The growing threat of antimicrobial resistance has intensified the search for new bioactive compounds, particularly in extreme environments such as Antarctica. Streptomyces fildesensis So13.3, isolated from Antarctic soil, harbours a biosynthetic gene cluster (BGC) associated with actinomycin D production, an antibiotic with biomedical relevance. This study investigates the regulatory role of TetR/AcrR transcription factors encoded within this biosynthetic gene cluster (BGC), focusing on their structural features and expression under different nutritional conditions. Additionally, we propose that repressing an active pathway could lead to the activation of silent biosynthetic routes, and our in-silico analysis provides a foundation for selecting key mutations and experimentally validating this strategy. Expression analysis revealed that TetR-279, in particular, was upregulated in ISP4 and IMA media, suggesting its participation in nutrient-dependent BGC regulation. Structural modelling identified key differences between TetR-206 and TetR-279, with the latter containing a tetracycline-repressor-like domain. Molecular dynamics simulations confirmed TetR-279’s structural stability but showed that the S166P CRISPy-web-guided mutation considerably affected its flexibility, while V167A and V167I had modest effects. These results underscore the importance of integrating omics, structural prediction, and gene editing to evaluate and manipulate transcriptional regulation in non-model bacteria. Targeted disruption of TetR-279 may derepress actinomycin biosynthesis, enabling access to silent or cryptic secondary metabolites with potential pharmaceutical applications.

Photodynamic therapy (PDT) treats nonmelanoma skin cancer. PDT kills cells through reactive oxygen species (ROS), generated by interaction among cellular O_2, photosensitizer and specific light. Protoporphyrin IX (PpIX) is a photosensitizer produced from methyl aminolevulinate (MAL) by heme group synthesis (HGS) pathway. In PDT-resistant cells, PDT efficacy has been improved by addition of epigallocatechin gallate (EGCG). Therefore, the aim of this work is to evaluate the effect of EGCG properties over MAL-TFD and PpIX production on A-431 cell line. EGCG’s role over cell proliferation (flow cytometry and wound healing assay) and clonogenic capability (clonogenic assay) was evaluated in A-431 cell line, while the effect of EGCG over MAL-PDT was determined by cell viability assay (MTT), PpIX and ROS detection (flow cytometry), intracellular iron quantification and gene expression of HGS enzymes (RT-qPCR). Low concentrations of EGCG (<50 µM) did not have an antiproliferative effect over A-431 cells; however, EGCG inhibited clonogenic cell capability. Furthermore, EGCG (<50 µM) improved MAL-PDT cytotoxicity, increasing PpIX and ROS levels, exerting a positive influence on PpIX synthesis, decreasing intracellular iron concentration and modifying HGS enzyme gene expression such as PGB (upregulated) and FECH (downregulated). EGCG inhibits clonogenic capability and modulates PpIX synthesis, enhancing PDT efficacy in resistant cells.

The growing threat of antimicrobial resistance has driven the search for new bioactive compounds in extreme environments such as Antarctica. Streptomyces fildesensis So13.3, isolated from Antarctic soil, has been shown to contain a biosynthetic gene cluster associated with producing actinomycin D, an antibiotic with therapeutic potential. In this study, we analysed the regulatory role of TetR/AcrR family transcription factors present within this BGC, focusing on their activation under different nutritional conditions and their structural scharacterisation using bioinformatics tools and molecular dynamics simulations. The results showed that TetR/AcrR expression increased significantly in ISP4 and IMA media, suggesting their involvement in nutrient-dependent regulation of the cluster. At the structural level, two TetR proteins (TetR-206 and TetR-279) were modelled, with the latter standing out due to a C-terminal tetracycline repressor-like domain. A 200 ns molecular dynamics simulation was performed in GROMACS to evaluate the stability and flexibility of TetR-279, including analysis of point mutations (S166P, V167A, V167I). The S166P mutation significantly impacted structural flexibility, while V167A and V167I caused only minor alterations. This work demonstrates the value of integrating omics approaches, structural modelling, and gene editing with CRISPR to study and potentially activate silent BGCs in non-model bacteria such as Antarctic Streptomyces. In particular, the targeted inhibition of TetR-279 may trigger metabolic rewiring and facilitate the expression of novel antibiotics encoded in cryptic biosynthetic gene clusters.

Ovarian cancer (OC) remains one of the deadliest gynecological malignancies, largely due to late diagnosis and the emergence of resistance to platinum–based chemotherapy. Long non–coding RNAs (lncRNAs) have recently emerged as key regulators of tumor progression and therapeutic adaptation. In this study, we performed integrative transcriptomic profiling of patient–derived TCGA ovarian tumor samples and carboplatin–resistant A2780 (CBDCA–R–A2780) cells to identify lncRNAs whose dysregulation overlaps between a cell–line resistance model and patient tumors. Our analyses revealed extensive transcriptional remodeling across both datasets, with MNX1–AS1 consistently emerging as a strongly deregulated transcript. Differential expression analysis showed robust upregulation of MNX1–AS1 in resistant cells and tumor tissues, accompanied by correlations with epithelial–mesenchymal transition (EMT)–related transcription factors such as FOXA1 and SNAI2 and inverse associations with epithelial markers including CDH1. Computational predictions using RIblast identified specific MNX1–AS1 binding regions with candidate miRNAs and mRNAs, prioritizing EMT–related transcripts (e.g., SNAI2, FOXA1, ZEB1) with favorable hybridization energies for future validation. Additional prioritized interactors included genes linked to stress response (IER2, FOSB) and invasion (MMP11, MMP1). Because A2780 has been discussed as an endometrioid–like/non–serous ovarian cancer model, mechanistic inferences primarily apply to this in vitro context, while TCGA analyses provide associative support rather than mechanistic validation. Collectively, these findings highlight MNX1–AS1 as a candidate regulator associated with transcriptional reprogramming in OC and a promising prognostic biomarker warranting further functional testing.