PRX5 as a critical driver of colorectal cancer stemness and tumorigenicity.

PRX5 appears to significantly influence colorectal cancer stem cell characteristics and tumor growth in rodent models, but further research is needed to determine its relevance in human cancers.

Summary and findings

This study investigated the role of peroxiredoxin 5 (PRX5) in colorectal cancer stem cells (CSCs) using HCT116 models. PRX5 expression was manipulated through gene disruption and overexpression, and various assays were conducted to assess its impact on tumorigenicity. The findings indicated that PRX5 influences CSC characteristics and tumor growth.

Abstract

<h4>Background</h4>Cancer stem cells (CSCs) support colorectal cancer progression and therapy resistance, yet the redox regulators that sustain CSC identity are incompletely defined. We investigated the role of peroxiredoxin 5 (PRX5) in CSC formation and tumorigenicity using HCT116 colorectal cancer models.<h4>Methods</h4>CSCs were enriched by serum-free spheroid culture and characterized by qPCR and western blotting for pluripotency and surface markers. PRX5 expression was regulated via siRNA or shRNA gene disruption and overexpression. Intracellular ROS was measured with DCF-DA staining. STAT3 activation was analyzed by <i>p</i>-STAT3 immunoblot. Functional assays included sphere formation, extreme limiting dilution analysis (ELDA), colony formation, and <i>in vivo</i> xenograft tumorigenicity in BALB/c-nu mice.<h4>Results</h4>Spheroid induction selectively upregulated PRX5 among PRX isoforms. Efficient PRX5 knockdown (>95%) reduced OCT4, SOX2, NANOG, and CD133 expression, increased intracellular ROS, lowered <i>p</i>-STAT3 levels, and decreased sphere-forming frequency. Conversely, PRX5 overexpression enhanced pluripotency marker expression and proliferation. <i>In vivo</i>, PRX5-overexpressing xenografts grew faster, achieving a 2.5-fold greater tumor volume by day 19 and a 1.82-fold higher mean tumor weight compared with controls. Tumor tissues showed elevated OCT4, SOX2, NANOG, CD133, and EPCAM.<h4>Conclusion</h4>PRX5 contributes to maintaining a redox environment associated with STAT3 activation and core stemness programs in CRC, promoting CSC phenotypes and tumorigenicity. Targeting PRX5-mediated redox signaling may warrant further investigation as a potential approach to disrupt CSC maintenance and overcome chemoresistance.