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Background: Triple negative breast cancer (TNBC) represents around 15% of all breast tumors. Therapeutic strategies in TNBC are mainly based on classical chemotherapeutic agents, with limited success in the metastatic setting. Here we have explored the action of a novel mithramycin analog named EC-8042 in TNBC. Methods: we used a panel of cell lines representative of triple negative tumors including BT549, HBL100, HCC-1037, HS578T, MDA-MB213, HCC-1187, HCC-3153 and HCC-70. Proliferation studies with EC-8042 were measured by MTT assays. Propidium iodide (PI) staining followed by FACS was used for cell cycle analyses and AnnexinV-fluorescein for analysis of apoptosis. Proteins involved in cell cycle control and apoptosis were evaluated by western blot. Mitochondrial membrane potential was assessed by measuring the fluorescence of tetramethylrhodamineethylester (TMRE) dye. Results: The IC50 values obtained were in the nM range, indicating that the drug had a potent effect on these cell lines. Mechanistically, the drug caused accumulation of cells in the S phase of the cell cycle at doses of 100 and 500 nM in MDA-MB231. Biochemically, EC-8042 caused an increase in cyclin E, cyclin A, cyclin D3, cyclin B, and p27, and decreased cyclin D1 and Rb phosphorylation at serine 780. These data are consistent with an action of EC-8042 on the cell cycle. Moreover, the increase in wee1 and pY15-CDK1 are in line with an effect of the drug blocking cell cycle progression through the S phase. Annexin V staining indicated that treatment with 500 nM of EC8042 provoked apoptosis, which was also revealed by PARP processing. The treatment reduced the amounts of MCL1, BCLXL, and XIAP, but did not affect BCL2 levels. Conclusion: our results indicate that EC-8042 has a strong antitumoral action on TNBC cells, which is caused by increased apoptosis and a decrease in cell cycle progression, and opens the possibility for further development of this drug in TNBC. [ABSTRACT FROM AUTHOR]

Fungal infections are a growing global health concern due to the limited number of available antifungal therapies as well as the emergence of fungi that are resistant to first-line antimicrobials, particularly azoles and echinocandins. Development of novel, selective antifungal therapies is challenging due to similarities between fungal and mammalian cells. An attractive source of potential antifungal treatments is provided by ecological niches co-inhabited by bacteria, fungi, and multicellular organisms, where complex relationships between multiple organisms have resulted in evolution of a wide variety of selective antimicrobials. Here, we characterized several analogs of one such natural compound, collismycin A. We show that NR-6226C has antifungal activity against several pathogenic Candida species, including C. albicans and C. glabrata , whereas it only has little toxicity against mammalian cells. Mechanistically, NR-6226C selectively chelates iron, which is a limiting factor for pathogenic fungi during infection. As a result, NR-6226C treatment causes severe mitochondrial dysfunction, leading to formation of reactive oxygen species, metabolic reprogramming, and a severe reduction in ATP levels. Using an in vivo model for fungal infections, we show that NR-6226C significantly increases survival of Candida -infected Galleria mellonella larvae. Finally, our data indicate that NR-6226C synergizes strongly with fluconazole in inhibition of C. albicans . Taken together, NR-6226C is a promising antifungal compound that acts by chelating iron and disrupting mitochondrial functions.IMPORTANCEDrug-resistant fungal infections are an emerging global threat, and pan-resistance to current antifungal therapies is an increasing problem. Clearly, there is a need for new antifungal drugs. In this study, we characterized a novel antifungal agent, the collismycin analog NR-6226C. NR-6226C has a favorable toxicity profile for human cells, which is essential for further clinical development. We unraveled the mechanism of action of NR-6226C and found that it disrupts iron homeostasis and thereby depletes fungal cells of energy. Importantly, NR-6226C strongly potentiates the antifungal activity of fluconazole, thereby providing inroads for combination therapy that may reduce or prevent azole resistance. Thus, NR-6226C is a promising compound for further development into antifungal treatment., Competing Interests: F.M. is employed by the biotechnology company EntreChem SL, which provided several compounds used in this study.

