Hydrogen peroxide responsive theranostics for cancer-selective activation of DNA alkylators and real-time fluorescence monitoring in living cells

Inhibition of mitochondrial genome-encoded mitomiR-3 contributes to ZEB1 mediated GPX4 downregulation and pro-ferroptotic lipid metabolism to induce ferroptosis in breast cancer cells

Ferroptosis, an iron-dependent form of regulated cell death driven by lipid peroxidation, represents a unique vulnerability in cancer cells. However, current ferroptosis-inducing therapies face clinical limitations due to poor cancer cell specificity, systemic toxicity, and off-target effects. Therefore, a deeper understanding of molecular regulators of ferroptosis sensitivity is critical for developing targeted therapies. The metabolic plasticity of cancer cells determines their sensitivity to ferroptosis. While mitochondrial dysfunction contributes to metabolic reprogramming in cancer, its role in modulating ferroptosis remains poorly characterized. Previously, studies have identified that mitochondrial genome also encodes several non-coding RNAs. We identified 13 novel mitochondrial genome-encoded miRNAs (mitomiRs) that are aberrantly overexpressed in triple-negative breast cancer (TNBC) cell lines and patient tumors. We observed higher levels of mitomiRs in basal-like triple-negative breast cancer (TNBC) cells compared to mesenchymal stem-like TNBC cells. Strikingly, 11 of these mitomiRs directly target the 3'UTR of ZEB1, a master regulator of epithelial-to-mesenchymal transition (EMT). Using mitomiR-3 mimic, inhibitor and sponges, we demonstrated its role as a key regulator of ZEB1 expression in TNBC cells. Inhibition of mitomiR-3 via sponge construct in basal-like TNBC, MDA-MB-468 cells, promoted ZEB1 upregulation and induced a mesenchymal phenotype. Further, mitomiR-3 inhibition in TNBC cells contributed to reduced cancer cell proliferation, migration, and invasion. Mechanistically, mitomiR-3 inhibition in TNBC cells promote metabolic reprogramming toward pro-ferroptotic pathways, including iron accumulation, increased polyunsaturated fatty acid (PUFA) metabolites, and lipid peroxidation, contributing to ferroptotic cell death via ZEB1-mediated downregulation of GPX4, a critical ferroptosis defense enzyme. We observed that mitomiR-3 inhibition significantly suppressed tumor growth in vivo. Our identified mitomiR-3 has low expression in normal breast cells, minimizing potential off-target toxicity, making them a promising target for pro-ferroptotic cancer therapy. Our study reveals a novel link between mitochondrial miRNAs and ferroptosis sensitivity in TNBC paving a way for miRNA-based therapeutics.

The Role of Reactive Oxygen Species in Colorectal Cancer Initiation and Progression: Perspectives on Theranostic Approaches

Altered levels of reactive oxygen species (ROS) are recognized as one of the key factors in mediating tumor cell survival in the tissue microenvironment, where they play a role in the initiation, progression and recurrence/relapse of colorectal cancer (CRC). Tumor cells can adapt to oxidative stress (OS) using genetic or metabolic reprogramming in the long or short term. In addition, tumor cells defend themselves through positive regulation of antioxidant molecules, enhancing ROS-driven proliferation. Balanced oxidative eustress levels can influence chemotherapy resistance, allowing tumor cells to survive treatment. Secondary effects of chemotherapy include increased ROS production and redox stress, which can kill cancer cells and eliminate drug resistance. Anticancer treatments based on manipulating ROS levels could represent the gold standard in CRC therapy. Therefore, exploring the modulation of the response to OS in deregulated signaling pathways may lead to the development of new personalized CRC treatments to overcome therapy resistance. In this review, we explore the role of ROS in the initiation and progression of CRC and their diagnostic implications as biomarkers of disease. Furthermore, we focused on the involvement of ROS in different CRC therapeutic options, such as surgery, radiotherapy, theranostic imaging, chemotherapy and immunotherapy and other precision medicine approaches.

Precision-engineered PROTACs minimize off-tissue effects in cancer therapy

Proteolysis-targeting chimeras (PROTACs) offer a groundbreaking approach to selectively degrade disease-related proteins by utilizing the ubiquitin-proteasome system. While this strategy shows great potential in preclinical and clinical settings, off-tissue effects remain a major challenge, leading to toxicity in healthy tissues. This review explores recent advancements aimed at improving PROTAC specificity, including tumor-specific ligand-directed PROTACs, pro-PROTACs activated in tumor environments, and E3 ligase overexpression strategies. Innovations such as PEGylation and nanotechnology also play a role in optimizing PROTAC efficacy. These developments hold promise for safer, more effective cancer therapies, though challenges remain for clinical translation.