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DIG-MSK regulates the expression of SP1 and key oncogenic genes in ovarian tumor cells. (a) Relative changes in luciferase activity of a transfected Sp1-reported vector in the presence of 200 nM MTA or DIG-MSK compared to untreated ovarian cancer cells. qRT-PCR analysis of the expression of SP1 gene and several key Sp1-regulated oncogenic genes in ovarian cancer cells treated or untreated with 200 nM MTA or DIG-MSK. Data represent the mean ± SEM of Ct values obtained from at least three independent experiments made by duplicate. The relative mRNA expression was obtained by comparison of the expression profiles of untreated cells (DMSO) versus treated ones (*p<0.05; **p<0.01, Mann-Whitney U test).
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Demycarosyl-3D-ß-D-digitoxosyl-mithramycin SK (DIG-MSK) is a recently isolated analogue of mithramycin A (MTA) that showed differences with MTA in the DNA binding strength and selectivity. These differences correlated with a better therapeutic index and less toxicity in animal studies. Herein, we show that DIG-MSK displays a potent anti-tumor activ...
Citations
... The treatment of the cells with a combination of mithramycin and cycloheximide (a protein synthesis inhibitor) or MG132 (a 26S proteasome inhibitor) demonstrated that the inhibitory effect of mithramycin on SP1 was related to proteasome functioning [45]. Incubation of testicular carcinoma cells with 200 nM mithramycin or its analog DIG-MSK resulted in a decrease in the SP1 mRNA concentration by more than 20% as early as in 8 h [47]. The SP1 inhibition in murine myeloma 5TGM1 cells was not nearly observed, which did not allow an unambiguous conclusion on the mithramycin effect on the SP1 expression [48]. ...
Aureolic acid-derived antibiotics such as mithramycin, chromomycin A3, and olivomycin А, are aromatic glycosylated polyketides produced by actinomycetes. The structure of aureolic acid is represented by a tricyclic aglycone conjugated with two oligosaccharide chains and a pentyl side chain in the C3 position. Microbial biosynthesis in producer strains, as well as functioning of individual enzymes and the role of each biosynthetic step for biological activities of mithramycin and chromomycin А3, have been comprehensively studied. This knowledge supports a rational search for new, more specific and less toxic analogs of currently known antibiotics derived from aureolic acid. In this review, we summarized basic and the latest data on the biosynthesis of aureolic acid-derived antibiotics and discussed current approaches to chemical and semisynthetic modifications and structure–activity relationship studies. Molecular processes of cytotoxicity and opportunities for the development of this class of compounds as potential antitumor antibiotics have been considered.
... Mithramycin and additional analogs demonstrated rapid intracellular accumulation in OVCAR-3 cell lines [38]. The IC 50 values of mithramycin and related compounds were in the low-nanomolar range in OVCAR-3 cell cultures, induce cell arrest in G1 [70]. This finding raises the possibility of mithramycin or its analog as a potential treatment for chemotherapy-resistant ovarian cancer, particularly platinum-resistant cancer. ...
... One of the most promising mithralogs, demycarosyl-3D-betat-D-digitoxosyl-mithramycin SK (MTM-DIG-MSK or EC-8042), has demonstrated retained anti-tumor properties, including in vitro ovarian cancer lines, but reduced in vitro toxicity in fibroblasts and mononuclear blood cells, compared to mithramycin [37,40,70,82]. Mithramycin and EC-8042 reduced the viability and invasiveness of malignant melanoma cell lines [85]. ...
... Mithramycin analogs also demonstrated efficacy in pre-clinical ovarian studies. EC-8042 displayed significant anti-tumor activity against ovarian cancer cell lines with significantly lower toxicity to fibroblasts and peripheral blood cells compared to mithramycin; while strongly inhibiting Sp1 transcription and reduction in several genes implicated in tumorigenesis including VEGF, BRCA2, cMyc, and src [38,70]. In one of the most detailed studies involving ovarian cancer and MTM analogs, MTM-SDK and MTM-SK, demonstrated considerable inhibition of Sp1 dependent transcription in vitro. ...
Ovarian cancer is a highly deadly malignancy in which recurrence is considered incurable. Resistance to platinum-based chemotherapy bodes a particularly abysmal prognosis, underscoring the need for novel therapeutic agents and strategies. The use of mithramycin, an antineoplastic antibiotic, has been previously limited by its narrow therapeutic window. Recent advances in semisynthetic methods have led to mithramycin analogs with improved pharmacological profiles. Mithramycin inhibits the activity of the transcription factor Sp1, which is closely linked with ovarian tumorigenesis and platinum-resistance. This article summarizes recent clinical developments related to mithramycin and postulates a role for the use of mithramycin, or its analog, in the treatment of platinum-resistant ovarian cancer.
