Modulation of growth and stemness in colorectal cancer cells by anticancer agents

Abstract

Background: Existing chemotherapeutic drugs are inefficient in addressing the rising incidences of recurrent colorectal cancer (CRC). Cancer stem cells are a tumour subset population underlying CRC recurrence. To combat recurrent CRC, novel therapeutic strategies involving the discovery of novel anticancer drugs targeting cancer stem cells are urgently required. We therefore evaluated anticancer activity of novel series of synthetic tetrazole dithiocarbamate derivatives (TDTCs) in CRC cells and explored their modulatory anticancer effects on CRC stem cell biomarkers. Methods: Anticancer activity of ten novel TDTCs were assessed by an initial qualitative screening using Alamar Blue, followed by a quantitative cell death counting using Trypan blue; and the inhibitory concentrations (IC50) were determined in HT29 and DLD1 CRC cells. CRC cells were monitored for their growth response to tested TDTCs using the Muse cell cycle assay and the xCelligence real time cell analyser. The CRC stem cells were studied for their ability to form spheroids in response to the TDTCs using real time microscopy imaging. The effect of the active TDTCs on CRC stem cell markers was evaluated using a proteome profiler assay and real time PCR Results: TDTC1, 2, 4 and 5 were found to be the most active compounds (IC50<0.1 to 0.4mg/ml) among the tested TDTCs against CRC cells. Active TDTCs induced cell cycle arrest in different phases in HT29 and DLD1 cells. Active TDTCs targeted exponential and stationary growth phases in treated CRC cells. TDTCs also prevented spheroid formation in HT29 stem cells. Active TDTCs upregulated E-cadherin, and Sox17, and downregulated β-catenin, VEGF1, VEGFR1 and FoxA2 in CRC stem cells. Conclusion: Active TDTCs were potent anticancer agents as evident by the present study and warrant further in vivo validation.