Peroxiredoxin 1 as a novel pyroptosis inducer in colorectal cancer: Insights and future directions.

TO THE EDITOR
We highly appreciate the study published by He et al[1]. This study is both scientific and innovative in the field of colorectal cancer (CRC). The paired “tumor-adjacent” sample design across 60 cases effectively minimized confounding effects from individual variability, thereby strengthening the clinical evidence linking peroxiredoxin 1 (Prdx1) to CRC. Moreover, Prdx1 was found to be associated with the NOD-like receptor thermal protein domain associated protein 3 (NLRP3)/caspase-1/gasdermin D (GSDMD)-mediated pyroptosis pathway. Notably, the selective anti-tumor activity of recombinant Prdx1 (rPrdx1) was further validated through both in vitro and in vivo experiments, suggesting its potential as a novel candidate molecule for targeted therapy in CRC[1]. Here, we would like to share additional insights, unresolved questions, and potential research directions to further extend the significance of this work, which we believe will facilitate its clinical translation and mechanism refinement.

CELLULAR FUNCTIONS AND EXPRESSION OF PRDX1 IN CANCER
The authors’ conclusion that Prdx1 is significantly overexpressed in CRC was firmly established by leveraging a rigorous paired-sample design (n = 60). This internal control reliably minimized patient-to-patient variability, demonstrating a substantial increase in Prdx1 levels in CRC tissues and thereby underscoring its dysregulation[1].
Prdx1 is a cytosolic antioxidant enzyme that detoxifies hydrogen peroxide and other reactive oxygen species (ROS) via a thioredoxin-dependent reduction mechanism, thereby maintaining intracellular redox homeostasis[2]. Consistent with previous findings, Chu et al[3] and Zhang et al[4] have both reported elevated Prdx1 expression in CRC, with Chu et al[3] further associating its high levels in 80 tumor samples with advanced tumor stage, lymph node metastasis, and poor prognosis. Notably, another study revealed that Prdx1 was upregulated in tumor cells to scavenge 5-fluorouracil (5-FU)-induced ROS, thereby inhibiting tumor cell apoptosis and ultimately promoting 5-FU resistance in CRC[5]. However, a paradox emerges between the pro-tumor role of endogenous Prdx1 and the anti-tumor effect of exogenous rPrdx1. We propose that this “Janus-faced” nature is likely attributed to distinct subcellular localizations, where intracellular Prdx1 functions as an antioxidant while extracellular forms act as damage-associated molecular patterns to trigger immunity. Additionally, the supraphysiological concentrations of rPrdx1 might activate signaling thresholds distinct from physiological levels. Furthermore, structural differences may be critical. The hypoxic and acidic tumor microenvironment likely induces aberrant post-translational modifications in endogenous Prdx1, whereas purified rPrdx1 may retain the optimal conformation necessary to activate the NLRP3 pathway.

RPRDX1 AS A NOVEL ACTIVATOR OF NLRP3/GSDMD-MEDIATED PYROPTOSIS
The groundbreaking work by He et al[1] established rPrdx1 as a novel activator of the NLRP3/GSDMD pyroptosis pathway in CRC. This pathway, central to the execution of pyroptosis, is triggered by inflammasome assembly leading to caspase-1 activation, which cleaves GSDMD to cause cell membrane permeabilization and the release of pro-inflammatory cytokines like interleukin (IL)-1β and IL-18[6,7]. Previous studies demonstrated that rPrdx1 directly activated the NLRP3/GSDMD pathway, which induced pyroptotic death in CRC cells and enhanced oxaliplatin chemosensitivity. In combination therapy groups, the tumor inhibition rate increased by over 40%, providing a new molecular strategy for targeted therapy in CRC[8]. To rigorously validate this dependency and rule out other potential pyroptosis-executing proteins, it would be beneficial to employ reverse verification strategies by using gene knockout, antibody blockade, or small molecule inhibitors to confirm the specific interaction between rPrdx1 and the NLRP3 inflammasome.
Beyond direct tumor cell lysis, the therapeutic significance of this mechanism is amplified by the established role of GSDMD-mediated pyroptosis in anti-tumor immunity. This form of cell death was known to recruit cluster of differentiation (CD) 8+ T cells and reverse the immunosuppressive tumor microenvironment[9]. Another study pointed out that molecules targeting the pyroptosis pathway have the dual advantages of “direct lysis of tumor cells” and “activation of adaptive immunity”, and the inflammatory microenvironment remodeling induced by them can break the immunosuppressive state, which was an ideal synergistic partner for combined immunotherapy, potentially involving targets like LILRB4[10,11]. He et al[1] were the first to confirm that rPrdx1 elicited this comprehensive pyroptosis activation effect. The translational potential of rPrdx1 was strongly supported by robust in vivo efficacy and a preliminary safety profile, as the treatment of rPrdx1 significantly suppressed tumor growth in xenograft models without apparent toxicity[1]. These findings not only support its development as an anti-tumor agent but also pave the way for utilizing Prdx1/GSDMD co-expression as a predictive biomarker to identify patients for personalized pyroptosis-targeting therapies.

PROSPECTS OF CLINICAL TRANSLATION BASED ON ORIGINAL RESEARCH
Given the capacity of rPrdx1 to induce pyroptosis and its potential to enhance tumor immunogenicity[9], exploring its combination with existing CRC therapies is highly recommended. A promising avenue involves combining it with anti-programmed cell death 1 (PD-1) immunotherapy, which could be evaluated by assessing the enhanced inhibitory effect of the combination (rPrdx1 + anti-PD-1) on cancer cells and the release of IL-1β and IL-18 in vitro, followed by verifying the synergistic effect in a mouse model through comparisons of tumor volume, intratumoral CD8+ T cell infiltration, and PD-1/programmed cell death ligand 1 expression. Crucially, since protein therapeutics often face off-target challenges and the NLRP3 pathway is involved in systemic inflammation, systemic administration of rPrdx1 carries risks of off-target adverse effects. Therefore, future preclinical evaluations are needed to optimize the safety profile by comparing administration routes, refining formulations, and developing novel protein delivery systems to restrict pyroptosis induction strictly to the tumor site.
Beyond immunotherapy, the combination of rPrdx1 with chemotherapeutic agents such as capecitabine and oxaliplatin also holds significant promise. Investigating the impact of rPrdx1 on the half maximal inhibitory concentration values of these drugs could evaluate a potential pyroptosis-mediated chemosensitization effect, thereby offering a novel combination strategy for patients with advanced disease[10].
To further substantiate the translational relevance of these findings, it would be valuable to employ clinical specimens for establishing patient-derived organoid co-culture models or patient-derived xenograft models in subsequent studies[12,13]. Advanced three-dimensional models may serve as more physiologically representative platforms for validating the efficacy of rPrdx1, thereby bridging the gap between experimental data and clinical application.

CONCLUSION
In conclusion, He et al’s study[1], based on 60 pairs of clinical samples, is the first to systematically confirm Prdx1’s anti-tumor effect via activating the NLRP3/GSDMD pathway to induce CRC cell pyroptosis. The innovations lie in its strengthened clinical association evidence through the use of paired samples, along with an expansion of mechanistic research linking Prdx1 to the classical pyroptosis pathway. Subsequent studies focusing on Prdx1/GSDMD co-expression markers and rPrdx1-based combination therapy are expected to further validate their clinical value and promote individualized CRC treatment.