Augmented Therapeutic Potential of EC-Synthetic Retinoids in Caco-2 Cancer Cells Using an In Vitro Approach

Abstract

Colorectal cancer therapies have produced promising clinical responses, but tumor cells rapidly develop resistance to these drugs. It has been previously shown that EC19 and EC23, two EC-synthetic retinoids, have single-agent preclinical anticancer activity in colorectal carcinoma. Here, isobologram analysis revealed that they have synergistic cytotoxicity with retinoic acid receptor (RAR) isoform-selective agonistic retinoids such as AC261066 (RARβ2-selective agonist) and CD437 (RARγ-selective agonist) in Caco-2 cells. This synergism was confirmed by calculating the combination index (lower than 1) and the dose reduction index (higher than 1). Flow cytometry of combinatorial IC50 (the concentration causing 50% cell death) confirmed the cell cycle arrest at the SubG0-G1 phase with potentiated apoptotic and necrotic effects. The reported synergistic anticancer activity can be attributed to their ability to reduce the expression of ATP-binding cassette (ABC) transporters including P-glycoprotein (P-gp1), breast cancer resistance protein (BCRP) and multi-drug resistance-associated protein-1 (MRP1) and Heat Shock Protein 70 (Hsp70). This adds up to the apoptosis-promoting activity of EC19 and EC23, as shown by the increased Caspase-3/7 activities and DNA fragmentation leading to DNA double-strand breaks. This study sheds the light on the possible use of EC-synthetic retinoids in the rescue of multi-drug resistance in colorectal cancer using Caco-2 as a model and suggests new promising combinations between different synthetic retinoids. The current in vitro results pave the way for future studies on these compounds as possible cures for colorectal carcinoma.

Novel N -Arylmethyl-aniline/chalcone hybrids as potential VEGFR inhibitors: synthesis, biological evaluations, and molecular dynamic simulations

“…The HCT-116 cancer cell line was obtained from the tissue culture unit’s cell culture bank at the Holding company for the production of vaccines, sera, and drugs (VACSERA), Giza, Egypt, and grown, maintained, observed for growth and further assays in the Centre of Scientific Excellence "Helwan Structural Biology Research, (HSBR)" according to the previous protocol 72 , 73 . Briefly, HCT-116 cells were cultured in McCoys5a culturing media supplemented with 10% foetal bovine serum (FBS) and 1% penicillin/streptomycin at 37 °C in a humidified atmosphere containing 5% CO 2 and kept for observation until 90% confluency and being ready for splitting using 0.25% Trypsin.…”

“…Assessment for the gene expression analysis of key regulatory genes were performed using real-time quantitative PCR (RT-qPCR) as previously documented 72 , 73 . Briefly, HCT-116 cancer cells were treated with IC 50 of compounds 5e and 5h for 24 h and cells were harvested, and total RNA was extracted using Favor-PrepTM Blood/Cultured cell total RNA purification mini kit (Favorgen Biotech Corp., Ping-Tung, Taiwan).…”