Abstract
A major problem in the treatment of breast cancer is the development of resistance to chemotherapeutic agents. Although the role of multidrug resistance 1 (MDR1) and multidrug resistance associated protein 1 (MRP1) in inducing drug resistance in many cancers has been widely investigated the clinical significance of expression of these genes in breast cancer remains unclear and the data is still controversial. We investigated the expression of MDR1 and MRP1 in breast cancer patients as well as the possible correlation between MDR1 and MRP1 and clinical response to chemotherapy. In the present study, MDR1 and MRP1 gene expression were investigated by real time reverse transcription polymerase chain reaction (RT-PCR) assay in 54 breast cancer tumors and in corresponding adjacent normal tissues before neoadjuvant chemotherapy. The expression level of MDR1 and MRP1 were significantly higher in breast tumors than normal breast tissues. Although a significant relationship was found between the MRP1 expression and response to treatment no association was observed between MDR1 expression and response to treatment. MDR1 and MRP1 expression levels have been shown to be independent of tumor size, histological grade and the status of progesterone or estrogen receptor.
Highlights
Resistance to chemotherapy limits the effectiveness of anti neoplastic treatments
Neoadjuvant chemotherapy is an approach in the management of locally advanced breast cancer
Despite the advances in therapeutic methods about 40–50% of patients will eventually die from the disease [14]
Summary
Resistance to chemotherapy limits the effectiveness of anti neoplastic treatments. Even though breast cancer is one of the sensitive tumors to chemotherapy many of them become multidrug resistance [2]. Neoadjuvant chemotherapy is an approach in the management of locally advanced breast cancer. It gives benefit in the operable breast cancers by increasing the chances of breast conservation. About 70% of patients demonstrate a clinical response and merely 3%–27% achieve a complete histopathologic response (3). Roughly 30% of the patients received neoadjuvant chemotherapy are no responsive to this treatment and suffer from the side effects. The patients achieving a complete pathologic response after neoadjuvant chemotherapy have significantly longer disease-free overall and overall survival than nonresponders (3). In any clinical practice it would be very important and beneficial for each patient
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