Riboceine and N-acetylcysteine protect normal prostate cells from chemotherapy-induced oxidative stress while selectively modulating the cytotoxicity of methotrexate and docetaxel in prostate (PC-3) and breast cancer (MCF-7) cells

Abstract

Background: Cancer chemotherapy often results in severe side effects due to its non-selective cytotoxicity toward rapidly dividing normal cells. These adverse effects are largely driven by oxidative stress resulting from elevated reactive oxygen species (ROS) production. Riboceine (RIB), a synthetic precursor of glutathione (GSH), and N- acetylcysteine (NAC), a clinically used antioxidant, hold promise in mitigating oxidative damage; however, their impact on chemotherapy efficacy and the molecular mechanisms involved remain incompletely understood. Aim: This study aimed to evaluate the cytoprotective potential of RIB and NAC against methotrexate (MET)- and docetaxel (DOC)-induced toxicity in normal and cancer cells, and to explore mechanistic pathways using inte grative network pharmacology and molecular docking approaches. Methodology: Cytotoxic effects of MET and DOC, alone or in combination with RIB or NAC, were assessed in normal prostate epithelial (PNT-2), prostate cancer (PC3), and breast cancer (MCF-7) cell lines using the Resazurin assay. Intracellular ROS and GSH levels were quantified using DCF and OPA fluorescence assays, respectively. Network pharmacology, protein–protein interaction (PPI) analysis, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment, and molecular docking were conducted using Swis sTargetPrediction, STRING, ShinyGO, Cytoscape, and AutoDock Vina platforms. Results: MET and DOC showed dose-dependent cytotoxicity in PNT-2 and PC3 cells, but limited efficacy in chemo resistant MCF-7 cells. RIB and NAC significantly reduced ROS and restored GSH levels in PNT-2 cells, protecting them against oxidative injury. These antioxidants preserved anticancer effects in PC3 cells but reduced chemotherapy efficacy in MCF-7 cells, likely due to elevated redox buffering and transporter expression. Network analyses identified BCL-2, MAPK8, and SOD among key antioxidant and apoptotic targets. However, no direct experimental validation of these mechanisms was performed, and apoptotic markers such as Annexin V or caspase-3 were not assessed. Conclusion: RIB and NAC provide selective cytoprotection to normal prostate cells during chemotherapy while maintaining anticancer effects in sensitive prostate cancer cells. However, their concurrent use in resistant cancers like MCF-7 may reduce drug efficacy, warranting cautious clinical application. Time-shifted antioxidant administration (e.g., post-chemotherapy) could be explored as a strategy to balance protection and efficacy. Future studies should include in vivo validation, apoptosis profiling, and protein-level mechanistic assays to confirm the predicted pathways.