... However, abnormal angiogenesis is the consequence of the uneven expression of these growth factors to the cancer site, which may further influence the EPR. Further exploration of this mechanism has opened up several research options including the development of antiangiogenic therapies through targeting these proangiogenic targets, which are in process to treat and cure cancer [59]. Further, the application of VEGF to the human colon tumor xenograft animal models has shown to enhance the porosity of the blood vessels at the cancer site, to allow the macromolecules more that leaky area [60]. ...
Differentiating the external environment to the internal environment of the body is always a concern to establish the safety of the living systems. Thus, the natural existence of different biological barriers is highly significant for the function and integrity of numerous vertebrate organs. The chapter summarizes several important characteristics of existing biological barriers, which are known to have an inverse relationship between concentrations of the drugs in plasma to the efficacy of the drug. Overexpression of certain cellular proteins on the cellular membrane or internal components of the cells is known to hamper transcellular or paracellular transport of therapeutics, whereas cancer microenvironment and phagocytic systems are known to hinder and clear the therapeutics from the circulation. Thus, to obtain an effective drug delivery of therapeutic agents, attenuation or bypass of the barrier is highly necessary; which might allow the drug to reach a concentration effective to exert therapeutic efficacy.
... 32 Therefore, EC-8042 molecule achieved beneficial effects in pre-clinical studies for the treatment of several malignancies, including Triple-negative breast cancer, ovarian cancer, sarcoma, head and neck cancer and prostate cancer. [68][69][70][71][72][73] For all these reasons, we investigated the effects of EC-8042 in melanoma. Here we showed that EC-8042 suppressed the expression of SETDB1; melanoma cells were highly sensitive to EC-8042 and, in a similar way as observed following mit treatment, exerted antitumor effects related to SETDB1 mechanisms of action and augmented the action of MAPK inhibitors. ...
Malignant melanoma is the most deadly skin cancer, associated with rising incidence and mortality rates. Most of the patients with melanoma treated with current targeted therapies develop a drug resistance, causing tumor relapse. Gaining a better understanding of novel cancer-promoting molecular mechanisms driving melanoma progression is essential for the development of more effective targeted therapeutic approaches. Recent studies, including the research previously conducted in our laboratory, reported that the histone methyltransferase SETDB1 contributes to melanoma pathogenesis. In this follow-up study, we further elucidated the role of SETDB1 in melanoma, showing that SETDB1 modulated relevant transcriptomic effects in melanoma, in particular as activator of cancer-related secreted (CRS) factors and as repressor of melanocyte-lineage differentiation (MLD) and metabolic enzymes. Next, we investigated the effects of SETDB1 inhibition via compounds belonging to mithramycin family, mithramycin A and mithralog EC-8042: melanoma cells showed strong sensitivity to these drugs, which effectively suppressed the expression of SETDB1 and induced changes at the transcriptomic, morphological and functional level. Moreover, SETDB1 inhibitors enhanced the efficacy of MAPK inhibitor-based therapies against melanoma. Taken together, this work highlights the key regulatory role of SETDB1 in melanoma and supports the development of SETDB1-targeting therapeutic strategies for the treatment of melanoma patients.
... Some of these new analogs showed higher antitumor activity and/or lower toxicity than the parental compound [13][14][15][16], and were shown to affect the Ewing sarcoma xenograft growth and triple negative breast cancer growth in mice [17,18]. These promising activities have led to the development of these compounds as potential new anticancer drugs [19,20], which requires sufficient amounts for preclinical and clinical trials. ...
Background:
Mithramycin is an anti-tumor compound of the aureolic acid family produced by Streptomyces argillaceus. Its biosynthesis gene cluster has been cloned and characterized, and several new analogs with improved pharmacological properties have been generated through combinatorial biosynthesis. To further study these compounds as potential new anticancer drugs requires their production yields to be improved significantly. The biosynthesis of mithramycin proceeds through the formation of the key intermediate 4-demethyl-premithramycinone. Extensive studies have characterized the biosynthesis pathway from this intermediate to mithramycin. However, the biosynthesis pathway for 4-demethyl-premithramycinone remains unclear.
Results:
Expression of cosmid cosAR7, containing a set of mithramycin biosynthesis genes, in Streptomyces albus resulted in the production of 4-demethyl-premithramycinone, delimiting genes required for its biosynthesis. Inactivation of mtmL, encoding an ATP-dependent acyl-CoA ligase, led to the accumulation of the tricyclic intermediate 2-hydroxy-nogalonic acid, proving its essential role in the formation of the fourth ring of 4-demethyl-premithramycinone. Expression of different sets of mithramycin biosynthesis genes as cassettes in S. albus and analysis of the resulting metabolites, allowed the reconstitution of the biosynthesis pathway for 4-demethyl-premithramycinone, assigning gene functions and establishing the order of biosynthetic steps.
