Prostate adenocarcinoma (PRAD) poses a significant challenge due to therapy resistance and an immunosuppressive tumor microenvironment (TME). Ferroptosis has emerged as a therapeutic vulnerability, yet its immunomodulatory role in PRAD remains elusive. Here, we employed a multi-omics approach—integrating bulk RNA-seq (498 tumors), single-cell RNA-seq (68,322 cells), and spatial transcriptomics (19,483 spots)—to decode the ferroptosis-immune landscape. We derived a robust 16-gene ferroptosis signature that predicted biochemical recurrence (C-index = 0.76) and validated it in two independent cohorts. Crucially, high-risk tumors exhibited a “cold” immunosuppressive TME enriched in regulatory T cells and M2 macrophages, alongside elevated immune checkpoints (HAVCR2, CTLA4, PDCD1). Single-cell and virtual knockout analyses revealed that cancer epithelial cells evade ferroptosis via NFE2L2-associated antioxidant defenses, which strongly correlates with immune exclusion. Spatial transcriptomics further demonstrated spatially organized vulnerabilities, with ferroptosis-resistant tumor cores and immune-infiltrated invasive margins. To identify therapeutic interventions, we utilized drug response modeling and molecular docking, prioritizing RSL3, Atovaquone (targeting NOX4 (NADPH oxidase 4)/DHODH), and Sorafenib (targeting TrxR1 (thioredoxin reductase 1, encoded by TXNRD1)) as potent agents with potential ferroptosis-modulatory activity. Collectively, our findings demonstrate that NFE2L2-associated ferroptosis resistance shapes immune evasion in PRAD. Targeting ferroptosis regulators provides a compelling therapeutic rationale to remodel the TME and synergize with immune checkpoint blockade.

Nicotinamide adenine dinucleotide (NAD⁺) serves as a critical cofactor in redox reactions and metabolic transformations catalyzed by NAD-dependent enzymes and is essential for bacterial survival and virulence. The biosynthesis of NAD⁺ in the cariogenic pathogen Streptococcus Sobrinus (S. sobrinus), a pivotal participant in oral cavities of children and adolescents with a history of caries, has yet to be explored. Bioinformatics, genetics, and biochemical techniques were used to identify NAD⁺ biosynthesis pathways and corresponding regulator in S. Sobrinus. S. sobrinus lacks de novo NAD⁺ synthesis pathway but comprises NA and Nam salvage pathway I (PncA-PncB-NadD-NadE) and PnuC-NadR salvage pathway III. NiaY and PnuC were involved in the salvage pathways. N-terminal domain of SsNrtR regulator was identified as DNA-binding domain binding to the pnuC and pncB probe, and addition of ADP-ribose reversed the binding of SsNrtR to the target promoters to regulate NAD⁺ salvage pathways. C-terminal domain of SsNrtR was non-catalytic, consistent with loss of Nudix motif conservation. Furthermore, the abrogation of niaR compromised multiple pathogenic traits, including cellular proliferation, acidogenesis, and the architecture/mechanical integrity of biofilms. Consequently, this mutant exhibited attenuated virulence in a rat caries model. Our findings conclusively demonstrate that SsNrtR-mediated regulation of NAD⁺ homeostasis is a critical determinant of the cariogenic potential of S. sobrinus. This study identifies SsNrtR as a previously uncharacterized NAD⁺-responsive regulator that integrates metabolic homeostasis with the control of virulence in Streptococcus sobrinus. These findings elucidate a novel metabolic–virulence regulatory axis in this species and position SsNrtR as a promising target for the development of anti-caries interventions.