Antibody-drug conjugates (ADCs) have emerged as a novel therapeutic strategy that has successfully reached patient treatment in different clinical scenarios. ADCs are formed by an antibody against a specific tumor-associated antigen (TAA), a cytotoxic payload, and a chemical linker that binds both. To this regard, most efforts have been focused on target identification, antibody design and linker optimization, but other relevant aspects for clinical development have not received the necessary attention. In this article using data from approved ADCs, we evaluated all characteristics of these agents, including payload physicochemical properties, in vitro potency, drug antibody ratio (DAR), exposure-response relationships, and clinical development strategies. We suggest that compounds with best options for clinical development include those with optimal payload physicochemical properties and cleavable linkers that would lead to a bystander effect. These modalities can facilitate the development of ADCs in indications with low expression of the TAA. Early clinical development strategies including changes in the schedule of administration with more frequent doses are also discussed in the context of an efficient strategy. In conclusion, we highlight relevant aspects that are needed for the optimal development of ADCs in cancer, proposing options for improvement., (© 2023. The Author(s).)

Osteosarcomas are frequently associated to a poor prognosis and a modest response to current treatments. EC-8042 is a well-tolerated mithramycin analog that has demonstrated an efficient ability to eliminate tumor cells, including cancer stem cell subpopulations (CSC), in sarcomas. In transcriptomic and protein expression analyses, we identified NOTCH1 signaling as one of the main pro-stemness pathways repressed by EC-8042 in osteosarcomas. Overexpression of NOTCH-1 resulted in a reduced anti-tumor effect of EC-8042 in CSC-enriched 3D tumorspheres cultures. On the other hand, the depletion of the NOTCH-1 downstream target HES-1 was able to enhance the action of EC-8042 on CSCs. Moreover, HES1 depleted cells failed to recover after treatment withdrawal and showed reduced tumor growth potential in vivo. In contrast, mice xenografted with NOTCH1-overexpressing cells responded worse than parental cells to EC-8042. Finally, we found that active NOTCH1 levels in sarcoma patients was associated to advanced disease and lower survival. Overall, these data highlight the relevant role that NOTCH1 signaling plays in mediating stemness in osteosarcoma. Moreover, we demonstrate that EC-8042 is powerful inhibitor of NOTCH signaling and that the anti-CSC activity of this mithramycin analog highly rely on its ability to repress this pathway., Competing Interests: Conflict of interest statement The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Francisco Moris was an employee and reported ownership of stock in of EntreChem SL until April 2022. All other authors declare they have no competing interests., (Copyright © 2023 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Regulatory elements activate promoters by recruiting transcription factors (TFs) to specific motifs. Notably, TF-DNA interactions often depend on cooperativity with colocalized partners, suggesting an underlying cis-regulatory syntax. To explore TF cooperativity in mammals, we analyze ∼500 mouse and human primary cells by combining an atlas of TF motifs, footprints, ChIP-seq, transcriptomes, and accessibility. We uncover two TF groups that colocalize with most expressed factors, forming stripes in hierarchical clustering maps. The first group includes lineage-determining factors that occupy DNA elements broadly, consistent with their key role in tissue-specific transcription. The second one, dubbed universal stripe factors (USFs), comprises ∼30 SP, KLF, EGR, and ZBTB family members that recognize overlapping GC-rich sequences in all tissues analyzed. Knockouts and single-molecule tracking reveal that USFs impart accessibility to colocalized partners and increase their residence time. Mammalian cells have thus evolved a TF superfamily with overlapping DNA binding that facilitate chromatin accessibility., Competing Interests: Declaration of interests S.P. and L.V. are employees of Astra Zeneca and may own stock or stock options., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Cytotoxic drugs like doxorubicin remain as the most utilized agents in sarcoma treatment. However, advanced sarcomas are often resistant, thus stressing the need for new therapies aimed to overcome this resistance. Multikinase inhibitors provide an efficient way to target several pro-tumorigenic pathways using a single agent and may constitute a valuable strategy in the treatment of sarcomas, which frequently show an aberrant activation of pro-tumoral kinases. Therefore, we studied the antitumor activity of EC-70124, an indolocarbazole analog that have demonstrated a robust ability to inhibit a wide range of pro-survival kinases. Evaluation of the phospho-kinase profile in cell-of-origin sarcoma models and/or sarcoma primary cell lines evidenced that PI3K/AKT/mTOR, JAK/STAT or SRC were among the most highly activated pathways. In striking contrast with the structurally related drug midostaurin, EC-70124 efficiently prevented the phosphorylation of these targets and robustly inhibited proliferation through a mechanism associated to the induction of DNA damage, cell cycle arrest and apoptosis. In addition, EC-70124 was able to partially reduce tumor growth in vivo. Importantly, this compound inhibited the expression and activity of ABC efflux pumps involved in drug resistance. In line with this ability, we found that the combined treatment of EC-70124 with doxorubicin resulted in a synergistic cytotoxic effect in vitro and an increased antitumor activity of this cytotoxic drug in vivo. Altogether, these results uncover the capability of the novel multikinase inhibitor EC-70124 to counteract drug resistance in sarcoma and highlight its therapeutic potential when combined with current treatments., (© 2018 UICC.)

