Recombinant expression of cytochrome P450-2D6 and its application in tamoxifen metabolism

Abstract

Breast cancer is regarded as the most common form of cancer in women and it comprises of approximately 23 % of female cancers, while affecting women at any age range. For oestrogen receptor positive patients, tamoxifen is used as a prescribed medication for breast cancer therapy. However, tamoxifen in its natural form is not active to achieve the required treatment and prevention of breast cells proliferation. Since tamoxifen is a prodrug, it need to be converted into its active form, endoxifen, for which it is achieved by the action of the cytochrome P450 enzymes. Cytochrome P450 2D6 (CYP2D6) is a member of cytochrome P450 enzymes for which are superfamily of heme enzymes characterised by their ability to catalyse the oxidative reactions of compounds, including the pathway of tamoxifen metabolism. However, due to polymorphism that lead to inactive phenotypes of CYP2D6 in this gene, there is a challenge of diagnosing if a patient can metabolise tamoxifen or not. The current diagnostic tool, Amplichip CYP450, for CYP2D6 is based on genotypes, and it lead to uncertainness as to whether the presence of functionalCYP2D6 alleles of CYP2D6 may lead to coding of active protein, thus leading to wrong treatment measures and overdose of tamoxifen. Electrochemical techniques have provided reliable, simple, quick, and sensitive methods for the determination of drug metabolism by enzymes. Therefore, it is important to develop a CYP2D6 phenotype-based sensor to detect and tell whether a particular individual can metabolise the drug or not.