LncRNAs are involved in many physiological and pathological processes, including chromatin remodeling, transcription, posttranscriptional gene expression, mRNA stability, translation, and posttranslational modification, and their functions depend on subcellular localization. MIR503HG is a lncRNA as well as a host gene for the miRNAs miR-503 and miR-424. MIR503HG functions independently or synergistically with miR-503. MIR503HG affects cell proliferation, invasion, metastasis, apoptosis, angiogenesis, and other biological behaviors. The mechanism of MIR503HG in disease includes interaction with protein, sponging miRNA to regulate downstream target gene, and participation in NF-κB, TGF-β, ERK/MAPK, and PI3K/AKT signaling pathways. In this review, we summarize the molecular mechanisms of MIR503HG in disease and its potential applications in diagnosis, prognosis, and treatment. We also raise some unanswered questions in this area, providing insights for future research.

Breast cancer (BC) is the most frequently diagnosed malignancy among women worldwide, with a high incidence and mortality rate. Despite advances in treatment, approximately 10%–15% of patients with BC still face recurrence. Therefore, improving BC therapy remains a significant challenge. In this article, we provide a detailed overview, categorizing and elaborating the developments of current research progress on nanodrug delivery systems based on ferroptosis for BC treatment. By increasing the iron content in BC cells and inhibiting the defense system against ferroptosis, the accumulation of lipid peroxides is promoted, and ferroptosis is induced in BC cells. In addition to directly targeting tumor cells, nanodrug delivery systems can remodel the tumor microenvironment, inhibit BC primary growth, and prevent distant metastasis. These nanomaterials, after drug loading and modification, possess characteristics such as smart activation, controlled release, specific targeting, good biocompatibility, and long circulation time, thereby enhancing the efficacy of BC treatment. We also classify and discuss the mechanisms and advantages of different types of nanomaterials. Finally, we discuss how multifunctional nanosystems can sensitize ferroptosis when combined with radiotherapy, chemotherapy, immunotherapy, and phototherapy to achieve synergistic effects in BC treatment. This work reveals the potential of ferroptosis-based nanomaterials in overcoming BC, analyzes the limitations of the clinical application and proposes possible solutions, offering a promising direction for future treatment strategies. Graphical Abstract 1. Ferroptosis-based nanodrugs induce ferroptosis by increasing intracellular iron levels, disrupting redox homeostasis, and promoting LPO accumulation. 2. Nanodrugs not only target BC cells, but also target TME. 3. Ferroptosis-based nanodrugs can also synergize with chemotherapy, radiotherapy, immunotherapy, PDT, PTT, and other treatment modalities for enhanced BC management.