Small-molecule inhibitors of the PERK-mediated Unfolded Protein Response signaling pathway in targeted therapy for colorectal cancer

Introduction: The newest data has reported that endoplasmic reticulum (ER) stress and PERK-dependent Unfolded Protein Response (UPR) signaling pathway may constitute a key factor in colorectal cancer (CRC) pathogenesis on the molecular level. Nowadays used anti-cancer treatment strategies are still insufficient, since patients suffer from various side effects that are directly evoked via therapeutic agents characterized by non-specific action in normal and cancer cells. Aim: Thereby, the main aim of the presented research was to analyze the effectiveness of the small-molecule PERK inhibitor NCI 12487 in an in vitro cellular model of CRC. Materials and methods: The study was performed on colorectal cancer HT-29 and normal human colon epithelial CCD 841 CoN cell lines. The cytotoxicity was measured by XTT assay, evaluation of apoptosis was performed by caspase-3 assay, whereas cell cycle analysis via the propidium iodide (PI) staining. Results: Results obtained have demonstrated that the investigated compound is selective only for HT-29 cancer cells, since at 25 mu M concentration it significantly decreased HT-29 cells viability in a dose- and time-dependent manner, evoked increased caspase-3 activity and arrest in the G2/M phase of the cell cycle. Moreover, NCI 12487 compound markedly decreased HT-29 cells viability, increased caspase-3 activity and percentage of cells in sub-G0/G1, thus promoted apoptosis of cancer HT-29 cells with induced ER stress conditions. Conclusion: Thus, based on the results obtained in this study it may be concluded that small-molecule modulators of the PERK-dependent UPR signaling pathway may constitute an innovative, targeted treatment strategy against CRC.