Assessment of Gene Expression Level of ATP Binding Cassette G Member 2 Transporter in Breast Cancer Patients

Abstract

The efficacy of cancer chemotherapy is limited by cellular mechanisms of resistance that result in increased drug efflux of chemotherapeutic agents thereby reducing intracellular drug levels and causing drug resistance. Overexpression of some members of ATP binding cassette transporter superfamily, including ATP binding cassette G member 2 (ABCG2), which mediates energy-dependent transport of drugs out of the cells against concentration gradient, is one of the major mechanisms responsible for multidrug resistance in the treatment of breast cancer. In the current study, peripheral blood ABCG2 gene expression was sequentially evaluated in newly diagnosed non-metastatic breast cancer (NMBC) patients receiving adjuvant chemotherapy using quantitative real time polymerase chain reaction (qRT-PCR) at three time intervals, starting immediately after mastectomy, as well as after receiving three and six cycles of chemotherapy. A gradual significant increase in the expression of blood ABCG2 gene of NMBC patients among different treatment periods was obtained. Furthermore, a significant correlation between blood ABCG2 gene expression and disease progression during the patients’ follow-up was found. In conclusion, initial assessment of ABCG2 gene expression may be a prerequisite in evaluating the effectiveness of chemotherapy-treated breast cancer patients.