Transforming tumor microenvironments: nanotechnology and gene therapy in cellular signaling and epigenetic insight...

Chemoresistance remains the primary cause of cancer treatment failure, yet current understanding remains fragmented across isolated mechanistic studies. This review provides a unified framework linking tumor microenvironment (TME) signaling, epigenetic reprogramming, and nanotherapeutic intervention as an integrated axis driving and potentially reversing chemoresistance. We systematically examine how TME components: hypoxia (HIF-1α pathway), acidosis, cancer-associated fibroblasts (TGF-β/PDGF signaling), and immune cells (NF-κB-mediated immunosuppression) activate signaling cascades that directly interface with epigenetic machinery. These TME-activated pathways recruit DNA methyltransferases, histone-modifying enzymes, and regulate microRNA (miRNA) networks, establishing stable resistant phenotypes including epithelial-mesenchymal transition, cancer stem cells, and metabolic adaptation. Critically, miRNA dysregulation serves as a central integrator, creating bidirectional crosstalk between signaling pathways and epigenetic modifications through self-reinforcing circuits. Unlike previous reviews focusing on isolated resistance mechanisms, we demonstrate how this integrated TME-epigenetic axis creates specific therapeutic vulnerabilities exploitable through rationally designed nanotechnology platforms delivering epigenetic modulators (DNMT inhibitors, HDAC inhibitors, EZH2 inhibitors) and gene therapy tools (CRISPR-Cas9 epigenetic editors, miRNA mimics/antagomirs). We critically evaluate clinical translation challenges, including EPR effect heterogeneity, delivery barriers, and biomarker gaps, providing a balanced perspective on both potential and obstacles. This mechanistic framework guides the development of next-generation combination therapies targeting multiple nodes within the TME-epigenetic-nanotherapy axis.