メラノーマ関連線維芽細胞を標的としてがん幹細胞駆動型の薬剤耐性を克服する

Acquired resistance to BRAF V600E inhibitors remains a major obstacle in melanoma treatment. We hypothesized that melanoma-initiating cells (MICs), regulated by cancer-associated fibroblasts (CAFs) in the tumor microenvironment, mediate drug resistance through stromal Notch1 signaling.

Patient-derived melanoma-associated fibroblasts (MAFs) were engineered to activate Notch1 signaling (MAF N1IC-GFP) via lentiviral transduction. Drug resistance was assessed using BRAF inhibitor-resistant melanoma cells (451LuBR) in 3D spheroid co-culture assays with PLX4720 treatment.In vivo efficacy was evaluated in NSG mice co-grafted with 451LuBR cells and MAF N1IC-GFP or control MAF GFP (n=8/group). Primary endpoints included tumor growth, angiogenesis, and CD271⁺ MIC populations assessed by immunofluorescence and quantitative imaging.

In vitro, MAF N1IC-GFP suppressed drug-resistant melanoma spheroid formation across PLX4720 concentrations (1-100 μM, P <0.01). In vivo, MAF N1IC-GFP co-grafting reduced tumor growth by 50% (mean tumor weight, P <0.01) and bioluminescence signal (P <0.05). Mechanistically, MAF N1IC-GFP selectively depleted CD271⁺ MICs (~50% reduction in fluorescence intensity, P<0.01), decreased their proliferation (P <0.01), and induced apoptosis (P <0.01).

Activating Notch1 signaling in melanoma-associated fibroblasts overcomes BRAF inhibitor resistance by disrupting cancer stem cell niches. This stromal-targeted approach represents a novel therapeutic strategy to complement surgical and systemic therapies in melanoma patients with drug-resistant disease.