Induction of Continuous Expression of Cyclooxygenase -2 in Human Breast Cancer Cell Line Using COX-2 cDNA Plasmid Transfection

Background and One of the major problems in chemotherapy is resistance to anti-cancer drugs. Recent studies have demonstrated a relationship between cyclooxygenase-2 (COX-2) expression and progression of multidrug resistance (MDR). One of the proteins involved in drug resistance is ABCG2 (ATP-binding cassette sub-family G member 2) that is often overexpressed in patients with cancer. This study was performed to develop the MCF7 and MCF7/MX human breast cancer cell line which continuously expressed COX-2 in order to evaluate the effect of induction of COX-2 expression on ABCG2 expression.
For this purpose, a plasmid containing the sequence of cyclooxygenase-2 was cloned in E. coli. The purified plasmid was then transferred into the MCF7 and MCF7/MX cell lines by transfection process. Finally, the protein content of transfected cells were extracted and analyzed by Western blotting. The COX-2 expression was compared between transfected cells.
The results showed that COX-2 protein levels were the highest in MCF7 cells transfected with a DNA and Fusion 6 ratio of 3:1 and the medium containing genticine added after 24 hours. Also, compared to the control cell line, in MCF7/MX cells the expression of COX-2 gene increased in transfected cells with a DNA and Fusion 6 ratio of 3:2 (P In fact, the level of target gene expression may vary based on the cell line and culture conditions. Increase in the amount of DNA does not necessarily lead to increase in transfection efficiency.