Conclusions:
We established the biosynthesis pathway for 4-demethyl-premithramycinone, and identified the minimal set of genes required for its assembly. We propose that the biosynthesis starts with the formation of a linear decaketide by the minimal polyketide synthase MtmPKS. Then, the cyclase/aromatase MtmQ catalyzes the cyclization of the first ring (C7-C12), followed by formation of the second and third rings (C5-C14; C3-C16) catalyzed by the cyclase MtmY. Formation of the fourth ring (C1-C18) requires MtmL and MtmX. Finally, further oxygenation and reduction is catalyzed by MtmOII and MtmTI/MtmTII respectively, to generate the final stable tetracyclic intermediate 4-demethyl-premithramycinone. Understanding the biosynthesis of this compound affords enhanced possibilities to generate new mithramycin analogs and improve their production titers for bioactivity investigation.
... In a functional study, it was found that two new analogs of MTA, namely MTMSDK and MTM-SK, hindered the growth of OC cells in xenografts via inhibition of Sp1-based transcription [87]. Another efficient analog of MTA is demycarosyl-3D-ß-D-digitoxosyl-mithramycin SK (DIG-MSK), as it can inhibit Sp1-mediated transcription, mRNA expression, and various other genes regulated by Sp1 that have a pivotal role in OC, like VEGFA, BCL2L1 (Bcl-2-like 1; Bcl-XL), human telomerase Reverse Transcriptase (hTERT), BRCA2, and MYC [88]. Similar to this study, Vizcaino et al. also observed that DIG-MSK can downregulate the binding of Sp1 to pro-oncogenes in OC cells [89]. ...
Ovarian cancer (OC) is one of the deadliest cancers among women contributing to high risk of mortality, mainly owing to delayed detection. There is no specific biomarker for its detection in early stages. However, recent findings show that over-expression of specificity protein 1 (Sp1) is involved in many OC cases. The ubiquitous transcription of Sp1 apparently mediates the maintenance of normal and cancerous biological processes such as cell growth, differentiation, angiogenesis, apoptosis, cellular reprogramming and tumorigenesis. Sp1 exerts its effects on cellular genes containing putative GC–rich Sp1–binding site in their promoters. A better understanding of the mechanisms underlying Sp1 transcription factor (TF) regulation and functions in OC tumorigenesis could help identify novel prognostic markers, to target cancer stem cells (CSCs) by following cellular reprogramming and enable the development of novel therapies for future generations. In this review, we address the structure, function, and biology of Sp1 in normal and cancer cells, underpinning the involvement of Sp1 in OC tumorigenesis. In addition, we have highlighted the influence of Sp1 TF in cellular reprogramming of iPSCs and how it plays a role in controlling CSCs. This review highlights the drugs targeting Sp1 and their action on cancer cells. In conclusion, we predict that research in this direction will be highly beneficial for OC treatment, and chemotherapeutic drugs targeting Sp1 will emerge as a promising therapy for OC.
... In a functional study, it was found that two new analogs of MTA, namely MTMSDK and MTM-SK, hindered the growth of OC cells in xenografts via inhibition of Sp1-based transcription [87]. Another efficient analog of MTA is demycarosyl-3D-ß-D-digitoxosyl-mithramycin SK (DIG-MSK), as it can inhibit Sp1-mediated transcription, mRNA expression, and various other genes regulated by Sp1 that have a pivotal role in OC, like VEGFA, BCL2L1 (Bcl-2-like 1; Bcl-XL), human telomerase Reverse Transcriptase (hTERT), BRCA2, and MYC [88]. Similar to this study, Vizcaino et al. also observed that DIG-MSK can downregulate the binding of Sp1 to pro-oncogenes in OC cells [89]. ...
