Background: Colorectal cancer constitutes one of the most common cancer with a high
mortality rate. The newest data has reported that activation of the pro-apoptotic PERK-dependent
Unfolded Protein Response signaling pathway by small-molecule inhibitors may constitute an innovative
anti-cancer treatment strategy.
Objective: In the presented study, we evaluated the effectiveness of the PERK-dependent Unfolded
Protein Response signaling pathway small-molecule inhibitor 42215 both on HT-29 human colon
adenocarcinoma and CCD 841 CoN normal human colon epithelial cell lines.
Methods: Cytotoxicity of the PERK inhibitor was evaluated by the resazurin-based and lactate dehydrogenase
(LDH) tests. Apoptotic cell death was measured by flow cytometry using the FITCconjugated
Annexin V to indicate apoptosis and propidium iodide to indicate necrosis as well as by
colorimetric caspase-3 assay. The effect of tested PERK inhibitor on cell cycle progression was
measured by flow cytometry using the propidium iodide staining. The level of the phosphorylated
form of the eukaryotic initiation factor 2 alpha was detected by the Western blot technique.
Results: Obtained results showed that investigated PERK inhibitor is selective only toward cancer
cells, since inhibited their viability in a dose- and time-dependent manner and induced their apoptosis
and G2/M cell cycle arrest. Furthermore, 42215 PERK inhibitor evoked significant inhibition of
eIF2α phosphorylation within HT-29 cancer cells.
Conclusion: Highly-selective PERK inhibitors may provide a ground-breaking, anti-cancer treatment
strategy via activation of the pro-apoptotic branch of the PERK-dependent Unfolded Protein
Response signaling pathway.