The effect of anthocyanin on the biological behaviour of colorectal cancer

Surgery, radiotherapy, and chemotherapy are standard treatment methods for colorectal cancer. These treatment methods can be applied alone or in combination depending on the type, stage, molecular characteristics of the cancer and the patient's condition. Chemotherapeutic treatments are classified as cytotoxic agents and biologic agents. Thus, they target various biological and biochemical pathways such as cell proliferation, apoptosis or metastasis. However, cancer patients may show resistance to this treatment. Increase in the expression of carrier proteins such as ATP-binding cassette proteins, increase in DNA repair mechanisms, inhibition of apoptosis and increase in EMT can be shown among the main causes of drug resistance to treatment. Few studies in the literature have shown that in colorectal cancer, the increased amount of ROS induces EMT, and the cell develops drug resistance. The aim of this study is to investigate the inhibition of the effect of the increase in ROS caused by the chemotherapeutic resistance to oxaliplatin in the colorectal cancer HCT-116 cell line on the EMT formation process by cyanidin-3-O-glycoside, which has anti-oxidant and anti-cancer properties. For the drug resistance development assay, cells were exposed to increasing doses of oxaliplatin. The resistance development experiment was terminated at the dose where the proliferation rate of the cells was higher than the death rate at the applied dose. The increased amount of ROS in resistant cells was determined by ROS Detection Assay Kit, EMT biomarkers were determined by qRT-PCR method and immunofluorescence staining method, their migratory properties were determined by wound healing method, and decreased sensitivity to the drug in resistant cells was determined by WST-1 proliferation agent. After the development of oxaliplatin resistance, characterization experiments were performed to prove that drug resistance developed between HCT-116 and HCT-116-ROx. The migratory feature of the resistant cell, vimentin and N-cadherin amounts were found to be higher than the parent cell. The amount of intracellular ROS was decreased in both resistant and C3G-treated resistant cells. At the same time, the sensitivity of resistant cells to oxaliplatin is decreased. In the experimental phase, the migration feature of resistant cells treated with C3G decreased, the amount of epithelial biomarker E-cadherin increased, and the amount of vimentin and N-cadherin decreased. In conclusion, we showed that drug resistance against oxaliplatin can develop via the EMT pathway without being directly related to ROS. We also demonstrated the usability of C3G as a molecule that can prevent drug resistance by reversing the EMT process.