Abstract 5880: Induction of the p-glycoprotein with atorvastatin using colorectal cancer cells

Abstract

Abstract Chemotherapy resistance is responsible for a majority of the cancer-associated mortalities. Efflux of the P-glycoprotein (P-gp) transporter is one of the many causes for chemotherapy resistance. The increased activity of the P-gp on the surface of the tumor cells leads to the removal chemotherapy drugs and allows a cancer to survive. The purpose of this study was to evaluate how atorvastatin impacts the P-gp expression in colorectal cancer cells. The colorectal cells, CACO2 cell line, were separated into drug treatment groups. The experimental groups were treated with the statin drug, atorvastatin, at different concentrations and doxorubicin as the positive control, for 3-4 months. Atorvastatin was selected for the study since it is a P-gp substrate and a potential inducer. Exon-spanning primers for the ABCB1 gene were used to monitor changes in mRNA expression of the P-gp. Once overexpression of the ABCB1 gene was achieved, the cells were tested for protein expression through western blots and flow cytometry. The P-pg-induced cells, which consisted of the atorvastatin-treated and doxorubicin-treated cells, and the untreated cells were then tested for chemotherapy-resistance using the PrestoBlue proliferation assay. The atorvastatin treatments were repeated for reproducibility by using two other colorectal cancer cell lines. The P-pg-induced cells, which consisted of the atorvastatin-treated and doxorubicin-treated cells, and the untreated cells were also studied for stability by removing the treatments of the atorvastatin for three months and monitoring for changes in expression of the ABCB1 gene with rt-qPCR. Drug pathways of the treated cells were also studied for expression changes using RNA Sequencing (RNA-Seq). For the results, the overexpression of the ABCB1 gene occurred in the 4th month of the study of the bi-weekly atorvastatin and doxorubicin treatments using the CACO2 cells. Protein assays were able to confirm the P-gp overexpression in the atorvastatin-treated and doxorubicin-treated cells. The chemotherapy-resistant assay revealed that the atorvastatin-treated cells were just as drug resistant to the chemotherapy as the doxorubicin-treated cells. Through the reproducibility experiment, the overexpression of the ABCB1 gene was observed in two other cell lines after long-term treatment of the drug therapy. Removal of the atorvastatin for three months revealed that the P-gp overexpression was not reversible. The RNA-Seq analysis identified other possible drug resistant markers in the atorvastatin pathway. This study implicates that late-stage cancer patients, who are treated for hypercholesterolemia, may be at higher risk for developing chemotherapy-resistant tumor cells. With the identification of chemotherapy-resistant tumors in chemotherapy-naïve cancer patients, doctors will be able to provide more precise approaches to treating patients through effective drug therapies. Citation Format: Christopher L. Farrell, Amy Messersmith, Wei Lei, Brianna Dyer. Induction of the p-glycoprotein with atorvastatin using colorectal cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5880.