The role of alpha 7 nicotinic acetylcholine receptors gene suppression by small interfering RNA (siRNA) on drug resistance to oxaliplatin in colorectal cancer cell line

Abstract

Colorectal cancer (CRC) is one of the most common cancers in the world, affecting nearly 1.2 million people annually, resulting in the death of approximately 700,000 patients with this cancer worldwide. Oxaliplatin (OXA) is one of the chemotherapy drugs used in this cancer. On the other hand, the alpha-7 receptor for nicotine acetylcholine, or α7nAchR, is one of the components of the nicotine receptor family, which is important in different types of cancers and the resistance to chemical agents. The role of α7nAchR expression in CRC progression, especially in drug-resistant cells, has not yet been identified. Therefore, this study was designed and performed to evaluate the effect of suppression of α7nAchR by siRNA in combination with oxaliplatin in drug-resistant SW-480 cells. Methods: OXA-resistant SW-480 cells were produced. Then, electroporation method was used to transfer siRNA to cells to inhibit α7nAchR expression. Cells were treated with OXA after transfection. IC50 OXA and the combination of α7nAchR siRNA and OXA on the survival of resistant cells were determined using MTT assay. QRT-PCR was used to evaluate the expression of α7nAchR, MDR-1, BCL-2, and Caspase-3 genes. Results: The results showed that suppression of α7nAchR expression could cause sensitization in oxaliplatin-resistant SW-480 cells. This study also showed a significant reduction in α7nAchR mRNA expression when siRNA and OXA are used simultaneously in resistant cells. Decreased expression of MDR-1 and BCL-2 genes was also observed along with increased expression of Caspase-3 gene following transfection with a7-siRNA.