Xiao Zhang

Ferroptosis is an iron-dependent form of regulated cell death driven by the lethal accumulation of lipid peroxides. Accumulating evidence indicates that the extracellular landscape, the acellular functional subset of the tumor microenvironment (TME) comprising the extracellular matrix, soluble metabolites, cytokines, extracellular vesicles (EVs), and physicochemical conditions such as pH and oxygen content, actively determines cellular susceptibility to ferroptosis. Extracellular nutrients, acidic and hypoxic conditions modulate intracellular redox homeostasis, while ferroptosis-related signals are transmitted between cells through EVs, cytokines, and metabolites. Ferroptosis in turn bidirectionally shapes anti-tumor immunity, acting as immunogenic cell death yet also releasing immunosuppressive mediators that impair T cells. This review summarizes the canonical intracellular mechanisms of ferroptosis, highlights the bidirectional crosstalk between cells and the extracellular landscape, and discusses therapeutic strategies targeting this landscape, including reshaping nutrient availability, engineering EV-based delivery systems, and designing microenvironment-responsive nanomaterials. Key limitations of the field and perspectives are also outlined for safe and effective ferroptosis-based anti-tumor therapies.

Background: Lung adenocarcinoma (LUAD) continues to be the primary contributor to cancer mortality. Macropinocytosis is a bulk nutrient uptake pathway known to support tumor growth in various cancers, but its functional role and molecular effectors in LUAD cell malignant phenotypes remain unclear. KCNH1 has been reported to modulate progression in multiple types of cancer, yet it has never been linked to macropinocytosis. This study aims to investigate whether macropinocytosis enhances LUAD cell proliferation, migration, and invasion and to identify its key downstream targets. Methods: Two LUAD cell lines, NCI-H358 (KRAS-G12C mutant) and NCI-H1975 (KRAS wild-type), were used. For pharmacological inhibition, cells were treated with 5-(N-ethyl-N-isopropyl)-amiloride (EIPA) (25 μM, 24 h) or dimethyl sulfoxide (DMSO) control. For genetic manipulations, CRISPR/Cas9 knockout and lentiviral overexpression were established, with wild-type (WT) cells and empty vector as controls. Functional effects on proliferation [Cell Counting Kit-8 (CCK-8)], apoptosis (flow cytometry), migration (wound healing), and invasion (Transwell) were evaluated. Transcriptomic changes were analyzed by RNA-sequencing (RNA-seq), with candidate gene expression validated by quantitative real-time polymerase chain reaction (qPCR) and Western blot. Dual-luciferase reporter assay was performed to assess KCNH1 promoter activity. The involvement of the AKT signaling pathway was examined by Western blot. Clinical relevance was examined using The Cancer Genome Atlas (TCGA) database. Results: Inhibition of macropinocytosis significantly reduced the invasion (PKCNH1 as a commonly downregulated target upon EIPA treatment. Dual-luciferase reporter assay confirmed that EIPA treatment directly reduced KCNH1 promoter activity, indicating transcriptional regulation by macropinocytosis. Further experiments established a unidirectional regulatory axis: KCNH1 expression was positively regulated by macropinocytosis at both the mRNA and protein levels, whereas genetic modulation of KCNH1 did not alter macropinocytic activity. Functionally, overexpression of KCNH1 enhanced malignant phenotypes and conferred partial resistance to EIPA, while its knockout suppressed proliferation, migration, and invasion. Mechanistically, KCNH1 modulated AKT phosphorylation, and this pathway mediated its effects on LUAD cell malignant phenotypes. TCGA database analysis revealed elevated KCNH1 expression in LUAD tumors relative to normal tissues, suggesting potential clinical relevance. Conclusions: This study demonstrates that macropinocytosis enhances LUAD cell proliferation, migration, and invasion primarily through the transcriptional upregulation of KCNH1. KCNH1 functions as a crucial downstream effector, mediating the pro-tumorigenic effects of macropinocytosis at least in part via AKT phosphorylation. These findings identify the macropinocytosis-KCNH1 axis as a potential therapeutic target for LUAD.

Retinoic acid (RA) signaling through CRABP2 and FABP5 differentially influences therapeutic responses and drug resistance in anaplastic thyroid cancer (ATC), yet regulatory mechanisms remain unclear. Our study reveals low CRABP2 and high FABP5 expression in ATC cell lines (THJ-11T/16T/21T), with RA alone showing no growth inhibition but RA/gemcitabine (GEM) combination exhibiting synergistic effects. ZEB1 transcriptionally regulates both proteins, where RA/GEM treatment alters its promoter binding pattern—reducing FABP5 association while enhancing CRABP2 binding. Co-regulators KAT2B and EP300 compete for ZEB1’s CP domain during transcriptional regulation. Notably, RA/GEM modulates m⁶A modifications: suppressing CRABP2 and enhancing FABP5 methylation through METTL3/ALKBH5 interactions, thereby reducing mRNA stability. Clinical analysis of 286 thyroid cancer specimens confirmed variable CRABP2/FABP5 expression. Crucially, ZEB1 and ALKBH5 overexpression potentiated GEM/RA efficacy against ATCs. These findings identify m⁶A-mediated post-transcriptional regulation and ZEB1-driven transcriptional dynamics as key determinants of the combined effects of GEM and RA in ATCs, providing new targets for combination therapy optimization.

Fat mass and obesity-associated protein (FTO), which is closely linked with obesity and dietary intake, plays an important role in diet-related metabolic diseases. However, the underlying mechanism of the N⁶-methyladenosine (m⁶A) demethyltransferase FTO in tumor development and progression remains largely unexplored. Here, we demonstrated that FTO expression was largely lower in non-small cell lung cancer (NSCLC) samples than in adjacent healthy tissues, and its expression negatively correlated with poor prognosis. Gain- and loss-of-function assays revealed that FTO inhibited NSCLC tumor cell growth and metastasis in vitro and in vivo. Mechanistically, estrogen receptor alpha (ESR1) is a target of FTO, and increased FTO expression significantly impaired the m⁶A levels of ESR1 mRNA. There were two clear m⁶A modification sites (5247A and 5409A) in the 3′ untranslated region (3ʹUTR) of ESR1, and FTO could decrease their methylation. Moreover, the m⁶A readers YTHDF1 and IGF2BP3 recognized and bound the m⁶A sites in ESR1 mRNA, thereby enhancing its stability and facilitating tumor growth. We also showed that ESR1 has good diagnostic value for NSCLC. In conclusion, we uncovered an important mechanism of epitranscriptomic regulation by the FTO-YTHDF1-IGF2BP3-ESR1 axis and identified the potential of m⁶A-dependent therapeutic strategies for NSCLC.