Targeting Ion Channel Dysregulation in Colorectal Cancer: Identification of Clofilium as a Potent Inhibitor of Tumor Growth and Metastatic Potential

Colorectal cancer (CRC) accounts for the second-highest number of cancer-related deaths in the United States. Targeting colon cancer channelopathies that drive proliferation and metastasis has recently emerged as a new strategy towards developing ionoceutical therapeutics. We used existing RNA seq data to compare non-cancerous colon tissue to both primary CRC samples and the colon cancer cell line COLO 205 and found many shared upregulated ion channel genes. We produced several stable cell lines with fluorescent reporters to enable our screen of 19 compounds that target the products of those genes. Nine compounds were found to reduce COLO 205 proliferation, most showing cytostatic effects. FUCCI cell cycle analysis revealed that the cytostatic concentrations increased the proportions of cells in the G0/G1 phase. COLO 205 spheroids exhibited differential responses to the compounds as compared to 2D but all compounds significantly reduced spheroid migration, invasion or both. Analysis of cytotoxic effects in three non-cancerous cell types identified clofilium (IC50 3.314 μM) as the leading candidate. Western blot analysis showed that clofilium decreased key cancer growth pathways and induced a strong upregulation of NDRG1 activity. A xenograft COLO 205 mouse model showed that clofilium treatment significantly reduced tumor volume without signs of overt toxicity.