Multidrug resistance associated genes MRP1, MRP2 and MRP3 in primary and anthracycline exposed breast cancer.

BACKGROUND

Multidrug resistance associated proteins MRP1, MRP2 and MRP3 confer in vitro multidrug resistance. We investigated their role in breast cancer resistance to anthracycline-based chemotherapy.

MATERIALS AND METHODS

Using real-time reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC), the expression of MRP1 - 3 was quantified in nine breast cancer cell lines and 30 breast carcinoma samples.

RESULTS

MRP1 - 3 mRNA was detectable in all breast cancer cell lines and tumor samples. No increase of expression was detected between untreated carcinoma and post-neoadjuvant anthracycline treatment tumor samples. IHC failed to detect the proteins. MRP1 - 3 expression was not associated with tumor response to treatment or with outcome.

CONCLUSION

MRP1 - 3 are expressed in breast cancer cells, but are not detected with IHC. We have found no evidence linking these proteins to clinical drug resistance in a small but well-documented series of breast cancer samples.