IGFBP-3 enhances irinotecan efficacy in colorectal cancer via ROS-mediated apoptosis and β-catenin suppression

Colorectal cancer, a leading cause of mortality, is treated with surgery early and irinotecan (IRI) chemotherapy in advanced stages. Insulin-like growth factor-binding protein 3 (IGFBP-3), regulated by p53, mediates tumor suppression and apoptosis. This study evaluates the combined therapeutic effects of IGFBP-3 and IRI in colorectal cancer.

SW480 colorectal cancer cells were treated with IGFBP-3, IRI, and their combination; IC₅₀ values were determined by MTT assay, and combination effects were analyzed by CompuSyn. Oxidative stress markers, apoptosis, and cell cycle progression were assessed utilizing flow cytometry. Furthermore, caspase 3/7 activity was measured, and expression levels of Bax, Bcl2, and β-catenin were determined using RT-PCR.

The MTT assay revealed IC₅₀ of 8.4 μM for IRI and 43.03 nM for IGFBP-3, with CompuSyn confirming synergistic interaction (CI < 1). Compared to single agents, the combination treatment significantly enhanced apoptosis, induced greater G₂/M cell cycle arrest, and markedly increased levels of ROS, MDA, and protein carbonyls while significantly depleting GSH. At the molecular level, the combination synergistically upregulated pro-apoptotic Bax and downregulated anti-apoptotic Bcl2 and oncogenic β-catenin.

Our results indicated that IRI and IGFBP-3 show cytotoxicity, with IGFBP-3 enhancing IRI effect by inhibiting Wnt/β-catenin and increasing drug uptake, warranting assessment in normal cells.