Collismycin A is a member of the 2,2'-bipyridyl family of natural products that shows cytotoxic activity. Structurally, it belongs to the hybrid polyketides-nonribosomal peptides. After the isolation and characterization of the collismycin A gene cluster, we have used the combination of two different approaches (insertional inactivation and biocatalysis) to increase structural diversity in this natural product class. Twelve collismycin analogs were generated with modifications in the second pyridine ring of collismycin A, thus potentially maintaining biologic activity. None of these analogs showed better cytotoxic activity than the parental collismycin. However, some analogs showed neuroprotective activity and one of them (collismycin H) showed better values for neuroprotection against oxidative stress in a zebrafish model than those of collismycin A. Interestingly, this analog also showed very poor cytotoxic activity, a feature very desirable for a neuroprotectant compound., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The gene cluster for the bipyridyl compound collismycin was characterized from Streptomyces sp. CS40. Sequence analysis of a 46.7 kb DNA region revealed 27 open reading frames, 23 of which are involved in collismycin biosynthesis. Eight insertional inactivation mutants were generated in the sequenced region to prove its involvement in collismycin biosynthesis, define the boundaries of the cluster, functionally characterize some genes, and isolate two biosynthetic intermediates. A model for collismycin biosynthesis--which includes the conversion of lysine into picolinic acid, participation of a polyketide synthase-non-ribosomal peptide synthetase system, and some further modifications--is proposed. The biosynthetic pathway would include an unusual NRPS-mediated incorporation of a cysteine residue, possibly through a Michael addition and followed by the extension of the peptide chain by leucine incorporation and later removal by amidohydrolase., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Cancer initiating cells have been described to be the only cell population with tumorigenic capacity in glioblastoma multiforme, one of the most aggressive and untreatable cancers. Recent work from our group described that NFκB pathway was activated in glioblastoma initiating cells undergoing differentiation, and that blockade of this activation promoted senescence of differentiating cells. NFκB activation in cancer may be the result of either exposure to proinflammatory stimuli in the tumor microenvironment or upregulation of the signaling pathway by upstream regulators. Appropriate control of NFκB activity, which can be achieved by gene modification or pharmacological strategies, would provide a potential approach for the management of NFκB related tumors, including glioblastoma. Here, we summarize the current knowledge of the relevance of NFκB in cancer and its possible role as a target of therapeutic intervention..

We report the generation of novel glycosylated indolocarbazoles by combinatorial biosynthesis, and the identification of two novel potent and selective compounds inhibitors of JAK2 and Ikkb kinases.