Objective: Breast cancer is known as the most prevalent cancer among women and the second most common cancer in the world. Different studies mentioned the chemoresponsiveness potential of breast cancer among solid tumors. Though resistance against chemotherapy drugs is a major problem in cancer therapies that could lead to treatment failure. Multidrug resistance proteins (MDRs) are one of the main members of transporting protein that play a crucial role in pharmacokinetics. P-glycoprotein (P-gp) is the product of MDR1 gene, which is responsible for absorption, distribution, metabolism, excretion (ADME), and drug-drug interaction (DDI) of drugs in humans. The role of MDR1 3435C>T variation on alteration of P-glycoprotein expression and its contribution in risk of breast cancer is proven. Therefore, we decided to examine the role of 3435C>T polymorphism on breast cancer risk in Mazandaran, Iran.
Patients and Methods: A case-control study involving 196 breast cancer patients and 98 healthy subjects was conducted. Genomic DNA was isolated from the whole blood sample by a column-based method. The polymerase chain reaction/restriction fragment length polymorphism (PCR-RFLP) technique was used for genotyping of MDR1 3435C>T polymorphism.
Results: Distributions of the TT, CT, and CC genotypes of MDR1 were 34.7, 50, and 15.3%, respectively, in controls, and 32.2, 48.9, and 19% in breast cancer patients. There were no significant differences between the cases and controls.
Conclusions: Genetic polymorphism of MDR1 C3435T was not found to be associated with increased risk of breast cancer. Further studies on different larger population are needed to confirm these data.