Ovarian cancer (OC) is one of the deadliest cancers among women contributing to high risk of mortality, mainly owing to delayed detection. There is no specific biomarker for its detection in early stages. However, recent findings show that over-expression of specificity protein 1 (Sp1) is involved in many OC cases. The ubiquitous transcription of Sp1 apparently mediates the maintenance of normal and cancerous biological processes such as cell growth, differentiation, angiogenesis, apoptosis, cellular reprogramming and tumorigenesis. Sp1 exerts its effects on cellular genes containing putative GC-rich Sp1-binding site in their promoters. A better understanding of the mechanisms underlying Sp1 transcription factor (TF) regulation and functions in OC tumorigenesis could help identify novel prognostic markers, to target cancer stem cells (CSCs) by following cellular reprogramming and enable the development of novel therapies for future generations. In this review, we address the structure, function, and biology of Sp1 in normal and cancer cells, underpinning the involvement of Sp1 in OC tumorigenesis. In addition, we have highlighted the influence of Sp1 TF in cellular reprogramming of iPSCs and how it plays a role in controlling CSCs. This review highlights the drugs targeting Sp1 and their action on cancer cells. In conclusion, we predict that research in this direction will be highly beneficial for OC treatment, and chemotherapeutic drugs targeting Sp1 will emerge as a promising therapy for OC.
... This increased permeability facilitates enhanced permeability and retention (EPR), however uneven expression of growth factors results in abnormal angiogenesis, which further may affect in EPR. Moreover, these receptors and the corresponding growth factors serve as proangiogenic targets for the development of antiangiogenic therapies in the cure of cancer (Fernández-Guizán et al., 2015). Alternatively, application of VEGF establishes to increase pore size to penetrate the nanocarrier within the human colon tumor xenograft experimental animals (Dewhirst and Ashcraft, 2016). ...
The biological barriers in the body have been fabricated by nature to protect the body from foreign molecules. The successful delivery of drugs is limited and being challenged by these biological barriers including the gastrointestinal tract, brain, skin, lungs, nose, mouth mucosa, and immune system. In this review article, we envisage to understand the functionalities of these barriers and revealing various drug-loaded biodegradable polymeric nanoparticles to overcome these barriers and deliver the entrapped drugs to cancer targeted site. Apart from it, tissue-specific multifunctional ligands, linkers and transporters when employed imparts an effective active delivery strategy by receptor-mediated transcytosis. Together, these strategies enable to deliver various drugs across the biological membranes for the treatment of solid tumors and malignant cancer.
... EC-8042 is one of the most recent analogs generated via this approach [13,17]. EC-8042 exhibits much lower toxicity than MTM and has antitumor activity in a variety of cellular and xenograft models [18][19][20][21][22][23]. In terms of the favorable therapeutic index, EC-8042 is currently the lead MTM analog for clinical testing. ...
... Recently, the new mithralog demycarosyl-3Dβ-D-digitoxosyl-mithramycin SK (EC-8042; DIG-MSK) has been obtained and characterized [17]. As expected, EC-8042 preferentially binds GC-rich sequences, is a potent inhibitor of SP-driven gene expression and shows pleiotropic anti-angiogenic and anti-oncogenic activities [18][19][20]. EC-8042 altered the expression of cell cycle related genes resulting in cell cycle arrest and apoptosis in breast cancer cell lines [21]. In Ewing sarcoma, EC-8042 was substantially less toxic than mithramycin but maintained suppression of EWS-FLI1 at similar concentrations as MTM, and markedly suppressed Ewing sarcoma xenograft growth [22]. ...
Tumor initiating cells (TICs), responsible for tumor initiation, and cancer stem cells (CSCs), responsible for tumor expansion and propagation, are often resistant to chemotherapeutic agents. To find therapeutic targets against sarcoma initiating and propagating cells we used models of myxoid liposarcoma (MLS) and undifferentiated pleomorphic sarcoma (UPS) developed from human mesenchymal stromal/stem cells (hMSCs), which constitute the most likely cell-of-origin for sarcoma. We found that SP1-mediated transcription was among the most significantly altered signaling. To inhibit SP1 activity, we used EC-8042, a mithramycin (MTM) analog (mithralog) with enhanced anti-tumor activity and highly improved safety. EC-8042 inhibited the growth of TIC cultures, induced cell cycle arrest and apoptosis and upregulated the adipogenic factor CEBPα. SP1 knockdown was able to mimic the anti-proliferative effects induced by EC-8042. Importantly, EC-8042 was not recognized as a substrate by several ABC efflux pumps involved in drug resistance, and, opposite to the chemotherapeutic drug doxorubicin, repressed the expression of many genes responsible for the TIC/CSC phenotype, including SOX2, C-MYC, NOTCH1 and NFκB1. Accordingly, EC-8042, but not doxorubicin, efficiently reduced the survival of CSC-enriched tumorsphere sarcoma cultures. In vivo, EC-8042 induced a profound inhibition of tumor growth associated to a strong reduction of the mitotic index and the induction of adipogenic differentiation and senescence. Finally, EC-8042 reduced the ability of tumor cells to reinitiate tumor growth. These data suggest that EC-8042 could constitute an effective treatment against both TIC and CSC subpopulations in sarcoma.
