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.

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 integrative 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 SwissTargetPrediction, 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 chemoresistant 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.