycin; Promoter Regions, Genetic; Transcription, Genetic
PubMed: 1827033
DOI: 10.1021/bi00231a027 -
Chemical Biology & Drug Design May 2013Mithramycin (MTM) is a potent anti-cancer agent that has recently garnered renewed attention. This manuscript describes the design and development of mithramycin...
Mithramycin (MTM) is a potent anti-cancer agent that has recently garnered renewed attention. This manuscript describes the design and development of mithramycin derivatives through a combinational approach of biosynthetic analogue generation followed by synthetic manipulation for further derivatization. Mithramycin SA is a previously discovered analogue produced by the M7W1 mutant strain alongside the improved mithramycin analogues mithramycin SK and mithramycin SDK. Mithramycin SA shows decreased anti-cancer activity compared to mithramycin and has a shorter, two carbon aglycon side chain that is terminated in a carboxylic acid. The aglycon side chain is responsible for an interaction with the DNA-phosphate backbone as mithramycin interacts with its target DNA. It was therefore decided to further functionalize this side chain through reactions with the terminal carboxylic acid in an effort to enhance the interaction with the DNA phosphate backbone and improve the anti-cancer activity. This side chain was modified with a variety of molecules increasing the anti-cancer activity to a comparable level to mithramycin SK. This work shows the ability to transform the previously useless mithramycin SA into a valuable molecule and opens the door to further functionalization and semi-synthetic modification for the development of molecules with increased specificity and/or drug formulation.
Topics: Antibiotics, Antineoplastic; Cell Line, Tumor; DNA, Neoplasm; Drug Screening Assays, Antitumor; Humans; Neoplasms; Plicamycin
PubMed: 23331575
DOI: 10.1111/cbdd.12107 -
International Journal of Nanomedicine 2017Previous studies have shown that mithramycin A (MIT) is a promising candidate for the treatment of pancreatic carcinoma through inhibiting transcription factor Sp1....
Previous studies have shown that mithramycin A (MIT) is a promising candidate for the treatment of pancreatic carcinoma through inhibiting transcription factor Sp1. However, systemic toxicities may limit its clinical application. Here, we report a rationally designed formulation of MIT-loaded nanoparticles (MIT-NPs) with a small size and sustained release for improved passive targeting and enhanced therapeutic efficacy. Nearly spherical MIT-NPs with a mean particle size of 25.0±4.6 nm were prepared by encapsulating MIT into methoxy poly(ethylene glycol)-block-poly(d,l-lactic--glycolic acid) (mPEG-PLGA) nanoparticles (NPs) with drug loading of 2.11%±0.51%. The in vitro release of the MIT-NPs lasted for >48 h with a sustained-release pattern. The cytotoxicity of MIT-NPs to human pancreatic cancer BxPC-3 and MIA Paca-2 cells was comparable to that of free MIT. Determined by flow cytometry and confocal microscopy, the NPs internalized into the cells quickly and efficiently, reaching the peak level at 1-2 h. In vivo fluorescence imaging showed that the prepared NPs were gradually accumulated in BxPC-3 and MIA Paca-2 xenografts and retained for 168 h. The fluorescence intensity in both BxPC-3 and MIA Paca-2 tumors was much stronger than that of various tested organs. Therapeutic efficacy was evaluated with the poorly permeable BxPC-3 pancreatic carcinoma xenograft model. At a well-tolerated dose of 2 mg/kg, MIT-NPs suppressed BxPC-3 tumor growth by 96%. Compared at an equivalent dose, MIT-NPs exerted significantly higher therapeutic effect than free MIT (86% versus 51%, <0.01). Moreover, the treatment of MIT and MIT-NPs reduced the expression level of oncogene regulated by Sp1, and notably, both of them decreased the protein level of CD47. In summary, the novel formulation of MIT-NPs shows highly therapeutic efficacy against pancreatic carcinoma xenograft. In addition, MIT-NPs can downregulate CD47 expression, implying that it might play a positive role in cancer immunotherapy.
Topics: Animals; Antibiotics, Antineoplastic; Cell Line, Tumor; Drug Carriers; Drug Liberation; Female; Humans; Mice, Inbred BALB C; Microscopy, Confocal; Nanoparticles; Pancreatic Neoplasms; Particle Size; Plicamycin; Polyesters; Polyethylene Glycols; Tissue Distribution; Xenograft Model Antitumor Assays
PubMed: 28769562
DOI: 10.2147/IJN.S139507 -
The Medical Letter on Drugs and... Oct 1973
Topics: Calcium; Female; Humans; Hypercalcemia; Male; Neoplasm Metastasis; Osteitis Deformans; Plicamycin; Teratoma; Testicular Neoplasms
PubMed: 4270066
DOI: No ID Found