To ensure
in vivo safety, we administered IRONKILL at an FMT concentration of 50 μg/mL, which showed low toxicity in both cancer and normal cells (
Figure S3). For subsequent experiments, we selected cancer and normal cell pairs, including 4T1, LLC, and Hepa1-6, and their normal counterparts, NMuMG, MLE-15, and AML-12. Evaluation of the gene interference efficiency of IRONKILL indicated significant decreases in
GBA mRNA and protein levels, and consequently GBA activity in cancer cells; moreover, FMT did not interfere with DMP-miGBA or DGDFi-mediated gene knockdown (
Figure 1D–F).
GBA inhibition resulted in excessive accumulation of the GlcCer substrate in lysosomes, thereby inducing lysosomal damage (increased Galectin-3-positive cells, decreasing LysoTracker fluorescence, and elevating
Lamp1/
Lamp2 expression); these findings together suggested compromised lysosomal iron storage (
Figures 1G, H and S4, S5). Subsequently, measurement of intracellular Fe
2+ levels revealed that
GBA knockdown triggered substantial Fe
2+ release in cancer cells (
Figure 1I). Notably, lysosomal damage was prevented in normal cells, because
GBA remained unaffected, given the cells’ low p-p65 levels (
Figures 1C–I and S2, S4 and S5). Additionally, DMP-FPN or DGDFi-mediated
FPN knockdown significantly suppressed
FPN mRNA and protein expression, and further increased intracellular Fe
2+ levels, in cancer cells, whereas normal cells remained unaffected (
Figure 1J–L). Importantly, FMT supplementation did not interfere with IRONKILL-mediated
FPN knockdown and further elevated Fe
2+ levels in cancer cells (
Figure 1J–L). These findings demonstrated that IRONKILL selectively modulated iron metabolism in cancer cells and led to a substantial increase in Fe
2+ content.